In vivo reprogramming: A new approach for tissue repair in chronic diseases

Medical researchers and biologists have long been fascinated by the possibility of changing the identity of cells, a phenomenon known as cellular plasticity. Now, we know that differentiated cells can be experimentally coaxed to become pluripotent (cellular reprogramming). Recent studies have demonstrated that changes in cell identity are not limited to the laboratory, but also the tissue cells in live organisms are subjected to this process, too (endogenous cellular reprograming). Nowadays “reprogramming technology” has created new opportunities in understanding human chronic diseases, drug discovery, and regenerative medicine. This technology have enabled the generation of various specific cell types including cardiomyocytes, pancreatic beta cell, and neurons, from patient's cells such as skin fibroblasts. Reprogramming technology provides a novel cell source for autologous cell transplantation. But, cell transplantation faces several difficult hurdles such as cell production and purification, long-term survival, and functional integration after transplantation. Recently, in vivo reprogramming, which uses endogenous cells for tissue repair, has emerged as a new approach to circumvent cell transplantation. Up till now, in vivo reprogramming has been practiced in the mouse pancreas, heart, brain, and spinal cord with various degrees of success. In this review, we summarize the progress made, therapeutic potentials, and the challenges ahead in this emerging research area.