25 Embryological origin of human smooth muscle cells influences their ability to support vasculogenesis

Background We hypothesised that the distinct embryonic origins of vascular smooth muscle cells (SMCs) at different anatomic locations, contribute to differences in vascular development and disease. Here we investigated the respective vasculogeneic potential of different embryonic-origin specific SMC derived from human embryonic stem cells (hESCs) to support vasculogenesis in vitro . Methods and results SMCs of three distinct embryonic origins were derived from an mStrawberry-expressing hESC line and were co-cultured with GFP-expressing human umbilical vein endothelial cells (HUVEC) to investigate the effects of distinct SMC subtypes on endothelial network formation. As demonstrated by quantitative data, LM-derived SMCs best supported HUVEC network survival in 3D co-culture in matrigel. In addition, LM-SMCs facilitated more complex endothelial networks, with narrower cords and more branch points, compared with the other SMC types and HUVECs alone. The effects of the LM-SMCs on HUVECs were at least in part paracrine in nature. A TaqMan Array was performed to identify possible mediators responsible for the differential effects of the SMC lineages and a microarray to determine lineage-specific angiogenesis gene signatures. Midkine (MDK) was identified as one important mediator for the enhanced vasculogenic effect of LM-SMCs. Subsequent siRNA-mediated knockdown of MDK in SMCs resulted in a decrease of total HUVEC network area and number of branch points in LM-derived SMC co-cultures. Conclusion SMCs from distinct embryonic origins differ in their ability to support HUVEC network formation. LM-derived SMCs best support vasculogenesis in vitro , in part through increased expression of MDK.