ALK2 Manipulation Increases Bone Formation in Fat-Based Stem Cells


Mesenchymal stem cells possess a cell-surface protein called ALK2. ALK2 acts as a receptor for bone-inducing growth factors. ALK2, for example, is expressed in cartilage and if mesenchymal stem cells express a constantly-active form of ALK2, known as caALK2, these cells are driven to become cartilage-making cells (known as chondrocytes).

Can this receptor be used to drive bone formation? It turns out that manipulating ALK2 can drive fat-based stem cells (ASCs) to become bone making cells that ultimately improve bone tissue engineering. Researchers from the laboratory of Benjamin Levi at Massachusetts General Hospital, Boston, Massachusetts have fiddled with ALK2 in mesenchymal stem cells to for formation of bone from ASCs, and to enhance bone regeneration in a living animal.

To do this, Levi’s team genetically manipulated mice so that they expressed a form of ALK2 that was constantly turned on known as caALK2. The fat-based MSCs were then isolated and analyzed for their ability to make bone in culture. caALK ASCs were much more responsive to bone-inducing growth factors. These cells also expressed a whole host of bone-specific genes (e.g., Alp, Runx2, Ocn, Ops) after seven days. Since the caALK2 MSCs did so well in culture, they were then tested in mice with skull defects. Bone formation was significantly higher in mice treated with caALK2-expressing ASCs than those treated with normal ASCs.

Thus, Levi’s laboratory has shown that by treating mice with fat-based stem cells that express a constitutively active ALK2 receptor showed significantly increased bone formation. This increased bone formation can also be harnessed to improve skull healing in mice with bone defects.

Mesenchymal Stem Cells Assist Kidney Transplants in Cats


Dr. Chad Schmiedt, a veterinary surgeon from the University of Georgia (UGA) Veterinary Teaching Hospital, and his colleagues have used mesenchymal stem cells from the fat of cats to optimize the acceptance of a new kidney in cats.

The recipient of this kidney transplant was a four-year-old flame point Siamese male cat named Arthur. Arthur’s owners brought him from Virginia to the University of Georgia after he was diagnosed with chronic renal failure about a year ago. Two other veterinary hospitals declined to operate on Arthur, since they did not deem this cat an optimal candidate for a kidney transplant. As it turns out, Arthur has trouble absorbing cyclosporine, which is the anti-rejection drug used to prevent the recipient of the kidney transplant from rejecting it.

Arthur
Arthur

In his initial consultation with Arthur’s owners, Schmiedt had the idea of using adult feline stem cells as a part of Arthur’s immunosuppressive protocol. There was precedent for this, since a cat that was operated on at University of Georgia Veterinary Teaching Hospital in 2013 had received a kidney transplant with doses of its own mesenchymal stem cells to prevent rejection of the transplanted organ. This cat was doing well one year after surgery.

“To the best of my knowledge, UGA is the only veterinary facility in the world to use adult stem cells in feline kidney transplantation,” said Schmiedt, who actually heads UGA’s feline kidney transplant program.”

Schmiedt continued: “We used feline adult stem cells in one other transplant that we did last year. A study published in 2012 found that the use of MSCs during renal transplant surgery i humans lowered the risk of acute organ rejection, decreased the risk of infection, and the patients had better estimated renal function one year after surgery.”

Mesenchymal stem cells can be harvested fat, bone marrow, and umbilical cord or placenta. Before the transplant surgery, Schmiedt isolated mesenchymal stem cells (MSCs) from Arthur’s fat and the UGA Regenerative Medicine Service grew the stem cells from the fat sample for use in Arthur after his surgery.

Arthur has his kidney transplant on May 15, 2014. The first surgery harvests a kidney from the donor cat (named Joey) and the second surgery transplants the donated kidney into Arthur. The UGA transplant program for cats requires that the donor cat be adopted by the recipient family’s family, which means that Joey and Arthur will become lifelong playmates.

“Cat owners who seek kidney transplants for their sick cats have to be very dedicated,” said Schmiedt. “They will give their car medication twice a day for the rest of its life. They also must be willing to take their cats to the veterinarian for frequent check-ups… a significant amount of time and expense is involved in keeping the recipient and donor cats healthy. But cat lovers who will go to this extent are willing to extend this kind of care to all cats they own.”

Apparently, Joey will be joined by Arthur and five other felines as well.

Stem cells do not replace the need for antirejection medication, and since Arthur’s body poorly absorbs cyclosporine, he will need to take a second antirejection drug as well called mycophenolate. Schmiedt, however, and his colleague stem cell scientist Dr. John Peroni sees MSCs making an important contribution to transplant medicine: “MSCs in veterinary species have been primarily used to treat musculo-skeletal injury – problems with bones, tendons, and joints – and those are our most frequent uses here at the UGA College of Veterinary Medicine. But there is good evidence to support using stem cells to modulate the immune system and regulate inflammation. So, the transplant setting might be another optimal use for these types of stem cells.”

In order to access the efficacy of MSCs in a transplant setting, controlled studies must be done. It is clear that transplanted MSCs do not improve kidney function, but they do seem to slow down the progression of kidney disease. Schmiedt thinks that benefits to patients are possible: “The only down side is harvesting the cells seven to 10 days ahead of the surgery, which adds to the cost of transplant procedure.”

Adaptation of this procedure to animals could smooth the path to making this procedure readily available in humans as well.

Nerve Growth Factor-Secreting Mesenchymal Stem Cells To Treat Huntington’s Disease


Vicki Wheelock at the UC Davis Medical Center has registered clinical trial number NCT01937923, which is otherwise known as “PRE-CELL.” This clinical trial will use various imaging techniques, laboratory tests, and clinical evaluations of Huntington’s disease (HD) patients to map the disease progression over 12-18 months. This trial will then hopefully identify candidates for a new trial in which these patients will be implanted with mesenchymal stem cells that secrete nerve growth factors. This represents one of the first clinical trials to examine the use of mesenchymal stem cells in the treatment of HD

The rationale for this study comes from a 2012 study in mice. Ofer Sadan, Eldad Melamed, and Daniel Offen from the Rabin Medical Center in Tel Aviv University, Israel, used R6/2 mice to test the efficacy of nerve growth factor-secreting mesenchymal stem cells isolated from bone marrow . In this paper, Sadan and others isolated mesenchymal stem cells from the bone marrow of healthy human volunteers and mice and then cultured them in special growth media that induces these cells to secrete special nerve growth factors. These so-called NTF+ cells were then transplanted into the striatum of R6/2 mice.

R6/2 mice express part of the human HTT gene; specifically the part that causes HD. Since HD is an inherited disease, there is a specific gene responsible for the vast majority of HD cases, and that gene is the human HTT gene, which encodes the Huntington protein. The function of the Huntington protein is uncertain, but it is found at high levels in neurons, even though it is found in other tissues as well, and dysfunctional Huntington protein affects neuron health.

Huntingtin Function

The HTT gene in HD patients contains the insertion of extra copies of the CAG triplet. The more CAG triplets are inserted into the HTT gene, the more severe the HD caused by the mutation. The hitch is that normal copies of the HTT gene has multiple copies of this CAG repeat. CAG encodes the amino acid glutamine, and Huntington contains a stretch of glutamine residues that seem to allow the protein to interact with other proteins found in neurons. When this glutamine stretch becomes too long, the protein is toxic and it begins to kill the cells. How long is too long? Research has pretty clearly shown that people whose HTT genes contain less than 28 CAG virtually never develop HD. People with between 28–35 CAG repeats, are usually unaffected, but their children are at increased risk of developing HD. People whose HTT genes contain 36–40 CAG repeats may or may not show HD symptoms, and those who have over 40 copies almost always are afflicted with HD.

hunt_gene_big

Now, back to R6/2 mice. These animals contain a part of the human HTT gene that has 150 CAG triplets. These mice show the characteristic cell death in the striatum and have behavioral deficits. In short R6/2 mice are pretty good model systems to study HD.

Sadan and others implanted MSCs that had been conditioned in culture to express high levels of nerve growth factors. Then these cells were transplanted into the striatum of R6/2 mice. R6/2 mice were also injected with buffer as a control.

The results showed that injections of NTF+ MSCs before the onset of symptoms did little good. The mice still showed cell death in the brains and behavioral deficits. However, NTF+ MSCs injected later (6.5 weeks), resulted in temporary improvement in the ability of the R6/2 mice to move and these cells also extended their life span. These results were published in the journal PLoS Currents (2012 Jul 10;4:e4f7f6dc013d4e).

Other work, also by Sadan and others, showed that injected MSCs tended to migrate to the damaged areas. When the injected cells were labeled with iron particles, they could be robustly observed with MRIs, and MRIs clearly showed that the injected cells migrated to the damaged areas in the brain (Stem Cells 2008; 26(10):2542-51). Another paper by Sadan and others also demonstrated that the striatum of NTF+ MSC-injected mice show less cell death than control mice (Sadan, et al. Exp Neurol. 2012; 234(2): 417-27). Other workers have also shown that implanted MSCs can provide improve symptoms in R6/2 mice and that they primary means by which they do this is by the secretion of nerve growth factors (Lee ST, et al. Ann Neurol 2009; 66(5): 671-81).

Thus, there is ample reason to suspect the PRECELL trial may lead to a stem cell-based clinical trial that will yield valuable clinical information. The animal data shows definite value in using preconditioned MSCs as a treatment for HD, and if the proper patients are identified by the PRE-CELL trials, then hopefully it will lead to a “CELL” trial in which HD patients are treated with NTF+ MSCs.

Mind you, this treatment will only delay HD at best and buy them time. Such treatments will not cure them. The NTF+ MSCs survive for a finite period of time in the hostile environment of the striatum of the HD patient, and the relief they will provide will be temporary. MSCs do not differentiate into neurons in this case, and they do not replace dead neurons, but they only help spare living neurons from suffering the same fate.

Huntington disease striatum

There is an MSC cell line that does make neurons, and if this cell line were used in combination with NTF+ MSCs, then perhaps neural replacement could be a possibility.  Also neural precursor cells could be used in combination with NTF+ MSCs to increase their survival.  Even then, as long as diseased neurons are producing toxic products, until gene therapy is perfected to the point that the actual genetic lesion in the striatal neurons is fixed, the deterioration of the striatum is inevitable. However, treatments like this could, potentially, delay this deterioration. This clinical trial should give us more information on exactly that question.

Two more points are worth mentioning.  When fetal striatal grafts were implanted into the brains of HD patients, the grafts underwent disease-like degeneration, and actually made the patients worse (see Cicchetti et al. PNAS 2009; 106(30): 12483-8 and Cicchetti F, et al. Brain 2011; 134(pt 3): 641-52).  Straight fetal implants do not seem to work.  Please let’s put the kibosh on these gruesome experiments.  Secondly, when neuronal precursor cells differentiated from human embryonic stem cells were implanted into HD rodents, the implanted cells formed some neurons and improved behavior to some extent, but non-neuronal differentiation remained a problem (Song J, et al., Neurosci Lett 2007; 423(1): 58-61).  Having non-brain cells in your brain is a significant safety problem.  Thus, embryonic stem cell-derived neuronal precursor cells do not seem to be the best bet to date either.  So, this present clinical trial seems to be making the most of what is presently safely available.

Transplantation of Neurons Made from Bioreactor-Grown Human Neural Precursor Cells Restores Brains of Rats With Huntington’s Disease


Huntington’s disease (HD) is an inherited disorder of the central nervous system characterized by progressive dementia, involuntary movements, and emotional deterioration.  The brain is affected in patients with HD and the part of the brain that takes the biggest beating is the “neostriatum.”

The term “neostriatum” is almost certainly not a word that you hear terribly often in conversation.  Therefore I will try to explain what it is.  The outer layers of the brain are known as the cerebral cortex and they are composed of so-called “grey matter.”  The cerebral cortex consists of grey matter because it is loaded with cells known as neurons.  Beneath the cortical layer of the brain, lies a whole host of extensions of these neurons that reside in the cerebral cortex.  These extensions are called “axons,” and beneath the cerebral cortex lies white matter, which consists, largely, of bundles of axons.  Think of the neurons are plugs and the axons as extension cords.  The neurons are plugged into each other by means of extension cords that extend from the cerebral cortex.

Now the cerebral cortex is not the only game in town.  There are also clusters of neurons that lie beneath the cerebral cortex called “nuclei.”  One of these nuclei beneath the cerebral cortex plays an extremely important role in voluntary motion, and this structure is called the “basal ganglia.”  Here’s a picture to make things a little clearer:

Basal ganglia

As you can see in the figure, the striatum consists of two structures: the putamen and the caudate nucleus.  The striatum or striate nucleus receives neural inputs from the cerebral cortex and inputs this neural information to the basal ganglia.

From a functional perspective, the striatum helps coordinate motivation with body movement.  It facilitates and balances motivation with both higher-level and lower-level functions – for example, inhibiting one’s behavior in a complex social interaction and fine-motor functions involved in inhibiting small voluntary movement.

Some of the neural outputs from the striatum are excitatory – they stimulate other neurons.  Other signals are inhibitory – they prevent the neurons to which they are connected from becoming stimulated.  Inhibitory neurons release a chemical called “GABA.”  These GABA-using neurons are very important for the work of the striatum, and it is exactly these neurons that die off at the greatest rate in patients with HD.  Therefore, treatments for patients with HD have focused on replacing or protecting these GABA-using neurons.

Experimentally, you can induce an HD-like disease in rodents if you inject a chemical into their brains called quinolinic acid.  Quinolinic acid causes many of the GABA-using neurons in the striatum to pack up and die, and for this reason, this chemical is heavily used in the laboratories of scientists who study HD and HD treatments.

In a paper by Marcus McLeod and others who did their work in the laboratory of Ivar Mendez, who was at Dalhousie University in Nova Scotia, Canada, but has since moved to the University of Saskatchewan, GABA-using neurons were made from cultured human neural precursor cells (hNPCs) and then implanted into the brains of rats that had been injected with quinolinic acid.  The results were spectacularly successful.  This work was published in the journal Cell Transplantation.

A definite twist with this particular paper is the way the GABA-using neurons were grown in culture; they were grown in bioreactors.  Bioreactors are devices that support biological cells, processes, or organisms.  They keep the environment of the cells constant, and provide a far superior way to grow cells or tissues in the laboratory.  McLeod and his colleagues used human neural progenitor cells and grew them to large numbers in bioreactors.  These expanded hNPCs were then differentiated them into GABA-using neurons and then injected into the brains of rats who has been treated with quinolinic acid.

The rat model allows the scientist to inject only one side of the brain with quinolinic acid.  This leaves the intact side of the brain as a control tissue that can be compared with the injected one.  The injected rats showed the characteristic death of the GABA-using neurons and the behavioral features that result from the death of these neurons.  Such animals do not walk normally when they are led through a cylinder, and they have trouble finding their way through a maze.  The animals that received the transplantations of the GABA-using neurons, however, performed almost as well in these tests as normal rats; not quite as well, but almost as well.  The rats treated with quinolinic acid did quite poorly, as expected.

Upon post-mortem examination, the rats transplanted with GABA-using neurons shows a host of new GABA-using neurons in their striatums.  These cells also underwent further maturation after transplantation, and they also made connections with other neurons.

Now this paper shows that the injected cells not only survived the transplantations, but they also matured, made connections and promoted recovery of many of the behavioral symptoms of HD.  This procedure certainly has promise.

Having said all that, there are two caveats to these experiments.  The rodent model is a good model as far as it goes, but it seems clear that the actual human disease turns the environment of the brain into a very inhospitable place.  Transplanted cells in the case of human HD patients do not usually survive terribly well.  It seems to me that treatments like this must be coupled with other treatments that seek to improve the actual cerebral environment.  The second caveat to this experiment is that the neural progenitor cells were taken 10-week-old from aborted fetuses.  While these scientists did not perform the abortions that ended the lives of these babies, it is more than little troubling that this research was done using the corpses of those babies whose lives were prematurely ended.

Nevertheless, despite these caveats, this paper represents a definite advance in the regenerative strategies available to treat HD patients.

Putting Peps in Your Heps


The liver is a special organ that performs a whole host of essential functions. The liver stores iron, vitamins and minerals; it detoxifies alcohol, drugs, and other chemicals that accumulate in our bloodstreams, and it produces bile (used to dissolve fats so that they can be degraded), and blood-based proteins like clotting factors and albumin. The liver also stores sugar in the form of glycogen. All of these tasks are undertaken by a single cell type, the hepatocyte (otherwise known as a liver cell).

human-liver-diagram

When your liver fails, you get really sick. This was greatly illustrated to me by one of my colleagues where I teach whose wife suffered extensive liver damage as a result of her battle with lupus (short for systemic lupus erythematosus, an autoimmune disease). Now that this dear lady has had a liver transplant, she is a new person. What a difference a healthy liver makes.

What can regenerative medicine do for patients with failing livers? Human pluripotent stem cells, either embryonic stem cells or induced pluripotent stem cells, can be directed to differentiate into liver cells in culture, but the liver cells made by these cells are very immature. They express proteins commonly found in fetal liver cells (for example, alpha-fetoprotein) and they also lack key enzymes associated with adult cells (such as cytochrome P450s). Rashid and others in the Journal of Clinical Investigation (2010; 120: 3127-3136) showed this. The development of three-dimensional culture systems have increased the maturity of such cells, but there is still a long way to go (see T Takebe and others, Nature 2013; 499:481-484 and J Shan and others, Nature Chemical Biology 2013; 9: 514-520).

Two papers from the journal Cell Stem Cell might show a way forward to making mature liver cells for regenerative liver treatments without destroying embryos or even using and pluripotent stem cell lines. These papers utilize the procedure known as “direct reprogramming,” otherwise known as “direct lineage conversion.” Direct reprogramming requires the forced overexpression of particular genes that causes the cells to switch their cell types.

In the first of these papers, Pengyu Huang and his colleagues from the Chinese Academy of Sciences in Shanghai, China overexpressed a three-gene combination in mouse embryonic fibroblasts that converted the cells into hepatocytes at an efficiency of 20% after 14 days in culture. This gene combination, known as 3TF (HNF4/HNF1A/FOXA3), converted the mouse embryonic skin cells into mature liver cells that made blood proteins and drug-processing enzymes. The only problem was that these mature cells could not grow in culture because they were mature. Therefore, Huang and others infected these cells with a virus called SV40, which drove the cells to divide. Now these cells could be grow in culture and expanded for further experiments.

When transplanted into the livers of mice with failing livers, the induced liver cells made by Huang and others restored proper liver function and allowed the mice to survive.

A second paper by Yuanyuan Du and others from the Peking-Tsinghua Center for Life Sciences at Peking University in Beijing, China, used a large gene combination to make mature liver cells from human skin fibroblasts. This gene combination included eight genes (HNF1A/HNF4A/HNF6/ATF5/PROX1/CEBPA/p53 ShRNA/C-MYC) that converted the human skin cells into liver cells after 30 days in culture at an efficiency of nearly 80%. Again, these cells metabolized drugs as they should, made blood proteins, took up cholesterol, and stored glycogen. Du and others compared the gene expression profile of these human induced hepatocytes or “hiHeps” to the gene expression profile of liver cells taken from liver biopsies. While there were differences in gene expression, there was also significant overlap and a large overall similarity. In fact the authors state, “these results indicate that hiHeps show a similar expression profile to primary human hepatocytes.”

Next, Du and others used three different mouse models of liver failure in all three cases, the hiHeps were capable of colonizing the damaged liver of the mouse and regenerating it. Mind you, the hiHeps did not do as good a job as human primary hepatocytes, but they still worked pretty well. This shows that this direct reprogramming protocol, as good as it is, can still be optimized and improved.

These studies show that the production of highly functional human hepatocyte-like cells using direct reprogramming is feasible and represents an exciting step towards the production of a supply source of cells for drug development, and therapies for liver disease.

FDA Approves Pneumostem Clinical Trial for Bronchopulmonary Dysplasia


MEDIPOST America Inc. has announced that the US Food and Drug Administration (USFDA) has approved their product Pneumostem for a Phase 1/2 clinical trial. This Phase 1/2 trial will assess the safety and efficacy of Pneumostem on prematurely born infants who are at high-risk of developing Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is a serious lung condition that affects infants. BPD usually affects premature infants who need oxygen given through nasal prongs, a mask, or a breathing tube in order to properly breathe.

Most infants who develop BPD are born more than 10 weeks before their due dates and weigh less than 2 pounds (about 1,000 grams) at birth, and have breathing problems. Respiratory infections that hit before or shortly after birth also can contribute to BPD.

Some infants who suffer from BPD may need long-term breathing support from breathing (NCPAP) machines or ventilators. BPD is the leading cause of mortality and severe complications in premature infants. Currently there is no approved therapies or drugs exist for BPD. This pneumostem trial is expected to draw global attention in the field of neonatal medicine, since it would provide a potential treatment for BPD where none presently exists.

Pneumostem is an off-the-shelf product made from human Umbilical Cord Blood-derived Mesenchymal Stem Cells (hUCB-MSCs). hUCB-MSCs show a terrific ability to grow in the laboratory and can also differentiate into multiple types of cells or tissues. They are immune-privileged and thus if they are used in patients other than from whom they are isolated, they do not cause adverse immune reactions. hUCB-MSCs harvested from cord blood show the lowest levels of immunogenicity compared to those by other types of adult stem cells. Thus, instead of provoking immunogenicity, they rather modulate the adverse immune reactions within the host, which makes hUCB-MSCs an ideal candidates for mass-producible stem cell drug for allogeneic use. These cells seem to facilitate regeneration of lung tissue and suppress the inflammatory responses in the lungs of premature infants.

Pneumostem has received Orphan Drug designation in Korea by the Ministry of Food and Drug Safety (MFDS) and the Korean Phase 2 study is 80% complete. The US FDA also granted Orphan Drug designation for Pneumostem demonstrating its medical value and commercial potential.

Presently, MEDIPOST America is rapidly moving begin this Pneumostem trial in the U.S. At the same time, Medipost will continue its licensing and technology transfer negotiations with multinational pharmaceutical companies.

The approval of this Pneumostem clinical trial by the US FDA, whose regulation of medicinal products is very strict (including stem cell products), might boost clinical trial approvals in other European and Asian countries.

Clinical development of Pneumostem was partly supported by Translational Stem Cell & Regenerative Medicine Consortium grant as a part of Public Health and Medicinal Technology R&D Project funded by the Korea Ministry of Health & Welfare and the Korea Health Industry Development Institute.

Bone Therapeutics Cleared to Test ALLOB in Spinal Fusion Trial


Bone Therapeutics is a biotechnology company that specializes in regenerative therapies for orthopaedic conditions. Founded in 2006, Bone Therapeutics is headquartered in Gosselies, Belgium. One of the products developed by Bone Therapeutics is called ALLOB, which is a bone making (osteoblastic) cell product that has the ability to regenerate bone, and has been developed for the treatment of bone diseases. ALLOB is meant to be an off-the-shelf product that can be used to treat patients with various types of bone diseases.

Bone Therapeutics has recently announced that it has received approval from the Belgium regulatory agencies for a phase II proof-of-concept study to assess the safety and efficacy of ALLOB in spinal fusion procedures that are commonly used to treat degenerative lumbar disc disease. The hope is that this clinical trial will demonstrate that ALLOB improves spinal fusion surgery outcomes. Bone Therapeutics hopes to market ALLOB as an off-the-shelf treatment for spinal fusion surgery.

In previous studies, ALLOB has shown that it can enhance bone formation, and that it is a safe product in laboratory animals. Currently ALLOB is being evaluated in a phase I/IIa trial for delayed-union fractures. This is a pilot proof-of-concept study that examines 16 patients with symptomatic degenerative lumbar disc disease, all of whom require interbody vertebral fusion. These patients will be treated with a single dose of ALLOB mixed with bioceramic granules to promote bone formation and fusion at the within the degenerative discs. The bioceramic scaffold in this trials promotes bone formation by guiding bone growth in three dimensions and restoring a healthy bone environment. Patients will be enrolled in this trial at four different centres. The safety and efficacy of the treatment will be monitored over 12 months by clinical and radiological means. Additionally, there will be a 24-month post-study follow-up.

Back pain is a widespread medical disorder in industrialized societies that sometimes requires spinal surgery. Around 1.3 million spinal fusions are performed each year in Europe and the USA, the majority of which are to address degenerative lumbar disc disease. Despite the frequency of this surgery, non-union of bone and persistent pain following the intervention is still somewhat common. Further improvements to this procedure would be most welcome to patients and medical practitioners alike.

Enrico Bastianelli, CEO of Bone Therapeutics commented, “This new clinical trial clearance from the Competent Authorities in Belgium is an important milestone in the development of ALLOB® and further validates Bone Therapeutics’ clinical, regulatory and manufacturing capabilities.”

Inhibition of signaling pathway stimulates adult muscle satellite cell function


Stem cell researcher Michael Rudnicki and his team from the University of Ottawa in Ontario, Canada has done it again. Rudnicki works on muscle stem cells and his work has greatly expanded our understanding of muscle satellite cells.

Muscle satellite cells are found in skeletal muscle, and they are a prime example of a “unipotent” stem cell, or a stem cell that can differentiate into only one cell type. Muscle satellite cells can only form skeletal muscle, but they can be isolated from skeletal muscle and grown in culture. When muscle is injured by exercise or shear forces, satellite cells move into action and divide to form muscle cells that fuse with existing muscle cells and firm them up. Lifting weights will also increase the activity of satellite cells and they will divide and contribute to the formation of new muscle fibers.

As we age, our capacity to regenerate damaged muscle slows way down. As someone who lifted weights in high school and then on and of after high school, I can attest to this as I have entered my later years. My joints get sore faster and I cannot handle heavier weights any more. Also, I do not get big from lifting anymore. This is due to the reduction in muscle repair and I have become older.

Rudnicki and others have identified a reduced capacity in adult mice to repair their muscles, and this reduction in muscle regenerative ability has been directly linked to reduced muscle satellite cell activity. Aged mice have muscle satellite cells that show a diminished ability to contribute to muscle regeneration and repopulate themselves.

In a recent paper published in the journal Nature Medicine, Rudnicki and his colleagues compared used gene expression profiles in the satellite cells of older and younger mice. Curiously, they identified the genes that encode the components of a cell signaling pathway called the “JAK-STAT” pathway that are more highly expressed in the satellite cells of older mice than in those of younger mice.

These data suggested that inhibition of the JAK-STAT pathway in the satellite cells of older mice might lead to higher satellite cell activity in older mice. Fortunately, there are drugs that will inhibit the JAK-STAT signaling pathway.

Knockdown of the activity of the Jak2 or Stat3 proteins significantly stimulated satellite stem cell divisions in culture (the satellite cells were grown in cultured muscles). When Jak2 of Stat3 were inhibited genetically (by introducing loss-of-function mutations in these genes), the isolated satellite cells showed a markedly ability to repopulate local satellite cell populations after they were transplanted into a wounded muscle.

Inhibition of Jak2 and Stat3 activity with drugs also stimulated the engraftment of satellite cells in a living animal. If these same rugs were injected into the muscle of older laboratory mice, these mice showed marked enhancement of muscle repair and force generation after injury.

Thus, these results from the Rudnicki lab show that they is an intrinsic property of satellite cells that separate the satellite cells of younger animals with those of older animals. These results also suggest a promising therapeutic avenue for the treatment of muscle-wasting diseases.

Directly Reprogramming Skin Cells into White Blood Cells


Scientists from the Salk Institute have, for the first time, directly converted human skin cells into transplantable white blood cells, which are the soldiers of the immune system that fight infections and invaders. This work could prompt the creation of new therapies that introduce new white blood cells into the body that can attack diseased or cancerous cells or augment immune responses for other conditions.

This work, which shows that only a small amount of genetic manipulation could prompt this direct conversion, was published in the journal Stem Cells.

“The process is quick and safe in mice,” says senior author Juan Carlos Izpisua Belmonte, who holds the Salk’s Roger Guillemin Chair. “It circumvents long-standing obstacles that have plagued the reprogramming of human cells for therapeutic and regenerative purposes.”

The problems that Izpisua Belmonte mentions, includes the long time (at least two months) numbingly tedious cell culture work it takes to produce, characterize and differentiate induced pluripotent stem (iPS) cells. Blood cells derived from iPSCs also have other obstacles: they engraft into organs or bone marrow poorly and can cause tumors.

The new method designed by Izpisua Belmonte and his team, however, only takes two weeks, does not produce tumors, and engrafts well.

“We tell skin cells to forget what they are and become what we tell them to be—in this case, white blood cells,” says one of the first authors and Salk researcher Ignacio Sancho-Martinez. “Only two biological molecules are needed to induce such cellular memory loss and to direct a new cell fate.”

This faster reprogramming technique developed by Belmonte’s team utilized a form of reprogramming that does not go through a pluripotency stage. Such techniques are called indirect lineage conversion or direct reprogramming. Belmonte’s group has demonstrated that such approaches can reprogram cells to form the cells that line blood vessels. Thus instead of de-differentiating cells into an embryonic stem cell-type stage, these cells are rewound just enough to instruct them to form the more than 200 cell types that constitute the human body.

Direct reprogramming used in this study uses a molecule called SOX2 to move the cells into a more plastic state. Then, the cells are transfected with a genetic factor called miRNA125b that drives the cells to become white blood cells. Belmonte and his group are presently conducting toxicology studies and cell transplantation proof-of-concept studies in advance of potential preclinical and clinical studies.

“It is fair to say that the promise of stem cell transplantation is now closer to realization,” Sancho-Martinez says.

Study co-authors include investigators from the Center of Regenerative Medicine in Barcelona, Spain, and the Centro de Investigacion Biomedica en Red de Enfermedades Raras in Madrid, Spain.

The First Patient Treated with iPSC-Derived Cells


Nature News has reported that a Japanese patient was received the first treatment derived from induced pluripotent stem cells.

Ophthalmologist Masayo Takahashi from the Riken Center for Developmental Biology and her team used genetic engineering techniques to reprogram skin fibroblasts from this patient into induced pluripotent stem cells. These cultured iPSCs were then differentiated into retinal pigment epithelium cells. Takahashi’s colleagues, led by Yasuo Kurimoto at Kobe City Medical Center General Hospital, then implanted those retinal pigment epithelium cells into the retina of this female patient, who suffers from age-related macular degeneration.

It is unlikely that this procedure will restore the woman’s vision. However, because age-related macular degeneration is a progressive process, Takahashi and her research team will be examining if this procedure prevents further deterioration of her sight. Takahashi’s Riken team has extensively tested this procedure in laboratory animals and recently received human trial clearance. Takahashi’s team will also be looking particularly hard at the side effects of this procedure; such as immune reaction or cancerous growth.

“We’ve taken a momentous first step toward regenerative medicine using iPS cells,” Takahashi says in a statement, according to Nature News. “With this as a starting point, I definitely want to bring [iPS cell-based regenerative medicine] to as many people as possible.”

Transplanted Mesenchymal Stem Cells Prevent Bladder Scarring After Spinal Cord Injury


A collaborative research effort between laboratories from Canada and South Korea have shown that a cultured mesenchymal stem cell line called B10 can differentiate into smooth muscle cells and improve bladder function after a spinal cord injury.

Spinal cord injury can affect the lower portion of the urinary tract. Overactive bladder, urinary retention, and increased bladder thickness and fibrosis (bladder scarring) can result from spinal cord injuries. Human mesenchymal stem cells (MSCs) can differentiate under certain conditions into smooth muscle. For this reason, MSCs have therapeutic potential for patients who have suffered from spinal cord injuries.

Seung U. Kim and his colleagues from Gachon University Gil Hospital in Inchon, South Korea have made an immortalized human mesenchymal stem cell line by transfecting primary cell cultures of fetal human bone marrow mesenchymal stem cells with a retroviral vector that contains the v-myc oncogene. This particular cells line, which they called HM3.B10 (or B10 for short), grows well in culture and can also differentiates into several different cell types.

In this present study, which was published in the journal Cell Transplantation, Kim and his colleagues and collaborators injected B10 hMSCs directly into the bladder wall of mice that had suffered a spinal cord injury but were not treated showed no such improvement.

“Human MSCs can secrete growth factors,” said study co-author Seung U. Kim of the Division of Neurology at the University of British Columbia Hospital, Vancouver, Canada. “In a previous study, we showed that B 10 cells secrete various growth factors including hepatocyte growth factor (HGF) and that HGF inhibits collagen deposits in bladder outlet obstructions in rats more than hMSCs alone. In this study, the SCI control group that did not receive B10 cells showed degenerated spinal neurons and did not recover. The B10-injected group appeared to have regenerated bladder smooth muscle cells.”

Four weeks after the initial spinal cord injury, the mice in the B10-treated group received injections of B10 cells transplanted directly into the bladder wall. Kim and his team used magnetic resonance imaging (MRI) to track the transplanted B10 cells. The injected B10 cells had been previously labeled with fluorescent magnetic particles, which made them visible in an MRI.

“HGF plays an essential role in tissue regeneration and angiogenesis and acts as a potent antifibrotic agent,” explained Kim.

These experiments also indicated that local stem cell injections rather than systemic, intravenous infusion was the preferred method of administration, since systemic injection caused the hMSCs get stuck largely in the blood vessels of the lungs instead of the bladder.

The ability of the mice to void their bladders was assessed four weeks after the B10 transplantations. MRI analyses clearly showed strong signals in the bladder as a result of the labeled cells that had been previously transplanted. Post-mortem analyses of the bladders of the transplanted group showed even more pronounced differences, since the B10-injected animals had improved smooth muscle cells and reduced scarring.

These results suggest that MSC-based cell transplantation may be a novel therapeutic strategy for bladder dysfunction in patients with SCI.

“This study provides potential evidence that an human [sic] stable immortalized MSC line could be useful in the treatment of spinal cord injury-related problems such as bladder dysfunction.” said Dr. David Eve, associate editor of Cell Transplantation and Instructor at the Center of Excellence for Aging & Brain Repair at the University of South Florida. “Further studies to elucidate the mechanisms of action and the long-term effects of the cells, as well as confirm the optimal route of administration, will help to illuminate what the true benefit of these cells could be.”

Bioinformatic Analysis Leads to Gene Combination that Makes Clinical Quality Mouse iPSCs


Adult cells can be de-differentiated so that they resemble embryonic stem cells by genetically engineering them to overexpress particular genes. Such reprogrammed cells are known as induced pluripotent stem cells or iPSCs, and these cells might have the potential to cure damaged nerves, regrow limbs and organs, and precisely model a patient’s particular disease. Unfortunately, the very process of reprogramming triggers replication stress, which causes iPSCs to acquire serious genetic and epigenetic abnormalities that lower the cells’ quality and limit their therapeutic usefulness.

When iPSCs were first derived in 2006, the efficiency of their derivation was quite low, since only a fraction of a percentage of reprogrammed cells successfully grew to become cell lines. Thus some of the earliest work with iPSCs tried to increase the efficiency of reprogramming. These experiments provided a greater understanding of the reprogramming process and demonstrated that many different variables, including the ratio of reprogramming factors and the reprogramming environment, could also greatly affect the quality of the iPSCs that were derived.

A research group from the Whitehead Institute, which includes founding member Rudolf Jaenisch, in collaboration with scientists from Hebrew University, has shown that the reprogramming factors themselves greatly influence the reprogramming efficiency and the quality of the resulting cells. This work was published in the current issue of the journal Cell Stem Cell.

“Postdoctoral researcher Yosef Buganim and Research Scientist Styliani Markoulaki show that a different combination of reprogramming factors may be less efficient than the original, but can produce higher quality iPSCs,” says Jaenisch, who is also a professor of biology at MIT. “And quality is a really important issue. At this point, it doesn’t matter if we get one colony out of 10,000 or one out of 100,000 cells, as long as it is of high quality.”

In order to derive iPSCs from mature adult cells, scientists transfect adult cells to a cocktail of genes. The genes used are all active in embryonic stem cells. By pushing cells to overexpress these embryonic stem cell-specific genes, adult cells can become iPSCs, which can then be differentiated into almost any other cell type, such as nerve, liver, or muscle cells. The original gene combination included Oct4, Sox2, Klf4, and Myc or (OSKM). This combination efficiently reprograms cells, but a relatively high percentage of the resulting cells have serious genomic aberrations, including aneuploidy, and trisomy 8, which make them unsuitable for use in clinical research.

Buganim and Markoulaki used bioinformatic analysis of a network of 48 genes that are integral to the reprogramming process. With this analysis, Buganim and Markoulaki designed a new reprogramming gene cocktail: Sall4, Nanog, Esrrb, and Lin28 (SNEL). With this gene combination, approximately 80% of SNEL colonies made from mouse cells were of high quality and fulfilled the tetraploid complementation assay, which is the most stringent pluripotency test available. As a comparison, only 20-30% of high quality OSKM passed the same test. Buganim hypothesizes that SNEL reprograms cells better because, unlike OSKM, the cocktail does not rely on a potent oncogene like Myc, which might be the source of some of the genetic problems produced by the reprogramming process. Even importantly, the cocktail does not rely on the potent key master regulators Oct4 and Sox2 that seem to abnormally activate some regions in the adult cell genome.

buganim-slider-570

Buganim and Markoulaki also analyzed SNEL colonies down to the genetic and epigenetic level. On their DNA, SNEL cells have deposits of the histone protein H2AX in locations very similar to those in ESCs, and the position of H2AX seems to predict the quality of the cell. This characteristic might be a fast way to quickly screen for high quality colonies.

It must be stressed that this SNEL gene combination was designed for mouse cells; it is unable to reprogram human cells, which are generally more difficult to manipulate than mouse cells. However, the same bioinformatic analysis might provide the proper insights to find the right combination for human cells that produce clinical quality iPSCs.

“We know that SNEL is not the ideal combination of factors,” says Buganim, who is currently a Principal Investigator at Hebrew University in Jerusalem. “This work is only a proof of principle that says we must find this ideal combination. SNEL is an example that shows if you use bioinformatics tools you can get better quality. Now we should be able to find the optimal combination and try it in human cells to see if it works.”

Yale Scientists Find Marker for High-Quality Induced Pluripotent Stem Cells


Pluripotent stem cells can be made by genetically engineering adult cells into less mature cells that have pluripotency. These induced pluripotent stem cells or iPSCs can potentially differentiate into any cell type in the adult body and because they are made from the patient’s own cells, they have a lower risk of being rejected by the patient’s immune system.

However, iPSCs suffer from an increased mutation rate when they are made and these increased mutation rate increases their risk of causing tumors and being rejected by the patient’s immune system. Having said that, not all iPSCs are created equal, and the safety of iPSCs seems to be very line-specific. Thus, how do you know a good stem cell from a bad one?

Yale Stem Cell Center researchers led by Andrew Xiao Yale have published a report in the Sept. 4 issue of Cell Stem Cell in which they describe an indicator that seems to predict which batch of personalized stem cells will differentiate into patient-specific tissue types and which will develop into unusable placental or tumor-like tissues.

Xiao’s group identified a variant histone protein called H2A.X that seems to predict the developmental path of iPSC cells in mice. Histone proteins assemble into tiny spools around which DNA winds. This DNA spooling allows cells to tightly package their DNA into a tight, compact structure that is easily stored called “chromatin.” Histones that are commonly used include histones H2A, H2B, H3 and H4.

Core histones

Two copies of each of these proteins assemble into a globular structure called a core histone and the DNA of the cell winds around this core histone to form a “nucleosome.” Then linker histones (H1 or H5) take these nucleosomes package them into spiraled coils.

DNA solenoids

H2A.X is a variant version of histone H2A is modified when DNA damage occurs. Modified H2A.X signals to the DNA repair machinery to fix the broken DNA (see TT Paull, and others, Curr. Biol. 10(15):886–95).

nrm3659-f3

According to the data from Xiao’s research team, in pluripotent stem cells, H2A.X is specifically targeted to those genes typically expressed in cells used to make the placenta, and it helps suppress differentiation of pluripotent stem cells into cells of the placental lineage. Given this distribution in mouse embryonic stem cells, H2A.X deposition pattern is a functional marker of the quality of iPSCs. Conversely, defective H2A.X deposition predisposes iPSCs toward differentiating into placental-type cells and tumors.

“The trend is to raise the standards and quality very high, so we can think about using these cells in clinic,” Xiao said. “With our assay, we have a reliable molecular marker that can tell what is a good cell and what is a bad one.”

Neuralstem Treats Final Patient in Phase 2 ALS Stem Cell Trial


NeuralStem, Inc. has announced that the final patient in its Phase 2 clinical trial that assessed the efficacy of its NSI-566 spinal cord-derived neural stem cell line in the treatment of amyotrophic lateral sclerosis (ALS), which is otherwise known as Lou Gehring’s disease.

ALS is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells responsible for controlling voluntary muscles; that is, muscle action we are able to control, such as those in the arms, legs, and face, etc.  ALS is a member of those disorders known as motor neuron diseases, all of which are characterized by the gradual degeneration and death of motor neurons.

Motor neurons are nerve cells located in the brain, brain stem, and spinal cord that serve as controlling units and vital communication links between the nervous system and the voluntary muscles of the body. Messages from motor neurons in the brain (so-called upper motor neurons) are transmitted to motor neurons in the spinal cord (so-called lower motor neurons) to particular muscles. In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, and stop sending messages to muscles. Unable to function, the muscles gradually weaken, waste away (atrophy), and have very fine twitches (called fasciculations). Eventually, the ability of the brain to start and control voluntary movement is lost.

ALS causes weakness with a wide range of disabilities. Eventually, all muscles under voluntary control are affected, and individuals lose their strength and the ability to move their arms, legs, and body. When muscles in the diaphragm and chest wall fail, people lose the ability to breathe without ventilatory support. Most people with ALS die from respiratory failure, usually within 3 to 5 years from the onset of symptoms. However, about 10 percent of those with ALS survive for 10 or more years.

Although the disease usually does not impair a person’s mind or intelligence, several recent studies suggest that some persons with ALS may have depression or alterations in cognitive functions involving decision-making and memory.

ALS does not affect a person’s ability to see, smell, taste, hear, or recognize touch. Patients usually maintain control of eye muscles and bladder and bowel functions, although in the late stages of the disease most individuals will need help getting to and from the bathroom.

In this multicenter Phase 2 trial, 15 patients who still had the ability to walk were treated in five different dosing cohorts. The first 12 of these patients received injections only in the cervical regions of the spinal cord in increasing doses (5 injections of 200,000 cells per injection to injections of 4000,000 cells each . In the cervical region, these injected stem cells could potentially preserve the nerves that mediate breathing and this is precisely that this part of the trail aims to test.

spinal cord regions

In the final three patients injected in this trial, patients received a total of 40 injections of 400,000 cells each into both cervical and lumbar regions (a total of 16 million cells were injected. This is in contrast to the patients who participated in the Phase 1 study who received 15 injections of 100,000 cells each (total of 1.5 million cells). This trial will continue until six months past the final surgery, after which the data will be analyzed.

“By early next year, we will have six-month follow-up data on the last patients who received what we believe will be the maximum safe tolerated-dose for this therapy,” said Dr. Eva Feldman, principal investigator in this clinical trial, and a member of the ALS Clinic at the University of Michigan. Dr. Feldman also serves as an unpaid consultant to Neuralstem.

Induced Pluripotent Stem Cells Form Limbal-Like Stem Cells


Limbal epithelial stem cells or LESCs are found at the periphery of the cornea and they continuously renew the corneal epithelium. Loss of this stem cell population can cause loss of corneal transparency and eventual loss of vision.

Genetic conditions can cause LESC deficiency, such as congenital aniridia, Stevens-Johnson syndrome or Ocular cicatricial pemphigoid. Other causes of LESC deficiency include chemical or thermal burns to the eye, microbial infections, extended contact lens wear, sulfur mustard gas poisoning, or chronic inflammation of the eye,

Limbal epithelial stem cells reside in the basal layer of the epithelium (Ep), which undulates at the limbus. Daughter transient amplifying cells (TACs) divide and migrate towards the central cornea (arrowed) to replenish the epithelium, which rests on Bowman's layer (BL). The stroma (St) of the limbal epithelial stem cell niche is populated with fibroblasts and melanocytes and also has a blood supply.
Limbal epithelial stem cells reside in the basal layer of the epithelium (Ep), which undulates at the limbus. Daughter transient amplifying cells (TACs) divide and migrate towards the central cornea (arrowed) to replenish the epithelium, which rests on Bowman’s layer (BL). The stroma (St) of the limbal epithelial stem cell niche is populated with fibroblasts and melanocytes and also has a blood supply.

Treatments of LESC deficiency include limbal stem cell grafts from one eye to another, but these grafts have a 3-5-year graft survival of only 30%-45%. If LESCs are expanded in culture on human amniotic membrane, then 76% of the grafts will successfully take 1-3 years after grafting. This procedure is not standardized. If LESCs are grafted from a cadaver, their survival is low.

Given these less than optimal treatments for LESC deficiencies, Alexander Ljubimov and his team from UCLA have used induced pluripotent stem cells (iPSCs) to make cultured LESCs. Ljubimov and his coworkers derived iPSCs from the skin cells of volunteers with non-integrating plasmids. Then they grew these cells on corneas that have been stripped of their cells and human amniotic membranes and these cells differentiated into LESC-like cells.

Ljubimov and others also made iPSCs from human LESCs, and when they cultured these iPSCs derived from LESCs on human amniotic membranes for two weeks, the cells differentiated into LESCs that made LESC-specific genes, and had the epigenetic characteristics of LESCs.

These experiments show that the cell source for iPSC derivation can greatly influence the epigenetic characteristics of the iPSC line. Also these experiments show that iPSCs can be used to make LESCs that can potentially be used for therapeutic purposes.

Mesenchymal Stem Cells Repair Cartilage Defects in Cynomolgus Monkeys


Repairing cartilage defects in the knee represents one of the primary goals of orthopedic regenerative medicine. Cartilage that covers the joints, otherwise known as articular cartilage, has a limited capacity for repair, which leads to further degeneration of the cartilage when it is damaged if it remains untreated. A number of surgical options for treating cartilage defects include microfracture, osteochondral grafting, and cell-based techniques such as autologous chondrocyte implantation (ACI). Each of these procedures have been used in clinical settings. Unfortunately cartilage injuries treated with microfracturing deteriorate with time, since the cartilage made by microfracturing has a high proportion of softer. less durable fibrocartilage.  Also osteochondral grafting suffers from a lack of lateral integration between host and donor cartilage.

Alternatively, tissue engineering has shown some promise when it comes to the healing of cartilage defects.  Mesenchymal stem cells (MSCs) are multipotent progenitor cells that have the ability to differentiate into several different cell lineages including cartilage-making chondrocytes.  MSCs have theoretical advantages over implanted chondrocytes when it come to healing potential.  MSCs have the ability to proliferate without losing their ability to differentiate into mature chondrocytes and produce collagen II and aggrecan. In the short-term, bone marrow-derived MSCs combined with scaffolds have been successful in cartilage repair using animal models such as rabbits (Dashtdar H, et al., J Orthop Res 2011; 29: 1336-42) sheep (Zscharnack M, et al., Am J Sports Med 2010; 38: 185769) and horses (Wilke MM, et al.,l J Orthop Res 2007; 25: 9132).  

In a recent study, Kazumasa Ogasawara and Yoshitaka Matsusue and their colleagues from Shiga University of Medical Science in Shiga, Japan, tested the ability of expanded bone marrow-derived MSCs that had been placed in a collagen scaffold to improve healing of cartilage defects in cynomolgus macaques (type of monkey).  Before this study, there were no previous studies using MSCs from primates for cartilage repair.  The monkey MSCs were shown to properly differentiate into fat, bone, or cartilage in culture, and then were transplanted into the injured cartilage in the cynomolgus macaque.  The efficacy of these cells were ascertained at 6, 12, and 24 weeks after transplantation.

In culture, the cynomolgus MSCs were able to differentiate into fat, bone, and cartilage.

Characteristics of bone marrow-derived MSCs. Panel (a) demonstrates the colony-forming properties of MSCs isolated from bone marrow of cynomolgus macaques using the present protocol (arrows). Bar: 1 cm. Panel (b) shows the adipogenetic properties of MSC-derived cells from staining of lipid droplets with oil red O (arrowheads). Bar: 20 μm. Panel (c) confirms the osteoblastic properties of MSC-derived cells with alkaline phosphatase staining (arrowheads). Bar: 30 μm. Panel (d) confirms the chondrogenetic properties from immunostaining of type-II collagen. Type-II collagen-positive matrix is stained red. Bar: 0.5 mm. Read More: http://informahealthcare.com/doi/full/10.3109/17453674.2014.958807.
Characteristics of bone marrow-derived MSCs. Panel (a) demonstrates the colony-forming properties of MSCs isolated from bone marrow of cynomolgus macaques using the present protocol (arrows). Bar: 1 cm. Panel (b) shows the adipogenetic properties of MSC-derived cells from staining of lipid droplets with oil red O (arrowheads). Bar: 20 μm. Panel (c) confirms the osteoblastic properties of MSC-derived cells with alkaline phosphatase staining (arrowheads). Bar: 30 μm. Panel (d) confirms the chondrogenetic properties from immunostaining of type-II collagen. Type-II collagen-positive matrix is stained red. Bar: 0.5 mm.
Read More: http://informahealthcare.com/doi/full/10.3109/17453674.2014.958807.

Upon transplantation into cartilage defects in the knee cartilage of cynomolgus monkeys, MSCs were compared with collagen gel devoid of MSCs.  The knees that received the transplantations did not show any signs of irritation, bone spurs or infection.  All of the animals had so-called “full-thickness cartilage defects,” and those in the non-treated group showed cartilage defects that did not change all that much.  The cartilage defects of the gel group had sharp edges at 6 weeks that were thinly covered with reparative tissue by 12 weeks, and at 24 weeks, the defect was covered with thick tissue, but the central region of the defects often remained uncovered, with a hollow-like deformity.  In the cartilage defects of those animals treated with MSCs plus the collagen gel, the sharp edges of the defects were visible at 6 weeks after the operation, but at 12 weeks, the defects were evenly covered with yellowish reparative tissue.  At 24 weeks, the defects were covered with watery hyaline cartilage-like tissue that was very similar to the neighboring naïve cartilage.

Macroscopic observations of the repaired defects in the 3 groups at 6 weeks (a, d, g), 12 weeks (b, e, h), and 24 weeks (c, f, i) after implantation. Scale bar: 5 mm. Arrow in (d): the sharp edge of the defect is visible at 6 weeks in the gel group. Arrow in (f): a hollow-like deformity remains in the central region of the defect, despite thick coverage by the reparative tissue. Arrow in (g): the sharp edge of the defect is also visible in the MSC group at 6 weeks. Read More: http://informahealthcare.com/doi/full/10.3109/17453674.2014.958807.
Macroscopic observations of the repaired defects in the 3 groups at 6 weeks (a, d, g), 12 weeks (b, e, h), and 24 weeks (c, f, i) after implantation. Scale bar: 5 mm. Arrow in (d): the sharp edge of the defect is visible at 6 weeks in the gel group. Arrow in (f): a hollow-like deformity remains in the central region of the defect, despite thick coverage by the reparative tissue. Arrow in (g): the sharp edge of the defect is also visible in the MSC group at 6 weeks.
Read More: http://informahealthcare.com/doi/full/10.3109/17453674.2014.958807.

When evaluated at the tissue level, Ogasawara and Matsusue and others used a stain called toluidine blue to visualize the amount of cartilage made by each treatment.  As you can see in the picture below, the non-treated group didn’t do so well.  In the full-thickness defect the region below the cartilage was filled with amorphous stuff 6 weeks after the procedure, and at 12 weeks, amorphous stuff faintly stained with toluidine blue, which reflects the conversion of the amorphous stuff into bone.  At 24 weeks, bone tissue reappeared below the cartilage zone, even though the bone did not look all that normal (no trabecular structure but woven bone-like structure).

In the gel group, cartilage-like tissue is seen at 6 weeks, and at 12 weeks, the faintly stained layer covered the cartilage defect. At 24 weeks, the defect was covered with the cartilage-like stuff, even though the central region had only a little cartilage, as ascertained by toluidine blue staining.  The bone underneath the cartilage looked crummy and there was excessive growth of cartilage into the region underneath the cartilage layer.

In the MSC group, the bone underneath the cartilage healed normally, and at 12 weeks, the boundary between the articular cartilage and the bone layer beneath it had reappeared.  At 24 weeks, the thickness of the toluidine blue-stained cartilage layer was comparable to that of the neighboring naïve cartilage.

Even though the gel group showed most cartilage-rich tissue covering the defect, this was due to the formation of excessive cartilage extruding through the abnormal lower bone layer.  Despite the lower amount of new cartilage produced, the MSC group showed better-quality cartilage with a regular surface, seamless integration with neighboring naïve cartilage, and reconstruction of the bone underneath the cartilage layer.

Histological findings after toluidine blue staining in the 3 groups at 6 weeks (a, d, g), 12 weeks (b, e, h), and 24 weeks (c, f, i) after implantation. Scale bar: 2 mm. Dotted line in (a): amorphous reparative tissue filling the subchondral region. Arrowheads in (b): faint toluidine blue staining that reflects involvement of endochondral ossification. Arrowhead in (c): toluidine blue-negative reparative tissue covering the defect. Dotted line in (c): reconstructed subchondral bone consisting of woven bone-like structure. Arrowhead in (d): toluidine blue-positive cartilaginous tissue. Arrowhead in (e): thin faintly toluidine blue-positive layer covering the defect. Arrowhead in (f): the unstained central region of the cartilaginous layer covering the defect. Arrow in (f): excessive cartilage extruding through the deficient tidemark. Dotted line in (g): woven bone-like subchondral bone already re-appearing at 6 weeks. Arrowhead in (h): reconstructed tidemark distinctly discriminating the articular cartilage from the subchondral bone.
Histological findings after toluidine blue staining in the 3 groups at 6 weeks (a, d, g), 12 weeks (b, e, h), and 24 weeks (c, f, i) after implantation. Scale bar: 2 mm. Dotted line in (a): amorphous reparative tissue filling the subchondral region. Arrowheads in (b): faint toluidine blue staining that reflects involvement of endochondral ossification. Arrowhead in (c): toluidine blue-negative reparative tissue covering the defect. Dotted line in (c): reconstructed subchondral bone consisting of woven bone-like structure. Arrowhead in (d): toluidine blue-positive cartilaginous tissue. Arrowhead in (e): thin faintly toluidine blue-positive layer covering the defect. Arrowhead in (f): the unstained central region of the cartilaginous layer covering the defect. Arrow in (f): excessive cartilage extruding through the deficient tidemark. Dotted line in (g): woven bone-like subchondral bone already re-appearing at 6 weeks. Arrowhead in (h): reconstructed tidemark distinctly discriminating the articular cartilage from the subchondral bone.

This protocol has been nicely optimized by Ogasawara and Matsusue and their research team.  From these data, they conclude:  “Application in larger defects is certainly in line with future clinical use. If MSCs—under optimized conditions—turn out to be superior to chondrocyte implantation in experimental cartilage repair, the procedure should be introduced to clinical practice after well-controlled randomized clinical trials.”  Hopefully, clinical trials will commence before long.  This procedure uses a patient’s own MSCs, and if such a procedure could reduce or delay the number of knee replacements, then it would surely be a godsend to clinicians and patients alike.

Skin Cells Converted into Blood Cells By Direct Reprogramming


Making tissue-specific progenitor cells that possess the ability to survive, but have not passed through the pluripotency state is a highly desirable goal of regenerative medicine. The technique known as “direct reprogramming” uses various genetic tricks to transdifferentiate mature, adult cells into different cell types that can be used for regenerative treatments.

Juan Carlos Izpisua Belmonte and his colleagues from the Salk Institute for Biological Studies in La Jolla, California and his collaborators from Spain have used direct reprogramming to convert human skin cells into a type of white blood cells.

These experiments began with harvesting skin fibroblasts from human volunteers that were then forced to overexpress a gene called “Sox2.” The Sox2 gene is heavily expressed in mice whose bone marrow stem cells are being reconstituted with an infusion of new stem cells. Thus this gene might play a central role is the differentiation of bone marrow stem cells.

Sox2 overexpression in human skin fibroblasts cause the cells express a cell surface protein called CD34. Now this might seem so boring and unimportant, but it is actually really important because CD34 is expressed of the surfaces of hematopoietic stem cells. Hematopoietic stem cells make all the different types of white and red blood cells in our bodies. Therefore, the expression of these protein is not small potatoes.

In addition to the expression of CD34, other genes found in hematopoietic stem cells were also induced, but not strongly. Thus overexpression of SOX2 seems to induce an incipient hematopoietic stem cell‐like status on these fibroblasts. However, could these cells be pushed further?

Gene profiling of hematopoietic stem cells from Umbilical Cord Blood identified a small regulatory RNA known as miR-125b as a factor that pushes SOX2-generated CD34+ cells towards an immature hematopoietic stem cell-like progenitor cell that can be grafted into a laboratory animal.

When SOX2 and miR-125b were overexpressed in combination, the cells transdifferentiated into monocytic lineage progenitor cells.

What are monocytes? They are a type of white blood cells and are, in fact, the largest of all white blood cells. Monocytes compose 2% to 10% of all white blood cells in the human body. They play multiple roles in immune function, including phagocytosis (gobbling up bacteria and other stuff), antigen presentation (identifying and altering other cells to the presence of foreign substances), and cytokine production (small proteins that regulate the immune response).

Monocytes express a molecule on their cell surfaces called CD14, and when human fibroblasts overexpressed Sox2 and miR-125b, they became CD14-expressing cells that looked and acted like monocytes. These cells were able to gobble up bacteria and other foreign material, and when transplanted into a laboratory animal, these directly reprogrammed cells generated cells that established the monocytic/macrophage lineage.

Cancer patients, and other patients with bone marrow diseases can have trouble making sufficient white blood cells. A technique like this can generate transplantable monocytes (at least in laboratory animals) without many of the drawbacks associated with reprogramming human cells into hematopoietic stem cells that possess true clinical potential. Also because this technique skips the pluipotency stage, it is potentially safer.

The Australian Football League Approves Regeneus’ Fat-Based HiQCell Stem Cell Therapy for Injured Players


The regenerative medicine company Regeneus Ltd announced this week that the Australian Football League or AFL has decided to approve, on a case-by-case basis, the use of its innovative HiQCell stem cell therapy as an optional treatment for injured AFL players. Football (soccer) players tend to suffer from impact-related osteoarthritis and tendonitis.

Regeneus’ Commercial Development Director for Human Health, Steve Barbera, said, “It’s pleasing that HiQCell has been approved under the new AFL Prohibited Treatments List released in March 2014. HiQCell also received clearance as an approved therapy from the Australian Sports Anti-Doping Authority (ASADA) for use with athletes who participate in sporting competitions subject to the WADA Anti-Doping Code, including the AFL. This recent decision by the AFL demonstrates a further level of compliance, specifically for players within that sporting code.”

Regeneus’ HiQCell treatment is the only stem cell treatment for osteoarthritis that has been subjected to the highest level of clinical scrutiny. A double-blind placebo-controlled safety trial is the gold standard for clinical trials. The particular clinical trial to which HiQCell treatments were subjected showed that HiQCell is safe and it reduces pain and halts cartilage degradation in arthritic joints. Additionally, the ongoing effects of HiQCell are being tracked in over 380 patients in an independent ethics-approved registry. A recent registry update demonstrated that patients are maintaining significant improvements 2 years after their treatment.

HiQCell has already been used to treat several high-profile athletes across several sporting codes, including the National Rugby League, which was announced on May 7th, 2014. It is encouraging for Regeneus that elite sports patients can use their HiQ therapy to much quickly return to sports from hard-to-treat injuries and continue their playing careers after receiving this innovative therapy.

Dr Phil Bloom, a Melbourne based Specialist Sports and Exercise Physician and HiQCell treating medical practitioner, said, “permission from the AFL for HiQCell treatment is a positive progression as it allows for an additional option for players with conditions that are unresponsive to existing treatments”.

The HiQCell treatment uses stem cells harvested from a small amount of a patient’s fat. After separating and concentrating these regenerative cells, they are re-injected in osteoarthritic-affected joints such as knees, hips and ankles. The HiQCell treatment reduces inflammation and repairs damaged tissue when it is carried out under the supervision of a medical practitioner.

Mesenchymal Stem Cells Treat Dry Eye Syndrome in Mice


Nearly 10% of all Americans suffer from Dry eye syndrome (DES), which makes this disorder one of the most common ocular diseases. Most of the currently-available treatments are palliative, but few therapeutic agents target the biological causes of DES. Many factors contribute to DES, but one of the most important factors in the cause of DES is inflammation of the ocular surface.

Since mesenchymal stem cells (MSCs) have been shown to suppress inflammation, using MSCs to treat DES seems to be a viable treatment option. MSCs can also repair tissues by regulating excessive immune responses in various diseases.

Thus Joo Youn Oh from the Seoul National University in Seoul, Korea and his colleagues investigated the therapeutic potential of MSCs in a mouse model of an inflammation-mediated dry eye. They induced DES in these mice by injecting a plant protein into the eye that grabs sugars into the eye. This protein injection dries out the eyes in these mice and induces a kind of DES-like condition.

Then they found that the administration of MSCs into the eye reduced the infiltration of immune cells into the eye and overall decreased eye inflammation. Administration of MSCs into the eye also significantly increased tear production and also increased the number of conjunctival goblet cells, which secrete lubricating mucus so that the eye lid slides gently over the eye surface. Further investigation showed that the structural integrity of the eye surface, known as the cornea, was well-preserved by MSCs.

When taken together, ocular administration of MSCs seem to suppress the inflammation that either accompanies or contributes to DES.  These results also suggest that MSCs may provide a potential therapy for those diseases that cause inflammation of the ocular surface and adversely affect the eye because of it.  

Induced Pluripotent Stem Cells Make Lungs


Since my father died of disseminated lung cancer (squamous cell carcinoma), this report has particular meaning to me.

When a person dies, their lungs can be harvested and stripped of their cells. This leaves a so-called “lung scaffold” that can then be used to build new lungs by means of tissue engineering techniques. Lung scaffolds consist of a protein called collagen, and sugar-rich proteins called “proteoglycans” (say that fast five times) and a rubber band-like protein called elastin. Depending on how the lung scaffolds are made more or less of these components can remain in the lung scaffold (see TH Peterson, and others, Cells Tissues Organs. Feb 2012; 195(3): 222–231). The important thing is that the cells are gone and this greatly reduces the tendency for the lung scaffold to be rejected by someone else’s immune system.

Once a lung scaffold is generated from a whole lung, cells can be used to reconstitute the lung. The key is to use the right cell type or mix of cell types and to induce them to form mature lung tissue.

The laboratory of Harald Ott at Harvard University Medical School used a technique called “perfusion decellularization” to make lung scaffolds from the lungs of cadavers. Then he and his co-workers used lung progenitor cells that were derived from induced pluripotent stem cells (iPSCs). This study was published in The Annals of Thoracic Surgery, and it examined the ability of iPSCs to regenerate a functional pulmonary organ

Whole lungs from rat and human cadavers were stripped of their living material by means of constant-pressure perfusion with a strong detergent called sodium dodecyl sulfate (SDS; 0.1% if anyone is interested). Ott and his crew then sectioned some of the resulting lung scaffolds and left others intact, and then applied human iPSCs that had been differentiated into developing lung tissue.

Lung tissue develops from the front part of the developing gut. This tissue is called “endoderm,” since it is in the very innermost layer of the embryo.

Lung Development

Therefore, the iPSCs were differentiated into endoderm with a cocktail of growth factors (FGF, Wnt, Retinoic acid), and then further differentiated in the anterior endoderm (foregut; treated cells with Activin-A, followed by transforming growth factor-β inhibition), and then even further differentiated into anterior, ventral endoderm, which is the precise tissue from which lungs form. In order to be sure that this tissue is lung tissue, they must express a gene called NK2 homeobox 1 (Nkx2.1). If these cells express this gene, then they are certainly lung cells.

Ott and his group showed that their differentiate iPSCs strongly expressed Nkx2.1, and then seeded them on slices and whole lung scaffolds. Then Otts’s group maintained these tissues in a culture system that was meant to mimic physiological conditions.

Those cells cultured on decellularized lung slices divided robustly and committed to the lung lineage after 5 days. Within whole-lung scaffolds and under the physiological mimicking culture, cells upgraded their expression of Nkx2.1. When the culture-grown rat lungs were transplanted into rats, they were perfused and ventilated by host vasculature and airways.

Thus these decellularized lung scaffolds supports the culture and lineage commitment of human iPSC-derived lung progenitor cells. Furthermore, whole-organ scaffolds and a culture system that mimics physiological conditions, allows scientists to enable seeding a combination of iPSC-derived endothelial and epithelial progenitors and enhance early lung fate. Transplantation of these laboratory-grown lungs seem to further maturation of these grafted lung tissues.