Blood Vessel Cells Are Key to Growing Unlimited Amounts of Adult Stem Cells

Howard Hughes Medical Institute (HHMI) scientists have discovered that endothelial cells, the building blocks of the vascular system, keep blood stem cells dividing healthily in a lab dish much longer and more effectively than previous methods of growing the cells. The new advance dramatically improves scientists’ ability to manufacture large quantities of authentic adult blood stem cells, which may help revolutionize the field of bone marrow transplantation.

Shahin Rafii, an HHMI investigator at Weill Cornell Medical College in New York City, and his colleagues report on the development of an endothelial cell platform that supports self-renewal of the blood stem cells, known as long-term hematopoietic stem cells (LT-HSCs), in the March 2010 issue of the journal Cell Stem Cell. Their study also describes a novel mechanism by which endothelial cells support propagation of LT-HSCs in adult mice.

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Keeping Stem Cells Strong

When infections occur in the body, stem cells in the blood often jump into action by multiplying and differentiating into mature immune cells that can fight off illness. But repeated infections and inflammation can deplete these cell populations, potentially leading to the development of serious blood conditions such as cancer.

Now, a team of researchers led by biologists at the California Institute of Technology (Caltech) has found that, in mouse models, the molecule microRNA-146a (miR-146a) acts as a critical regulator and protector of blood-forming stem cells (called hematopoietic stem cells, or HSCs) during chronic inflammation, suggesting that a deficiency of miR-146a may be one important cause of blood cancers and bone marrow failure.

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Efficient process using microRNA converts human skin cells into neurons

The addition of two particular gene snippets to a skin cell’s usual genetic material is enough to turn that cell into a fully functional neuron, report researchers from the Stanford University School of Medicine. The finding, published online July 13 in Nature, is one of just a few recent reports of ways to create human neurons in a lab dish.

The new capability to essentially grow neurons from scratch is a big step for neuroscience research, which has been stymied by the lack of human neurons for study. Unlike skin cells or blood cells, neurons are not something that’s easy for a living human to donate for research.

“A major problem in neurobiology has been the lack of a good human model,” said senior author Gerald Crabtree, MD, professor of pathology and of developmental biology. “Neurons aren’t like blood. They’re not something people want to give up.”

Generating neurons from easily accessible cells, such as skin cells, makes possible new ways to study neuronal development, model disease processes and test treatments.

It also helps advance the effort, still in its infancy, to replace damaged or dead neurons with new ones.

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Now, a new tool to examine cancer growth

University of California, Berkeley
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Scientists have developed a new tool that illuminates connections between stem cells and cancer.
Researchers have been successful in breaking apart human prostate tissue, extract the stem cells in the tissue, and alter those cells genetically so that they spur cancer.

Many tissues contain pools of stem cells that replenish the tissue when it’s damaged or when changes take place. For example, stem cells in the skin produce new cells to replace those irreparably damaged by the sun, and stem cells in the breast create milk-producing cells when a woman is pregnant.

A characteristic of these stem cells is that they self-renew. This means that in addition to making cells with a specific function, they also make many new stem cells.

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How To Heal Diabetes Using Stem Cells

'Diabetes causes amputations', warns poster
Image by engineroomblog via Flickr

Using skin cells from people with type 1 diabetes, researchers were able to produce cells that made insulin in response to changing blood sugar levels, though not as efficiently as normal insulin-producing cells do. (…) “This is a big deal,” said Susan Solomon, CEO of the New York Stem Cell Foundation, which provided some of the funding for the study. “Tackling the basic biology of type 1 diabetes, which is a very complex disease, is a critical step. With these cells, we can see in a dish what’s happening to the immune system, and if you don’t understand the immune response, you get nowhere with type 1 diabetes.”

“This is very preliminary data, but now we could potentially look at the interaction between immune system cells and insulin-producing cells to find the root cause or trigger, which we think might vary from patient to patient,” explained Meri Firpo, an assistant professor at the Stem Cell Institute at the University of Minnesota (…)

In the current study, researchers from the Howard Hughes Medical Institute at the Harvard Stem Cell Institute and the Naomi Berrie Diabetes Center at Columbia University, obtained skin samples from two white males who had type 1 diabetes. One was diagnosed at 3 years of age, while the other was first diagnosed when he was 21.

Normal skin cells are already specialized cells. Their job is to protect the body with a covering of skin, explained Firpo. To transform these cells into embryonic-like stem cells, essentially getting them back to the beginning when they weren’t already specialized, researcher Doug Melton and his colleagues used three inserted genes to reprogram the cells, creating what’s known as an induced pluripotent stem cell (iPS). In this case, the cells were then turned into insulin-producing cells (…)

She said that this study helps further at least two areas of research that JDRF is focusing on: developing a self-source for islet-cell transplants and blocking the immune response. Another area of research that JDRF is actively pursuing is the possible encapsulation of islet cells before transplantation so that they could hide from the immune system (…)

from http://www.ajc.com/health/content/shared-auto/healthnews/diab/630511.html

A study published today in the Proceedings of the National Academy of Sciences describes a way to create induced pluripotent stem (iPS) cells from ordinary adult cells taken from patients with type 1 diabetes. These stem cells then can be reprogrammed to produce all of the cell types relevant to the disease.

“What you get is the ability to watch, for the first time, type 1 diabetes develop,” says senior author Douglas Melton, a professor of natural sciences at Harvard University and co-director of the Harvard Stem Cell Institute. “Until you watch a disease develop, you will not understand the mechanism, and you therefore cannot devise any kind of sensible treatment or cure.”

Melton and his colleagues show that the reprogrammed iPS cells–so called for their ability to give rise to many cell types–can be spurred to differentiate into tissue resembling the insulin-producing pancreatic beta cells that are destroyed by the immune system in type 1 diabetes.

Embryonic stem (ES) cells have long been the gold standard for deriving pluripotent cell lines. But ES cells can only be used to create disease models for disorders such as cystic fibrosis, where the genetic underpinnings are straightforward. Because the genetics underlying type 1diabetes are complex and poorly understood, researchers have no way to identify diabetes-specific ES cells (…)

Ultimately, Melton plans to construct a “living test tube” for probing the interplay between the beta cells and the immune system in diabetes. He hopes to use the diabetic iPS cells to generate all three relevant cell types and then to put those cells into a so-called humanized mouse that can accept human cells to see how they interact.

from http://www.technologyreview.com/biomedicine/23335/

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