During fetal growth, cells differentiate into various types, such as cardiomyocytes and neurons, through an intricately orchestrated set of genetic and epigenetic instructions, with the input of developmental cues. Once cells migrate to their adult destination, they are highly differentiated. Cardiomyocytes beat away year after year; neurons make memories; hepatocytes clear toxins. The function of these cells remains unchanged until they die naturally or as a consequence of disease. Many tissues contain intrinsic progenitor cells that repopulate the key working cells of that tissue as they die; satellite cells in skeletal muscle are but one example. Yet even such progenitor cells have a limited number of possible fates. Advances in science now make it feasible, in many cases, to redirect cell fate: fibroblasts in the heart can become working cardiomyocytes, and pancreatic exocrine cells can turn into beta cells.
Marbán E, Cingolani E. Direct ReprogrammingBypassing Stem Cells for Therapeutics. JAMA. 2015;314(1):19-20. doi:10.1001/jama.2015.4504