Study finds blood cells can be reprogrammed to act as embryonic ...( (WASHINGTON April 20 2009) - In a re...)

(WASHINGTON, April 20, 2009) - In a recent study, U.S. researchers have reprogrammed cells found in circulating blood into cells that are molecularly and functionally indistinguishable from embryonic stem cells, a revolutionary achievement that provides a readily accessible source of stem cells and an alternative to harvesting embryonic stem cells. The findings were prepublished online in Blood, the official journal of the American Society of Hematology.

Embryonic stem cells have long been coveted for their potential to treat a multitude of diseases as a result of their unique properties of nearly indefinite self-renewal and pluripotency (the ability to develop into any type of cell in the body), but their use has been the subject of political controversy.

"Our findings provide the first proof that cells from human blood can morph into stem cells," said senior study author George Q. Daley, MD, PhD, an investigator for the Howard Hughes Medical Institute at Children's Hospital, Boston. "Making pluripotent stem cells from blood, which is one of the easiest tissues to obtain, provides an easy strategy for generating patient-specific stem cells that are valuable research tools and may one day be used to treat a number of diseases."

To generate induced pluripotent stem cells (dubbed iPS cells), blood was collected from a 26-year-old male donor. From the blood sample, the researchers isolated CD34+ cells, a type of stem cell that produces only blood cells, and cultured them in growth factors for six days to increase their number.

During the culture, the scientists infected the CD34+ cells with viruses carrying reprogramming factors, genes normally expressed in embryonic stem cells that can reset the blood cells to an embryonic state. Colonies of cells exhibiting physical characteristics similar to embryonic stem (ES) cells appeared about two weeks after the procedure. To determine whether these cells were also functionally
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