Table 1.

Summary of some clinically relevant stem cell types and properties

Stem cell categories	Examples of specific stem cell types	Stem cell sources	Properties/Challenges
Pluripotent stem cells	Embryonic stem cells (ESCs) Induced pluripotent stem cells (iPSCs)	Surplus human IVF blastocysts (ESCs) Reprogrammed somatic cells (iPSCs)	Can produce any cell in the body (ESCs, iPSCs)
			Unlimited self-renewal capacity in vitro (ESCs, iPSCs)
			Difficult to generate pure populations of mature cells with current culture conditions (ESCs, iPSCs)
			Perceived ethical issues with some community groups (ESCs)
			Can be used for autologous (iPSC) or allogenic (ESC, iPSC) treatment
Tissue-specific stem cells	Hematopoietic stem cells (HSCs) Skin stem cells (SSCs) Mesenchymal stem cells (MSCs)	Bone marrow (HSCs, MSCs) Peripheral blood (HSCs)	Normally produce only cells from the particular tissue in which they are found
		Skin (SSCs)	Typically have limited self-renewal and expansion capacity in vitro with current culture conditions
		Fat (MSCs)
		Cartilage (MSCs)
			Difficult to generate pure populations of mature cells with current culture conditions
			Can be used for autologous or allogenic treatment