A System For Sphingosine-1-Phosphate Delivery Using The Enzyme Sphingosine Kinase

摘要

Endothelialization of synthetic vascular grafts and implants is critical in enhancing the biocompatibility of these devices. Sphingosine 1-phosphate (S1P) is a potent chemotactic factor that is abundantly stored in platelets. We believe that the delivery of S1P from a biomaterial will enhance the endothelialization of that material. In vivo, S1P is produced from sphingosine by the enzyme sph-ingosine kinase (SphK). While most SphK is cytosolic, vascular endothelial cells can release an active form of SphK that is able to produce extracellular S1P. This extracellular S1P can interact with a family of G-protein coupled receptors on endothelial cells. Human umbilical vein endothelial cells (HUVEC) express the receptors S1P_1, S1P_2 and S1P_3, with S1P_1 expressed in the highest amount. S1P-induced endothelial cell migration requires signaling through the S1P_1 receptor. Therefore, we hypothesize that a thin coating containing SphK on the surface of a vascular graft will enhance endothelial cell migration onto the graft. In the current study, we have cloned an isoform of human SphK. Additionally, we have modeled the kinetics of the production of S1P by SphK and the equilibrium interaction of S1P with the endothelial cell receptor S1P_1 in an in vitro environment.