Once the assay was up and running, the scientists discovered that all five women had cheek cells that contained both X and Y chromosomes. The range was from 0.8 percent in one woman to 12.7 percent in another. Because some of the women had sons, the scientists performed an additional DNA analysis that ruled out the possibility of the cells originating from their male offspring. The cells also tested positive for cytokeratin.
Interestingly, of the 9,700 cells that were examined in the study, only two showed signs of possible fusion. In the previous reports of cell fusion from celll culture studies, the rate was also extremely low, ranging from one every 100,000 to one million adult stem cells.
While Tran said this paper does not provide the definitive answer to the transdifferentiation debate, it does offer a higher level of evidence. "I hadn't studied stem cells previously," said Tran, who is employing tissue engineering techniques to develop an artificial salivary gland. "But I saw an opportunity to help forward the field with a model that perhaps some had overlooked. I think these data will be helpful to many."
Contact: Bob Kuska
NIH/National Institute of Dental and Craniofacial Research