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Stem cell study leads to potential new dementia treatment

By adminJanuary 1, 2015Stem Cell Treatment

The research involved creating human cells in a laboratory dish instead of relying on tests on mice. Photograph: corfield / Alamy/Alamy

Cells used to study dementia in a dish have led scientists to a potential new treatment strategy for an inherited form of the brain disease.

Defective stem cells grown in the lab revealed a signalling pathway linked to frontotemporal dementia (FTD), which accounts for about half of dementia cases before the age of 60.

Treatment with a drug that suppressed the pathway, known as Wnt, restored the ability of neurons affected by the disease to develop normally.

Prof Philip Van Damme, from the Leuven Research Institute for Neuroscience and Disease in Belgium, said: Our findings suggest that signalling events required for neurodevelopment may also play major roles in neurodegeneration.

Targeting such pathways, as for instance the Wnt pathway presented in this study, may result in the creation of novel therapeutic approaches for frontotemporal dementia.

Mutations in the progranulin (GRN) gene are commonly associated with FTD, which results in damage to the frontal and temporal lobes of the brain.

The fact that GRN mutations produced in mice do not display all the features of the human disorder has limited progress towards effective treatments for FTD.

Instead of relying on animal tests, the new research involved creating human cells in a laboratory dish.

The scientists reprogrammed skin cells from three dementia patients into induced pluripotent stem cells (iPSCs), immature cells that mimic stem cells taken from early-stage embryos.

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Stem cell study leads to potential new dementia treatment

Brainstorm Cell Therapeutics (BCLI) Stock Rises Ahead of ALS Treatment Trial Data Release

By adminJanuary 1, 2015Stem Cell Treatment

NEW YORK (TheStreet) -- Shares ofBrainstorm Cell Therapeutics (BCLI) soared 20.88% to $4.69 on higher-than-average volume in morning trading Wednesday ahead of the biotech company's data release on Monday.

Brainstorm intends to release the final results from its Phase 2a trial of its stem cell therapy NurOwn on Monday. The company describes NurOwn as an "autologous, adult stem cell therapy technology" designed to treat ALS, also known as Lou Gehrig's Disease.

The company will host a conference call on Monday to discuss the results.

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Brainstorm Cell Therapeutics (BCLI) Stock Rises Ahead of ALS Treatment Trial Data Release

Patient stem cells used to make dementia-in-a-dish; help identify new treatment strategy

By adminJanuary 1, 2015Stem Cell Treatment

IMAGE:Induced pluripotent stem cells (iPSCs) derived from patients with frontotemporal dementia were genetically corrected and converted to cortical neurons. The green staining indicates the cortical marker CTIP2, the red stain... view more

Credit: Susanna Raitano/Stem Cell Reports 2014

Belgian researchers have identified a new strategy for treating an inherited form of dementia after attempting to turn stem cells derived from patients into the neurons most affected by the disease. In patient-derived stem cells carrying a mutation predisposing them to frontotemporal dementia, which accounts for about half of dementia cases before the age of 60, the scientists found a targetable defect that prevents normal neurodevelopment. These stem cells partially return to normal when the defect is corrected.

The study appears in the December 31st issue of Stem Cell Reports, the official journal of the International Society of Stem Cell Research published by Cell Press.

"Use of induced pluripotent stem cell (iPSC) technology"--which involves taking skin cells from patients and reprogramming them into embryonic-like stem cells capable of turning into other specific cell types relevant for studying a particular disease--"makes it possible to model dementias that affect people later in life," says senior study author Catherine Verfaillie of KU Leuven.

Frontotemporal disorders are the result of damage to neurons in parts of the brain called the frontal and temporal lobes, gradually leading to behavioral symptoms or language and emotional disorders. Mutations in a gene called progranulin (GRN) are commonly associated with frontotemporal dementia, but GRN mutations in mice do not mimic all the features of the human disorder, which has limited progress in the development of effective treatments.

"iPSC models can now be used to better understand dementia, and in particular frontotemporal dementia, and might lead to the development of drugs that can curtail or slow down the degeneration of cortical neurons," Verfaillie says.

Verfaillie and Philip Van Damme of the Leuven Research Institute for Neuroscience and Disease explore this approach in the Stem Cell Reports study by creating iPSCs from three patients carrying a GRN mutation. These immature cells were impaired at turning into mature, specialized cells called cortical neurons--the most affected cell type in frontotemporal dementia.

One of the top defective pathways in the iPSCs was the Wnt signaling pathway, which plays an important role in neuronal development. However, genetic correction or treatment with a compound that inhibits the Wnt signaling pathway restored the ability of the iPSCs to turn into cortical neurons. Taken together, the findings demonstrate that the GRN mutation causes the defect in cortical neuron formation by altering the Wnt signaling pathway.

"Our findings suggest that signaling events required for neurodevelopment may also play major roles in neurodegeneration," Van Damme says. "Targeting such pathways, as for instance the Wnt pathway presented in this study, may result in the creation of novel therapeutic approaches for frontotemporal dementia."

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Patient stem cells used to make dementia-in-a-dish; help identify new treatment strategy

Stopping Multiple Sclerosis with Stem Cell Transplants

By adminDecember 31, 2014Stem Cell Doctors

Washington, DC - infoZine - Three-year outcomes from an ongoing clinical trial suggest that high-dose immunosuppressive therapy followed by transplantation of a person's own blood-forming stem cells may induce sustained remission in some people with relapsing-remitting multiple sclerosis (RRMS). RRMS is the most common form of MS, a progressive autoimmune disease in which the immune system attacks the brain and spinal cord.

Three years after the treatment, called high-dose immunosuppressive therapy and autologous hematopoietic cell transplant or HDIT/HCT, nearly 80 percent of trial participants had survived without experiencing an increase in disability, a relapse of MS symptoms or new brain lesions. Investigators observed few serious early complications or unexpected side effects, although many participants experienced expected side effects of high-dose immunosuppression, including infections and gastrointestinal problems.

Scientists estimate that MS affects more than 2.3 million people worldwide. Symptoms can vary widely and may include disturbances in speech, vision and movement. Most people with MS are diagnosed with RRMS, which is characterized by periods of relapse or flare up of symptoms followed by periods of recovery or remission. Over years, the disease can worsen and shift to a more progressive form.

In the study, researchers tested the effectiveness of HDIT/HCT in 25 volunteers with RRMS who had relapsed and experienced worsened neurological disability while taking standard medications. Doctors collected blood-forming stem cells from participants and then gave them high-dose chemotherapy to destroy their immune systems. The doctors returned the stem cells to the participants to rebuild and reset their immune systems.

"Notably, participants did not receive any MS drugs after transplant, yet most remained in remission after three years," said Daniel Rotrosen, M.D., director of NIAID's Division of Allergy, Immunology and Transplantation. "In contrast, other studies have shown that the best alternative MS treatments induce much shorter remissions and require long-term use of immunosuppressive drugs that can cause serious side effects."

The study researchers plan to follow participants for a total of five years, recording all side effects associated with the treatment. Final results from this and similar studies promise to help inform the design of larger trials to further evaluate HDIT/HCT in people with MS.

The trial is funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and conducted by the NIAID-funded Immune Tolerance Network (ITN).

The three-year findings are published in the Dec. 29, 2014, online issue of JAMA Neurology.

Related Link Immune Tolerance Network (ITN)

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Stopping Multiple Sclerosis with Stem Cell Transplants

Houston-based company leads nation in medical wave of the future

By adminDecember 31, 2014Stem Cell Doctors

When Pearland residents Todd and Linsey Hyatts son, Tucker Beau, received a diagnosis of Juvenile Rheumatoid Arthritis when he was just two years old, the future looked agonizing for the previously precocious little boy. His parents refused to lose hope, however, and took a chance on stem cell therapy to improve Tuckers quality of life.

Now at age six, Tucker Beau looks and acts like any other normal boy his age, save for taking rests more often. He has had two separate stem cell infusions in August and November that have turned his slow, painful decline into a fading memory.

Celltex Therapeutics Corp., a Houston-based biotechnology company located in the Galleria area, uses proprietary technology to isolate, multiply and store their clients own stem cells to be used for regenerative therapy. This therapy has been proven effective with many conditions, including vascular (e.g. Raynauds Disease, kidney artery disease), autoimmune (e.g. arthritis, multiple sclerosis, lupus) and degenerative (e.g. Parkinsons, Alzheimers) diseases.

To get stem cells for a client, fat is extracted from the abdomen in a minimally invasive process that takes 15 30 minutes with no recovery time. This fat is then taken to Celltex, where the components of the fat are separated.

Celltex isolates the mesenchymal stem cells (MSCs) and places them in a nutrient-rich environment to grow. The initial extraction contains about 250,000 stem cells. Celltexs methods can produce one billion cells from that original extraction in as little as 5 weeks, making it unnecessary for clients to have a second extraction in most cases. The cells are frozen and banked at Celltexs lab, ready if and when the client needs another infusion, whether that is in three months or 30 years.

Adult [as opposed to embryonic] MSCs have the remarkable potential of migrating to different parts of the body, recognizing sites of injury and inflammation, and are then able to transform into many different types of cells, says Celltex Chairman and CEO David Eller.

Celltex takes great care in providing safe, pure cells to their clients. The Quality Control Dept,, headed up by QC Manager Kathy Gohlke, tests the cells at different stages throughout the process to ensure that no contaminants are present and that the cells are healthy and viable. Should contaminants be found at some point, which has only happened once out of about 500 clients served since 2011, a second fat extraction may be required.

Erik Eller, Head of Operations, explained that Celltex is also prepared for all kinds of negative scenarios so that the banked cells will stay safe. In the event of a long-term power failure, large generators located on site automatically provide electricity for up to two weeks. An even longer-term solution is in the works. The actual vats that the cells are stored in do not require electricity at all.

The labs at Celltex contain two clean rooms; one for manufacturing and another for Quality Control. These rooms are kept at a constant and optimal temperature, are pressure controlled and the air is continuously filtered through hospital-grade HEPA filters to reduce the chances of contamination. Employees who work in the clean rooms must be covered from head to toe in protective gear to keep the stem cells as healthy as possible.

When a client is ready for treatment, Celltex ships that persons harvested stem cells to either Guadalajara or Cancun Mexico, where the client will receive the infusion in a top-of-the-line hospital by a licensed physician.

Adipose-derived Stem Cells: Current Findings and Future …

By adminDecember 31, 2014Uncategorized

Abstract: Adipose tissue is an abundant source of mesenchymal stem cells, which have shown promise in the field of regenerative medicine. Furthermore, these cells can be readily harvested in large numbers with low donor-site morbidity. During the past decade, numerous studies have provided preclinical data on the safety and efficacy of adipose-derived stem cells, supporting the use of these cells in future clinical applications. Various clinical trials have shown the regenerative capability of adipose-derived stem cells in subspecialties of medical fields such as plastic surgery, orthopedic surgery, oral and maxillofacial surgery, and cardiac surgery. In addition, a great deal of knowledge concerning the harvesting, characterization, and culture of adipose-derived stem cells has been reported. This review will summarize data from in vitro studies, pre-clinical animal models, and recent clinical trials concerning the use of adipose-derived stem cells in regenerative medicine.

Introduction

In the field of regenerative medicine, basic research and preclinical studies have been conducted to overcome clinical shortcomings with the use of mesenchymal stem cells (MSCs). MSCs are present in adult tissues, including bone marrow and adipose tissue. For many years, bone marrow-derived stem cells (BSCs) were the primary source of stem cells for tissue engineering applications (Caplan, 1991; Pittenger et al., 1999; Caplan, 2007). However, recent studies have shown that subcutaneous adipose tissue provides a clear advantage over other stem cell sources due to the ease with which adipose tissue can be accessed as well as the ease of isolating stem cells from harvested tissue (Schffler et al., 2007). Initial enzymatic digestion of adipose tissue yields a mixture of stromal and vascular cells referred to as the stromal-vascular fraction (SVF) (Traktuev et al., 2008). A putative stem cell population within this SVF was first identified by Zuk et al. and named processed lipoaspirate (PLA) cells (Zuk et al., 2001; Zuk et al., 2002).

There is no consensus when it comes to the nomenclature used to describe progenitor cells from adipose tissue-derived stroma, which can sometimes lead to confusion. The term PLA refers to adipose-derived stromal cells and adipose-derived stem cells (ASCs) and describes cells obtained immediately after collagenase digestion. Accordingly, the term ASC will be used throughout this review.

ASCs exhibit stable growth and proliferation kinetics and can differentiate toward osteogenic, chondrogenic, adipogenic, myogenic, or neurogenic lineages in vitro (Zuk et al., 2002; Izadpanah et al., 2006; Romanov et al., 2005). Furthermore, a group has recently described the isolation and culture of ASCs with multipotent differentiation capacity at the single-cell level (Rodriguez, et al., 2005).

Using these attractive cell populations, recent studies have explored the safety and efficacy of implanted/administrated ASCs in various animal models. Furthermore, clinical trials using ASCs have been initiated in some medical subspecialties. This review summarizes the current preclinical data and ongoing clinical trials and their outcomes in a variety of medical fields.

Characterization and Localization

ASCs express the mesenchymal stem cell markers CD10, CD13, CD29, CD34, CD44, CD54, CD71, CD90, CD105, CD106, CD117, and STRO-1. They are negative for the hematopoietic lineage markers CD45, CD14, CD16, CD56, CD61, CD62E, CD104, and CD106 and for the endothelial cell (EC) markers CD31, CD144, and von Willebrand factor (Zuk et al., 2002; Musina et al., 2005; Romanov et al., 2005). Morphologically, they are fibroblast-like and preserve their shape after expansion in vitro (Zuk et al., 2002; Arrigoni et al., 2009; Zannettino et al., 2008).

The similarities between ASCs and BSCs may indicate that ASCs are derived from circulating BSCs, which infiltrate into the adipose compartment through vessel walls (Zuk et al., 2002; Zannettino et al., 2008; Brighton et al., 1992; Canfield et al., 2000; Bianco et al., 2001). On the other hand, according to a recent theory, these stem cells are actually pericytes (Traktuev et al., 2008; Chen et al., 2009; Crisan et al., 2008; Zannettino et al., 2008; Tintut et al., 2003; Abedin et al., 2004; Amos et al., 2008). Pericytes around microvessels express alpha-smooth muscle actin (-SMA) as well as certain MSC markers (CD44, CD73, CD90, CD105); however, they do not express endothelial or hematopoietic cell markers (Chen et al., 2009). Pericytes adhere, proliferate in culture, sustain their initial antigenic profile, and can differentiate into bone, cartilage and fat cells (Chen et al., 2009). Moreover, injected MSCs migrate to the blood vessels in vivo and become pericytes (Chen et al., 2009). Considering the above-mentioned data, it can be speculated that pericytes are the ancestors of MSCs, but this does not mean that all MSCs are descendants of pericytes (Chen et al., 2009) or that all pericytes are necessarily stem cells (Lin et al., 2008; Traktuev et al., 2008; da Silva et al., 2008; Abedin et al., 2004; Tintut et al., 2003; Zannettino et al., 2008; Amos et al., 2008).

Traktuev et al. (2008) defined a periendothelial pericyte-like subpopulation of ASCs. These cells were CD34+, CD31-, CD45-, and CD144- and expressed mesenchymal cell markers, smooth muscle antigens, and pericytic markers, including chondroitin sulfate proteoglycan (NG2), CD140a, and CD140b (PDGF receptor and , respectively) (Traktuev et al., 2008; Amos et al., 2008). However, Lin et al. (2008) could not co-localize CD34 and CD104b, and thus concluded that CD34+/CD31- cells of adipose vasculature are not pericytes.

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Adipose-derived Stem Cells: Current Findings and Future ...

Stem cells to transplant in the brain: Stealth UCSF spinout Neurona Therapeutics raises $7.6M

By adminDecember 30, 2014Stem Cell Medicine

A UCSF spinout is growing neuronal stemcells to transplant into the brain, for potential use in treating epilepsy, spinal cord injury, Parkinsons and Alzheimers disease and investors are listening. Because one thing thatdifferentiatesNeurona Therapeutics is that its stem cells turn exclusively intointerneuron cells which are less likely to be tumorigenic than other IPS cells.

The companyhasraised $7.6 million of a proposed $24.3 million round, according to a regulatory filing. But the companys staying a touch under the radar it lacks a website, and tis the season for calls to the company to remain unanswered.

But funding for the six-year-old company comes from 11 investors. Listed on the documents contact pages areTim Kutzkeyand David Goeddel, both partners at early stage healthcare venture firm The Column Group giving some insight into who the startupsinvestors are.

Also listed is Leo Guthart, a managing partner at New York private equity firm TopSpin Partner, and Arnold Kriegstein, director of the UCSF developmental and stem cell biology program.

Kriegsteinand his UCSF colleagues filed a patentfor the in vitro production of medial ganglionic eminence (MGE) precursor cells which are, in essence, immature cells that morphinto nerve cells. The work that led to the patent was funded bythe California Institute of Regenerative Medicine, the NIH and the Osher Foundation.

We think this one type of cell may be useful in treating several types of neurodevelopmental and neurodegenerative disorders in a targeted way,Kriegstein said in a UCSF statement last year.

Neurona Therapeutics scientific backers collaborated on a paper on these MGE cells inCell Stem Cell,finding that mouse models closely mimicked human cells inneural cell development and that human cells can successfully be transplanted into mouse brains. UCSF writes:

Kriegstein sees MGE cells as a potential treatment to better control nerve circuits that become overactive in certain neurological disorders. Unlike other neural stem cells that can form many cell types and that may potentially be less controllable as a consequence most MGE cells are restricted to producing a type of cell called an interneuron. Interneurons integrate into the brain and provide controlled inhibition to balance the activity of nerve circuits.

To generate MGE cells in the lab, the researchers reliably directed the differentiation of human pluripotent stem cells either human embryonic stem cells or induced pluripotent stem cells derived from human skin. These two kinds of stem cells have virtually unlimited potential to become any human cell type. When transplanted into a strain of mice that does not reject human tissue, the human MGE-like cells survived within the rodent forebrain, integrated into the brain by forming connections with rodent nerve cells, and matured into specialized subtypes of interneurons.

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Report on remission in patients with MS 3 Years after stem cell transplant

By adminDecember 30, 2014Stem Cell Clinic

Three years after a small number of patients with multiple sclerosis (MS) were treated with high-dose immunosuppressive therapy (HDIT) and then transplanted with their own hematopoietic stem cells, most of the patients sustained remission of active relapsing-remitting MS (RRMS) and had improvements in neurological function, according to a study published online by JAMA Neurology.

MS is a degenerative disease and most patients with RRMS who received disease-modifying therapies experience breakthrough disease. Autologous (using a patient's own cells) hematopoietic cell transplant (HCT) has been studied in MS with the goal of removing disease-causing immune cells and resetting the immune system, according to the study background.

The Hematopoietic Cell Transplantation for Relapsing-Remitting Multiple Sclerosis (HALT-MS) study examines the effectiveness of early intervention with HDIT/HCT for patients with RRMS and breakthrough disease. The article by Richard A. Nash, M.D., of the Colorado Blood Cancer Institute at Presbyterian/St. Luke's Medical Center, Denver, and coauthors reports on the safety, efficacy and sustainability of MS disease stabilization though three years after the procedures. Patients were evaluated through five years.

Study results indicate that of the 24 patients who received HDIT/HCT, the overall rate of event-free survival was 78.4 percent at three years, which was defined as survival without death or disease from a loss of neurologic function, clinical relapse or new lesions observed on imaging. Progression-free survival and clinical relapse-free survival were 90.9 percent and 86.3 percent, respectively, at three years. The authors note that adverse events were consistent with the expected toxic effect of HDIT/HCT and that no acute treatment-related neurologic adverse events were seen. Improvements in neurologic disability, quality-of-life and functional scores also were noted.

"In the present study, HDIT/HCT induced remission of MS disease activity up to three years in most participants. It may therefore represent a potential therapeutic option for patients with MS in whom conventional immunotherapy fails, as well as for other severe immune-mediated diseases of the central nervous system. Most early toxic effects were hematologic and gastrointestinal and were expected and reversible. Longer follow-up is needed to determine the durability of the response," the authors conclude.

(JAMA Neurol. Published online December 29, 2014. doi:10.1001/jamaneurol.2014.3780. Available pre-embargo to the media at http://media.jamanetwork.com.)

Editor's Note: Authors made conflict of interest disclosures. This work was sponsored by the Division of Allergy, Immunology and Transplantation, National Institute of Allergy and Infectious Diseases, National Institutes of Health. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

Editorial: Moving Targets for Stem Cell Transplantation for Patients with MS

In a related editorial, M. Mateo Paz Soldn, M.D., Ph.D., of the University of Utah, Salt Lake City, and Brian G. Weinshenker, M.D., of the Mayo Clinic, Rochester, Minn., write: "This study and another phase 2 single-arm study leave little doubt that high-dose immunotherapy is able to substantially suppress inflammatory disease activity in patients with MS who have active disease in the short term. There is some evidence for long-term suppression of MS. Lessons have been learned about how treatment-related morbidity and mortality may be reduced. However, deaths have occurred, even in small studies, and aggressive regimens have resulted in lymphomas associated with Epstein-Barr virus."

"Nash et al show evidence of prolonged depletion of memory CD4+ cells, depletion of CD4+-dominant T-cell receptor clones and evidence of 'immune reset'; however, clinical or radiologic evidence of relapse trumps immunologic evidence of immune reset, and this study raises concern that those end points have not been adequately achieved. The jury is still out regarding the appropriateness and indication of HCT for MS," the authors conclude.

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Report on remission in patients with MS 3 Years after stem cell transplant

Report on remission in patients with MS three years after stem cell transplant

By adminDecember 30, 2014Stem Cell Clinic

Editorial: Moving Targets for Stem Cell Transplantation for Patients with MS

Story Source:

The above story is based on materials provided by The JAMA Network Journals. Note: Materials may be edited for content and length.

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Report on remission in patients with MS three years after stem cell transplant

Reprogramming stem cells may prevent cancer after radiation

By adminDecember 30, 2014Uncategorized

The body has evolved ways to get rid of faulty stem cells. A University of Colorado Cancer Center study published in the journal Stem Cells shows that one of these ways is a "program" that makes stem cells damaged by radiation differentiate into other cells that can no longer survive forever. Radiation makes a stem cell lose its "stemness." That makes sense: you don't want damaged stem cells sticking around to crank out damaged cells.

The study also shows that this same safeguard of "programmed mediocrity" that weeds out stem cells damaged by radiation allows blood cancers to grow in cases when the full body is irradiated. And by reprogramming this safeguard, we may be able to prevent cancer in the aftermath of full body radiation.

"The body didn't evolve to deal with leaking nuclear reactors and CT scans. It evolved to deal with only a few cells at a time receiving dangerous doses of radiation or other insults to their DNA," says James DeGregori, PhD, investigator at the CU Cancer Center, professor of Biochemistry and Molecular Genetics at the CU School of Medicine, and the paper's senior author.

DeGregori, doctoral student Courtney Fleenor, and colleagues explored the effects of full body radiation on the blood stem cells of mice. In this case, radiation increased the probability that cells in the hematopoietic stem cell system would differentiate. Only, while most followed this instruction, a few did not. Stem cells with a very specific mutation were able to disobey the instruction to differentiate and retain their "stemness." Genetic inhibition of the gene C/EBPA allowed a few stem cells to keep the ability to act as stem cells. With competition from other, healthy stem cells removed, the stem cells with reduced C/EBPA were able to dominate the blood cell production system. In this way, the blood system transitioned from C/EBPA+ cells to primarily C/EBPA- cells.

Mutations and other genetic alterations resulting in inhibition of the C/EBPA gene are associated with acute myeloid leukemia in humans. Thus, it's not mutations caused by radiation but a blood system reengineered by faulty stem cells that creates cancer risk in people who have experienced radiation.

"It's about evolution driven by natural selection," DeGregori says. "In a healthy blood system, healthy stem cells out-compete stem cells that happen to have the C/EBPA mutation. But when radiation reduces the heath and robustness (what we call 'fitness') of the stem cell population, the mutated cells that have been there all along are suddenly given the opportunity to take over."

Think about it in terms of chipmunks and squirrels: reducing an ecosystem's population of chipmunks may allow squirrels to flourish -- especially if the way in which chipmunks are reduced changes the ecosystem to favor squirrels, similar to how radiation changes the body in a way that favors C/EBPA-mutant stem cells).

These studies don't just tell us why radiation makes hematopoietic stem cells (HSCs) differentiate; they also show that by activating a stem cell maintenance pathway, we can keep it from happening. Even months after irradiation, artificially activating the NOTCH signaling pathway of irradiated HSCs lets them act "stemmy" again -- restarting the blood cell assembly line in these HSCs that would have otherwise differentiated in response to radiation.

When DeGregori, Fleenor and colleagues activated NOTCH in previously irradiated HSCs, it kept the population of dangerous, C/EBPA cells at bay. Competition from non-C/EBPA-mutant stem cells, with their fitness restored by NOTCH activation, meant that there was no evolutionary space for C/EBPA-mutant stem cells.

"If I were working in a situation in which I was likely to experience full-body radiation, I would freeze a bunch of my HSCs," DeGregori says, explaining that an infusion of healthy HSCs after radiation exposure would likely allow the healthy blood system to out-compete the radiation-exposed HSC with their "programmed mediocrity" (increased differentiation) and even HSC with cancer-causing mutations. "But there's also hope that in the future, we could offer drugs that would restore the fitness of stem cells left over after radiation."

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Reprogramming stem cells may prevent cancer after radiation