Embryonic stem cells (ESCs), which are derived from the inner cell mass (ICM) of blastocysts, are pluripotent cells that have the ability to proliferate indefinitely. But still they maintain their pluripotency with the capability to differentiate into cells of all three germ layers: ectoderm, mesoderm and endoderm (Evans and Kaufman, 1981; Martin, 1981). In addition, these cells serve as an internal repair system, limitlessly regenerating into either differentiated cell progeny or additional stem cells (Keller, 1995; Thomson et al., 1998). Since first isolated in 1998, human ESCs have featured high importance as a potential treatment of a variety of diseases like PD, spinal cord injury (SCI) and DM (Thomson et al., 1998). However, the extraction of ESCs raises sharp ethical controversies as they are derived from human embryos and their transplantation in patients may present serious risks with a possibility of rejection (Lo and Parham, 2009).
