Reprogramming of human Fibroblast into Induced Pluripotent Stem Cells

Human Embryonic stem cells (hESCs) represent a pluripotent cell population derived from the inner cell mass of the blastocyst stage of the developing embryo. Ethical concerns have been raised regarding the derivation process, as the procedure ultimately results in the destruction of the embryos. Recently, alternative approach has been devised that encompasses reprogramming of terminally differentiated cells into a hESC-like state. This process relies on the over-expression of four pluripotency-associated factors, and successfully reprogrammed cells are termed induced pluripotent stem cells. These cells hold great promise for the use in future cell-based therapeutics such as evaluating drug induced toxicity and developing personalized medicines. However, the intricacies of the reprogramming mechanism are not fully understood, mostly due to the random nature of the expression of the four transcription factors. In this study, a novel molecular switch, known as Rheostat system, was utilized in conjunction with the doxycycline system to regulate the expression of the transcription factors in a precise temporal manner and elucidate underlying mechanisms of the reprogramming process.