“Latest Stem Cells News”

The team at Children’s Hospital Boston and the Harvard Stem Cell Institute were working with a new type of cell called induced pluripotent stem cells or iPS cells, which closely resemble embryonic stem cells but are made from ordinary skin cells.

In this case, they wanted to study a rare, inherited premature aging disorder called dyskeratosis congenita. The blood marrow disorder resembles the better-known aging disease progeria and causes premature graying, warped fingernails and other symptoms as well as a high risk of cancer.

One of the benefits of stem cells and iPS cells is that researchers can make them from a person with a disease and study that disease in the lab. Harvard’s Dr. George Daley and colleagues were making iPS cells from dyskeratosis congenita patients to do this (…)

Cells from people with premature aging disease get “younger” with the help of stem cell technology.

Premature aging is one of the most difficult-to-deal with conditions in the world. In addition to its physical consequences, its psychological impact is devastating on a person suffering from it. At this point, experts believe that the disease is caused by the fact that people predisposed to it have very short telomeres, which are repetitive stretches of DNA attached to the end of each chromosome in each cell featuring genetic material in the human body. As chromosomes multiply, the telomeres naturally get shorter, and scientists believe that this may be playing a role in aging.

Even Superman needed to retire to a phone booth for a quick change. But now scientists at the Stanford University School of Medicine have succeeded in the ultimate switch: transforming mouse skin cells in a laboratory dish directly into functional nerve cells with the application of just three genes. The cells make the change without first becoming a pluripotent type of stem cell — a step long thought to be required for cells to acquire new identities.

The finding could revolutionize the future of human stem cell therapy and recast our understanding of how cells choose and maintain their specialties in the body.

“We actively and directly induced one cell type to become a completely different cell type,” said Marius Wernig, MD, assistant professor of pathology and a member of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine. “These are fully functional neurons. They can do all the principal things that neurons in the brain do.” That includes making connections with and signaling to other nerve cells — critical functions if the cells are eventually to be used as therapy for Parkinson’s disease or other disorders.

Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs) by defined factors. However, the low efficiency and slow kinetics of the reprogramming process have hampered progress with this technology. Here we report that a natural compound, vitamin C (Vc), enhances iPSC generation from both mouse and human somatic cells. Vc acts at least in part by alleviating cell senescence, a recently identified roadblock for reprogramming.

In addition, Vc accelerates gene expression changes and promotes the transition of pre-iPSC colonies to a fully reprogrammed state. Our results therefore highlight a straightforward method for improving the speed and efficiency of iPSC generation and provide additional insights into the mechanistic basis of the reprogramming process.► Vitamin C improves the speed and efficiency of mouse iPSC generation ► Adding vitamin C converts pre-iPSCs to iPSCs ► Vitamin C alleviates the senescence roadblock to reprogramming ► Human iPSC generation is also improved by vitamin C

The same genes that are chemically altered during normal cell differentiation, as well as when normal cells become cancer cells, are also changed in stem cells that scientists derive from adult cells, according to new research from Johns Hopkins and Harvard.

Although genetically identical to the mature body cells from which they are derived, induced pluripotent stem cells (iPSCs) are notably special in their ability to self-renew and differentiate into all kinds of cells. And now scientists have detected a remarkable if subtle molecular disparity between the two: They have distinct “epigenetic” signatures; that is, they differ in what gets copied when the cell divides, even though these differences aren’t part of the DNA sequence.

“Relatively little study has been done on the epigenetic nature of stem cells,” says Andrew Feinberg, M.D., M.P.H., a professor of medicine at the Johns Hopkins University School of Medicine. “To date, the bulk of what is known about stem cells is focused on how you create them and grow them and so forth, but not on the essence of them, and what is fundamentally different about these cells.”

To compare and contrast mature connective tissue cells called fibroblasts with the pluripotent stem cells into which they were reprogrammed, the investigators focused on a chemical change known as methylation. This chemical change which, associated with silencing genes, is classified as epigenetic because, although not part of the DNA sequence, is copied when a cell divides. They identified and then measured so-called differentially methylated regions (DMRs) of genes whose expression was changed in the process of being reprogrammed from a parent cell to a stem cell.

Building on previous research that looked at where differently methylated sites were located in cancer cells, as well as on research that had shown these same sites matching up with many of the methylated areas that had been implicated in the differentiation of normal brain, liver and spleen tissues, the team discovered that the reprogramming of a cell to become a stem cell apparently involves many of the very same DMRs and genes.

“The surprise,” says Feinberg, “is that there is such a degree of overlap between the differently methylated regions and genes that are involved in turning a fibroblast into a stem cell and turning a normal cell into a cancer cell.”

The study, done jointly with George Q. Daley, M.D., Ph.D., and colleagues from Harvard University, was published Nov. 1 in the advanced online edition of Nature Genetics. The researchers suggest in the study that certain sites throughout the genome appear to be generally involved in distinguishing DNA methylation among different cell types and cancers, and these same sites are involved in reprogramming fibroblasts back into stem cells (…)

from http://newswire.ascribe.org/cgi-bin/behold.pl?ascribeid=20091104.074444&time=09%2059%20PST&year=2009&public=0

Researchers and using stem cells as tools for disease study, drug screening, clinical trial strategy, and personalized medicine. The induced Pluripotent Stem cell (iPS) is giving us a chance to rethink the way we are developing new drugs. These iPS cells are usually created from somatic cells (such as skin), and not embryos or adult stem cells. In creating iPS from patients’ diseased cells, scientists can study the disease in vitro, looking for disease phenotypes, applying microenvironmental stress, and testing new drugs. Compared to animal model testing (e.g. mice), this represents a significant breakthrough, that can be used to validate clinical development strategy and test efficacy in specific groups of patients. iPS is bringing a revolution in drug discovery methodology which is being used to bridge genetics, cell biology, and physiology.

from http://biobusiness.tv/videos/208