Vascular Endothelial Growth Factor Expression of Adipose-Derived Stromal Cells and Adipocytes Initiated from Fat Aspirations

Background: Fat grafting is frequently employed in aesthetic and reconstructive plastic surgery with a low complication rate. However, fat necrosis may occur in dependence of the mode of fat aspiration, processing of the tissue and graft size. Graft survival is critically dependent on the contained adipose-derived stromal cells (ADSCs), adipocyte precursors and their potential for vascular supply. This work investigated the potential role of the expression of vascular endothelial growth factor A (VEGF) and various cytokines by ADSCs and differentiated adipocytes as key factors of fat grafting.

Methods: Adipokine expression of ADSCs and differentiated adipocytes were assessed using Proteome Profiler Arrays that detect 58 relevant proteins.

Results: Collected fat grafts could be categorized according to their adipokine expression into VEGF^high and VEGF^low ADSCs groups, the former exhibiting higher content of VEGF-related angiopoietin-like 2, nidogen-1/entactin, CCL2/MCP-1 and elevated expression of IGFBPs in association with a fourfold higher VEGF expression. Differentiation of ADSCs into adipocytes increased VEGF concentrations in VEGF^low ADSCs but not in ADSCs exhibiting initial high VEGF concentrations. The adipocytes revealed high expression of HGF, leptin, CCL2/MCP-1, nidogen-1/entactin, M-CSF but lower induction of angiopoietin-like 2.

Conclusion: Half of the ADSCs from fat grafts express high concentrations of VEGF and other adipokines that support angiogenesis and survival of this tissues following transfer. Differentiation of ADSC^low cells to adipocytes may make up for the initially low VEGF expression, but this activation is 7-10 days delayed compared to the VEGF^high ADSC cells and may fail to support angiogenesis from the beginning.

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