Microlens topography combined with vascular endothelial growth factor induces endothelial differentiation of human mesenchymal stem cells into vasculogenic progenitors

Abstract

Cell therapy for vascular damage has been showing promises as alternative therapy for endothelial dysfunctions since the discovery of the endothelial progenitor cells (EPCs). However, isolated EPCs from peripheral blood yield low cell amounts and alternative cell source must be explored. The aim of this study was to investigate the influence of topography on the endothelial differentiation of an alternative cell source - human mesenchymal stem cells (hMSCs) from bone marrow. Utilizing the MultiARChitecture (MARC) chip, a systematic screening of variety of patterned surfaces and different medium compositions was performed. While topographical patterns alone induce endothelial differentiation, a synergistic enhancement was observed when topography was combined with a medium enriched with vascular endothelial growth factor (VEGF). The 1.8 μm diameter convex microlens pattern in combination with the VEGF enriched medium was shown to be the most efficient on the endothelial differentiation, yielding up to 10% of CD34⁺CD133⁺KDR⁺ marker expressing differentiated hMSCs as analyzed by flow cytometry. The quantified tube-like structures in the Matrigel assay in vitro indicated a vasculogenic potential of these endothelial progenitor-like differentiated hMSCs that was investigated further in a Matrigel plug assay in vivo in a rat for seven days. Explanted Matrigel plugs were processed with hematoxylin-eosin (H&E) and anti-Ulex Europaeus agglutinin (UEA-1) staining to visualize the capillaries and to identify the presence of human cells. The hMSCs cultured on the 1.8 μm diameter convex microlens in a medium enriched with VEGF, implanted in a Matrigel plug in a rat, showed the highest capillary density, the highest UEA-1⁺ capillary density, as well as the highest UEA-1⁺ cell survival density that were not included in the vasculogenesis. These findings indicate the active participation of the vasculogenic hMSCs in the vasculogenesis. The endothelial differentiation of hMSCs using this synergistic combination of microlens and VEGF enriched medium was also demonstrated in hMSCs from different male and female donors. The culture platform with combination of topography and biochemical cues could generate vasculogenic cell populations that may prove useful in vascular damage or other clinical applications.

Keywords: Endothelial progenitor cells; Matrigel assay; Microtopography; Vasculogenesis.