HUMAN EMBRYONIC STEM CELLS
Very recent advances in stem cell technology enable the generation of pluripotent human stem cells using a process known as reprogramming or dedifferentiation. The procedure exploits viral vector-mediated expression of only four genes (namely, c-myc, oct3/4, sox2 and klf4) to program mouse and human somatic cells (specifically, skin fibroblast) into embryonic-like “induced pluripotent stem cells” (iPS cells). These cells appear to be just as plastic as embryonic stem cells, but one draw back to their clinical application in humans is the use of lentiviral or other retroviral vectors to introduce the genes. Although still at an early stage, the use of iPS cells could greatly advance the practicality of regenerative medicine as a therapeutic option. By creating patient-specific, pluripotent human stem cells, cell replacement therapies that avoid human embryo destruction may now be within reach.