(722e) Endothelial Differentiation of Mesenchymal Stem Cells Using Surface-Bound Cues

In the emerging field of tissue engineering, there is a growing need for vascularizing tissues in vitro.  Implants will spontaneously vascularize, but this process is limited to fractions of a micrometer per day.  Without a vasculature to overcome diffusion limitations, in vivo cell viability is limited to 100-200 microns within the implant.  Tissues can be prevascularized in vitro, a process that accelerates anastomosis with host vasculature in vivo.  Endothelial cells can be used as a source for in vitro vascularization, but their drawbacks include donor site morbidity and low proliferative capacity.  Recently, it has been shown that mesenchymal stem cells (MSCs) can be differentiated into endothelial cells via soluble vascular endothelial growth factor (VEGF).  Since MSCs can be differentiated into a variety of cell types, spatial control of differentiation could allow the development of an entire tissue from a single initial cell source.  

The objective of this study is to covalently attach VEGF to a surface and evaluate the use of this surface in differentiating MSCs to the endothelial cell fate.  The bifunctional, heterogeneous cross-linker, sulfo-SANPAH, was used to attach VEGF to tissue-culture polystyrene.  Successful reaction was confirmed by spectrophotometry and ELISA.  VEGF surface densities ranging from 10 – 50 ng/ cm² were obtained.  MSC differentiation was evaluated by immunofluorescence, qPCR, and capillary formation on Matrigel^TM.  This study demonstrated that the VEGF-modified surface resulted in an increase in endothelial markers.