Liver Regenerating Potential of the Secretome Obtained from Adipose-derived Stem Cells Cultured under the Hypoxic Environment

Abstract

Background: The stem cell-derived secretome has received considerable attention as an alternative to stem cells for therapeutic applications. However, establishing optimal culture conditions is key to obtaining appropriate secretome contents. Here, the optimal culturing environment for achieving a high-efficiency secretome was determined via hypoxic preconditioning of human adipose-derived stem cells (ASC). Methods: Normoxic conditioned media (NCM) and hypoxic conditioned media (HCM) were obtained after culturing human ASCs under normoxia (20% O2) or hypoxia (1% O2), respectively. Subsequently, both normal and thioacetamide-induced hepatotoxic hepatocytes were treated with NCM or HCM. In addition, partially hepatectomized mice were infused with control saline, NCM, and HCM. The effects on liver regeneration and serum transaminases levels were then compared. Results: Hypoxic preconditioning significantly increased mRNA expression of proinflammatory cytokines (interleukin-6 and tumor necrosis factor-) and growth factors (hepatocyte growth factor and vascular endothelial growth factor). In both normal and thioacetamide-induced hepatotoxic hepatocyte (alpha mouse liver 12 [AML12]) cell lines, HCM treatment resulted in the highest cell viability (122% and 95%, respectively), followed by NCM (111% and 78%, respectively). In addition, intravenous administration of HCM to partially hepatectomized mice resulted in substantially enhanced liver regeneration compared with the NCM group (P<0.05). Conclusions: Taken together, the secretome obtained from ASC with hypoxic preconditioning showed potential to alleviate liver damage both in vitro and in vivo. Hypoxic culture of ASC is expected to play an important role in regenerative medicine by inducing secretome production that is beneficial for improving liver regeneration.