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Blood stem cells can form blood vessels

GAINESVILLE, Fla., May 31 (UPI) -- A type of stem cell found in bone marrow, which can develop into all the different cell types that make up blood, carries the ability to generate new blood vessels as well, researchers reported Friday.

Harnessing this ability could lead to treatments for diabetes, heart attacks, strokes and other conditions where blood vessels are damaged, Edward Scott, director of the Program in Stem Cell Biology at the University of Florida in Gainesville and co-author of the study, told United Press International.

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The capability of stem cells to cultivate different cell types has been suggested in previous research, but this is the first study to show definitively how the cells can produce functional structures, Scott said. "We showed that one cell can make all of these things and that's really part of the equation that's been missing," he added.

Scott and his colleagues took a single blood or hematopoietic stem cell from a mouse and inserted a chemical tracer into it that makes the cell -- and any cell that stems from it -- glow green. They then injected this cell into a mouse and found it produced fully functional blood vessels in the eye. The vessel cells must have originated from the stem cell because they glowed green.

"If the stem cells are able to form capillaries in damaged tissues or organs, I think this is very important," Donald Orlic, associate investigator at the National Human Genome Research Institute in Bethesda, Md., who has specialized in blood stem cells and heart attacks, told UPI.

"Regeneration of blood vessels would be a very beneficial thing," Orlic said, particularly in the case of diabetes, because the peripheral circulation is often damaged by this disease.

Treatments based on blood vessels regenerated by stem cells could also have applications for almost any organ in the body, he added. "All organs are supplied with blood vessels and if a vessel becomes (plugged up), that organ or a portion of it will be deprived of oxygen and nutrients," which could lead to organ death, "so there would be a need to regenerate vessels."

Some researchers in the field speculated the cells might give rise to blood vessels "but that they could do this so actively might not have been predicted," Orlic noted. "The extent to which (the stem cells generate new blood vessels) is surprising," he added.

Scott pointed out although his group only reported new blood vessels in the eyes of the mice, they have looked for new or green blood vessels elsewhere in the body and have found them "everywhere we've looked."

The researchers are now "looking for factors that will spur this process within the body," Scott said. "Your body probably does this at some fairly low level anyway and what we want to do is to take that low level and ramp it up."

Researchers already know chemicals called cytokines can stimulate blood stem cells when injected into the body, Orlic said, and studies are underway in animal models, which could speed up applying these findings to humans.

The research is reported in the May 31 issue of Nature Medicine.

(Reported by UPI medical correspondent Steve Mitchell in Washington)

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