Lazarus's gate: challenges and potential of epigenetic reprogramming of somatic cells.

The past year has seen tremendous advances in epigenetic reprogramming of somatic cells. Direct genesis of pluripotent stem cells, in contrast to earlier somatic cell nuclear transfer (SCNT) techniques, removes significant ethical and regulatory concerns regarding the utilization of human oocytes and zygotes, and represents a significant step toward the development of nonxenogeneic production methods. While significant technical hurdles remain, this and related technologies are enabling new approaches toward clinical treatments, basic research and diagnostics, and drug evaluation.