Table 1.

Embryonic versus adult versus induced pluripotent stem cells for cell-based therapy.

Cell type	Advantages	Disadvantages
Embryonic stem cell	(i) Pluripotent (can form all lineages of the body: ectoderm, mesoderm, endoderm) (ii) Grown relatively easily	(i) Likely to be rejected (if donor is allogeneic, unmatched) (ii) Harbors disease-causing genes of donor Ethical problems  (iii) Chromosomal errors (aneuploidy), mitochondrion DNA defects, karyotype instability [40], and risk of teratoma formation following transplantation [10]
Adult stem cell	(i) Multipotent (can form multiple cell types of 1 lineage, e.g., retinal progenitor cell) (ii) Not rejected if transplanted into donor	(i) Relatively hard to harvest (ii) Harbors disease-causing genes of donor
Induced pluripotent stem cell	(i) Pluripotent (ii) Grown relatively easily (iii) Probably not rejected if transplanted into donor	(i) May retain epigenetic features of cell type of origin (ii) Harbors disease-causing genes of donor (iii) Oncogenic potential of cells as a consequence of genetic manipulation [41]