Current available PSCs types. Regular ESCs, produced from IVF embryos, represent an ideal stem cell source for regenerative medicine; however, ethical and technical limitations regarding human use thereof remain barriers to their research and use. Uniparental ESCs include an entire maternal parthenogenetic ESCs) or paternal (androgenetic ESCs) genome. To produce a parthenogenetic embryo, MII oocytes are activated artificially. Heterozygous or homozygous parthenogenetic ESCs can be generated depending on extrusion of the second polar body; extrusion for homozygous or no extrusion for heterozygous ESCs. Another method involves removing the male pronucleus from the zygote. In the generation of androgenetic embryos, the female pronucleus is removed from the zygote. Another approach is the removal of the nucleus from MII oocytes and replaces it with sperm head. These uniparental ESCs are usually generated for research, with no possibility for clinical applications currently. Fibroblasts could be reprogrammed to PSCs by SCNT or iPSC generation. The SCNT technique can cure mitochondrial disease because mtDNA mutated fibroblasts are transferred to enucleated MII oocytes with healthy mtDNA; the derived SCNT-ESCs then harbor healthy mtDNA. However, this is prevented by ethical issues surrounding oocyte use. While iPSCs are unfettered by ethical concerns, these are produced from mtDNA mutated fibroblasts directly and will still include mutated mtDNA after reprogramming. PSCs, pluripotent stem cells; ESCs, embryonic stem cells; IVF, in vitro fertilization; MII, metaphase II; SCNT, somatic cell nuclear transfer; iPSCs, induced pluripotent stem cells; mtDNA, mitochondrial DNA.