Monday, July 2, 2007

France: Scientists Use Embryonic Stem Cells to Regenerate a Heart

Thump, thump, ... The beating of the heart begins again. Laboratory rats, sick, have regained their well-being.. The reason for this convalescence: their defective heart cells have been, in a fashion, replaced by stem cells from human embryos, specially prepared to become healthy heart cells. This is a first. In a report in Stem Cells co-signed by the teams of Michel Pucéat at INSERM and of Philippe Menasché, cardiac surgeon at the Georges-Pompidou Hospital, this research promises some benefits for therapy. Cardiac insufficiency is in effect one of the principal causes of death in rich countries. And if one could treat a heart damaged by a heart attack, using stem cells ? Patience! ...

Bear in mind that the stem cells of the human embryo, capable of becoming cells of the heart, the blood, the nerves, are a bit more reticent to specialize than are their animal homologues. To differentiate, say the specialists. The team of Michel Pucéat, one of the first to be permitted to experiment with these particular cells, made use of a growth hormone, the BMP2. This boost to the stem cells enabled them to get started on the correct track for differentiation. They were then implanted in the diseased cardiac tissue of the rats. Two months later, the rodents were feeling better. The human heart cells had taken over for their own deficient cells. The oriented stem cells are thus transformed into cardiac muscle cells, called cardiomyocytes. And the heart begins to beat again ...

"Until recently, we knew how to differentiate stem cells, but not in a quantity necessary to repair a human heart", explains Michel Pucéat, in an email sent from Washington. The new idea was to create the healthy cells before implanting them. "You need about a billion cells, and that’s impossible in the test tube", the scientist adds. It’s better to let them differentiate in the tissue.

The good news: no anomaly was observed in the rats. The new cells had stopped reproducing themselves in time. The research team plans now to test this procedure on monkeys, who are ever so close to the human species.

Can one do without the embryo?

Japanese and American teams have succeeded in obtaining the equivalent of stem cells from ordinary adult skin cells, without having recourse to embryos or ovocytes. Traditionally, scientists obtain these particular cells from embryos. This practice has often led to lively polemics with religious authorities. In the present work, researchers have forced the skin cells to produce proteins rendering them pluri-potent, that is, having properties very close to those of embryonic stem cells. A return to youth, one might say.

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