Angiogenic Activity of Human Adipose-Derived Mesenchymal Stem Cells Under Simulated Microgravity.

Multipotent mesenchymal stem/stromal cells (MSCs) are strongly involved in tissue homeostasis mainly through paracrine regulation. In this study, we examined the influence of simulated microgravity on the angiogenic potential of adipose-derived MSCs (ASCs). The conditioned medium (CM) from random positioning machine (RPM)-exposed ASCs stimulated the formation of vessel network in ovo, endothelial cell (EC) capillary-like network, and nondirected EC migration in vitro. These effects were driven by alteration of both angiogenesis-related gene and protein expression. The elevation of angiogenic regulators Serpin E1, Serpin F1, IGFBP, VEGF, and IL-8 was detected in ASC-CM after 3D-clinorotation. In addition, transcription of genes encoding growth factors with proangiogenic activity were upregulated including VEGF-c and VEGF-a. These data evidenced that besides direct effect on ECs, microgravity could provoke MSC-mediating specific microenvironment for ECs supporting their functions, that is, proliferation and migration via increased production of IL-8 and VEGF as well as other paracrine factors involved in angiogenesis regulation.