(261c) Effects of Hypoxic Microenvironment On hMSC Characteristics

Mimicking the human mesenchymal stem cell (hMSC) niche in bone marrow is an important approach to maintain hMSCs’ stemness during ex vivo expansion.  The ECM is an important component of the hMSC niche, providing critical biochemical and physical signals to efficiently retain stem cell properties.  Recent studies have shown that cell derived ECM matrices promote hMSC proliferation and preserve their mutilineage potentials.  Another component of the hMSC niche is a low oxygen tension environment.  MSCs exhibited greater colony forming ability, proliferated faster and longer, and maintained their undifferentiated characteristics better under low oxygen conditions.  As both oxygen tension and ECM matrices are important components of the in vivo hMSC microenvironment, the objective of this study is to investigate the effects of oxygen tension on the properties of the hMSC-derived ECM matrices and their combined influences on hMSC characteristics.  ECM matrices were derived by decellularizing ECM matrices formed by hMSC under both hypoxia (2% O₂) and normoxia (20% O₂) conditions; hMSCs were subsequently reseeded onto the hypoxic and normoxic ECM matrices and cultured under hypoxia and normoxia conditions, respectively.  Oxygen tension regulates the composition of the ECM matrices, resulting in higher production of ECM proteins, including fibronectin and collagen under 2% O₂.  In addition, the hypoxic ECM matrices promoted hMSC proliferation and maintained higher CFU-F forming ability compared to their normoxia counterparts.  Compared to the normoxic ECM, the hypoxic ECM also better preserved hMSC’s tri-lineage potentials with enhanced differentiation into osteogenic, adipogenic, and chondrogenic lineages upon induction.  Together, the results highlight the role of oxygen tension in the formation of an ex vivo microenvironment, which preserves hMSC proliferation potential and potentiates hMSC’s capacity in tri-lineage differentiations upon induction.