Therapeutic cloning or somatic cell nuclear transfer are names given to a method of producing embryonic stem cells from a patient's own cells. These embryonic stem cells could then be used to generate cells of any type as a basis for regenerative therapies. Making the process work has proven to be challenging, however, both from a technical point of view and thanks to misguided attempts to make it illegal. In recent years the focus shifted towards work on induced pluripotent stem cells instead, but a research group now claims success in the original goal:
Scientists [have] successfully reprogrammed human skin cells to become embryonic stem cells capable of transforming into any other cell type in the body. It is believed that stem cell therapies hold the promise of replacing cells damaged through injury or illness. The technique used [is] a variation of a commonly used method called somatic cell nuclear transfer, or SCNT. It involves transplanting the nucleus of one cell, containing an individual's DNA, into an egg cell that has had its genetic material removed. The unfertilized egg cell then develops and eventually produces stem cells.
Previous unsuccessful attempts by several labs showed that human egg cells appear to be more fragile than eggs from other species. Therefore, known reprogramming methods stalled before stem cells were produced. To solve this problem, the [researchers] studied various alternative approaches first developed in monkey cells and then applied to human cells. Through moving findings between monkey cells and human cells, the researchers were able to develop a successful method. The key to this success was finding a way to prompt egg cells to stay in a state called "metaphase" during the nuclear transfer process. Metaphase is a stage in the cell's natural division process (meiosis) when genetic material aligns in the middle of the cell before the cell divides. The research team found that chemically maintaining metaphase throughout the transfer process prevented the process from stalling and allowed the cells to develop and produce stem cells.