Scientists in the USA have discovered a new way of obtaining embryonic stem cells that avoids contamination by other types of cells and reduces the numbers of embryos needed to create embryonic stem cell lines.
Dr Takumi Takeuchi told the 21st annual conference of the European Society of Human Reproduction and Embryology today (Monday 20 June) that if he and his colleagues could replicate the research, which had been carried out in mice, in humans, it would make it easier to collect embryonic stem cells (ESCs) and could make it possible to establish ESC banks. This would enable researchers to have easy access to ESCs to develop better treatments for patients suffering from a range of diseases, as well as for research on fertility.
Until now, embryonic stem cells have been collected from embryos that have developed to the blastocyst stage. In humans this occurs at about day five of development. Before the ESHRE conference began, lead author, Dr Ameeta Bahia, a senior andrologist who works with Professor Gianpiero Palermo at the Center for Reproductive Medicine and Infertility, Weill Medical College of Cornell University, New York, explained: "Blastocysts are composed of two components: an external one, defined as the trophoblast of about 55 cells that will form the placenta, and a polar mass of about 20 cells, defined as the inner cell mass (ICM) that will generate the embryo and from which we obtain the stem cells. In order to obtain ESCs from the blastocyst, we first have to isolate the ICM from the trophoblast. However, this often results in contamination of ESC cultures by trophoblastic or endodermal cells. Moreover, barely 50% of human fertilised eggs reach the blastocyst stage after being cultured in the laboratory. Therefore, the possibility of harvesting ESCs at an earlier stage of embryo development is enticing."
Dr Bahia took 46 individual cells (blastomeres) from six two-day mouse embryos, which were composed of eight cells. The blastomeres were cultured in the laboratory, and 43 of them started to divide and grow. After about two days, 22 of them started to form ICM-like structures. From these, Dr Bahia managed to establish one ESC line. From a control group of 51 blastocysts, she obtained nine ESC lines.