New harvesting techniques are crucial to successful stem cell research because they provide greater opportunities to treat diseases in a more unique case-by-case basis. They also provide ways to overcome challenges with current techniques as well as extending stem cell therapies to diseases that may otherwise have been untreatable by current therapies. Perhaps even more important they offer a possible solution to the ethical conundrum that continues to plague stem cell research.
Altered Nuclear Transfer
Altered nuclear transfer (ANT) may make it feasible for stem cells to be removed from embryos without destroying the embryo itself in the process. This could offer a way out of the current ethical dilemmas surrounding embryonic stem cell research. Normally, embryonic stem cells have been obtained by growing a human embryo into a cluster of cells that contain an inner cell mass. It is the inner cell mass that is abundant in the embryonic stem cells; after this inner cell mass is removed, the embryo is ultimately destroyed.
Traditionally, embryonic stem cells were harvested by destroying the human embryo in a process called somatic cell nuclear transfer (SCNT). A somatic cell is simply a body cell that is neither an egg nor a sperm cell. In this procedure, the nucleus is removed from a somatic cell and it is then implanted into a donor egg that first had its nucleus removed. The egg cell is essentially fooled into thinking it has been fertilized. It has its own DNA and after stimulation, it divides just as a normally fertilized egg would, before forming an embryo. Cells from the inner cell mass are extracted and cultured to provide embryonic stem cells but the technique destroys the embryo. This process has, of course, generated much debate because the embryo could potentially have become a living person.
ANT, however, prevents an embryo from actually being created. The nucleus of the somatic cell is altered, or genetically reprogrammed, prior to being transferred into the egg. The alteration consequence is that the somatic cell DNA still produces stem cells but does not generate an embryo.
This technique is one potential way around the ethical concerns that result from the destruction of an embryo. It is performed on a two-day old embryo, following the division of the fertilized egg into eight blastomeres, or cells. Previously, the techniques used for harvesting involving the derivation of embryonic stem cells at a later developmental stage, when the embryo is made up of approximately 150 cells. When these cells were harvested, the embryo was destroyed.
It was found that embryonic stem cells could be extracted from blastomeres, which thus avoids the destruction of the embryo. The cell could be triggered to divide and the resulting stem cells could still be used for research and disease treatment. Further strengthening the research for this technique is the fact that in fertility clinics, the blastomere is already often removed for diagnostic tests to detect genetic abnormalities. The embryo, now with only seven blastomeres can still be implanted into the mother, assuming no defect has been found. These embryos then grow into healthy babies.
Neither ANT nor blastomere extraction are perfect techniques but they do appease many of the ethical concerns surrounding stem cells and can pave the way for new techniques that may one day treat a disease that afflicts you or a loved one.