Researchers Use Human Stem Cells to Repair Hearts in Rats

Transplant News,  Sept, 2007  

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Scientists at the University of Washington and the biotechnology company Geron have used human embryonic stem cells to repair damaged heart tissue in rats that had suffered cardiac arrests, the Toronto Star reports. Their study, published in the September issue of the journal Nature Biotechnology, seems to overcome two of the most persistent and perplexing hurdles that have thwarted use of the promising embryonic cells for organ repair: how to coax human embryonic stem cells to turn into heart cells, and how to keep them alive after transplantation.

By treating the stem cells with two growth factors and then purifying the cells, the researchers were able to turn about 90 percent of stem cells into cardiac cells. Then, they dealt with the challenge of stem cell death by implanting the cells along with a cocktail of compounds aimed at helping them grow. This included a growth "matrix"-- a sort of scaffolding for the cells to latch on to as they grow -- and drugs that block processes related to cell death.

When using the pro-growth cocktail, the success rate of heart muscle grafts improved drastically: 100 percent of rat hearts showed successful tissue grafts, compared to only 18 percent in grafts without the cocktail.

When the researchers followed up on the stem-cell treatment by taking images of the rat hearts, they found that the grafts helped thicken the walls that normally stretch out after a heart attack and cause the heart to weaken. The thickened walls also were associated with more vigorous contraction.

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