The REPAIR-AMI clinical trial was a double-blind placebo-controlled trial in which 204 recent heart attach patients received either an infusion of bone marrow stem cells or a placebo. The results of this clinical trial have been published in three different papers (Schächinger, et al., N Engl J Med 2006 355: 1210-1221; Schächinger, et al., Eur Heart Journal 2006 27: 2775-2783; Schächinger, et al., Nat Clin Pract Cardvasc Med 2006 3(Suppl 1): 523-528).
This clinical trial showed that the bone marrow-treated group showed significant functional improvements over the placebo group. However, a long-term follow-up of these patients was required to demonstrate that the benefits conferred by the stem cell treatments were long-lasting and not merely transient.
Upon 5-year examination, the stem cell-treated group showed lower rates of a second heart attack, hospitalization, strokes, cancer, surgical interventions to open blocked vessels and death. Thus, the stem cell-treated group fared better in almost all the major categories.
There was, however, an additional experiment that gave a truly remarkable result. After each patient had their bone marrow extracted, the stem cells were subjected to individual tests, one of which were mobility tests. When this research group examined the stem cell motility data and correlated it to the five-year follow-up, they discovered a very tight association between the motility of the bone marrow stem cells and the absence of cardiac events. More active bone marrow cells provided greater recovery and fewer post-procedural events.
These data show that the quality of the bone marrow is a significant factor in the success of the stem cell treatment.
This also brings up another question: Can be beef up the quality of the bone marrow some how? Culturing stem cells can expand them, but it can also significantly change them. Therefore, this remains a fertile field for research and development, and the bone marrow quality may also explain why bone marrow transplants into the heart work so well or some patients and not at all for others.
A new analysis of stem cell trials that targeted degenerative disc disease of the spine in animals has shown that these treatments are effective in halting or even reversing this disease. Such results should facilitate the implementation of human clinical trials.
Our spinal cords are encased in a protective body of bone known as the vertebral column. The vertebral column consists of a stack of vertebral bodies that are positioned with one vertebra one on top of the other. Between each pair of vertebral bodies is a cushion-like structure known as the intervertebral disc. The intervertebral disc absorbs the stress and shock placed on the vertebral column when someone walks, runs, moves, bends, or twists. The discs prevent the vertebral bodies from grinding against each other.
Structurally, the intervertebral discs are unique. They have no blood supply of their own, and are, as a matter of fact, the largest structures in the body without their own blood vessel system. Instead they absorb the nutrients they need from circulating blood by means of osmosis.
Each intervertebral disc is composed of two parts: an outer annulus fibrosus (fibrous ring) and the nucleus pulposus (pulpy interior). The annulus fibrosus is a ring-like structure that completely encases the nucleus pulposus. It is composed of water and strong elastic collagen fibers bound together by glue-like material called proteoglycan. The arrangement of these collagen fibers at varying angles relative to each other makes the annulus fibrosus a rather strong structure. The annulus fibrous stabilizes the intervertebral disc and helps the spine can rotate properly and resist compression or other stresses placed on the spine.
The center portion of the intervertebral disc that is protected by the annulus fibrosus is a gel-like elastic substance called nucleus pulposus. The nucleus pulposus transmits and transfers stress and weight placed on vertebrae during movement and activity. The nucleus pulposus is made of the same basic materials as the nucleus fibrosus: water, collagen, and proteoglycans. The main difference between the ring-like annulus fibrosus and the gel-like nucleus pulposus is the relative amounts of these substances. The nucleus pulposus contains more water than the annulus fibrosus.
Recent developments in stem cell research have made it possible to measure the effects of stem cells treatments on intervertebral disc height. Researchers at the Mayo Clinic in Rochester, Minnesota have pioneered such techniques.
In preclinical animal studies, stem cell treatments have been used to treat animals with degenerative disc disease. Because degenerative disc disease can great affect someone’s quality of life and productivity, such a treatment has been highly sought after.
Wenchun Qu, MD, PhD, of the Mayo Clinic in Rochester, Minn said that stem cell injections into degenerating intervertebral discs not only increased disc height, but also increased disc water content and improved the expressed of particular genes. “These exciting developments place us in a position to prepare for translation of stem cell therapy for degenerative disc disease into clinical trials,” said Qu.
Animals that had received stem cell injections into their intervertebral discs had a disc structure that was large restored. The nucleus pulposus showed an increased water content and improved abilities to transfer shear forces.
In their analysis, Qu and his colleagues examined six preclinical trials and only examined those studies that were randomized and properly controlled. Because of various methodological differences between these studies, Qu and his gang used a random-effects model to analyze the data. Random-effects models, put simply, put all the animals in a group of studies together and assumes that they can be placed in a hierarchy of those who are the sickest to those who are the least sick. By placing the individuals in a hierarchy like this they can be classified accordingly and the effects of their treatments assessed fairly.
When properly and rigorously analyzed, the intervertebral disc height increases were significant in all six studies. What they found was an over 23.6% increase in the disc height index in the transplant group compared with the placebo group (95% confidence interval [CI], 19.7-23.5; p < 0.001). None of the 6 studies showed a decrease of the disc height index in the transplant group. Increases in the disc height index were statistically significant in all individual studies.
On the strength of these preclinical studies, Qu and his colleagues think that it is time to determine the safety, feasibility, and efficacy of stem cell transplants for degenerative disc disease in human patients.
Because intervertebral discs show such poor regenerative capabilities, degenerative disc disease is an excellent candidate for stem cell treatments. Also, present treatments tend to be very invasive and often make the disc worse.
Adi Shruster and Daniel Offen from Tel Aviv University in Israel have shown in a rodent model of Alzheimer’s disease (AD) that stimulating brain cell regeneration can alleviate some of the symptoms of AD.
A particular mouse strain called 3xTgAD serves as a model system for the study of AD. These mice have several genetic modifications that cause the formation of senile plaques in the brain that also lead to behavioral abnormalities and cognitive decline. In short, the Presenilin gene, which plays a definitive role in the onset of AD, has a mutation engineered in it. This particular mutation (M146V) shows a very strong causative link to inherited forms of AD (MA Riudavets, et al., Brain Pathology 2013 23(5): 595–600).
Additionally, 3xTgAD mice have a synthetic gene inserted in them that overproduces two proteins that also contribute to the onset of AD: amyloid precursor protein (APP) and another protein called tau. The combination of these three genes causes the formation of amyloid plaques and neurofibrillary tangles that are so characteristic of AD, although these plaques are not exactly the same as those observed in human AD patients (see Matthew J. Winton, et al., Journal of Neuroscience 31(21):7691–7699).
Shruster and Offen used these 3XTgAD mice to determine if inducing new brain cells in the brain could improve their condition. Offen overexpressed a gene called Wnt3a in a part of the brain known to play a role in regulating behavior. Wnt3a is known to drive cell proliferation in this part of the brain. After driving Wnt3a expression in the brains of 3XTgAD mice, Offen subjected them to behavioral tests.
Normal mice tend to pause and assess their surroundings when they enter unfamiliar places. However, 3xTgAD mice tend to charge straight in when entering new surroundings. This lack of proper danger assessment in 3xTgAD mice disappeared when Wnt3a was expressed in their brains. Upon post-mortem examination, these mice showed the formation of new nerve cells in their brains. When new brain cell formation was abrogated with X-rays, the behavioral defect was maintained.
Offen commented: “Until 15 years ago, the common belief was that you were born with a finite number of neurons. You would lose them as you age or as a result of injury or disease.”
Human AD patients can lose their sense of space and reality and do very inappropriate things at particular times. Therefore, these mice do recapitulate particular features of the human disease.
Offen and his colleagues think that establishing the growth of new brain cells in human AD patients might alleviate some of the behavioral abnormalities. Furthermore, stem cell treatments might also have a positive role to play in the treatment of AD, although Offen will readily admit that more work must be done.
The absence of recruited neutrophils to the periodontal tissue in LAD patients leads to unrestrained local production of IL-23 and hence IL-17 and G-CSF. Increased IL-17 leads to inflammatory bone loss and dysbiosis, whereas increased G-CSF leads to excessive release of mature neutrophils from the bone marrow. In contrast, normal recruitment of neutrophils regulates the expression of the same cytokines maintaining homeostasis in terms of periodontal health and release of mature neutrophils from the bone marrow. Credit: Copyright Niki Moutsopoulos and George Hajishengallis
Patients with leukocyte adhesion deficiency, or LAD, suffer from frequent bacterial infections, including the severe gum disease known as periodontitis. These patients often lose their teeth early in life. New research by University of Pennsylvania School of Dental Medicine researchers, teaming with investigators from the National Institutes of Health, has demonstrated a method of reversing this bone loss and inflammation.
Nrf2 is a protein that regulates the response of cells to oxidative damage, This protein normally sits in the cytoplasm of cells where it is routinely degraded by other proteins. However, once cells are exposed to oxidative damage by ultraviolet light, reactive oxygen species, various chemicals, or other conditions that damage cellular structures, the degradation of Nrf2 slows way down and this protein moves into the nucleus where it binds DNA and stimulates the expression of a host of genes that encode proteins with anti-oxidant activity. Thus Nrf2 is one of the primary cellular defenses against the toxic effects of oxidative stress.
Researchers at the University of Utah School of Medicine have made mice that lack functional Nrf2 and they found that the stem cells of these mice were seriously impaired.
Raj Soorappan and his colleagues have discovered that the muscles of these Nrf2-deficient mice do not regenerate as they get older.
Soorappan explained: “Physical activity is the key to everything.” He continued: “After this study we believe that moderate exercise could be one of the key ways to induce stem cells to regenerate especially during aging.”
Sarcopenia or the age-related loss of muscle mass, begins in most people around the age of 30. To delay this inevitable slide, muscle=producing stem cells help regenerate muscle lost by means of aging and the production of antioxidant molecules help protect stem cells populations so that they can maintain muscle mass.
However, as we age, the production of reactive oxygen species (ROS) overwhelms our endogenous antioxidant systems, and our stem cell populations take a hit. This compromises our ability to regenerate muscle and other tissues as well.
As previously mentioned, Nrf2 regulates the production of these antioxidant molecules. Soorappan used mice that were 23 months old or older (these are rodent senior citizens to be sure). One group of old mice made normal levels of Nrf2, but the other group had no functional Nrf2 protein. Soorappan and his colleagues put these mice through endurance training to determine the effects of ROS on these animals. Interestingly, the Nrf2-deficient mice showed an inability to mobilize their muscle stem cells (satellite cells) to regenerate their muscles. The Nrf2-containing mice, however, were able to properly regenerate their muscles.
“We now know that the antioxidant protein Nrf2 guards the muscle regeneration process in elderly mice and loss of Nrf2, when combined with endurance exercise stress, can cause severe muscle stem cell impairment,” said Mudhusudhanan Narasimhan, the primary author of this research and a research associate with Soorappan.
Soorappan thinks that by understanding the precise role of Nrf2 in muscle regeneration, he an his co-workers will be able to design more informed therapies of muscle loss in aging animals and humans.
Next on Soorappan’s agenda is to examine the effects of exercise on Nrf2 and whether or not an active lifestyle affects the function of Nrf2 and the efficiency of the anti-oxidant pathway it mediates.
The take-home message for now seems to be: “If you don’t use your muscles, you will lose them. At the same time, overdoing endurance training may detract from muscle regeneration,” said Soorappan.
Researchers from Chicago, Illinois have shown that a fatty fold of tissue within the abdomen contains a rich source of stem cells that can help heal diseased kidneys.
Scientists from the laboratory of Ashok K. Singh at Hospital of Cook County used a rat model of chronic kidney disease to examined the efficacy of these cells.
In past experiments, transplanted stem cells have failed to live very long in the body of the recipient. To solve this problem, Singh and his co-workers connected the a fatty fold of tissue located close to the kidney called the “omentum” to the kidney. The omentum is a wonderfully rich source of stem cells and by connecting the kidney to the omentum, Singh and his colleagues subjected the diseased kidney to a constant supply of stem cells.
After 12 weeks of being connected to the kidney, the kidney showed significant signs of improvement.
The progression of chronic kidney disease was slowed due to this continuous migration of stem cells from the omentum to the diseased kidney. The influx of these stem cells seemed to direct healing of the kidney.
This experiment is significant in that it suggests that resident stem cells that facilitate healing of the kidney, but only when they are in contact with the tissue over a long period of time. Also, it implies that a supposedly useless organ that lies close to the kidney can be fused with the kidney to heal it with a patient’s own stem cells. This therapeutic strategy seems to be ideal for kidney patients.
Patients who suffer from malformation of the spinal cord or have suffered a severe spinal cord injury sometimes have bladder malfunction as well. Replacing a poorly functioning bladder is a goal of regenerative medicine, but it is not an easy goal. The bladder is lined with a special cell population called “urothelium.” Urothelium is found throughout the urinary tract and it is highly elastic. Persuading stem cells to form a proper urothelium has proved difficult.
Now scientists from the University of California, Davis (my alma mater), have succeeded in devising a protocol for differentiating human pluripotent stem cells into urothelium. The laboratory of Eric Kurzock, chief of the division of pediatric urologic surgery at UC Davis Children’s Hospital, published this work in the journal Stem Cells Translational Medicine. This work is quite exciting, since it provides a way to potentially replace bladder tissue for patients whose bladders are too small or do not function properly.
Kurzock explained: “Our goal is to use human stem cells to regenerate tissue in the lab that can be transplanted into patients to augment or replace their malfunctioning bladders,”
In order to make bladder cells in the laboratory, Kurzrock and his coworkers used two different types of human pluripotent stem cells. First, they used two types of induced pluripotent stem cells (iPS cells). The first came from laboratory cultures of human skin cells that were genetically engineered and cultured to form iPS cultures. The second iPS line was derived from umbilical cord blood cells that had been genetically reprogrammed into an embryonic stem cell-like state.
Even though further work is needed to establish that bladder tissues made from such stem cells are safe or effective for human patients, Kurzrock thinks that iPS cell–derived bladder grafts made from a from a patient’s own skin or umbilical cord blood cells represent the ideal tissue source for regenerative bladder treatments. This type of tissue would be optimal, he said, because it lowers the risk of immunological rejection that typifies most transplants.
One of the truly milestone developments in this research is the protocol Kurzrock and his colleagues developed to direct pluripotent stem cells to differentiate into bladder cells. This protocol was efficient and, most importantly, allowed the stem cells to proliferate in culture over a long period of time. This is crucial in order to have enough material for therapeutic purposes.
“What’s exciting about this discovery is that it also opens up an array of opportunities using pluripotent cells,” said Jan Nolta, professor and director of the UC Davis Stem Cell program and a co-author on the new study. “When we can reliably direct and differentiate pluripotent stem cells, we have more options to develop new and effective regenerative medicine therapies. The protocols we used to create bladder tissue also provide insight into other types of tissue regeneration.”
To hone their urothelium-differentiation protocol, Kurzrock and his colleagues used human embryonic stem cells obtained from the National Institutes of Health’s human stem cell repository. These cells were successfully differentiated into bladder cells. Afterwards, the Kurzrock group used the same protocol to coax iPS cells made from skin and umbilical cord blood into urothelium. Not only did these cells look like urothelium, but they also expressed the protein “uroplakin,” which is unique to the bladder and helps make it impermeable to toxins in urine.
In order to bring this protocol to the clinic, the cells must proliferate, differentiate and express bladder-specific proteins without depending on any animal or human products. They must do all these things independent of signals from other human cells, said Kurzrock. Therefore, for future research, Kurzrock and his colleagues plan to modify their laboratory cultures so that they will not require any animal and human products, which will allow use of the cells in patients.
Kurzrock’s primary goal as a physician is with children who suffer from spina bifida and other pediatric congenital disorders. Currently, when he surgically reconstructs a child’s defective bladder, he must use a segment of their own intestine. Because the function of intestine, which absorbs food, is almost the opposite of bladder, bladder reconstruction with intestinal tissue may lead to serious complications, including urinary stone formation, electrolyte abnormalities and cancer. According to Kurzrock, developing a stem cell alternative not only will be less invasive, but should prove to be more effective, too, he said.
Another patient group who might benefit from this research is bladder cancer patients. More than 70,000 Americans each year are diagnosed with bladder cancer, according to the National Cancer Institute. “Our study may provide important data for basic research in determining the deviations from normal biological processes that trigger malignancies in developing bladder cells,” said Nolta. More than 90 percent of patients who need replacement bladder tissue are adults with bladder cancer. Kurzrock said “cells from these patients’ bladders cannot be used to generate tissue grafts because the implanted tissue could carry a high risk of becoming cancerous. On the other hand, using bladder cells derived from patients’ skin may alleviate that risk. Our next experiments will seek to prove that these cells are safer.”
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.
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.”
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.
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.
“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.
Achilles tendon injuries are somewhat common for professional, collegiate, and recreational athletes, and they are usually treated surgically. Torn tendons are reattached or patched with sutures.
A research group from Union Memorial Hospital, in Baltimore, Maryland has discovered that depositing stem cells onto sutures can lead to faster healing after surgery that also leads to stronger tendons.
Such a finding can lift the spirits of those who have had the misfortune of healing from an Achilles tendon repair procedure, Often, the patient has to keep their leg immobilized for days after surgery, and even after rehabilitation, tendon rupture remains a nagging risk.
This study showed, however, that when compared with traditional Achilles tendon repair surgery, laboratory animals that had mesenchymal stem cells from bone marrow embedded in their sutures healed faster and had tougher tendons that resisted post-surgical rupture.
Another bonus from this study was that the stem cells stayed in the tendon and promoted healing during the period when the patients are unable to their leg. Limb immobilization can cause muscle and tendon atrophy and may also cause adhesions. These can affect how strong and functional the muscle and tendon are after reattachment.
Not only did the stem cells encourage faster healing, by the tendon strength was great in the stem cell-treated group after four weeks. Hopefully these pre-clinical trials will give way to clinical trials with human patients.
Stem cell treatments for curing Parkinson’s disease have been one of the dreams of stem cell scientists ever since the first embryonic stem cells were derived from mouse embryos in 1981. Unfortunately, this proved to be one of the harder therapeutic nuts to crack. Several experiments have shown that while feasible, getting the recipe right has required a fair amount of tweaking.
Parkinson’s disease (PD) results from the progressive death of neurons in the midbrain that release a neurotransmitter called dopamine, To review briefly, the brain consists of the forebrain, midbrain and hindbrain. The forebrain consists of the two large cerebral hemispheres that occupy the vast majority of the space within your skull. In addition to the left and right cerebral hemispheres is the diencephalon that consists of the thalamus, subthalamus, hypothalamus, and epithalamus. The thalamus serves as a relay station for a whole variety of nerve fiber tracts, the hypothalamus regulates visceral activities by way of other brain regions and the autonomic nervous system. and the epithalamus connects the limbic system to the rest of the brain. The midbrain, which lies below the diencephalon, is part of the brain stem and dopamine produced in two regions of the midbrain, the substantia nigra and ventral tegmental area play roles in motivation and habituation, and refinement of the control of voluntary movement, The hindbrain consists of the metencephalon and the myelencephalon, both of which contain mutiple fiber tracts and nuclei for vital functions.
The death of dopamine-producing neurons in the pars compacta region of the substantia nigra region of the midbrain causes PD. The par compacta sends nerve fibers to the cerebral hemispheres, in particular to cluster of neurons called the basal ganglia. The basal ganglia do not initiate movement, but they refine movement and stabilize the limbs and other body parts while moving. Thus the basal ganglia normally exert a constant inhibitory influence on a wide range of movements. preventing movement at inappropriate times. When someone decides to move, this inhibition is reduced for the required motor system, thereby releasing it for activation. Dopamine releases this inhibition, and therefore high levels of dopamine tend to promote movement and low levels of dopamine demand greater exertion to generate any given movement. Thus the net effect of dopamine depletion is to produce hypokinesia, or less overall movement.
Now that we have some knowledge of PD and what causes it, we can examine how to cure it. Since the death of dopamine-secreting neurons causes PD, replacing death or moribund neurons should be possible. Several preclinical studies in laboratory animals and clinical studies with human patients has shown that this is possible.
Rodents can contract a synthetic form of PD if they are treated with a drug called 6-hydroxydopamine. This drug kills off their dopamine-secreting neurons and creates a PD-like disease. Embryonic stem cells can be differentiated in the laboratory into dopamine-secreting neurons, which can then be transplanted into the midbrain. In PD rats, this strategy has reversed the symptoms of PD, but tumor growth has been a nagging problem. The biggest problem is that isolating fully differentiated dopamine-secreting cells has proven difficult because of a lack of good, solid indicators that say to the scientists, “This one is a dopamine-secreting neuron and this one is not.” Thus, isolating nice, clean cultures of only dopamine-secreting cells has been kind of tough to do.
Fortunately, Doi and others in the Takahashi lab at the University of Kyoto showed that prolonged maturation culture system (42 days long) can eliminate most of the tumor-making cells. However, this culture system is laboriously long. Now, Takahashi and Doi and others have struck again in a paper published in Stem Cell Reports in which they used induced pluripotent stem cells to derive dopamine-secreting neurons to treat PD rats. Because induced pluripotent stem cells are made from a patient’s own adult cells and are converted into embryonic-like stem cells by means of a combination of genetic engineering and cell culture techniques, they are patient-specific and do not require the dismembering of human embryos.
The novelty of this paper is that Doi and others used a protein that acts as an earmark for dopamine-secreting midbrain neurons and this protein is called CORIN. CORIN is a protease, which simply means that it clips other proteins into small pieces. Nevertheless, by using the CORIN protein, Takahashi, Doi and others successfully and efficiently isolated dopamine-secreting midbrain neurons from other cells in their cultures. Additionally, Doi and the gang were able to differentiate the induced pluripotent stem cells into dopamine-secreting progenitor cells. This means that the cells were poised to differentiate into dopamine-secreting neurons, but were not quite there yet. This way, the cells would grow in culture, but upon transplantation, they would differentiate into dopamine-secreting neurons rather than form tumors. High numbers of cells are required for clinical purposes and this technique allows the for production of large number of cells.
The technique used in this paper also produced the cells under conditions that were safe, scalable and potentially usable for clinical use. These high-quality cells never produced any tumors and produced definitive behavioral improvements in the implanted laboratory animals. The problems that remain are one of scale. The grafts of dopamine-secreting cells that survived in the midbrains of these mice were relatively small (about 1 square millimeter in size or the thickness of a dime). This is probably due to the fact that the cells differentiate when transplanted rather than growing. Therefore, this technique will need to be adapted to somehow increase the size of the graphs of dopamine-secreting neurons. In some PD patients such small graphs will probably work just fine, but in others, probably not. The other issue is that these implanted cells might be subjected to the same bad intracerebral environment as the original cells and die off quickly, thus abrogating any positive clinical effect they might have. This is another issue that will need to be examined.
The work goes on, without the need to destroy any embryos.
See Daisuke Doi at al., Isolation of Human Induced Pluripotent Stem Cell-Derived Dopaminergic Progenitors by Cell Sorting for Successful Transplantation. Stem Cell Reports 2014, 2: 337-350.
Type 1 diabetes mellitus results from destruction of insulin-producing beta cells in the pancreas. Diabetics have to give themselves routine shots of insulin. The hope that stem cells offer is the production of cells that can replace the lost beta cells. “We are looking for ways to make new beta cells for these patients to one day replace daily insulin injections,” says Ben Stanger, MD, PhD, assistant professor of Medicine in the Division of Gastroenterology, Perelman School of Medicine at the University of Pennsylvania.
Some diabetics have had beta cells from cadavers transplanted into their bodies to replace the missing beta cells. Such a procedure shows that replacement therapy is, in principle possible. Therefore, transplanting islet cells to restore normal blood sugar levels in type 1 diabetics could treat and even cure disease. Unfortunately, transplantable islet cells are in short supply, and stem cell-based approaches have a long way to go before they reach the clinic. However, Stanger and his colleagues have tried a different strategy for treating type 1 diabetes. “It’s a powerful idea that if you have the right combination of transcription factors you can make any cell into any other cell. It’s cellular alchemy,” comments Stanger.
New research from Stanger and a postdoctoral fellow in his laboratory, Yi-Ju Chen that was published in Cell Reports, describes the production of new insulin-making cells in the gut of laboratory animals by introducing three new transcription factors. This experiment raises the prospect of using directly reprogrammed adult cells as a source for new beta cells.
In 2008, Stanger and others in Doug Melton’s laboratory used three beta-cell reprogramming factors (Pdx1, MafA, and Ngn3, collectively called PMN) to convert pancreatic acinar cells (the cells in the pancreas that secrete enzymes rather than hormones) into cells that had many of the features of pancreatic beta cells.
Following this report, the Stanger and his team set out to determine if other cells types could be directly reprogrammed into beta cells. “We expressed PMN in a wide spectrum of tissues in one-to-two-month-old mice,” says Stanger. “Three days later the mice died of hypoglycemia.” It was clear that Stanger and his crew were on to something. Further work showed that some of the mouse cells were making way too much extra insulin and that killed the mice.
When the dead mice were autopsied, “we saw transient expression of the three factors in crypt cells of the intestine near the pancreas,” explained Stanger.
They dubbed these beta-like, transformed cells “neoislet” cells. These neoislet cells express insulin and show outward structural features akin to beta cells. These neoislets also respond to glucose and release insulin when exposed to glucose. The cells were also able to improve hyperglycemia in diabetic mice.
Stanger and his co-workers also figured out how to turn on the expression of PMN in only the intestinal crypt cells to prevent the deadly whole-body hypoglycemia side effect that first killed the mice.
In culture, the expression of PMN in human intestinal ‘‘organoids,’ which are miniature intestinal units grown in culture, also converted intestinal epithelial cells into beta-like cells.
“Our results demonstrate that the intestine could be an accessible and abundant source of functional insulin-producing cells,” says Stanger. “Our ultimate goal is to obtain epithelial cells from diabetes patients who have had endoscopies, expand these cells, add PMN to them to make beta-like cells, and then give them back to the patient as an alternate therapy. There is a long way to go for this to be possible, including improving the functional properties of the cells, so that they more closely resemble beta cells, and figuring out alternate ways of converting intestinal cells to beta-like cells without gene therapy.”
This is hopefully a grand start to what might be a cure for type 1 diabetes.
Pluristem Therapeutics Inc. a leading developer of placenta-based cell therapies, has announced top-line results from its Phase I/II clinical trial that accesses the safety and efficacy of PLacental eXpanded (PLX-PAD) cells in the treatment of muscle injury. This clinical trial showed that PLX-PAD cells were safe and effective. These results provide evidence that PLX cells may be efficacious in the treatment of orthopedic injuries including muscles and tendons.
This Phase I/II trial was a randomized, placebo-controlled, double-blinded study conducted at the Orthopedic Clinic of the Charité University Medical School under the auspices of the Paul-Ehrlich-Institute (PEI), Germany’s health authority. The injured muscle studied was the gluteus medius muscle in the buttock. Hip-replacement patients undergo a surgical procedure that injuries the gluteus medius muscle healing of this muscle after hip replacement surgery is crucial for joint stability and function.
The 20 patients in the study were randomized into three treatment groups. Each patient received an injection in the gluteal muscle that had been traumatized during surgery. One group was treated with 150 million PLX-PAD cells per dose (n=7), the second was administered 300 million PLX-PAD cells per dose (n=6), and the third received placebo (n=7).
The primary safety endpoint was clearly met since no serious adverse events were reported at either dose level. The study showed that PLX-PAD cells were safe and well tolerated.
The primary efficacy endpoint of the study (how well the stem cells worked) was the change in maximal voluntary isometric contraction force of the gluteal muscle at six months after surgery. Efficacy was shown in both PLX-PAD-treated patient groups. The group that received a dose of 150 million cells showed a statistically significant 500% improvement over the placebo group in the change of the maximal contraction force of the gluteal muscle (p=0.0067). Patients who received the lower dose (300 million cells) showed a 300% improvement over the placebo (p=0.18).
An analysis of the overall structure of the gluteal muscle using magnetic resonance imaging (MRI) indicated an increase in muscle volume in those patients treated with PLX-PAD cells versus the placebo group. The patients who had received the 150 million cell dose displayed a statistically significant superiority over the placebo group. Patients treated at the 150 million cell dose showed an approximate 300% improvement over the placebo in the analysis of muscle volume (p=0.004). Patients treated at the 300 million cell dose showed an approximate 150% improvement over the placebo in the change of muscle volume (p=0.19).
The study’s Senior Scientist, Dr. Tobias Winkler of the Center for Musculoskeletal Surgery, Julius Wolff Institute Berlin, Charité – Universitaetsmedizin Berlin, Germany, commented, “I am very impressed with the magnitude of the efficacy results seen in this trial. PLX cells demonstrated safety and suggested that the increase in muscle volume could be a mechanism for the improvement of contraction force.”
Zami Aberman Chairman and CEO stated, “This was a very important study not only for Pluristem but for the cell therapy industry in general. The study confirms our pre-clinical findings that PLX-PAD cell therapy can be effective in treating muscle injury. Having a statistically significant result for our primary efficacy endpoint is very encouraging and consistent with our understanding of the mechanism of action associated with cell therapy. Based on these results, we intend to move forward with implementing our strategy towards using PLX cells in orthopedic indications and muscle trauma.”
Pluristem Therapuetics, a regenerative therapy company based in Haifa, Israel, has used placenta-based stem cells to treat animal with tendon damage, and the results of this preclinical study were announced at a poster presentation at the American Academy of Orthopedic Surgeons’ (AAOS) annual meeting in New Orleans.
Dr. Scott Rodeo of New York’s Hospital for Special Surgery (HSS) is the principal investigator for this preclinical trial. His poster session showed placental-based stem cells that were grown in culture and applied to damaged tendons seemed to have an early beneficial effect on tendon healing. In this experiment, animal tendons were injured by treatments with the enzyme collagenase. This enzyme degrades tendon-specific molecules and generates tendon damage, which provides an excellent model for tendon damage in laboratory animals. These placenta-based cells are not rejected by the immune system and can also be efficiently expanded in culture. The potential for “off-the-shelf” use of these cells is attractive but additional preclinical studies are necessary to understand how these cells actually help heal damaged tendons and affect tendon repair.
“Although our findings should be considered preliminary, adherent stromal cells derived from human placenta appear promising as a readily available cell source to aid tendon healing and regeneration,” stated Dr. Rodeo.
“These detailed preclinical results, as well as the favorable top-line results we announced from our Phase I/II muscle injury study in January, both validate our strategy to pursue advanced clinical studies of our PLX cells for the sports and orthopedic market,” stated Pluristem CEO Zami Aberman.
Dr. Rodeo and his orthopedic research team at HSS studied the effects of PLX-PAD cells, which stands for PLacental eXpanded cells in a preclinical model of tendons around the knee that had sustained collagenase-induced injuries. Favorable results from the study were announced by Pluristem on August 14, 2013. Interestingly, Dr. Rodeo, the Principal Investigator for this study is Professor of Orthopedic Surgery at Weill Cornell Medical College; Co-Chief of the Sports Medicine and Shoulder Service at HSS; Associate Team Physician for the New York Giants Football Team; and Physician for the U.S.A. Olympic Swim Team.
A research laboratory lead by Jean-François Côté at the Institut de Recherches Cliniques de Montréal, Montreal, Canada has identified an elusive protein that mediates the fusion of muscle precursor cells into mature muscle.
The development of skeletal muscles depends on the migration of muscle precursor cells called “myoblasts” to migrate to the right location and then fuse with each other to form the multi-nucleate skeletal muscle cells. This finding has the potential to improve the treatment of muscular diseases such as myopathies and muscular dystrophies.
“For several years, we have been studying myogenesis, a process by which muscles are formed during development,” said Côté.
In the fruit fly Drosophila melanogaster, muscle fusion is rather well understood. A protein called “Myoblast City” and a scaffolding protein called “ELMO” activate the Rac protein in response the muscle precursor cells adhering to surfaces. Rac initiates the intracellular mechanisms that culminate in muscle fusion. In vertebrates, the ELMO protein exists in muscle precursor cells and a vertebrate version of the myoblast city protein called DOCK1. However, identifying the receptor that kicks this process off had proven difficult.
Myoblast fusion plays a central role in muscle development because it determines muscle size. Also, the fusion of existing muscle fibers with muscle stem cells helps regenerate and maintain adult muscles. This fusion process has always been a poorly understood process.
However, Côté and his co-workers have identified a receptor called BAI3 as one of the crucial links in myoblast fusion. BAI3 activates a signaling process that initiates the fusion of nearby myoblasts.
In 2008, Côté and his colleagues elucidated the role of two proteins – DOCK1 and DOCK5 – in the development of muscles. DOCK1 and DOCK5 regulate myoblast fusion. When the interaction between BAI3 and the DOCK signaling proteins is inhibited, myoblast fusion is also inhibited.
Côté pointed out that this work could have far-reaching implications, since the delivery of functional proteins to diseased muscle is typically carried out by introducing genetically engineered stem cells into the muscle that fuse with the disease muscle. By increasing the efficiency of the muscle fusion process, the delivery of genes to diseased muscles could become routine rather than painstakingly inefficient.
In mammals, hearing loss is usually due to damage to the sound-sensing hair cells in the inner ear.
Originally, the hair cells were thought to be irreplaceable, but research in mice has shown that the supporting cells that provide structural support to the hair cells can turn into hair cells. If this technology can be applied in older animals, then it might provide a way to stimulate hair cell replacement in adults and treatments for deafness as a result of hair cell loss.
According to Albert Edge of the Harvard Medical School and Massachusetts Eye and Ear Infirmary, hair cell replacement definitely occurs, but does so as rather low levels. According to Edge: “The finding that newborn hair cells regenerate spontaneously is novel.”
New Hair Cells in the Pillar Cell Region after Gentamicin Damage (A) Illustration of organ of Corti structure showing the Pou4f3-positive hair cells (blue), the Lgr5-positive supporting cells (red), and the remaining supporting cells in gray. Both the red and gray supporting cells are Sox2 positive. The green line indicates the xy plane from which the confocal slices in (B)–(G) are taken. (B–G) Confocal slices and cross sections from the midapex of neonatal organ of Corti explant cultures, treated with gentamicin and lineage-traced using the CAG-tdTomato reporter, were stained for DsRed (red). A white line on the whole-mount image shows the location of the cross section, and yellow and white brackets indicate IHCs and OHCs, respectively. Arrows point to new reporter-positive (or reporter-negative for Pou4f3) hair cells in the pillar cell region. Scale bar, 10 mm. (B) A reporter-positive hair cell from the Lgr5 lineage (such as those counted in H) was visible in the pillar cell region. (C and D) Reporter staining identified the hair cells marked by the white arrows as derived fromLgr5-positive cells; costaining for SOX2 (C) and location in the pillar cell region indicated that they were newly differentiated, and an OHC phenotype was suggested by the expression of PRESTIN (D). (D0 ) PRESTIN channel from (D) shows staining in the membrane and cuticular plate of the new hair cell. (E and F) Staining for the Sox2 lineage reporter identified the hair cells marked by the white arrows as derived from supporting cells; their location (pillar cell region) and costaining for SOX2 (E) identified them as newly differentiated cells, and costaining for PRESTIN (F) indicated an OHC identity. (G) The lack of Pou4f3 lineage reporter staining and the location in the pillar region identified the hair cell marked by the white arrow as a new hair cell, and costaining for PRESTIN indicated an OHC identity. (H) Increased numbers of Lgr5(blue bars) andSox2(red bars) reporter-positive hair cells were observed in the pillar cell region of the organ of Corti after gentamicin treatment (mean ± SEM per 100 mm; *p < 0.05, ***p < 0.001).
Earlier work has shown that inhibition of the Notch signaling pathway increases the formation of new hair cells not from remaining hair cells but from nearby supporting cells that express a cell-surface protein called Lgr5.
When Edge and his team used small molecules to inhibit the Notch signaling pathway, even more support cells differentiated into hair cells, and the Lgr-5-expressing cells were the only supporting cells that differentiated under these conditions.
By combining these new findings about Lgr-5-expressing cells with the previous finding that Notch inhibition can regenerate hair cells, scientists should be able to design new hair cell regeneration strategies to treat hearing loss and deafness.
Premature ovarian failure (POF) or primary ovarian insufficiency is a condition characterized by loss of normal ovarian function before age 40. POF causes low levels of the hormone estrogen and irregular ovulation (release of eggs). POF causes infertility.
Some medical professional call POF premature menopause, even though these two conditions are not exactly the same. Women with POF may have irregular or occasional menstrual cycles for years and may even become pregnant. However, women with premature menopause cease having periods and can’t become pregnant.
The symptoms of POF are similar to those of menopause: irregular or skipped periods (amenorrhea), which may be present for years or may develop after a pregnancy or after stopping birth control pills; hot flashes, night sweats, vaginal dryness, irritability or difficulty concentrating, and decreased sexual desire.
In women with POF, infertility is very hard to treat, but restoring estrogen levels can avert many of the complications.
There are several causes of POF. Particular chromosomal defects such as Turner’s syndrome, in which a woman has only one X chromosome instead of the usual two, and fragile X syndrome, a major cause of intellectual disability can cause POF. Likewise, exposure to various toxins can also cause POF. Chemotherapy and radiation therapy are probably the most common causes of toxin-induced POF. Other toxins such as cigarette smoke, industrial chemicals, pesticides and viruses may also hasten POF. If the immune system mounts an immune response to ovarian tissue (autoimmune disease), then it might produce antibodies against the woman’s own ovarian tissue. Such antibodies will harm the egg-containing follicles and damage the egg. What triggers the immune response is unclear, but exposure to certain viruses is one possibility. Also various sundry unknown factors may also contribute to it.
There are no treatments for POF that restore the ovaries. For this reason a recent paper in the journal Stem Cells and Development represents a great advance in POF treatment.
Te Liu from the Shanghai Institute of Chinese Medicine and colleagues have used stem cells isolated from human menstrual blood to treat toxin-induced POF in mice.
Human endometrial stem cells exhibit stem cell properties in culture. These human endometrial stem cells are easily isolated from human menstrual blood. Other laboratories have even used them to treat heart conditions in clinical trials.
In this present study, Liu and colleagues treated female mice with the anti-cancer/anti-organ rejection drug cyclophosphamide. This drug pushed the mice into POF. Then one group of mice had human menstrual stem cells injected into their ovaries whereas another group received an injection of phosphate-buffered saline.
After 14 days, ovaries from those mice injected with human menstrual stem cells expressed higher levels of ovarian-specific proteins. Also, the blood levels of estrogen of the stem cell-injected mice were also higher. Postmortem examination also showed that the average ovarian weight of the stem cell-injected mice was much higher, as was the number of normal follicles. Follicles contain eggs surrounded with follicle cells and their absence is indicative of an ovary from a woman who is in menopause. That fact that the stem cell-treated POF mice had normal follicles and more of them suggests that the injected stem cells beefed up the supply of existing eggs and helped them survive and flourish.
These results suggest that these human menstrual stem cells, which are derived from the endometrium, can survive when introduced into a living organism and promote the regeneration of ovaries. There is no evidence that these cells differentiate into eggs, but instead they probably create an environment where the existing moribund eggs are rejuvenated and revitalized. This treatment for POF might be a viable option for human patients; all without destroying human embryos.
Japanese scientist, Teruhiko Wakayama, a professor at Japan’s University of Yamanashi, who was part of the research team that described the production and characterization of STAP cells, has called for his own headline-grabbing study on stem cells to be withdrawn from publication. Wakayama says that the main findings of this paper have been thrown into doubt.
When the STAP cells came out in January it was hailed as a game-changer that could herald a new era of medical biology. The paper was published in the prestigious journal Nature and was also widely covered in Japan and across the world.
Since that time, however, there have been reports that several other scientists have been unable to replicate the Japanese team’s results. Also there seem to be some disparities with some of the paper’s data and images.
“It is no longer clear what is right,” Wakayama told public broadcaster NHK.
STAP or stress-triggered acquisition of pluripotency cells seemed to represent a simple way to reprogram mature animal cells back into an embryonic-like state that would allow them to generate many types of tissue.
From these STAP cell papers, various editorials dreamed big and suggested that just about any cell in your body could be simply and cheaply reprogrammed back into embryonic cell-like cells, and be used to replace damaged cells or grow new organs for sick and injured people.
Wakayama even said, “When conducting the experiment, I believed it was absolutely right.” However, now he is not so sure. He continued: “But now that many mistakes have emerged, I think it is best to withdraw the research paper once and, using correct data and correct pictures, to prove once again the paper is right. If it turns out to be wrong, we would need to make it clear why a thing like this happened.”
A spokesperson from the journal Nature has said that they were aware of, “issues relating to this paper,” and that an investigation was underway. However, at this point, the journal had no further comment to make.
Robin Lovell-Badge, a stem cell expert at Britain’s National Institute for Medical Research, cautioned against premature assumptions on whether the research was flawed. “I have an open mind on this,” he told Reuters. “I’m waiting to hear from several serious stem cell labs around the world on whether they have been able to reproduce the methods.”
Wakayama’s co-researcher Haruko Obokata, the first author on the STAP paper, became an instant celebrity in Japan after she spoke during a Nature media briefing to science reporters all over the world about her findings.
The Japanese team was joined by other researchers from Brigham and Women’s Hospital and Harvard Medical School in the United States in this research. They took skin and blood cells from mice, grew them, and then subjected them to stresses that brought the cells “almost to the point of death.” They exposed the cells to a variety of stresses, including trauma, low oxygen levels, and acidic environments.
One of these “stressful” situations used by these researchers was to bathe their cells in a weak acid solution for around 30 minutes. Within days, the scientists said they had found that the cells had not only survived but had also recovered by naturally reverting into a state similar to that of an embryonic stem cell.
Unfortunately, other research teams have yet been able to replicate the findings, and the RIKEN Center for Developmental Biology in Japan, where Obokata works, said last week it had “launched an independent inquiry into the content of the paper.
That inquiry will be conducted by a panel of experts from within and outside RIKEN, it said, and would be published as soon as it was concluded.
A spokesperson from the RIKEN Institute declined to comment on Wakayama’s call for the paper to be withdrawn.
A Duke University research team has combined synthetic scaffolding materials with gene delivery techniques to generate replacement cartilage precisely where it’s needed in the body.
The ingenious strategy utilized by this research project circumvents the need for large quantities of growth factors, which are expensive and difficult to apply after implantation. The Duke team led by Farshid Guilak, director of orthopedic research at Duke University Medical Center, used gene therapy to make stem cells that synthesize their own growth factors.
In brief, Guilak and his collaborators used genetically engineered viruses to transfer genes to stem cells embedded in a synthetic matrix. Upon infection, the stem cells grew and differentiated as needed, but the scaffolding provided the necessary structural cues for the stem cells to move to the proper configuration and form cartilage with the proper shape and biomechanical properties.
Guilak has devoted several years to developing biodegradable synthetic scaffolds that mimic the mechanical properties of cartilage. After testing many different scaffolds, he settled on a 3D woven poly(ε-caprolactone) scaffold, which is completely biodegradable and provides an excellent structural matrix for the synthesis of cartilage. However, an additional challenge for engineering good cartilage is to coax stem cells embed themselves in the scaffold while differentiating into cartilage-making cells, known as chondrocytes, after the scaffold has been implanted into a living organism.
One widely used strategy is to treat the stem cells with growth factors to induce chrondrocyte formation and cartilage production. Such cartilage can be implanted after it has been grown in the laboratory. However, this approach has some inherent limitations.
Guilak explained that “a major limitation in engineering tissue replacements has been the difficulty in delivering growth factors to the stem cells once they are implanted in the body.” Guilak continued: “There’s a limited amount of growth factor that you can put into the scaffolding, and once it’s released, it’s all gone. We need a method for long-term delivery of growth factors, and that’s where the gene therapy comes in.”
To tackle this perennial problem, Guilak tapped a talented colleague of his, Charles Gersbach, an assistant professor of biomedical engineering, who happens to also be a gene therapy expert.
Gersbach looked at the tissue engineering problem in an entirely new way and suggested that if the mountain will not come to Mohammed (that is to say if the growth factors cannot be given to stem cells after implantation), then Mohammed should grow his own mountain (the stem cells should be genetically engineered to make their own growth factors). Unfortunately, the conventional gene therapy methods are too complex to be commercially feasible. Typically, stem cells are collected, infected with genetically modified viruses that introduces new genes into them, grown to large numbers, and applied to synthetic cartilage scaffolds and implanted into the patient. Sounds like a headache? That’s because it is.
Fortunately, Gersbach had a slick gene therapy trick up his lab coat sleeve: “There are a few challenges with that process, one of them being that there are way too many extra steps,” said Gersbach. “So we turned to a technique I had previously developed that affixes the viruses that deliver the new genes onto a material’s surface.”
This new study combines Gersbach’s gene therapy technique—dubbed biomaterial-mediated gene delivery—to induce those human mesenchymal stem cells embedded in Guilak’s synthetic cartilage scaffolding to produce growth factor proteins (in particular a molecule called transforming growth factor β3 or TGF-β3). Based on the results of their experiments, the technique works and that the resulting synthetic, composite cartilage-like material is at least as good biochemically and biomechanically as if the growth factors were introduced in the laboratory.
“We want the new cartilage to form in and around the synthetic scaffold at a rate that can match or exceed the scaffold’s degradation,” said Jonathan Brunger, a graduate student who has spent time in both Guilak’s and Gersbach’s laboratories developing and testing the new technique. “So while the stem cells are making new tissue (in the body), the scaffold can withstand the load of the joint. In the ideal case, one would eventually end up with a viable cartilage tissue substitute replacing the synthetic material.”
This particular study examines cartilage regeneration, but Guilak and Gersbach hope that their technique could be applied to the regeneration of many different kinds of tissues, especially orthopaedic tissues such as tendons, ligaments and bones. Also, because the platform comes ready to use with any stem cell, it presents an important step toward commercialization.
“One of the advantages of our method is getting rid of the growth factor delivery, which is expensive and unstable, and replacing it with scaffolding functionalized with the viral gene carrier,” said Gersbach. “The virus-laden scaffolding could be mass-produced and just sitting in a clinic ready to go. We hope this gets us one step closer to a translatable product.”
Citation: “Scaffold-mediated lentiviral transduction for functional tissue engineering of cartilage.” Brunger, J.M., Huynh, N.P.T., Guenther, C.M., Perez-Pinera, P., Moutos, F.T., Sanchez-Adams, J., Gersbach C.A., and Guilak F. PNAS Plus, 2014. DOI: 10.1073/pnas.1321744111/-/DCSupplemental
W. Jeremy Beckworth and his co-workers at Emory Orthopaedics and Spine Center, in collaboration with several other orthopedic care groups, have participated in a clinical trial that demonstrated that a single injection of stem cells into degenerative intervertebral discs significantly reduced lower back pain for at least 12 months according. Beckworth’s clinical trial consisted of 100-patients and was a phase II, international clinical trial.
Beckworth, assistant professor of Orthopaedics and Rehab Medicine, gave patient injections of a subset of mesenchymal stem cells isolated from bone marrow stem cells called mesenchymal precursor cells (MPCs) in order to attenuate pain in patients with lower back pain. On average, Beckworth and his colleagues discovered that stem cell injections led to a reduction in pain levels greater than 50 percent at 12 months. Additionally, patients who received stem cell injections felt less of a need for pain medications, showed an improvement in function, and less need for further surgical and non-surgical spine interventions. These results were compiled from patients with moderate to severe disc-related lower back pain.
“These are very exciting findings,” explains Beckworth. “The results provide significant hope for a condition that has been very tough to treat. Discogenic low back pain, a painful degenerative disc, is the most common cause of chronic low back pain.”
This phase II clinical trial builds on a previously reported preclinical study showed that highly purified MPCs were able to repair and restore disc structure. All the data from this trial showed that there were statistically significant improvements in patients who received stem cell injections compared to those in control groups who received no such injections.
“Currently there is no adequate treatment for discogenic low back pain,” says Beckworth. “Both conservative and surgical treatments fall short. These positive results pave the way for a phase III study that may be starting later this year.”
Beyond the Dish 
