Objectives: Adipose-derived stem cells (ADSCs) are currently used in a clinical study as treatment for ischemic heart disease (IHD). The cells are stimulated with vascular endothelial growth factor (VEGF) to differentiate them towards endothelial lineage prior to injection. The aim of this study was to investigate the effect of VEGF treatment on ADSCs from IHD patients, in terms of differentiation towards endothelial lineage and mesenchymal stem cell characteristics.
Methods: The ADSCs were stimulated with human recombinant VEGF-A165 for 1, 2, and 3 weeks, with controls receiving serum-deprived medium and complete medium. The expression of VEGF receptors and endothelial and stem cell markers was measured at mRNA level using RT-qPCR and at protein level using immunocytochemistry (ICC) and flowcytometry (FC). Functionally, in vitro angiogenesis potential was evaluated on ECMatrix®. Furthermore, mesenchymal stem cell characteristic markers were investigated using FC.
Results: ADSCs treated with VEGF and serum-deprived medium significantly increased the expression of FOXF1 and PDGFβ compared with ADSCs in complete medium culture. A non-significant trend of increased vWF, VEGFR1 and VEGFR2 expression was observed. Endothelial markers were sporadically positive for all media types on ICC, but not on FC. In vitro angiogenesis only occurred with ADSCs stimulated with VEGF and serum-deprived medium. Mesenchymal stem cell characteristics were equal across media types.
Conclusion: We found evidence of predisposition for ADSC differentiation towards endothelial lineage when cultured with serum-deprivation, with no additional effect of VEGF. The effect was subtle, with significant increase of only the earliest marker of endothelial differentiation on mRNA level. The serum-deprivation rendered the cells prone to form tubules on ECMatrix®, and did not affect the expression profile of mesenchymal stem cells markers. VEGF stimulation seems to predispose ADSCs for differentiation towards endothelial lineage, but the cells need additional stimuli to complete the process.