Human iPSCs can be generated from cells of all three germ layers. The most commonly used cell types are mesodermal fibroblasts or blood cells, hepatocytes of endodermal origin, or ectodermal keratinocytes. All somatic cells described here were used as the starting material for reprogramming and derived iPSCs show high similarity with embryonic stem cells in terms of morphology, gene expression, and renewal and differentiation capacity. Table 1 summarizes the pros and cons of the major starting materials for reprogramming.
