One of the major applications of iPSCs is the differentiation into specific cell types. Numerous protocols have been established to generate tissue specific progenitor or mature cells involving all three germ layers. This includes, amongst various other cell types, for example, cardiac muscle cells, endodermal progenitor cells [38], and photoreceptor cells of the retina [39] or specific neuronal subtypes. IPSCs are used to study differentiation into exotic cell types and their underlying differentiation mechanisms but they are also utilized for in vitro models to investigate a variety of diseases. The most desired goal and hope is the generation of patient specific iPSCs and further retransplantation of autologous cells into the malfunctioning organ. One of the benefits of using autologous cells is the circumvention of a graft-versus-host reaction. Furthermore, from an ethical point of view, iPSCs avoid the use of the controversially discussed embryonic stem cells, at least in many countries.
