A Type of Stem Cell May Repair Hearts

Although a number of studies have confirmed the ability of bone-marrow-derived stem cells to develop into cardiac tissue cells, in more recent trials these stem cells have not shown the ability to incorporate into ailing heart tissue as robustly as originally expected. The results appeared to indicate that something was missing.

Now researchers have found that a specific type of stem cell, bearing a surface antigen called CD133, is unusually adept at differentiating into a variety of organ-specific cell types. Although cells with this biomarker are rare in adult issues, they are abundant in the fetal liver. Using human fetal liver tissues, the researchers isolated CD133+ stem cells, then bathed them in a culture rich in growth factors and other biochemicals, including vascular endothelial growth factor-A (VEGF-A) and brain-derived neurotrophic factor (BDNF).

The researchers then injected cells derived from both CD133+ and CD133- liver stem cells into mice. The CD133+ stem cells developed into pulsating vascularized cardiomyocytes but the CD133- cells did not. This showed that the CD133+ cells were capable of forming both myocytes and angiogenic cells. Because of the potential for immune-system rejection, cells isolated from a patient's own body are the best choice rather than cells from fetal tissue. For this reason, the researchers are investigating whether adult livers might bear traces of CD133+. Pre-conditioning the cells in the laboratory may help ensure that the cells have the essential biologic cues critical for differentiation. The study results were reported in the March 2005 issue of Circulation.

"All these findings are re-igniting interest in using these biochemically activated stem cells to regenerate vascularized tissue,” said Dr. Shahin Rafii, professor of genetic medicine at Weill Cornell Medical College (New York, NY, USA), who led the study. "Some of our research may even help find new sources of expandable CD133+ stem cells within umbilical cord blood or adult bone marrow, livers, or other organs.”


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Weill Cornell Medical College