Endothelial Differentiation and Vasculogenesis Induced by Three-Dimensional Adipose-Derived Stem Cells

Recently, an angiogenic therapy based on adipose-derived stem cells (ASCs) in an ischemic model has been reported. This study demonstrates the differentiation of human ASCs (hASCs) into endothelial cells clusters by culturing the cells in the form of three dimensional cell masses (3DCMs), which is based on the adherent activity of ASCs for a substrate. The 3DCM composed of hASCs induced hypoxic conditions and expressed angiogenic factors, such as vascular endothelial growth factor and interleukin-8. From immunochemical staining analysis, the 3DCMs of hASCs were CD31⁺, KDR⁺, and CD34⁺, whereas monolayer-cultured hASCs were negative for the these markers. To evaluate the ability of vasculature to form within 3DCMs, the 3DCMs were mixed in Matrigel/fibrin gel and injected into mice. Mature tubular microvessels perfused with blood were observed in the 3DCM/gel 20 days after injection, but not in the gel alone or hASC/gel mixture. Vasculature formed in the 3DCM/gel was recognized by antibodies against human α-smooth muscle actin, KDR, CD31, and CD34, but not by antibodies against murine antigens. These results suggest that the vasculatures originated from the embedded human cells. The 3DCMs of hASCs could function as a source of vascular cells for neovascularization, and could also be co-implanted with other cell types for regenerative medicine.