Table 1.

Factors related to HSC aging

Cell	Factor	Fuction	Relevance to stem cell aging	Reference
HSCs	FOXO protein	Promoting cell cycle arrest, stress resistance or apoptosis Reducing age dependent disease	Maintenance of HSCs compartment	Eric L Greer et al., 2005 Zuzana Tothova et al., 2007.
	HOXB4	Increasing HSC self-renewal	Increase HSCs expansion capacity without functional impairmnet	Jennifer Antonchuk et al., 2002.
	Notch1	Regulating HSCs self renewal	Decrease	Barbara Varnum-Finney, 2000
	Wnt signaling	Upregulating HOXB4 /Notch1 Critical for HSC homeostasis including regulation of HSC development	May decrease in HSC? (Increase in some other stem cells)	Tannishtha Reya et al., 2003 Bryan D. White et al., 2007 Hongjun Liu et al., 2007
	c-Myc	Controlling the balance between HSC self renewal and differentiation, Stimulating tumorigenesis	Increase	Anne Wilson et al., 2004 Chi-Hwa Wu et al., 2007
	TNF-α	Interfere hematopoietic stem cells (HSCs) self renewal, expansion and hematopoiesis	Increase	Xiaoling Zhang1 et al., 2007
	KU70	DNA repair gene Part of DNA dependent protein kinase complex (DNA-PK) Telomerase maintenance	Decrease	Wolf C. Prall et al., 2007.
	MGST1	Microsomal glutathione S-transferase A gene protecing against oxidative stress	Increase	Wolf C. Prall et al., 2007.
	BIK	Bcl2-interacting killer Pro apoptoic gene	Increase	Wolf C. Prall et al., 2007.
	I-Kb kinase/NF-Kb cascade	Related to inflammation increase with aging	Increase	Stuart M. Chambers et al., 2007.

Self-renewal-, proliferation- and lymphoid-related genes are mostly decreased by aging, whereas inflammation-, apoptosis-, and tumorigenesis-related genes are increased.