Hypoxia promotes growth and viability of human adipose- derived stem cells with increased growth factors secretion.

Adipose-derived stem cells (ASCs) have been found residing in a native microenvironment with low oxygen tension (i.e hypoxia) in human body. Oxygen tension plays a crucial role in regulating their function. The aim of this study is to investigate the effects of hypoxia on proliferation and survival rate of ASCs. Human ASCs were cultured at 21% O2 (normoxia) or 2% O2 (hypoxia) for up to three passages. We found that ASCs displayed a higher proliferation rate under hypoxia as compared to normoxia. The viability of ASCs was higher in hypoxia than normoxia without altering their characteristics. These properties might be correlated with the up-regulation of HIF-1α and the