Human Neural Stem Cells Heal Damaged Limbs


The term “ischemia” refers to conditions under which a part of your body, organ, or tissue is deprived of oxygen. Without life-giving cells begin to die. Therefore, ischemia is usually a very bad thing.

Critical limb ischemia or CLI results when blood vessels to the legs, feet or arms are severely obstructed. The results of CLI are never pretty, and CLI remains a medical condition that presents few treatment options.

A study from a research team and the University of Bristol’s School of Clinical Sciences has used stem cells in a trial that uses laboratory mice to treat CLI. The success of this study provides a new direction and new hope for procedures that relieve symptoms and prolong the life of the limb.

Autologous stem cells treatments, or those stem treatments that utilize a patient’s own stem cells care subject to clear limitations. After collection from bone marrow, fat, or other source, the stem cells must be expanded in culture after stimulation with chemicals called cytokines. After growth in culture, the cells typically contain a collection of different types of stem cells of variable quality and potency. Also, if the patients has had a heart attack or has diabetes, then the quality and potency of their own stem cells are seriously compromised.

To circumvent this problem, Paulo Madeddu and his team at the Bristol Heart Institute have used an immortalized human neural stem cell line called CTX to treat animals who suffered from diabetes mellitus and CLI.

The CTX cell line comes from a biotechnology company called ReNeuron. This company is using this cell line in a clinical trial for stoke patients, and wants to use the CTX cell line in a clinical trial for CLI patients in the future.

When CTX cells are injected into the muscle of diabetic mice with CLI, the cells promote recovery from CLI. The CTX cells do so by promoting the growth of new blood vessels.

Madeddu said, “There are not effective drug interventions to treat CLI. The consequences are a very poor quality of life, possible major amputation and a life expectancy of less than one year from diagnosis in 50 percent of all CLI patients.”

Dr. Madeddu continued: “Our findings have shown a remarkable advancement towards more effective treatments for CLI and we have also demonstrated the importance of collaborations between universities and industry that can have a social and medical impact.”

New Approach for Corneal Stem Cell Treatments


More than 8 million people worldwide suffer from corneal blindness; a form of blindness that results from cloudiness of the outermost covering of the eye, the cornea.

Usually, the cornea copes quite well with minor injuries or scrapes and scratches. If the cornea is scratched, healthy cells slide over quickly and patch the injury before infection occurs and vision is not adversely affected. However, if the scratch penetrates the cornea more deeply, then the healing process takes longer and can result in greater pain, blurred vision, tearing, redness, and extreme sensitivity to light. Such scratches may require professional treatment. Even deeper scratches can also cause corneal scarring, which results in a haze on the cornea that can greatly impair vision, and the patient might require a corneal transplant.

Alternatively, corneal stem cells can help heal a damaged cornea; especially in those cases where the cornea has been damaged to the point where the native stem cell population has suffered irreparable damage (e.g., chemical burns, eye infections, or cases where the patient was born with a corneal stem cell deficiency).

A feasible treatment for such cases is a corneal stem cell transplant from another eye or from cultured corneal stem cells. Unfortunately, this procedure has not yet been standardized to date.

Fortunately, researchers at the Eye Program at the Cedar-Sinai Regenerative Medicine Institute have designed a fast, new procedure for preparing human amniotic membrane to use as a scaffold for corneal stem cells. The membrane provides a foundation that supports the growth of stem cells that can be grafted onto the cornea.

To date, a standardized method does not exist for the preparation of amniotic membranes for culturing corneal stem cells. Many methods use chemicals and may leave behind amniotic cells and membrane components.

This new procedure, however, takes less than one minute and ensures complete amniotic cell removal and preservation of amniotic membrane components, and, as an added bonus, supports the overall growth of various stem and tissue cells.

“We believe that this straightforward and relatively fast procedure would allow easier standardization of amniotic membrane as a valuable stem cell support and improve the current standard of care in corneal stem cell transplantation,” said the lead author of this work Alexander Ljubimov, the director of the Eye Program at the Cedar-Sinai Regenerative Medicine Institute. “This new method may provide a better method for researchers, transplant corneal surgeons, and manufacturing companies alike.”

The amniotic membrane has several beneficial properties for corneal stem cells culturing and use in corneal transplantations. For this reason it is an attractive framework for the growth and culture of corneal stem cells and for corneal transplantations.

The new method for amniotic membrane preparation will provide a fast way to create scaffolds for cell expansion and might potentially streamline clinical applications of cell therapies.

New Clinical Trial to Examine Stem Cell Treatment for Cerebral Palsy in Children


A new clinical trial that is probably one of the first of its kind will study two types of stem cell treatments for children who have cerebral palsy. The University of Texas Health Science Center at Houston (UTHealth) Medical School will host this trial.

This trial will be conducted in a blinded fashion and will test the efficacy of stem cells against a placebo. The types of stem cells investigated in this clinical trial include banked cord blood stem cells and bone marrow stem cells. Charles S. Cox Jr., M.D., professor of pediatric surgery at the UTHealth Medical School and director of the Pediatric Trauma Program at Children’s Memorial Hermann Hospital will lead this clinical trial, and Sean I. Savitz, M.D., chair of the UTHealth Department of Neurology will serve as the co-principal investigator.

This FDA-approved study builds on Dr. Cox’s previous work on traumatic brain injury and the use of stem cell therapy to treat it in children and adults. In particular, Cox has focuses on those patients who have been admitted to Children’s Memorial Hermann and Memorial Hermann-Texas Medical Center after having suffered a traumatic brain injury. Prior research by Cox and others have shown that stem cells derived from a patient’s own bone marrow can be used safely used in pediatric patients with traumatic brain injury. In this clinical trial, Cox is also studying cord blood stem cell treatment for these injuries in a separate clinical trial.

Cox’s trials will enroll a total of 30 children between the ages of 2 and 10 who have cerebral palsy. 15 of these subjects have will have their own cord blood banked at Cord Blood Registry (CBR), and 15 will not have banked any cord blood. In each of these groups, five subjects will be randomized to a placebo control group.

After treatment the children will be neurologically assessed at six, 12 and 24 months. None of the parents will be told if their child received stem cells or a placebo until the 12-month follow-up exam, and at this time, those parents whose children received the placebo may elect to have their child receive a stem cell treatment either by means of stem cells isolated from bone marrow harvest or with stem cells from cord blood banked with CBR.

Collaborators in the study include CBR, Let’s Cure CP, TIRR Foundation and Children’s Memorial Hermann Hospital.

Growing Intestinal Stem Cells


Researchers from MIT and Brigham and Women’s Hospital in Boston, MA have discovered a protocol that allows them to grow unlimited quantities of intestinal stem cells. These intestinal stem cells can then be induced to differentiate into pure populations of various types of mature intestinal cells. Scientists can used these cultured intestinal cells to develop new drugs and treat gastrointestinal diseases, such as Crohn’s disease or ulcerative colitis.,

The small intestine has a small repository of adult stem cells that differentiate into mature adult cells that have specialized functions. Until recently, there was no good way to grow large numbers of these intestinal stem cells in culture. Intestinal stem cells, you see, only retain their immature characteristics when they are in contact with supportive cells known as Paneth cells.

paneth cells

In order to grow intestinal stem cells in culture, researchers from the laboratories of Robert Langer at the MIT Koch Institute for Integrative Cancer Research and Jeffrey Karp from the Harvard Medical School and Brigham and Women’s Hospital, determined the specific molecules that Paneth cells make that keep the intestinal stem cells in their immature state. Then they designed small molecules that mimic the Paneth cell-specific molecules. When Langer and Karp’s groups grew the intestinal stem cells in culture with those small molecules, the cells remained immature and grew robustly in culture.

Langer said, “This opens the door to doing all kinds of thing, ranging from someday engineering a new gut for patients with intestinal diseases to doing drug screening for safety and efficacy. It’s really the first time this has been done.”

The inner mucosal layer of the intestine has several vital functions: the absorption of nutrients, the secretion of mucus of create a barrier between our own cells and the bacteria and viruses and habitually inhabit our bowels, and alerting the immune system to the presence of potential disease-causing agents in the bowel.

The intestinal mucosa is organized into a collection of folds with small indentations called “intestinal crypts.”  At the bottom of each crypt is a small pool of intestinal stem cells that divide to routinely replace the specialized cells of the intestinal epithelium.  Because the cells of the intestinal epithelium show a high rate of turnover (they only last for about five days), these stem cells must constantly divide to replenish the intestine.

INTESTINES COMPARED

Once these intestinal stem cells divide, they can differentiate into any type of mature intestinal cell type.  Therefore, these intestinal stem cells provide a marvelous example of a “multipotent stem cell.”

Obtaining large quantities of intestinal stem cells could certainly help gastroenterologists  treat gastrointestinal diseases that damage the epithelial layer of the gut.  Fortunately, recent studies in laboratory animals have demonstrated that the delivery of intestinal stem cells can promote the healing of ulcers and regeneration of new tissue, which offers a new way to treat inflammatory bowel diseases like ulcerative colitis.

This, however, is only one of the many uses for cultured intestinal stem cells.  Researchers are literally salivating over the potential of studying things like goblet cells, which control the immune response to proteins in foods to which many people are allergic.  Alternatively, scientists would like to investigate the properties of enteroendocrine cells, which secrete hunger hormones and play a role in obesity.  I think you can see, that large numbers of intestinal stem cells could be a boon to gastrointestinal research.

Karp said, “If we had ways of performing high-throughput screens of large numbers of these very specific cell types, we could potentially identify new targets and develop completely new drugs for diseases ranging from inflammatory bowel disease to diabetes.”

The laboratory of Hans Clevers in 2007 identified a molecule that is specifically made by intestinal stem cells called Lgr5.  Clevers is a professor at the Hubrecht Institute in the Netherlands and he and his co-workers have just identified particular molecules that enable intestinal stem cells to grow in synthetic culture.  In culture, these small clusters of intestinal stem cells differentiate and form small sphere-like structures called “organoids,” because they consist of a ball of intestinal cells that have many of the same organizational properties of our own intestines, but are made in culture.

Clevers and his colleagues tried to properly define the molecules that bind Paneth cells and intestinal stem cell together.  The purpose of this was to mimic the Paneth cells in culture so that the intestinal stem cells would grow robustly in culture.  Clevers’ team discovered that Paneth cells use two signal transduction pathways (biochemical pathways that cells use to talk to each other) to coordinate their “conversations” with the adjacent stem cells.  These two signal transduction pathways are the Notch and Wnt pathways.

Fortunately, two molecules could be used to induce intestinal stem cell proliferation and prevent their differentiation: valproic acid and CHIR-99021.  When Clevers and others grew mouse intestinal stem cells in the presence of these two compounds, they found that large clusters of cells grew that consisted of 70-90 percent pure stem cells.  When they used inhibitors of the Notch and Wnt pathway, they could drive the cells to form particular types of mature intestinal cells.

“We used different combinations of inhibitors and activators to drive stem cells to differentiate into specific populations of mature cells,” said Xiaolei Yin, first author of this paper.  Yin and others were able to get this strategy to work with mouse stomach and colon cells, and that these small molecules also drove the proliferation of human intestinal stem cells.

Presently, Clevers’ laboratory is trying to engineering intestinal tissues for potential transplantation in human patients and for rapidly testing the effects of drugs on intestinal cells.

Ramesh Shivdasani from Harvard Medical School and Dana-Farber Cancer Institute would like to use these cells to investigate what gives stem cells their ability to self-renew and differentiate into other cell types.  “There are a lot of things we don’t know about stem cells,” said Shivdasani.  “Without access to large quantities of these cells, it’s very difficult to do any experiments.  This opens the door to a systematic, incisive, reliable way of interrogating intestinal stem cell biology.”

X. Yi, et al. “Niche-independent high-purity cultures of Lgr5 intestinal stem cells and their progeny.” Nature Methods 2013; DOI:10.1038/nmeth.2737.

Human Stem Cells Converted into Functional Lung Cells


Scientists from the Columbia University Medical Center have succeeded in transforming human stem cells into functional lung and airway cells. This finding has significant potential for modeling lung disease, screening lung-specific drugs, and, hopefully, generating lung tissue for transplantation.

Study leader, Hans-Willem Snoeck, professor of medicine and affiliated with the Columbia Center for Translational Immunology and the Columbia Stem Cell Initiative, said, “Researchers have had relative success in turning human stem cells into heart cells, pancreatic beta cells, intestinal cells, liver cells, and nerve cells, raising all sorts of possibilities for regenerative medicine. Now, we are finally able to make lung and airway cells. This is important because lung transplants have a particularly poor prognosis. Although any clinical application is still many years away, we can begin thinking about making autologous lung transplants – that is, transplants that use a patient’s own skin cells to generate functional lung tissue.”

The research builds on Snoeck’s earlier discoveries in 2011 that a set of chemical factors could induce the differentiation of embryonic or induced pluripotent stem cells into “anterior foregut endoderm,” which is the embryo in the tissue from which the lungs form (Green MD, et al. Generation of anterior foregut endoderm from human embryonic and induced pluripotent stem cells. Nat Biotechnol. 2011 Mar;29(3):267-72).

Human Embryological Development - one month

In his new study, Snoeck and his colleagues found new factors that can transform anterior foregut endoderm cells into lung and airway cells. In particular, Snoeck and his co-workers were able to establish the presence of “type 2 alveolar epithelial cells,” which secrete the lung surfactant that maintains the lung alveoli (those tiny sacs in the lung where all the oxygen exchange takes place).

lung alveolus

With these techniques, lung researchers hope to study diseases like idiopathic pulmonary fibrosis (IPF), in which type 2 epithelial cells seem to divide and produce scarring in the lungs.

“No one knows what causes the disease, and there’s no way to treat it,” said Snoeck. “Using this technology, researchers will finally be able to create laboratory models of IPF, study the disease at the molecular level, and screen drugs for possible treatments or cures. In the longer term, we hope to use this technology to make an autologous lung graft. This would entail taking a lung from a donor, removing all the lung cells, leaving only the lung scaffold; and seeding the scaffold with new lung cells derived from the patient. In this way, rejection problems could be avoided.”

Snoeck is investigating this approach in collaboration with researchers in the Columbia University Department of Biomedical Engineering.

Priming Cocktail for Cardiac Stem Cell Grafts


Approximately 700,000 Americans suffer a heart attack every year and stem cells have the potential to heal the damage wrought by a heart attack. Stem cells therapy has tried to take stem cells cultured in the laboratory and apply them to damaged tissues.

In the case of the heart, transplanted stem cells do not always integrate into the heart tissue. In the words of Jeffrey Spees, Associate Professor of Medicine at the University of Vermont, “many grafts simply didn’t take. The cells would stick or would die.”

To solve this problem, Spees and his colleagues examined ways to increase the efficiency of stem cell engraftment. In his experiments, Spees and others used mesenchymal stem cells from bone marrow. Mesenchymal stem cells are also called stromal cells because they help compose the spider web-like filigree within the bone marrow known as “stroma.” Even though the stroma does not make blood cells, it supports the hematopoietic stem cells that do make all blood cells.  Here is a picture of bone marrow stroma to give you an idea of what it looks like:

Immunohistochemistry-Paraffin: Bone marrow stromal cell antigen 1 Antibody [NBP2-14363] Staining of human smooth muscle shows moderate cytoplasmic positivity in smooth muscle cells.
Immunohistochemistry-Paraffin: Bone marrow stromal cell antigen 1 Antibody [NBP2-14363] Staining of human smooth muscle shows moderate cytoplasmic positivity in smooth muscle cells.
Stromal cells are known to secrete a host of molecules that protect injured tissue, promote tissue repair, and support the growth and proliferation of stem cells.

Spees suspected that some of the molecules made by bone marrow stromal cells could enhance the engraftment of stem cells patches in the heart. To test this idea, Spees and others isolated proteins from the culture medium of bone marrow stem cells grown in the laboratory and tested their ability to improve the survival and tissue integration of stem cell patches in the heart.

Spees tenacity paid off when he and his team discovered that a protein called “Connective tissue growth factor” or CTGF plus the hormone insulin were in the culture medium of these stem cells. Furthermore, when this culture medium was injected into the heart prior to treating them with stem cells, the stem cell patches engrafted at a higher rate.

“We broke the record for engraftment,” said Spees. Spees and his co-workers called their culture medium from the bone marrow stem cells “Cell-Kro.” Cell-Kro significantly increases cell adhesion, proliferation, survival, and migration.

Spees is convinced that the presence of CTGF and insulin in Cell-Kro have something to do with its ability to enhance stem cell engraftment. “Both CTGF and insulin are protective,” said Spees. “Together they have a synergistic effect.”

Spees is continuing to examine Cell-Kro in rats, but he wants to take his work into human trials next. His goal is to use cardiac stem cells (CSCs) from humans, which already have a documented ability to heal the heart after a heart attack. See here, here, and here.

“There are about 650,000 bypass surgeries annually,” said Spees. “These patients could have cells harvested at their first surgery and banked for future application. If they return for another procedure, they could then receive a graft of their own cardiac progenitor cells, primed in Cell-Kro, and potentially re-build part of their injured heart.”

The Therapeutic Potential of Fat-Based Stem Cells Decreases With Age


Fat is a rich source of stem cells for regenerative medicine.  Treating someone with their own stem cells from their own fat certainly sounds like an attractive option.  However, a new study shows that demonstrates that the therapeutic value of fat-based stem cells declines when those cells come from older patients.

“This could restrict the effectiveness of autologous cell therapy using fat, or adipose-derived mesenchymal stromal cells (ADSCs), and require that we test cell material before use and develop ways to pretreat ADSCs from aged patients to enhance their therapeutic potential,” said Anastasia Efimenko, M.D., Ph.D.  Dr Efimenko and Nina Dzhoyashvili, M.D., were first authors of the study, which was led by Yelena Parfyonova, M.D., D.Sc., at Lomonosov Moscow State University, Moscow.

Heart disease remains the most common cause of death in most countries.  Mesenchymal stromal cells (MSCs) collected from either bone marrow or fat are considered one of the most promising therapeutic agents for regenerating damaged tissue because of their ability to proliferate in culture and differentiate into different cell types.  Even more importantly they also have the ability to stimulate the growth of new blood vessels (angiogenesis).

In particular, fat is considered an ideal source for MSCs because it is largely dispensable and the stem cells are easily accessible in large amounts with a minimally invasive procedure.  ADSCs have been used in several clinical trials looking at cell therapy for heart conditions, but most of the studies used stem cells from relatively healthy young donors rather than sick, older ones, which are the typical patients who suffer from heart disease.

“We knew that aging and disease itself may negatively affect MSC activities,” Dr. Dzhoyashvili said. “So the aim of our study was to investigate how patient age affects the properties of ADSCs, with special emphasis on their ability to stimulate angiogenesis.”

The Russian team analyzed age-associated changes in ADSCs collected from patients of different age groups, including some patients who suffered from coronary artery disease and some without.  The results showed that ADSCs from the older patients in both groups showed some of the characteristics of aging, including shorter telomeres (the caps on the ends of chromosomes that protect them from deterioration), which confirms that ADSCs do age.

“We showed that ADSCs from older patients both with and without coronary artery disease produced significantly less amounts of angiogenesis-stimulating factors compared with the younger patients in the study and their angiogenic capabilities lessened,” Dr. Efimenko concluded. “The results provide new insight into molecular mechanisms underlying the age-related decline of stem cells’ therapeutic potential.”

“These findings are significant because the successful development of cell therapies depends on a thorough understanding of how age may affect the regenerative potential of autologous cells,” said Anthony Atala, M.D., director of the Wake Forest Institute for Regenerative Medicine, and editor of STEM CELLS Translational Medicine, where this research was published.