Alterations of matrisome gene expression in multipotent mesenchymal stromal cells under physiological hypoxia in vitro.

Low O2 level (physiological hypoxia) is an important physical parameter in local tissue niches of multipotent mesenchymal stromal cells (MSCs). Hypoxia preconditioning is actively applied in cell therapy and regenerative medicine protocols. In the present study, the effect of physiologic hypoxia in vitro (5 % O2) on the extracellular matrix of MSCs from the stromal-vascular fraction of human adipose tissue was investigated. Compared to standard cell culture conditions (20 % O2), the genes encoding structural and regulatory proteins of the extracellular matrix (matrisome) were differentially expressed in MSCs under physiologic hypoxia. There was a significant downregulation of genes coding structural glycoproteins (COMP, ELN) in the core matrisome and upregulation of genes encoded matrisome-associated proteins with pro-migratory (CXCL12) and antioxidant (SRPX, SERPINF1) functions. At different O2 levels, there were no significant differences in immunocytochemically identified the core matrisome proteins: collagen I, fibronectin, osteonectin, versican, nor in the expression of the corresponding genes. Meanwhile, variations in packaging patterns of the fibrils were, however, demonstrated using scanning electron microscopy. Under 5 % O2 the activities of the soluble matrix metalloproteinases MMP-1 and MMP-2 were reduced. Thus, physiological hypoxia modulates the matrisome properties, and understanding this may be important for gaining mechanistic insights into the activity of MSCs in local tissue microenvironments, as well as in the protocols for scaffold production based on native ECMs for use in regenerative medicine.