Transplantation of Unique, Newly Discovered Stem Cells May Lead to Promising Stroke Therapy


Stroke treatments have seen some remarkable advances in the past few years. Stem cell treatments for stroke have even seen some successes in clinical trials, showing that stem cell transplantation aimed at neural repair after a stroke is a possible way to ameliorate the effects of stroke.

Now, collaboration between teams of American and Japanese researchers has shown that a newly-identified stem cell has the ability to successfully treat stroke in rats. When administered to rats who have suffered from an experimentally-induced stroke, MUSE or multilineage-differentiating stress-enduring cells induced the regeneration of neurons and resulted in “significant improvements in neurological and motor functions” compared to control groups that were not transplanted with MUSE cells. MUSE cells also do not cause tumors.

The study has increased the number of therapeutic arrows in the quiver of neurologists and neuroscientists and lengthens the list of cells that might one day be considered for human clinical trials if continued pre-clinical tests prove successful. Future clinical studies aimed at regenerating neurological and motor function in patients who have suffered ischemic stroke.

The paper describing this study appeared in a recent issue of Stem Cells (Sept. 2015).

“Muse cells are unique stem cells that are able to self-renew and display high-efficiency for differentiating into neuron-like cells,” explained lead author Dr. Cesar V Borlongan, Distinguished Professor and Vice-Chairman for Research at the University of South Florida (USF) College of Medicine Department of Neurosurgery and Brain Repair and Director of USF’s the Center of Excellence for Aging and Brain Repair. “Unlike mesenchymal stem cells (MSCs) that have previously been used in stem cell transplantation in stroke-related clinical trials, in the present study Muse cells were found to possess functional characteristics of neurons as they attain the attributes of the host microenvironment. When MUSEcells were transplanted into to the brains of rats modeled with stroke, they attained neuronal characteristics.”

MUSE cells are found in many different tissues, including bone marrow, skin and fat. Since these cells can be derived from dermal fibroblasts (a type of connective tissue cell that provides the structural framework for animal tissues and plays a critical role in wound healing), they can be accessed with relative ease, without the need for the painful, invasive procedures required for obtaining other kinds of stem cells. Furthermore, while some stem cells used in stem cell transplantation studies have been found to cause cancer, MUSE cells do not produce tumors and exhibit exceptional tissue repair potential when introduced into the blood stream.

Some researchers think that fetal stem cells might be better candidates for replacing lost neural circuitry. The main reason in favor of fetal stem cells is that they preferentially differentiate into neuronal cells. However, the accessibility to fetal stem cells is limited and, like embryonic stem cells, the immaturity of these cells may present safety issues, such as tumor development. Additionally, the use of fetal and embryonic stem cells has many ethical difficulties to say the least. Since MUSE cells can be derived from adult tissue rather than fetal or embryonic tissue, the ethical quandaries associated with using them is minimal.

Not only do MUSE cells also have the practical advantage of being non-tumorigenic, they are readily accessed commercially and can also be easily collected from patient skin biopsies. MUSE cells also do not have to be “induced,” or genetically manipulated in order to be used, since they already display inherent stem cell properties after isolation. MUSE cells also spontaneously home toward the stroke-damaged sites.

“Ours is the first study to show that human skin fibroblast-derived Muse cells can have neuron-like function, possess an inherent ability to assume ‘stemness’ properties, and to readily differentiate into neural-lineage cells after integration into the stroke brain,” said co-lead author Dr. Mari Dezawa, Department of Stem Cell Biology and Histology, Tohoku University Graduate School of Medicine in Sendai, Japan. “Our results show that Muse cells are a feasible and promising source for cell-based approaches to ischemic stroke therapy.”

Exosomes Work As Well As Stem Cells to Heal Stroke Damage


A German research team at the University of Duisburg-Essen has published a study in the latest issue of STEM CELLS Translational Medicine that shows tiny membrane-enclosed structures that travel between cells work as well as adult stem cells to help the brain recover from a stroke.

Extracellular vesicles (EVs), which are small, membrane-enclosed structures that pass between cells, which are also referred to as exosomes, were given to one group of stroke-impaired mice and adult stem cells from bone marrow to another. After monitoring these mice for four weeks, both groups experienced the same degree of neurological repair. Besides promoting brain recovery in the mice, the EVs also down-regulated the post-stroke immune responses and provided long-term neurological protection.

This study could lead to a new clinical treatment for ischemic strokes, since exosomes carry far fewer risks than adult stem cell transplants, according to the co-leaders of this research, neurologist Thorsten Doeppner, and Bernd Giebel, a transfusion medicine specialist.

“We predict that with stringent proof-of-concept strategies, it might be possible to translate this therapy from rodents to humans, since EVs are better suited to clinical use than stem cell transplants,” said Doeppner and Giebel.

Scientists think that EVs carry biological signals between cells and direct a wide range of processes. Exosomes are under a good deal of scientific investigation for the role they could play in cancer, infectious diseases, and neurological disorders.

Other studies have shown that exosome administration can be beneficial after a stroke, but the Duisburg-Essen study is the first to supply evidence through a side-by-side analysis that they act as a key agent in repairing the brain.

“The fact that intravenous EV delivery alone was enough to protect the post-stroke brain and help it recover highlights the clinical potential of EVs in future stroke treatment,” Doeppner and Giebel said.

This study included contributions from ten different researchers from Duisburg-Essen’s Department of Neurology and Institute for Transfusion Medicine. The study was supported by the university, Volkswagen Foundation and German Research Council.

“The current research, combined with the previous demonstration that EVs are well tolerated in men, suggests the potential for using this treatment in conjunction with clot-busting therapies for treatment of stroke,” said Anthony Atala, M.D., editor of STEM CELLS Translational Medicine and Director of the Wake Forest Institute for Regenerative Medicine.

Novastem Treats Its First Stroke Patient With Stemedica’s Mesenchymal and Neural Stem Cell Combination


The biotech company Novastem is a leader in regenerative medicine and has announced the treatment of its first patient in its clinical study for ischemic stroke at Clinica Santa Clarita, Mexico. This clinical trial is testing cell products made by Stemedica. In particular, Stemedica’s ischemia-tolerant mesenchymal stem cells (itMSCs) were administered in combination with ischemia-tolerant neural stem cells (itNSCs); both of which are proprietary products of Stemedica.

Stemedica‘s itMSCs and itNSCs are unique because of the manner in which they are manufactured – they are grown under conditions that make them resistant to low-oxygen conditions. Experiments conducted with these cells in culture and in living animals have definitely shown that when these cells are exposed to low-oxygen conditions, they show greater homing and engraftment than cells grown under normal conditions. Compared to other MSCs and NSCs, Stemedica’s stem cells secrete higher levels of growth factors and other important proteins associated with angiogenesis and healing.

According to the American Stroke Association, ischemic strokes account for 87 percent of all stroke cases. Novastem is continuing to enroll qualified patients in their study. This clinical trial is entitled “Internal Research Protocol in Combination Therapy of Intravenous Administration of Allogeneic Mesenchymal Stem Cells and Intrathecal Administration of Neural Stem Cells in Patients with Motor Aphasia due to Ischemic Stroke.” All participants in this clinical trial will receive a unique, combination stem cell therapy consisting of cells made by Stemedica Cell Technologies.

Novastem is sponsoring this clinical trial and Novastem is the only company licensed to use Stemedica’s stem cell products for studies in Mexico. Novastem’s Clinica Santa Clarita facility is federally licensed to use stem cell therapies, and this trial marks the first time ischemic stroke is being treated with a patented medical method that comprises administration of hypoxically-grown neural stem cells into the cerebrospinal fluid in combination with intravenous administration of hypoxically-grown mesenchymal stem cells. This combination approach is designed to treat the after effects of ischemic strokes.

“Novastem and Clinica Santa Clarita are committed to advancing the research of neurodegenerative disease, and we are pleased to be working with internationally-recognized physician Clemente Humberto Zuniga Gil, MD as the principal investigator and study designer,” says Rafael Carrillo, Novastem’s President. “Our medical team believes that Stemedica’s mesenchymal and neural stem cells, used in this unique combination therapy, will restore and build new vascularization, improve the blood supply, reconnect damaged neural networks and improve functionality of areas affected by our patients’ ischemic stroke.”

The aim of this Novastem study is to evaluate functional changes on subjects after the administration of ischemia-tolerant mesenchymal and neural stem cells. The protocol in use in this clinical trial has been approved by the Research Ethics Committee of Clinica Santa Clarita, which is federally registered and licensed by the Federal Commission for the Protection against Sanitary Risk (COFEPRIS), a division of Mexico’s Ministry of Health.

Patient progress will be tracked at the beginning of the study before any cells have been administered, at 90 days after stem cell administration, and then again at 180 days after administration. Patient improvement will be ascertained with the United States National Institute of Health Stroke Score (NIHSS), Stroke and Aphasia Quality of Life Scale-39 (SAQCOL-39) and the Boston Diagnostic Aphasia Examination (BDAE) neuropsychological evaluation for diagnosis. Additionally, MRIs taken with a gadolinium-based contrast agent (GBCA) will examine the structural integrity of the brain before and after stem cell administration. At the endpoint, the treatment will be evaluated for safety and tolerance of the two-cell treatment. Additionally, patients will be evaluated for changes in neurological functionality.

Pretreatment of Mesenchymal Stem Cells with Melatonin Improves Their Healing Properties in Animals with Strokes


The transplantation of mesenchymal stem cells or MSCs as they as affectionately known, does indeed benefit patients who have had a stroke. Unfortunately, the benefits of MSC transplantation if is limited by inability of these cells to survive after they are implanted into a low-oxygen environment. When a person suffers from a stroke, a blood vessel that feeds the brain has been blocked, and this blockage results in the death of particular cells in the brain. The affected areas of the brain, however, have been deprived of oxygen, and the transplantation of new cells into these areas can result in the prompt death of the implanted cells.

Fortunately, previous studies have revealed that pretreatment of the implanted cells with the hormone melatonin can increase the survival of MSCs that were implanted into kidneys that suffered oxygen deprivation. Therefore, could melatonin pretreatment also improve MSC survival in the case of strokes?

A new study by Guo-Yuan Yang and his colleagues at the Med-X Research Institute in Shanghai, China has examined the effects of melatonin pretreatment on the survival of MSCs that were implanted into the brains of laboratory animals that suffered a stroke.

In a nutshell, Yang and his colleagues showed that melatonin pretreatment greatly increased survival of cultured MSCs when these cells were subjected to low-oxygen conditions. Then when they went whole hog and transplanted their melatonin-pretreated MSCs into the brains of animals that had suffered a stroke, they once again observed that these cells survived at a substantially higher rate than their untreated counterparts. Melatonin-pretreated MSCs also further reduced bleeds into the brain (infarction) and improved the behavioral outcomes of the laboratory animals.

When Yang’s group examined the molecules secreted by the melatonin-treated MSCs, they discovered that the melatonin-pretreated MSCs made a lot more blood-vessel-promoting proteins (such as vascular endothelial growth factor or VEGF), and nerve cell-promoting molecules. Not surprisingly, the rats implanted with melatonin-pretreated MSCs shows significantly more new blood vessels formed, new neurons formed, and better looking brains in general.

Melatonin treatment increased the levels of two signaling molecules, p-ERK1/2, in MSCs. These particular signaling molecules are linked to higher survival rates. When Yang and his crew blocked melatonin signaling by treating cells with as drug called luzindole, these positive effects were reversed and when another drug called U0126, which prevents ERK from becoming phosphorylated was also applied to the cells, it completely reversed the protective effects of melatonin.

These results show that melatonin improves MSC survival and function. Furthermore, melatonin does this by activating the ERK1/2 signaling pathway. Therefore, mesenchymal cells pretreated by melatonin may represent a viable approach to enhance the beneficial effects of stem cell therapy for strokes, and maybe other conditions too? Well shall see. Stay tuned…..

Patient’s Own Peripheral Blood Stem Cells Benefits Stroke Patients


A study conducted in Taiwan has examined the ability of a patient’s circulating peripheral blood stem cells to benefit stroke patients.

In this study, one of two groups of stroke patients received injections of their own peripheral blood stem cells (PBSCs) directly into the brain but the other group received standard care. Those patients who received the PBSCs experienced some improvement in stroke scales and functional capabilities. Patients who received their own PBSCs also were given injections of granulocyte-colony stimulating factor (G-CSF), which seems to protect the nervous system after trauma to it.

“In this phase 2 study, we provide the first evidence that intracerebral injection of autologous (self-donated) PBSCs can improve motor function in those who have suffered a ,” said stroke and have motor deficits as a result,” said Woei-Cheng Shyu of the China Medical University, who is the corresponding author of this study. “Our study demonstrates that this therapeutic strategy was feasible and safe in stroke patients who suffered a prior stroke, but within five years from the onset of symptoms.”

Strokes, also known as trans-ischemic attacks (TIAs) result from blockage in blood vessels that feed the brain. The lack of blood flow to the brain starves it of oxygen, and the cells of the brain begin to die off. Because neuronal death as a result of stroke limits functional recovery, stem cell therapy is advancing as a potentially effective regenerative treatment for stroke.

Also, in many types of stem cell trials, PBSCs are the stem cell of choice. The ease of isolating these cells without invasive procedures makes them the stem cell choice for many clinical trials. In order to utilize PBSCs, patients must amplify their supply of PBSCs, and injections of G-CSF seems to do just that.

In this study, all patients had suffered a prior stroke as long as five years prior to being treated.

At the end of the 12-month follow-up, the group of 15 patients with neurological deficits who received the PBSC injections into the brain experienced neurological and functional improvements, according to several different clinical measurements.

On the other hand, the 15-patient control group who had neurological deficits but did not receive the PBSC injections did not experience the same beneficial results.

In the experimental group, nine of the 15 patients showed proper activation of the motor nerves after stimulating that part of the brain with a magnet. This procedure, called transcranial magnetic stimulation or TMS, places a magnet above skull, directly above the part of the brain you want to stimulate. The rapidly changing magnetic field generated by the magnet produces weak electrical currents in the brain, which stimulates nearby neurons. In this experiment, researchers targeted the precentral gyrus, which is the portion of the brain where the primary motor cortex. Because strokes sometimes kill off neurons in the primary motor cortex, stimulation of the primary motor cortex will not lead to stimulation of motor nerves, but in this experiment, 9 of 15 patients who received the PBSC injections who positive motor evoke potential or MEPs after TMS. Why this ratio was not 15 out of 15 remains unclear at this time.

primary motor cortex

One of the main conclusions of this work, is that “Despite this success, it should be noted that this was a preliminary study and, due to the small number of patients, are tentative. In the future we plan to conduct a multi-center, large-scale, double-blind, placebo-controlled randomized studies [sic] to better evaluate the effect of PBSC implantation in patients suffering from the effects of past stroke.”

Meta Study Shows that Mesenchymal Stem Cells Promote Healing in Animal Models of Stroke


Two scientists from my alma mater, UC Irvine, have examined experiments that treated stroke with bone marrow-derived stem cells. Their analysis has shown that infusions of these stem cells trigger repair mechanisms and limit inflammation in the brains of stroke patients.

UC Irvine neurologist Dr. Steven Cramer and biomedical engineer Weian Zhao identified 46 studies that examined the use of a specific type of bone marrow stem cells called mesenchymal stromal cells to treat stroke. Mesenchymal stromal cells are a type of multipotent adult stem cells that are found in many locations in the body. The best-known examples of mesenchymal stem cells are from bone marrow. When purified from whole bone marrow and used to treat stroke in animal models of stroke, Cramer and Zhao found that mesenchymal stromal cells (MSCs) were significantly better than control therapy in 44 of the 46 studies that were examined.

Further data culling of these studies showed that functional recovery from stroke were robust regardless of the MSC dosage or the time when MSCs were administered relative to the onset of the stroke, or the method of administration (whether introduced directly into the brain or injected via a blood vessel).

“Stroke remains a major cause of disability, and we are encouraged that the preclinical evidence shows [MSCs’] efficacy with ischemic stroke,” said Cramer, a professor of neurology and leading stroke expert. “MSCs are of particular interest because they come from bone marrow, which is readily available, and are relatively easy to culture. In addition, they already have demonstrated value when used to treat other human diseases.”

Another theme of these studies is that MSCs do not differentiate into brain-specific. MSCs have the capacity to differentiate into bone, cartilage and fat cells. “But they do their magic as an inducible pharmacy on wheels and as good immune system modulators, not as cells that directly replace lost brain parts,” he said.

In an earlier Cramer and Zhao examined the mechanism by which MSCs promote brain repair after stroke. These cells have the ability to home to the damages areas in the brain and release chemicals that stimulate healing. By releasing their cornucopia of healing-promoting molecules, MSCs orchestrate blood vessel creation to enhance circulation, the protection of moribund cells on the verge of death, and the growth of existing brain cells. Additionally, when MSCs reach the bloodstream, they settle in those parts of the body that control the immune system and they suppress the inflammatory response that can augment tissue damage. In this way, MSCs foster an environment more conducive to brain repair.

“We conclude that MSCs have consistently improved multiple outcome measures, with very large effect sizes, in a high number of animal studies and, therefore, that these findings should be the foundation of further studies on the use of MSCs in the treatment of ischemic stroke in humans,” said Cramer, who is also clinical director of the Sue & Bill Gross Stem Cell Research Center.

Long-Term Survival of Transplanted Human Neural Stem Cells in Primate Brains


A Korean research consortium has transplanted human neural stem cells (hNSCs) into the brains of nonhuman primates and ascertained the fate of these cells after being inside the brains of these animals for 22 and 24 months. They discovered that the implanted hNSCs had not only survived, but differentiated into neurons and never caused any tumors.

This important study is slated to be published in the journal Cell Transplantation.

To properly label the hNSCs so that they were detectable inside the brains of the animals, Lee and others loaded them with magnetic nanoparticles to enable them to be followed by magnetic resonance imaging (MRI). Also, they did not use immunosuppressants when they transplanted their hNSCs into the animals. This study is the first to examine the long-term survival and differentiation of hNSCs without the need for immunosuppression.

“Stroke is the fourth major cause of death in the US behind heart failure, cancer, and lower respiratory disease,” said study co-author Dr. Seung U. Kim of University of British Columbia Hospital’s department of neurology in Canada. “While tissue plasminogen activator (tPA) treatment within three hours after a stroke has shown good outcomes, stem cell therapy has the potential to address the treatment needs of those stroke patients for whom tPA treatment was unavailable or did not help.”

Based on the ability of hNSCs to differentiate into a variety of types of nerves cells, Lee and his colleagues thought that these cells have remarkable potential to treat damaged brain tissue and replace what was lost after a stroke, head injury or other type of brain trauma. Cell regeneration therapy can potentially treat brain-specific diseases like Parkinson’s disease, Huntington’s disease, Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), spinal cord injury and stroke.

Dr. Kim and colleagues in Korea grafted magnetic particle-labeled hNSCs into the brains of laboratory primates and evaluated their performance to assess their survival and differentiation over 24 months. Of particular interest was determining their ability to differentiate into neurons and to determine whether the cells caused tumors.

“We injected hNSCs into the frontal lobe and the putamen of the monkey brain because they are included in the middle cerebral artery (MCA) territory, which is the main target in the development of the ischemic lesion in animal stroke models,” commented Dr. Kim. “Thus, research on survival and differentiation of hNSCs in the MCA territory should provide more meaningful information to cell transplantation in the MCA occlusion stroke model.”

Lee’s team said that they chose NSCs for transplantation because the existence of multipotent NSCs “has been known in developing rodents and in the human brain with the properties of indefinite growth and multipotent potential to differentiate” into the three major CNS cell types – neurons, astrocytes and oligodendrocytes.

“The results of this study serve as a proof-of-principle and provide evidence that hNSCs transplanted into the non-human primate brain in the absence of immunosuppressants can survive and differentiate into neurons,” wrote the researchers. “The study also serves as a preliminary study in our planned preclinical studies of hNSC transplantation in non-human primate stroke models.”

“The absence of tumors and differentiation of the transplanted cells into neurons in the absence of immunosuppression after transplantation into non-human primates provides hope that such a therapy could be applicable for use in humans.” said Dr. Cesar V. Borlongan, Prof. of Neurosurgery and Director of the Center of Excellence for Aging & Brain Repair at the University of South Florida. “This is an encouraging study towards the use of NSCs to treat neurodegenerative disorders”.