Embryonic Stem Cells: Alternative Approaches to Their Isolation - 2/28/07

Dr. Rudolf Jaenisch
Whitehead Institute for Biomedical Research

Building on the current science of embryonic stem cell research, Dr. Jaenisch invites us to look at the next chapter in the progression of this science. Dr. Jaenisch is a leader in the field of therapeutic cloning, also called somatic cell nuclear transfer (SCNT), in which the genetic information from one cell is transplanted into an unfertilized egg from which DNA has been removed. When placed in a Petri dish, this egg develops into a blastocyst - one of the first stages of embryo development - from which embryonic or pluripotent stem cells can be taken.

Embryonic stem (ES) cells are derived from early-stage embryos and can grow indefinitely in culture. Existing human ES cells have been generated from "excess" IVF embryos that were donated for research. ES cells are pluripotent, which means they have the potential to become all cell types of the body. This ability provides these cells with an enormous potential for research aimed at understanding human development and treating human diseases.

One of the great promises of ES cells is their potential for use in developing new therapies for debilitating diseases such as cancer, diabetes, and Parkinson's. To realize this potential, much research is needed to learn how to differentiate the embryonic cells into cells that could be used for transplantation.

Using a form of SCNT called "altered nuclear transfer," Dr. Jaenisch created an embryo-like entity that was genetically incapable of implanting in a uterus. Although this entity was not a viable embryo, it did yield perfectly healthy embryonic stem cells. Dr. Jaenisch's therapeutic cloning research has used mice exclusively. One day this research may lead to therapies for currently untreatable human diseases.