Umbilical Cord Blood Cells Combined with Growth Factors Improves Traumatic Brain Injury Outcomes


Approximately 2 million Americans experience a traumatic brain injury every year. Most of these are individuals who employed in high-risk jobs such as the military, firefighting, police work and others types of essential but highly dangerous jobs. No matter how small the injury, individuals who have suffered a traumatic brain injury (TBI) can suffer from a whole host of motor, behavioral, intellectual and cognitive disabilities over the short or long-term. Unfortunately, there are few clinical treatments for TBI, and the few we have are rather ineffective.

In order to design better, more effective treatments for TBI, neuroscientists at the Center of Excellence for Aging and Brain Repair, Department of Neurosurgery in the USF Health Morsani College of Medicine, University of South Florida, have used umbilical cord stem cells in combination with growth factors to treat TBIs in mice.

This study investigated the ability of several strategies, both by themselves and in combination with other therapies, to treat rats with a laboratory form of TBI. In particular, the USF team discovered that a combination of human umbilical cord blood cells (hUBCs) and granulocyte colony stimulating factor (G-CSF), a growth factor, was more therapeutic than either administered alone, or each with saline, or saline alone.

“Chronic TBI is typically associated with major secondary molecular injuries, including chronic neuroinflammation, which not only contribute to the death of neuronal cells in the central nervous system, but also impede any natural repair mechanism,” said study lead author Cesar V. Borlongan, PhD, professor of neurosurgery and director of USF’s Center of Excellence for Aging and Brain Repair. “In our study, we used hUBCs and G-CSF alone and in combination. In previous studies, hUBCs have been shown to suppress inflammation, and G-CSF is currently being investigated as a potential therapeutic agent for patients with stroke or Alzheimer’s disease.”

In previous studies, Borlongan and his team showed that G-CSF can mobilize stem cells from bone marrow and induce them to home to and infiltrate injured tissues. While there, the cells promote neural cell self-repair. Cells from human umbilical cord blood also have the ability to suppress inflammation and promote cell growth.

“Our results showed that the combined therapy of hUBCs and G-CSF significantly reduced the TBI-induced loss of neuronal cells in the hippocampus,” said Borlongan. “Therapy with hUBCs and G-CSF alone or in combination produced beneficial results in animals with experimental TBI. G-CSF alone produced only short-lived benefits, while hUBCs alone afforded more robust and stable improvements. However, their combination offered the best motor improvement in the laboratory animals.”

“This outcome may indicate that the stem cells had more widespread biological action than the drug therapy,” said Paul R. Sanberg, distinguished professor at USF and principal investigator of the Department of Defense funded project. “Regardless, their combination had an apparent synergistic effect and resulted in the most effective amelioration of TBI-induced behavioral deficits.”

This particular study examined motor improvements or improvements in movement, but the USF group suggested that future combination therapy research should also include analysis of cognitive improvement in the laboratory animals with TBI.

In short, umbilical cord cell and growth factor treatments tested in animal models could offer hope for millions, including U.S. war veterans with traumatic brain injuries.

Post-script:  On Twitter, Alexey Bersenev made some very helpful observations about this paper.  In this paper, the authors used whole human umbilical cord blood.  They did not attempt to separate any of the different cell types from the cord blood.  Now when such whole blood is used, it is easy to assume that the stem cells in the blood that are doing the regenerative work.  However, as Alexey graciously pointed out, you cannot assume that the stem cells are responsible for the therapeutic effects for at least two main reasons:  1)  the number of stem cells in the cord blood is quite small relative to the other cells; 2) some of the non-stem cells in the blood turn out to have therapeutic effects.  See here and here.  I have seen some of these papers before, but I did not think much of them.  Therefore, until the cell populations in the umbilical cord blood are dissected out and studied, all we can say with any confidence is SOMETHING in the cord blood is conveying a therapeutic effect, but the identity of the therapeutic culprit remains unclear at this time.

Stem Cells from Muscle Can Repair Nerve Damage After Injury


Researchers from the University of Pittsburgh School of Medicine have discovered that stem cells derived from human muscle tissue can repair nerve damage and restore function in an animal model of sciatic nerve injury. These data have been recently published online in the Journal of Clinical Investigation, but more importantly, this work demonstrates the feasibility of cell therapy for certain nerve diseases, such as multiple sclerosis.

Presently there are few treatments for peripheral nerve damage. Peripheral nerve damage can leave patients with chronic pain, impaired muscle control and decreased sensation.

The senior author of this work, Henry J. Mankin, serves as the Chair in Orthopedic Surgery Research, Pitt School of Medicine, and deputy director for cellular therapy, McGowan Institute for Regenerative Medicine, and said, “This study indicates that placing adult, human muscle-derived stem cells at the site of peripheral nerve injury can help heal the lesion. The stem cells were able to make non-neuronal support cells to promote regeneration of the damaged nerve fiber.”

Muscle-derived stem cells

Workers in Mankin’s laboratory, in collaboration with Dr. Mitra Lavasani, assistant professor of orthopedic surgery, Pitt School of Medicine, grew human muscle-derived stem/progenitor cells in culture by using a culture medium suitable for nerve cells. In culture, Lavasani, Mankin and their colleagues found that when these muscle-derived stem cells were grown in the presence of specific nerve-growth factors, they differentiated into neurons and glial cells. Glial cells act as support cells from neurons. One type of glial cell that these muscle-derived stem cells could differentiate into was Schwann cells, which are the cells that form the myelin sheath around the axons of neurons to accelerate the speed at which nerve impulses are conducted.

Schwann Cell

Mankin and his colleagues then injected these human muscle-derived stem/progenitor cells into mice that had a quarter-inch injury in their right sciatic nerve. The sciatic nerve controls right leg movement. Six weeks later, the nerve had fully regenerated in stem-cell treated mice, but the untreated group showed only limited nerve regrowth and functionality. In other tests, 12 weeks after treatments, the stem cell-treated mice were able to keep their treated and untreated legs balanced at the same level while being held vertically by their tails. When the treated mice ran through a special maze, analyses of their paw prints showed that their gait, which had been abnormal, was now completely normal. Finally, treated and untreated mice experienced loss of muscle mass after nerve damage, but only the stem cell-treated mice regained normal muscle mass by 72 weeks after nerve damage.

sciatic-nerve

“Even 12 weeks after the injury, the regenerated sciatic nerve looked and behaved like a normal nerve,” Dr. Lavasani said. “This approach has great potential for not only acute nerve injury, but also conditions of chronic damage, such as diabetic neuropathy and multiple sclerosis.”

Drs. Huard and Lavasani and the team are now trying to understand how the human muscle-derived stem/progenitor cells triggered injury repair. They are also developing delivery systems, such as gels, that could hold the cells in place at larger injury sites.

The co-authors of this paper included Seth D. Thompson, Jonathan B. Pollett, Arvydas Usas, Aiping Lu, Donna B. Stolz, Katherine A. Clark, Bin Sun, and Bruno Péault, all of whom are from the University of Pittsburgh.

Human STAP cells – Troubling Possibilities


Soon after the publication of this paper that adult mouse cells could be reprogrammed into embryonic-like stem cells simply by exposing them to acidic environments or other stresses , Charles Vacanti at Harvard Medical School has reported that he and his colleagues have demonstrated that this procedure works with human cells.

STAP cells or stimulus-triggered acquisition of pluripotency cells were derived by Vacanti and his Japanese collaborators last year. These new findings show that adult cells can be reprogrammed into embryonic-like stem cells without genetic engineering. However, this technique worked well in mouse cells, but it was not clear that it would work with human adult cells.

Vacanti and others shocked the world when they published their paper in the journal Nature earlier this year when they announced that adult cells in mice could be reprogrammed through exposure to stresses and proper culture conditions.

Now Vacanti has made good on his promise to test his protocol on human adult cells. In the photo below, provided by Vacanti, human adult cells were reprogrammed to a pluripotent state by exposing them to stresses, followed by growth in culture under specific conditions.

Human STAP cells
Human STAP cells

“If they can do this in human cells, it changes everything, said Robert Lanza of Advanced Cell Technologies in Marlborough, Massachusetts. Such a procedure promises cheaper, faster, and potentially more flexible cells for regenerative medicine, cancer therapy and cell and tissue cloning.

Vacanti and his colleagues say they have taken human fibroblast cells and tested several environmental stressors on them to recreate human STAP cells. He will not presently disclose which particular stressors were applied, he says the resulting cells appear similar in form to the mouse STAP cells. His team is in the process of testing to see just how stem-cell-like these cells are.

According to Vacanti, the human cells took about a week to resemble STAP cells, and formed spherical clusters just like their mouse counterparts. Vacanti and his Harvard colleague Koji Kojima emphasized that these results are only preliminary and further analysis and validation is required.

Bioethical problems potentially emerge with STAP cells despite their obvious potential. The mouse cells that were derived and characterized by Vacanti’s group and his collaborators were capable of making placenta as well as adult cell types. This is different from embryonic stem cells, which can potentially form all adult cell types, but typically do not form placenta. Embryonic stem cells, therefore, are pluripotent, which means that they can form all adult cell types. However, the mouse STAP cells can form all embryonic and adult cell types and are, therefore, totipotent. Mouse STAP cells could form an entirely new mouse. While it is now clear if human STAP cells, if they in fact exist, have this capability, but if they do, they could potentially lead to human cloning.

Sally Cowley, who heads the James Martin Stem Cell Facility at the University of Oxford, said of Vacanti’s present experiments: “Even if these are STAP cells they may not necessarily have the same potential as mouse ones – they may not have the totipotency – which is one of the most interesting features of the mouse cells.”

However the only cells known to be naturally totipotent are in embryos that have only undergone the first couple of cell divisions immediately after fertilization. According to Cowley, any research that utilizes totipotent cells would have to be under very strict regulatory surveillance. “It would actually be ideal if the human cells could be pluripotent and not totipotent – it would make everyone’s life a lot easier,” she opined.

Cowley continued: “However, the whole idea that adult cells are so plastic is incredibly fascinating,” she says. “Using stem cells has been technically incredibly challenging up to now and if this is feasible in human cells it would make working with them cheaper, faster and technically a lot more feasible.”

This is all true, but Robert Lanza from Advanced Cell Technology in Marlborough, Massachusetts, a scientist with whom I have often deeply disagreed, noted: “The word totipotent brings up all kinds of issues,” says Robert Lanza of Advanced Cell Technology in Marlborough, Massachusetts. “If these cells are truly totipotent, and they are reproducible in humans then they can implant in a uterus and have the potential to be turned into a human being. At that point you’re entering into a right-to-life quagmire”

A quagmire indeed, for Vacanti has already talked about using these STAP cells to clone human embryos. Think of it: the creation of very young human beings just for the purpose of ripping them apart and using their cells for research or medicine. Would we allow this if the embryo were older; say the age of a toddler? No we would rightly condemn it as murder, but because the embryo is very young, that somehow counts against it. This is little more than morally grading the embryo according to astrology.

Therefore, whole Vacanti’s experiments are exciting and novel, they hold chilling possibilities. Lanza is right, and it is doubtful that scientists would show the same deference or sensitivities to the moral exigencies he has shown.

Stem Cell-based Baldness Cure One Step Closer


Scientists might be able to offer people with less that optimal amounts of hair new hope when it comes to reversing baldness. Researchers from the University of Pennsylvania say they’ve moved closer to using stem cells to treat thinning hair — at least in mice.

This group said that the use of stem cells to regenerate missing or dying hair follicles is considered a potential way to reverse hair loss. However, the technology did not exist to generate adequate numbers of hair-follicle-generating stem cells.

But new findings indicate that this may now be achievable. “This is the first time anyone has made scalable amounts of epithelial stem cells that are capable of generating the epithelial component of hair follicles,” Dr. Xiaowei Xu, an associate professor of dermatology at Penn’s Perelman School of Medicine, said in a university news release.

According to Xu, those cells have many potential applications that extend to wound healing, cosmetics and hair regeneration.

In their new study, Xu’s team converted induced pluripotent stem cells (iPSCs) – reprogrammed adult stem cells with many of the characteristics of embryonic stem cells – into epithelial stem cells. This is the first time this has been done in either mice or people.

The epithelial stem cells were mixed with certain other cells and implanted into mice. They produced the outermost layers of the skin and hair follicles that are similar to human hair follicles. This study was published in the Jan. 28 edition of the journal Nature Communications.

This suggests that these cells might eventually help regenerate hair in people.

Xu said this achievement with iPSC-derived epithelial stem cells does not mean that a treatment for baldness is around the corner. Hair follicles contain both epithelial cells and a second type of adult cells called dermal papillae.

“When a person loses hair, they lose both types of cells,” Xu said. “We have solved one major problem — the epithelial component of the hair follicle. We need to figure out a way to also make new dermal papillae cells, and no one has figured that part out yet.”

Experts also note that studies conducted in animals often fail when tested in humans.

Vascular Progenitors Made from Induced Pluripotent Stem Cells Repair Blood Vessels in the Eye Regardless of the Site of Injection


Johns Hopkins University medical researchers have reported the derivation of human induced-pluripotent stem cells (iPSCs) that can repair damaged retinal vascular tissue in mice. These stem cells, which were derived from human umbilical cord-blood cells and reprogrammed into an embryonic-like state, were derived without the conventional use of viruses, which can damage genes and initiate cancers. This safer method of growing the cells has drawn increased support among scientists, they say, and paves the way for a stem cell bank of cord-blood derived iPSCs to advance regenerative medical research.

In a report published Jan. 20 in the journal Circulation, Johns Hopkins University stem cell biologist Elias Zambidis and his colleagues described laboratory experiments with these non-viral, human retinal iPSCs, that were created generated using the virus-free method Zambidis first reported in 2011.

“We began with stem cells taken from cord-blood, which have fewer acquired mutations and little, if any, epigenetic memory, which cells accumulate as time goes on,” says Zambidis, associate professor of oncology and pediatrics at the Johns Hopkins Institute for Cell Engineering and the Kimmel Cancer Center. The scientists converted these cells to a status last experienced when they were part of six-day-old embryos.

Instead of using viruses to deliver a gene package to the cells to turn on processes that convert the cells back to stem cell states, Zambidis and his team used plasmids, which are rings of DNA that replicate briefly inside cells and then are degraded and disappear.

Next, the scientists identified and isolated high-quality, multipotent, vascular stem cells that resulted from the differentiation of these iPSC that can differentiate into the types of blood vessel-rich tissues that can repair retinas and other human tissues as well. They identified these cells by looking for cell surface proteins called CD31 and CD146. Zambidis says that they were able to create twice as many well-functioning vascular stem cells as compared with iPSCs made with other methods, and, “more importantly these cells engrafted and integrated into functioning blood vessels in damaged mouse retina.”

Working with Gerard Lutty, Ph.D., and his team at Johns Hopkins’ Wilmer Eye Institute, Zambidis’ team injected these newly iPSC-derived vascular progenitors into mice with damaged retinas (the light-sensitive part of the eyeball). The cells were injected into the eye, the sinus cavity near the eye or into a tail vein. When Zamdibis and his colleagues took images of the mouse retinas, they found that the iPSC-derived vascular progenitors, regardless of injection location, engrafted and repaired blood vessel structures in the retina.

“The blood vessels enlarged like a balloon in each of the locations where the iPSCs engrafted,” says Zambidis. Their vascular progenitors made from cord blood-derived iPSCs compared very well with the ability of vascular progenitors derived from fibroblast-derived iPSCs to repair retinal damage.

Zambidis says that he has plans to conduct additional experiments in diabetic rats, whose conditions more closely resemble human vascular damage to the retina than the mouse model used for the current study, he says.

With mounting requests from other laboratories, Zambidis says he frequently shares his cord blood-derived iPSC with other scientists. “The popular belief that iPSCs therapies need to be specific to individual patients may not be the case,” says Zambidis. He points to recent success of partially matched bone marrow transplants in humans, shown to be as effective as fully matched transplants.

“Support is growing for building a large bank of iPSCs that scientists around the world can access,” says Zambidis, although large resources and intense quality-control would be needed for such a feat. However, Japanese scientists led by stem-cell pioneer Shinya Yamanaka are doing exactly that, he says, creating a bank of stem cells derived from cord-blood samples from Japanese blood banks.

Synthetic Matrices that Induce Stem Cell-Mediated Bone Formation


Biomimetic matrices resemble living structures even though they are made from synthetic materials. Researchers in the laboratory of Shyni Varghese at the UC San Diego Jacobs School of Engineering have used calcium phosphate to direct mesenchymal stem cells to form bone. In doing so, Varghese and his colleagues have identified a surprising pathway from biomaterials to bone.

Varghese and his colleagues think that their work may point out new targets for treating bone defects, such as major fractures, and bone metabolic disorders such as osteoporosis.

The first goal of this research was to use materials to build something that looked like bone. This way, stem cells harvested from bone marrow (the squishy stuff inside our bones) could sense the presence of bone and differentiate into osteoblasts, the cells in our bodies that build bone.

“We knew for years that calcium phosphate-based materials promote osteogenic differentiation of stem cells, but none of use knew why.” said Varghese. “As engineers, we want to build something that is reproducible and consistent, so we need to know how building factors contribute to this end.”

Varghese and co-workers discovered that phosphate ions dissolved from calcium phosphate-based materials and these stray phosphate ions are taken up by the stem cells and used for the production of adenosine triphosphate or ATP. ATP is the energy currency of the cell, and it is the way cells store energy in a form that is readily usable for powering other reactions.

In stem cells, the generation of ATP eventually increases the intracellular concentration of the ATP breakdown product adenosine, and adenosine signals to stem cells to differentiate into osteoblasts and make bone.

Varghese said that she was surprised that “the biomaterials were connected to metabolic pathways. And we didn’t know how these metabolic pathways could influence stem cells,” and their commitment to bone formation.

These results also explain another clinical observation. Plastic surgeons have been using fat-based stem cells for eyelid lifts, breast augmentation, and other types of reconstructive surgeries. In once case, a plastic surgeon injected a dermal filler that contained calcium hydroxyapatite with the fat-based stem cells into a woman’s eyelid to provide an eye lift. However, the stem cells formed bone, and the poor lady’s lid painfully clicked every time she blinked and she had to have surgery to remove the ectopic bone. These results from Varghese’s laboratory explains why these fat-based stem cells formed bone in this case, and great care should be taken to never use such fillers in fat-based transplantation procedures.

Frozen Stem Cells Taken from a Cadaver Five Years Ago Vigorously Grow


It is incumbent upon regenerative medicine researchers to discover non-controversial sources of stem cells that are safe and abundant. To that end, harvesting stem cells from deceased donors might represent an innovative and potentially unlimited reservoir of different stem cells.

In this present study, tissues from the blood vessels of cadavers were used as a source of human cadaver mesenchymal stromal/stem cells (hC-MSCs). The scientists in this paper successfully isolated cells from arteries after the death of the patient and subjected them to cryogenic storage in a tissue-banking facility for at least 5 years.

After thawing, the hC-MSCs were re-isolated with high-efficiency (12 × 10[6]) and showed all the usual characteristics of mesenchymal stromal cells. They expressed all the proper markers, were able to differentiate into the right cell types, and showed the same immunosuppressive activity as mesenchymal stromal cells from living persons.

Thus the efficient procurement of stem cells from cadavers demonstrates that such cells can survive harsh conditions, low oxygen tensions, and freezing and dehydration. This paves the way for a scientific revolution where cadaver stromal/stem cells could effectively treat patients who need cell therapies.

See Sabrina Valente, and others, Human cadaver multipotent stromal/stem cells isolated from arteries stored in liquid nitrogen for 5 years.  Stem Cell Research & Therapy 2014, 5:8.

Controlling Transplanted Stem Cells from the Inside Out


Scientists have worked very hard to understand how to control stem cell differentiation.  However, despite how well you direct stem cell behavior in culture, once those stem cells have been transplanted, they will often do as they wish.  Sometimes, transplanted stem cells surprise people.

Several publications describe stem cells that, once transplanted undergo “heterotropic differentiation.” Heterotropic differentiation refers to tissues that form in the wrong place. For example, one lab found that transplantation of mesenchymal stem cells into mouse hearts after a heart attack produced bone (don’t believe me – see Martin Breitbach and others, “Potential risks of bone marrow cell transplantation into infarcted hearts.” Blood 2007 110:1362-1369).  Bone in the heart – that can’t be good. Therefore, new ways to control the differentiation of cells once they have been transplanted are a desirable goal for stem cell research.

From this motivation comes a weird but wonderful paper from Jeffrey Karp and James Ankrum of Brigham and Women’s Hospital and MIT, respectively, that loads stem cells with microparticles that give the transplanted stem cell continuous cues that tell them how to behave over the course of days or weeks as the particles degrade.

“Regardless of where the cell in the body, it’s going to be receiving its cues from the inside,” said Karp. “This is a completely different strategy than the current method of placing cells onto drug-doped microcarriers or scaffolds, which is limiting because the cells need to remain in close proximity to those materials in order to function. Also these types of materials are too large to be infused into the bloodstream.”

Controlling cells in culture is relatively easy. If cells take up the right molecules, they will change their behavior. This level of control, however, is lost after the cell is transplanted. Sometimes implanted cells readily respond to the environment within the body,. but other times, their behavior is erratic and unpredictable. Karp’s strategy, which her called “particle engineering,” corrects this problem by turning cells into pre-programmable units. The internalized particles stably remain inside the transplanted cell and instruct it precisely how to act. It can direct cells to release anti-inflammatory factors, or regenerate lost tissue and heal lesions or wounds.

“Once those particles are internalized into the cells, which can take on the order of 6-24 hours, we can deliver the transplant immediately or even cryopreserve the cells,” said Karp. “When the cells are thawed at the patient’s bedside, they can be administrated and the agents will start to be released inside the cells to control differentiation, immune modulation or matrix production, for example.”

It could take more than a decade for this type of cell therapy to be a common medical practice, but to speed up the pace of this research, Karp published the study to encourage others in the scientific community to apply the technique to their various fields. Karp’s paper also illustrates the range of different cell types that can be controlled by particle engineering, including stem cells, cells of the immune system, and pancreatic cells.

“With this versatile platform, which leveraged Harvard and MIT experts in drug delivery, cell engineering, and biology, we’ve demonstrated the ability to track cells in the body, control stem cell differentiation, and even change the way cells interact with immune cells, said Ankrum, who is a former graduate student in Karp’s laboratory. “We’re excited to see what applications other researchers will imagine using this platform.”

Skin-Based Stem Cells Repair Peripheral Nerves


Italian scientists from Milan have used skin-derived stem cells in combination with a previously developed collagen tube to successfully bridge the gaps in injured nerves in a rat model, On the strength of that animal model system, the Italian group successfully used this procedure to heal the damaged peripheral nerves in the upper arms of a patient whose only other option was limb amputation.

“Peripheral nerve repair with satisfactory functional remains a great surgical challenge, especially for severe nerve injuries resulting in extended nerve defects,” said the corresponding author of this study Dr, Yvan Torrente of the Department of Pathophysiology and Transplantation at the University of Milan. “However, we hypothesized that the combination of autologous (self donated) stem cells placed in collagen tubes to bridge gaps in the damaged nerves would restore the continuity of injured nerves and save from amputation the upper arms of a patient with poly-injury to motor and sensory nerves.”

Although autologous nerve grafting has been the “gold standard” for reconstructive surgeries, these researchers recognized the disadvantages of such a procedure. Graft availability is the first drawback of autologous nerve grafting. Secondly, the condition of the donor site or “donor site morbidity.” If the donor site is in bad shape, taking a nerve from that site will probably make the donor site worse and provide a nerve that does not work as well. Finally, neuropathic pain is also an issue.

Autologous skin-derived stem cells have several advantages over autologous nerve grafts. First, the skin provides an accessible source of stem cells that are rapidly expandable in culture. Secondly, these skin-derived cells are capable of survival and integration within host tissues.

The NeuraGen nerve guide is a tiny collagen tube that connects the two damaged ends of a nerve together to mediate and expedite nerve healing.  NeuraGen tubes guide the transplanted stem cells to the gaps in the damaged nerves.  Torrente and his co-workers developed and tested the NeuraGen tubes in rats, and the US Food and Drug Administration (FDA) has approved NeuraGen for use in human patients.  See this figure from the NeuraGen web site:

NeuraGen_Open

 

Torrente and others successfully used skin-derived stem cells and NeuraGen tubes to heal the severed sciatic nerves in rats.  Therefore, once the FDA approved NeuraGen tubes, Torrente tried NeuraGen tubes in human patients with severe peripheral nerve damage.

A three-year follow-up on one particular patient showed that injured median and ulnar nerves showed extensive healing as ascertained by magnetic resonance imaging.  Functional tests, such as pinch gauge tests, static two-point discrimination and monofilament touch tests established the functional recovery of these peripheral nerves in the patient.

“Our three-year follow-up has witnesses nerve regeneration with suitable functional recovery in the patient and the salvage of upper arms from amputation,” said researchers from Torrente’s group.  “This finding opens an alternative avenue for patients who are at-risk of amputation after the injury to important nerves.”

Treating Age-Related Blindness with a Stem Cell Replacement Method


A collaboration between German and American scientists in New York City has resulted in the invention of a new method for transplanting stem cells into the eyes of patients who suffer from age-related macular degeneration, which is the most frequent cause of blindness. In an animal test, the implanted stem cells survived in the eyes of rabbits for several weeks.

Approximately 4.5 millino people in Germany suffer from age-related macular degeneration (AMD), which causes gradual loss of visual acuity and affects the ability to read, drive a car or do fine work. The center of the vision field becomes blurry as though covered by a veil. This vision loss is a consequence of the death of cells in the retinal pigment epithelium or RPE, which lies are the back of the eye, underneath the neural retina.

Inflammation within the RPE causes AMD. Increased inflammation prevents efficient recycling of metabolic waste products, and the build-up of toxic wastes causes RPE die off. Without the RPE, the photoreceptors in front of the RPE cells that also depend on the RPE to repair the damage suffered from continuous light exposure, begin to die off too.

RPE

Retinal Pigmented Epithelium

Presently no cure exists for AMD, but scientists at Bonn University, in the Department of Ophthalmology and New York City have tested a new procedure that replaces damaged RPE cells.

In the present experiment, RPE cells made from human stem cells were successfully implanted into the retinas of rabbits.

Boris V. Stanzel, the lead author of this work, said, “These cells have now been used for the first time in research for transplantation purposes.”

The adult RPE stem cells were characterized by Timothy Blenkinsop and his colleagues at the Neural Stem Cell Institute in New York City. Blenkinsop designed methods to isolate and grow these cells. He also flew to Germany to assist Dr. Stanzel with the transplantation experiments.  Blenkinsop obtained his RPE cells from human cadavers, and he grew them on polyester matrices.

These experiments demonstrate that RPE cells obtained from adult stem cells can replace cells destroyed by AMD. This newly developed transplantation method makes it possible to test which stem cells lines are most suitable for transplantation into the eye.

Stem Cell-Based Gene Therapy Restores Normal Skin Function


Michele De Luca from the University of Modena, Italy and his collaborator Reggio Emilia have used a stem cell-based gene therapy to treat an inherited skin disorder.

Epidermolysis bullosa is a painful skin disorder that causes the skin to be very fragile and blister easily. These blisters can lead to life-threatening infections. Unfortunately, no cure exists for this condition and most treatments try to alleviate the symptoms and infections.

Stem cell-based therapy seems to be one of the best ways to treat this disease, there are no clinical studies that have examined the long-term outcomes of such a treatment.

However, De Luca and his colleagues have examined a particular patients with epidermolysis bullosa who was treated with a stem cell-based gene therapy nearly seven years ago as part of a clinical trial.

The treatment of this patient has established that transplantation of a small quantity of stem cells into the skin on this patient’s legs restored normal skin function without causing any adverse side effects.

“These findings pave the way for the future safe use of epidermal stem cells for combined cell and gene therapy of epidermolysis bullosa and other genetic skin diseases,” said Michele De Luca.

De Luca and his research team found that their treatment of their patient, named Claudio, caused the skin covering his upper legs to looker normal and show no signs of blisters. To treat Claudio, De Luca and his colleague extracted skin cells from Claudio’s palm, used genetic engineering techniques to correct the genetic defect in the cells, and then transplanted these cells back into the skin of his upper legs. This was part of a clinical trial conducted at the University of Modena.

Claudio’s legs also showed no signs of tumors and the small number of transplanted cells sufficiently repaired Claudio’s skin long-term. Keep in mind that Claudio’s skin cells had undergone approximately 80 cycles of cell division and still had many of the features of palm skin cells, they show proper elasticity and strength and did not blister.

“This finding suggests that adult stem cell primarily regenerate the tissue in which they normally reside, with little plasticity to regenerate other tissues,” De Luca said. “This calls into question the supposed plasticity of adult stem cells and highlights the need to carefully chose the right type of stem cell for therapeutic tissue regeneration.”

I think De Luca slightly overstates his case here. Certainly choosing the right stem cells is crucial for successful stem cell treatments, but to take stem cells from skin, which are dedicated to making skin and expect them to form other tissues is unreasonable. However, several experiments have shown that stem cells from hair follicles and form neural tissues and several other cell types as well (see Jaks V, Kasper M, Toftgård R. The hair follicle-a stem cell zoo. Exp Cell Res. 2010 May 1;316(8):1422-8).

Adult stem cells have limited plasticity to be sure, but their plasticity is far greater than originally thought and a wealth of experiments have established that.

Despite these quibbles, this is a remarkable experiment that illustrates the feasibility and safety of such a treatment.  A larger problem is that large quantities of cells will be required to treat a person.  It is doubtful that small skin biopsies around the body can provide enough cells to treat the whole person.  Therefore, this might a case for induced pluripotent skin cells, which seriously complicates this treatment strategy.

Stem Cell Therapy Following Meniscus Knee Surgery Reduces Pain and Regenerates Meniscus


According to a new study published in the January issue of the Journal of Bone and Joint Surgery (JBJS), a single stem cell injection after meniscus knee surgery can provide pain relief and aid in meniscus regrowth.

In the US alone, over one million knee arthroscopy procedures are performed each year. These surgeries are usually prescribed to treat tears to the wedge-shaped piece of cartilage on either side of the knee called the “meniscus.” The meniscus acts as an important shock absorber between the thighbone (femur) and the shinbone (tibia) at the knee-joint.

Knee-Ligament-Pain-and-Strains-Meniscus-Tear-and-Pain

This novel study, “Adult Human Mesenchymal Stem Cells (MSC) Delivered via Intra-Articular Injection to the Knee, Following Partial Medial Meniscectomy,” examined 55 patients who had undergone a surgical removal or all or part of a torn meniscus (known as a partial medial meniscectomy). Each patient was randomly assigned to one of three treatment groups: Groups A, B and C. The 18 patients in group A received a “low-dose” injection of 50 million stem cells within seven to 10 days after their meniscus surgery. Another 18 patients in group B received a higher dose of 150 million stem cells seven to ten days after their knee surgery. The controls group consisted of 19 patients who received injections of sodium hyaluronate only (no stem cells). All patients were evaluated to determine the safety of the procedure, the degree of meniscus regeneration (i.e. with MRI and X-ray images), the overall condition of the knee-joint, and the clinical outcomes through two years. Most of the patients enrolled in this study had some arthritis, but patients with severe (level three or four) arthritis, were excluded from the study.

Most of the patients who had received stem cell treatments reported a significant reduction in pain. 24 percent of the patients in one MSC group and 6 percent of the other showed at least a 15 percent increase in meniscal volume at one year. Unfortunately, there was no additional increase in meniscal volume at year two.

“The results demonstrated that high doses of mesenchymal stem cells can be safely delivered in a concentrated manner to a knee-joint without abnormal tissue formation,” said lead study author C. Thomas Vangsness, Jr., MD. “No one has ever done that before.” In addition, “the patients with arthritis got strong improvement in pain” and some experienced meniscal regrowth.

The key findings of this study are that there no abnormal (ectopic) tissue formation or “clinically important” safety issues identified. Also, 24 percent of the patients in the low-dose injection group (A) and six percent of the high-dose injection group (B) at one year showed “significantly increased meniscal volume,” as determined by an MRI, and this increase did not continue into the second year, but remained stable (should future studies try a second injection of MSCs?). Third, none of the patients in the control group (non-MSC group) showed significant meniscus regrowth. Finally, patients with osteoarthritis experienced a reduction in pain in the stem cell treatment groups, but there was no reduction in pain in the control (non-MSC group).

“The results of this study suggest that mesenchymal stem cells have the potential to improve the overall condition of the knee joint,” said Dr. Vangsness. “I am very excited and encouraged” by the results. With the success of a single injection, “it begs the question: What if we give a series of injections?”

New Tool for Stem Cell Transplantation into the Heart


Researchers from the famed Mayo Clinic, in collaboration with scientists at a biopharmaceutical biotechnology company in Belgium have invented a specialized catheter for transplanting stem cells into a beating heart.

This new device contains a curved needle with graded openings along the shaft of the needle. The cells are released into the needle and out through the openings in the side of the needle shaft. This results in maximum retention of implanted stem cells to repair the heart.

“Although biotherapies are increasingly more sophisticated, the tools for delivering regenerative therapies demonstrate a limited capacity in achieving high cell retention in the heart,” said Atta Behfar, the lead author of this study and a cardiologist. “Retention of cells is, of course, crucial to an effective, practical therapy.”

Researchers from the Mayo Clinic Center for Regenerative Medicine in Rochester, MN and Cardio3 Biosciences in Mont-Saint-Guibert, Belgium, collaborated to develop the device. Development of this technology began by modeling the dynamic motions of the heart in a computer model. Once the Belgium group had refined this computer model, the model was tested in North America for safety and retention efficiency.

These experiments showed that the new, curved design of the catheter eliminates backflow and minimizes cell loss. The graded holes that go from small to large diameters decrease the pressures in the heart and this helps properly target the cells. This new design works well in healthy and damaged hearts.

Clinical trials are already testing this new catheter. In Europe, the CHART-1 clinical trial is presently underway, and this is the first phase 3 trial to examine the regeneration of heart muscle in heart attack patients.

These particular studies are the culmination of years of basic science research at Mayo Clinic and earlier clinical studies with Cardio3 BioSciences and Cardiovascular Centre in Aalst, Belgium, which were conducted between 2009 and 2010.  This study, the C-CURE or Cardiopoietic stem Cell therapy in heart failURE study examined 47 patients, (15 control and 32 experimental) who received injections of bone marrow-derived mesenchymal stem cells from their own bone marrow into their heart muscle.  Control patients only received standard care.  After six months, those patients who received the stem cell treatment showed an increase in heart function and the distance they could walk in six minutes.   No adverse effects were observed in the stem cell recipients.

This study established the efficacy of mesenchymal stem cell treatments in heart attack patients.  However, other animal and computer studies established the efficacy of this new catheter for injecting heart muscle with stem cells.  Hopefully, the results of the CHART-1 study will be available soon.

Postscript:  The CHART-2 clinical trial is also starting.  See this video about it.

Stem Cells Treat Babies With Brittle Bone Disease While Still in the Womb


A new study published by the journal STEM CELLS Translational Medicine shows that stem cells can be effective in treating brittle bone disease, a debilitating and sometimes lethal genetic disorder.

Also known as osteogenesis imperfecta (OI), this genetic disorder was popularized by actor Samuel T. Jackson in the Bruce Willis movie “Unbreakable.” OI is characterized by fragile bones that cause patients to suffer hundreds of fractures over the course of a lifetime. According to the OI Foundation, other symptoms include muscle weakness, hearing loss, fatigue, joint laxity, curved bones, scoliosis, brittle teeth and short stature. In the more severe cases of OI, restrictive pulmonary disease also occurs. Unfortunately, to date no cure exists for OI.

Physicians use ultrasound to detect OI in babies before they are born. In this study, an international research team treated two patients for the disease with mesenchymal stem cells (MSCs) while the infants were still in the womb. After they were born, the babies were given additional mesenchymal stem cell treatments.

“We had previously reported on the prenatal transplantation for the patient with OI type III, which is the most severe form in children who survive the neonatal period,”said Cecilia Götherström, Ph.D., of the Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden. She and Jerry Chan, M.D., Ph.D., of the Yong Loo Lin School of Medicine and National University of Singapore, and KK Women’s and Children’s Hospital, led the study that also included colleagues from the United States, Canada, Taiwan and Australia.

“The first eight years after the prenatal transplant, our patient did well and grew at an acceptable rate. However, she then began to experience multiple complications, including fractures, scoliosis and reduction in growth, so the decision was made to give her another MSC infusion. In the two years since, she has not suffered any more fractures and improved her growth. She was even able to start dance classes, increase her participation in gymnastics at school and play modified indoor hockey,”Dr. Götherström added.

The second child suffered from a milder form of OI and received a stem cell transfusion 31 weeks into gestation and did not suffer any new fractures for the remainder of the pregnancy or during infancy. She followed her normal growth pattern — just under the third percentile in height, but when she was 13 months old, she stopped growing. Six months later, the doctors gave her another infusion of stem cells and she resumed growing at her previous rate.

“Our findings suggest that prenatal transplantation of autologous stem cells in OI appears safe and is of likely clinical benefit and that re-transplantation with same-donor cells is feasible. However, the limited experience to date means that it is not possible to be conclusive, for which further studies are required,”Dr. Chan said.

“Although the findings are preliminary, this report is encouraging in suggesting that prenatal transplantation may be a safe and effective treatment for this condition,”said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and director of the Wake Forest Institute for Regenerative Medicine.

Engineered Neural Stem Cells Deliver Anti-Cancer Drug to the Brain


Irinotecan is an anticancer drug that was approved for use in 1996. It is a modified version of the plant alkaloid camptothecin, and even though it shows significant activity against brain tumors in culture, but in a living body, this drug poorly penetrates the blood-brain barrier. Therefore irinotecan usually does not accumulate to appreciable levels in the brain and is typically not used to treat brain tumors.

That could change, however, if a new strategy published in paper by Marianne Metz and her colleagues from the laboratory of Karen Aboody at the Beckman Research Institute at the City of Hope in Duarte, California, in collaboration with colleagues from several other laboratories.

In this paper, Metz and her co-workers genetically engineered neural stem cells to express enzymes called “carboxylesterases.” These carboxyesterase enzymes convert irinotecan, which is an inactive metabolite, to the active form, which is known as “SN-38.” The efficient conversion of irinotecan to SN-38 in the brain greatly accelerates the therapeutic activity of this drug in the brain. Also, the constant conversion of irinotecan to another molecule accelerates the transport of irinotecan past the blood brain barrier.

To test this strategy. Metz and others grew the engineered neural stem cells in culture and measured their ability to make carboxylesterases in culture, and their ability to convert irinotecan into SN-38 in culture.  In both cases, the engineered neural stem cells made a boat-load of carboxylesterase and converted irinotecan into SN-38 in spades.  More importantly, the genetically engineered neural stem cells behaved exactly as they did before, which shows that the genetic manipulation of these cells did not change their properties.

Next, Metz others tested the ability of the engineered neural stem cells to kill human brain tumor cells in culture in the presence of irinotecan.  Once again, the genetically engineered neural stem cells effectively killed human brain tumor cells in culture in a irinotecan-concentration-dependent manner.  When these genetically engineered neural stem cells were injected into the brains of mice with brain tumors, intravenous administration of irinotecan produced high levels of SN-38 in the brain.  This shows that these cells have the capacity to increase the production of SN-38 in the brain.

This strategy is similar to other strategies that been used in various clinical trials, but because neural stem cells have a tendency to move into brain tumor tissue and surround it, they represent an efficient and effective way to deliver anticancer drugs to brain tumors.  Also, since the particular neural stem cell line used in this experiment (HB1.F3.CD) does not cause tumors and is also not recognized as foreign by the immune system, it is a particularly attractive stem cell line for such an anti-tumor strategy.

Umbilical Cord Blood Stem Cells in a Biodegradable Scaffold Regenerate Full-Thickness Skin Defects


In a new study published in the ASAIO Journal by Reza Zeinali and others in the laboratory of Kamal Asadipour, specific stem cell from umbilical cord blood called unrestricted somatic stem cells (USSCs) have been grown on a biodegradable scaffold to promote skin regeneration and wound healing.

USSCs are considered by many stem cell scientists to be a type of mesenchymal stem cell, but USSCs can be grown in the laboratory and have the ability to differentiate into a wide variety of adult cell types.

Asadipour and others used a material called PHBV or poly(3-hydroxybutyrate-co-3-hydroxyvalerate) to make a skin-like scaffold upon which the USSCs were grown. They discovered that attaching a molecule called “chitosan” to the PHBV made it quite resilient and a very good substrate for growing cells. When grown on these scaffolds, the USSCs adhered nicely to them and grew robustly.

Then Zeinali and his colleagues used these cell-impregnated scaffolds to treat open surgical wounds in laboratory rodents. After three weeks, the group treated with the cell grown on the scaffolds healed significantly better than those animals treated with just cells, just scaffolds, or neither.

Thus it seems likely that tissue-engineered skin made from modified PHBV scaffolds and embedded umbilical cord blood-based stem cells might be a potent treatment for wound patients with large injuries that do heal slowly.  In the words of the abstract of this paper, “These data suggest that chitosan-modified PHBV scaffold loaded with CB-derived USSCs could significantly contribute to wound repair and be potentially used in the tissue engineering.”

Some larger animal studies should further test this protocol and if it can augment the healing of large animal wounds, then human clinical trials should be considered.

A Patient’s Own Bone Marrow Stem Cells Defeat Drug-Resistant Tuberculosis


People infected with multidrug-resistant forms of tuberculosis could, potentially, be treated with stem cells from their own bone marrow. Even though this treatment is in the early stage of its development, the results of an early-stage trial of the technique show immense promise.

British and Swedish scientists have tested this procedure, which could introduce a new treatment strategy for the estimated 450,000 people worldwide who have multi drug-resistant (MDR) or extensively drug-resistant (XDR) TB.

This study, which was published in the medical journal, The Lancet, showed that over half of 30 drug-resistant TB patients treated with a transfusion of their own bone marrow stem cells were cured of the disease after six months.

“The results … show that the current challenges and difficulties of treating MDR-TB are not insurmountable, and they bring a unique opportunity with a fresh solution to treat hundreds of thousands of people who die unnecessarily,” said TB expert Alimuddin Zumla at University College London, who co-led the study.

TB initially infects the lungs but can rapidly spread from one person to another through coughing and sneezing. Despite its modern-day resurgence, TB is often regarded as a disease of the past. However, recently, drug-resistant strains of Mycobacterium tuberculosis, the microorganism that causes TB, have spread globally, rendering standard anti-TB drug treatments obsolete.

The World Health Organisation (WHO) estimates that in Eastern Europe, Asia and South Africa 450,000 people have MDR-TB, and close to half of these cases will fail to respond to existing treatments.

Mycobacterium tuberculosis, otherwise known as the “tubercle bacillus, trigger a characteristic inflammatory response (granulomatous response) in the surrounding lung tissue that elicits tissue damage (caseation necrosis).

Bone-marrow stem cells are known to migrate to areas of lung injury and inflammation. Upon arrival, they initiate the repair of damaged tissues. Since bone marrow stem cells also they also modify the body’s immune response, they can augment the clearance of tubercle bacilli from the body. Therefore, Zumla and his colleague, Markus Maeurer from Stockholm’s Karolinska University Hospital, wanted to test bone marrow stem cell infusions in patients with MDR-TB.

In a phase 1 trial, 30 patients with either MDR or XDR TB aged between 21 and 65 who were receiving standard TB antibiotic treatment were also given an infusion of around 10 million of their own bone marrow-derived stem cells.

The cells were obtained from the patient’s own bone marrow by means of a bone marrow aspiration, and then grown into large numbers in the laboratory before being re-transfused into the same patient.

During six months of follow-up, Zumla and his team found that the infusion treatment was generally safe and well tolerated, and no serious side effects were observed. The most common non-serious side effects were high cholesterol levels, nausea, low white blood cell counts and diarrhea.

Although a phase 1 trial is primarily designed only to test a treatment’s safety, the scientists said further analyses of the results showed that 16 patients treated with stem cells were deemed cured at 18 months compared with only five of 30 TB patients not treated with their own stem cells.

Maeurer stressed that further trials with more patients and longer follow-up were needed to better establish how safe and effective the stem cell treatment was.

But if future tests were successful, he said, this could become a viable extra new treatment for patients with MDR-TB who do not respond to conventional drug treatment or for those patients with severe lung damage.

Stem Cell Treatments for Aortic Aneurysms


The aorta is the largest blood vessel in our bodies and it emerges from the left ventricle of the heart, takes a U-turn, and swings down toward the legs (descending or dorsal aorta). There are several branches of the aorta as it sharply turns that extend towards the head and upper extremities.

Aorta structure

Sometimes, as a result of inflammation of the aorta or other types of problems, the elastic matrix that surrounds and reinforces the aorta breaks down.  This weakens the wall of the aorta and it bulges out.  This bulge is called an aortic aneurysm and it is a dangerous condition because the aneurysm can burst, which will cause the patient to bleed to death.

Aortic Aneurysm

If an aneurysm is discovered through medical imaging techniques, drugs are given to lower blood pressure and take some of the pressure off the aorta.  Also, drugs that prevent further degradation of the elastic matrix are also used.  Ultimately, for large or fast-growing aneurysms, surgical repair of the aorta is necessary.  For aneurysms of the abdominal aorta, a surgical procedure called abdominal aortic aneurysm open repair is the “industry standard.”  For this surgery, the abdomen is cut open, and the aneurysm is repaired by the use of a long cylinder-like tube called a graft.  Such grafts are made of different materials that include Dacron (textile polyester synthetic graft) or polytetrafluoroethylene (PTFE, a nontextile synthetic graft).  The surgeon sutures the graft to the aorta, and connects one end of the aorta at the site of the aneurysm to the other end.

A “kinder, gentler” way to fix an aneurysm is to use a procedure called endovascular aneurysm repair (EVAR).  EVAR uses these devices called “stents” to support the wall of the aorta.  A small insertion is made in the groin and the collapsed stent is inserted through the large artery in the leg.  Then the stent, which is long cylinder-like tube made of a thin metal framework and covered with various materials such as Dacron or polytetrafluoroethylene (PTFE), is inserted into the aneurysm.  Once in place, the stent-graft will be expanded in a spring-like fashion to attach to the wall of the aorta and support it.  The aneurysm will eventually shrink down onto the stent-graft.

In some cases, the patient is too weak for surgery, and is not a candidate for EVAR.  A much better option would be to non-surgically repair the elastic support framework that surrounds the aorta, and stem cells are candidates for such repair.

To repair the elastic mesh work that surrounds the wall of the aorta, smooth muscle cells that secrete the protein “elastin” must be introduced into the wall of the aorta.  Also, using the patient’s own stem cells offers a better strategy at this point, since this circumvents such issues as immune rejection of implanted tissues and so on.  The sources of stem cells for smooth muscle cells include bone marrow stem cells, fat-based stem cells, and stem cells from peripheral blood.  All three of these stem cell sources have problems with finding enough cells in the body and expanding them to high enough numbers in order to properly treat the aneurysm.

Fortunately, the use of induced pluripotent stem cells, which are made from a patient’s mature cells and have many, though not all of the characteristics of embryonic stem cells, can provide large quantities of elastin-secreting smooth muscle cells.  Also, one laboratory in particular has reported differentiating human induced pluripotent stem cells into smooth muscle cells (Lee TH, Song SH, Kim KL, et al. Circ Res 106:120–128).  While there are challenges to making functional elastin, there are possibilities that many of these can be overcome.

Ideal characteristics and expected roles of iPSCs and differentiated SMC-like derivatives for treating AAAs. Shown are several of the necessary properties for expansion/differentiation in culture, delivery to the AAA, and elastogenesis within the tunica media microenvironment. Abbreviations: AAA, abdominal aortic aneurysm; ECM, extracellular matrix; Eln, elastin; iPSC, induced pluripotent stem cell; LOX, lysyl oxidase; MMPs, matrix metalloproteinases; SMC, smooth muscle cell; TNFα, tumor necrosis factor-α.
Ideal characteristics and expected roles of iPSCs and differentiated SMC-like derivatives for treating AAAs. Shown are several of the necessary properties for expansion/differentiation in culture, delivery to the AAA, and elastogenesis within the tunica media microenvironment. Abbreviations: AAA, abdominal aortic aneurysm; ECM, extracellular matrix; Eln, elastin; iPSC, induced pluripotent stem cell; LOX, lysyl oxidase; MMPs, matrix metalloproteinases; SMC, smooth muscle cell; TNFα, tumor necrosis factor-α.

In addition to induced pluripotent stem cells, other laboratories have examined umbilical cord mesenchymal stem cells and their ability to decrease the inflammation within the aorta that leads to aneurysms.  The researchers discovered that all the indicators of inflammation decreased, but the synthesis of new elastin was not examined.  However, a Japanese laboratory used mouse mesenchymal stem cells from bone marrow and found that not only did these cells shut down enzymes that tend to degrade elastin, but also initiated new elastin synthesis in culture.  The same study also showed that MSCs implanted into the vessel walls of an aorta that was experiencing an aneurysm stabilized the aneurysm by inhibiting the elastin-degrading enzymes, and increasing the elastin content of the vessel wall.  This had the net effect of stabilizing the aneurysms and preventing them from growing further (see Hashizume R, Yamawaki-Ogata A, Ueda Y, et al. J Vasc Surg 54:1743–1752).  

These experiments show that stem cell treatments for abdominal aneurysms are feasible and would definitely be a much-needed nonsurgical treatment option for the high-risk elderly demographic, which is rapidly growing in the developed world.

For more information on this interesting topic, see Chris A. BashuraRaj R. Raob and Anand Ramamurthia. Perspectives on Stem Cell-Based Elastic Matrix Regenerative Therapies for Abdominal Aortic Aneurysms.  Stem Cells Trans Med June 2013 vol. 2 no. 6 401-408.

Kidney Tubular Cells Formed from Stem Cells


A collaborative effort between several research teams has successfully directed stem cells to differentiate into kidney tubular cells. This is a significant advance that could hasten the day when stem cell-based treatments are used to treat kidney failure.

Chronic kidney disease is a major global public health problem. Unfortunately, once patients progress to kidney failure, their treatment options are limited to dialysis and kidney transplantation. Regenerative medicine, whose goal is to rebuild or repair tissues and organs, might offer a promising alternative.

A team of researchers from the Harvard Stem Cell Institute (Cambridge, Mass.), Brigham and Women’s Hospital (Boston) and Keio University School of Medicine (Tokyo) that included Albert Lam, M.D., Benjamin Freedman, Ph.D. and Ryuji Morizane, M.D., Ph.D., has been diligently developing strategies for the past five years to develop strategies to direct human pluripotent stem cells (human embryonic stem cells or hESCs and human induced pluripotent stem cells or iPSCs) to differentiate into kidney cells for the purposes of kidney regeneration.

“Our goal was to develop a simple, efficient and reproducible method of differentiating human pluripotent stem cells into cells of the intermediate mesoderm, the earliest tissue in the developing embryo that is fated to give rise to the kidneys,” said Dr. Lam. Lam also noted that these intermediate mesoderm cells would be the “starting blocks” for deriving more specific kidney cells.

Lam and his collaborators discovered a blend of chemicals which, when added to stem cells in a precise sequence, caused the stem cells to turn off their stem cell-specific genes and activate those genes found in kidney cells. Furthermore, the activation of the kidney-specific genes occurred in the same order that they turn on during embryonic kidney development.

At E10.5, the metanephric mesenchyme (red) comprises a unique subpopulation of the nephrogenic cord (yellow). Expression of the Glial-derived neurotrophic factor (Gdnf) is resticted to the metanephric mesenchyme by the actions of transcriptional activators, secreted factors, and inhibitors. GDNF binds the Ret receptor and promotes the formation of the ureteric bud, an outgrowth from the nephric duct (blue). Ret initially depends upon the Gata3 transcription factor for its expression in the nephric duct. Spry1 acts as an intracellular inhibitor of the Ret signal transduction pathway. BMP4 inhibits GDNF signaling and is in turn inhibited by the Grem1 binding protein. At 11.5, the ureteric bud has branched, forming a T-shaped structure. Each ureteric bud tip is surrounded by a cap of condensed metanephric mesenchyme. Reciprocal signaling between the cap mesenchyme and ureteric bud, as well as signals coming from stromal cells (red), maintain expression of Ret in the bud tips and Gdnf in the cap mesenchyme. Nephrons are derived from cap mesenchyme cells that form pretubular aggregates and then renal vesicles on either side of each ureteric bud tip. Wnt9b and Wnt4 induce nephron formation and are necessary for maintaining ureteric bud branching. The Six2 transcription factor prevents ectopic nephron formation. BMP7 promotes survival of the cap mesenchyme. Not all genes implicated in metanephros formation are shown for clarity (see text for further details). Green arrows indicate the ligand-receptor interaction between GDNF and Ret. Black arrows indicate the epistasis between genes but in most cases it is not known if the interactions are direct. T-shaped symbols indicate inhibitory interactions.
At E10.5, the metanephric mesenchyme (red) comprises a unique subpopulation of the nephrogenic cord (yellow). Expression of the Glial-derived neurotrophic factor (Gdnf) is resticted to the metanephric mesenchyme by the actions of transcriptional activators, secreted factors, and inhibitors. GDNF binds the Ret receptor and promotes the formation of the ureteric bud, an outgrowth from the nephric duct (blue). Ret initially depends upon the Gata3 transcription factor for its expression in the nephric duct. Spry1 acts as an intracellular inhibitor of the Ret signal transduction pathway. BMP4 inhibits GDNF signaling and is in turn inhibited by the Grem1 binding protein. At 11.5, the ureteric bud has branched, forming a T-shaped structure. Each ureteric bud tip is surrounded by a cap of condensed metanephric mesenchyme. Reciprocal signaling between the cap mesenchyme and ureteric bud, as well as signals coming from stromal cells (red), maintain expression of Ret in the bud tips and Gdnf in the cap mesenchyme. Nephrons are derived from cap mesenchyme cells that form pretubular aggregates and then renal vesicles on either side of each ureteric bud tip. Wnt9b and Wnt4 induce nephron formation and are necessary for maintaining ureteric bud branching. The Six2 transcription factor prevents ectopic nephron formation. BMP7 promotes survival of the cap mesenchyme. Not all genes implicated in metanephros formation are shown for clarity (see text for further details). Green arrows indicate the ligand-receptor interaction between GDNF and Ret. Black arrows indicate the epistasis between genes but in most cases it is not known if the interactions are direct. T-shaped symbols indicate inhibitory interactions.

The investigators were able to differentiate both hESCs and human iPSCs into cells that expressed the PAX2 and LHX1 genes, which are two key elements of the intermediate mesoderm; the developmental tissue from which the kidney develops. The iPSCs were derived by reprogramming fibroblasts obtained from adult skin biopsies into pluripotent cells. The differentiated cells expressed multiple genes found in intermediate mesoderm and spontaneously produced tubular structures that expressed those genes found in mature kidney tubules.

The researchers could then differentiate the intermediate mesoderm cells into kidney precursor cells that expressed the SIX2, SALL1 and WT1 genes. These three genes designate an embryonic tissue called the “metanephric cap mesenchyme.” Metanephric cap mesenchyme is a critical tissue for kidney differentiation. During kidney development, the metanephric cap mesenchyme contains a population of progenitor cells that give rise to nearly all of the epithelial cells of the kidney (epithelial cells or cells in a sheet, generate the lion’s share of the tubules of the kidney).

Metanephric cap mesenchyme is is red
Metanephric cap mesenchyme is is red

The cells also continued to behave like kidney cells when transplanted into adult or embryonic mouse kidneys. This gives further hope that these investigators might one day be able to create kidney tissues that could function in a patient and would be fully compatible with the patient’s immune system.

The findings are published online in Journal of the American Society of Nephrology.

Heart Regeneration and the Heart’s Own Stem Cell Population


For years scientists were sure that the heart virtually never regenerated.

Today this view has changed, and researchers at the Max Plank Institute for Heart and Lung Research have identified a stem cell population that is responsible for heart regeneration. Human hearts, as it turns out, do constantly regenerate, but at a very slow rate.

This finding brings the possibility that it might be possible to stimulate and augment this self-healing process, especially in patients with diseases or disorders of the heart, with new treatments.

Some vertebrates have the ability to regenerate large portions of their heart. For example zebrafish and several species of amphibians have the ability to self-heal and constantly maintain the heart at maximum capacity. This situation is quite different for mammals that have a low capacity for heart regeneration. Heart muscle cells in mammals stop dividing soon after birth.

However, mammalian hearts do have a resident stem cell population these cells replace heart muscle cells throughout the life of the organism, In humans, between 1-4% of all heart muscle cells are replaced every year.

Experiments with laboratory mice have identified at heart stem cells called Sca-1 cells that replace adult heart muscle cells and are activated when the heart is damaged. Under such conditions, Sca-1 cells produce significantly more heart muscle.

Unfortunately, the proportion of Sca-1 cells in the heart is very low, and finding them has been likened to searching for a diamond at the bottom of the Pacific Ocean.

Shizuka Uchida, the project leader of this research, said, “We also faced the problem that Sca-1 is no longer available in the cells as a marker protein for stem cells after they have been changed into heart muscle cells. To prove this, we had to be inventive.”

This inventiveness came in the form of a visible protein that was made all the time in the Sca-1 cells that would continue being made even if the cells differentiated into heart muscle.

Uchida put it this way: “In this way, we were able to establish that the proportion of the heart muscle cells originating from Sca-1 stem cells increased continuously in healthy mice. Around five percent of the heart muscle cells regenerated themselves within 18 months.”

When the same measurements were taken in mice with heart disease, the number of heart muscle cells made from Sca-1 stem cells increased three-fold.

“The data show that in principle the mammalian heart is able to trigger regeneration and renewal processes. Under normal circumstances, however, these processes are not enough to ultimately repair cardiac damage,” said Thomas Braun, the principal investigator in whose laboratory this work was done.

The aim is to devise and test strategies to improve the activity and number of these stem cells and, ultimately, to strengthen and augment the heart’s self-healing powers.