Conflicting Stem Cell Research | Updates | PBS NewsHour | PBS

The answer appeared to be yes when the journal Nature published research results from Catherine Verfaillie of the University of Minnesota Medical School in Minneapolis and her team in January 2002.

The researchers had isolated a rare cell in bone marrow from a mouse, rat and human, and when they injected the mouse cells into mouse embryos, they discovered that the cells descendants spread throughout the body, appearing in blood as well as brain, muscle, lung and liver tissues, according to Nature.

The ability for a stem cell to grow into any type of tissue, a adaptability originally only attributed to early embryos, would mean cells from the patients own body could be used as a perfect match for tissue and even organ repairs.

So in addition to clearing the ethical hurdle, adult stem cells have the potential to avoid another obstacle posed by embryonic stem cell use the possibility that a patients body could reject the foreign cells.

But the apparent breakthrough did not put to rest the question of whether adult stem cells could become other cells. Some subsequent studies began to call into question the 2002 findings. As research continued, for every study that said the stem cells could grow into other functioning cells, another study seemed to indicate the opposite.

Dr. Amit Patel of the University of Pittsburgh Medical Center, who plans to perform his own clinical trials involving cardiac stem cell therapy in humans, said even trials that purport to use the exact same techniques in animals have produced contradictory results.

However, human patient tests so far have all showed positive data no matter what type of stem cells are used, said Patel. Heart patients receiving stem cell therapy showed improvement in the contraction of their hearts, less chest pain, etc., but those soft results didnt explain the mechanism for the improvements.

Thus far, no one has actually been able to show exactly what these cells are becoming or why these patients are becoming better, he said.

The problem in human trials unlike animal ones, in which the animals can be killed is once you inject the cells, you cant get them out again.

But Patel said he is hoping to rectify that with patients undergoing heart transplants. He is awaiting approval from the Food and Drug Administration to conduct human clinical trials as early as the fall in which he would inject stem cells into the patients heart muscle prior to the transplant, and then inspect the results after the heart is replaced with a healthy one.

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Conflicting Stem Cell Research | Updates | PBS NewsHour | PBS