There are different challenges to cope with achieving an easy, efficient, and fast reprogramming protocol. On one hand, the appropriate reprogramming method needs to be chosen. The most commonly used method is the integration of the reprogramming factors into the genome by lentiviral or retroviral transduction [7, 8]. It is the easiest and most efficient method by now, though in the future other solutions will be more in focus since cells generated by permanent and random integration of exogenous genes have a certain oncogenic potential and are therefore not suitable for use in therapeutic approaches. To avoid the use of integrating viruses, other reprogramming approaches, for example, the use of Sendai viruses [9], plasmids [10], modified RNA [11], or small molecules [12, 13], have been described. Another important issue is the choice of the starting material. Takahashi et al. used fibroblasts as the starting somatic cell type since fibroblasts were also used for reprogramming mouse cells earlier. In addition, fibroblasts are easily cultured and expanded. Nevertheless, some disadvantages of reprogramming fibroblasts such as their relatively low reprogramming efficiency and especially
