Somatic cell nuclear transfer (SCNT), the technique used to clone Dolly the sheep, involves transferring the nucleus from an adult cell into an egg that has had its nucleus removed. This creates an embryo that, when implanted into a uterus, can develop into a fetus.
One challenge in using SCNT to create stem cells is that the reprogramming process is inefficient, with only a small percentage of embryos developing into viable fetuses. Scientists at the Salk Institute have now identified a way to improve the efficiency of SCNT by adding a small molecule called valproic acid (VPA) to the culture medium of the embryos.
VPA is a known inhibitor of histone deacetylases, enzymes that remove acetyl groups from histones, the proteins that DNA wraps around to form chromosomes. By inhibiting histone deacetylases, VPA helps to keep the chromatin, the complex of DNA and proteins that make up chromosomes, in a more open state, making it more accessible to the transcription machinery that reads genes.
The researchers found that adding VPA to the culture medium of SCNT embryos increased the percentage of viable embryos that developed to term by 20-30%. They also found that the stem cells derived from these embryos were more pluripotent, meaning that they had the potential to develop into a wider range of cell types.
This discovery is an important step forward in the development of SCNT as a tool for regenerative medicine. By improving the efficiency of the reprogramming process, scientists may be able to use SCNT to create patient-specific stem cells for use in treatments for a variety of diseases and conditions.
