Transdifferentiation

Transdifferentiation, also known as lineage reprogramming, is the process in which one mature somatic cell is transformed into another mature somatic cell without undergoing an intermediate pluripotent or progenitor cell stage. It is a type of metaplasia, which includes all cell fate switches, including the interconversion of stem cells. Current uses of transdifferentiation include disease modeling and drug discovery and in the future may include gene therapy and regenerative medicine. The term 'transdifferentiation' was originally coined by Selman and Kafatos in 1974 to describe a change in cell properties as cuticle-producing cells became salt-secreting cells in silk moths undergoing metamorphosis. Davis et al. 1987 reported the first instance of transdifferentiation where a cell changed from one adult cell type to another. Forcing mouse embryonic fibroblasts to express MyoD was found to be sufficient to turn those cells into myoblasts. The only known instances where adult cells change directly from one lineage to another occur in the species Turritopsis dohrnii (also known as the immortal jellyfish) and Turritopsis nutricula. In newts, when the eye lens is removed, pigmented epithelial cells dedifferentiate and then redifferentiate into lens cells. Vincenzo Colucci described this phenomenon in 1891 and Gustav Wolff described the same thing in 1894; the priority issue is examined in Holland (2021).