Sphingosine-1-phosphate (S1P) has been known to promote endothelial cell (EC) proliferation and protect Syndecan-1 (SDC1) from shedding, thereby maintaining this antithrombotic signal. In the present study, we investigated the effect of S1P in the construction of a functional tissue-engineered blood vessel by using human endothelial cells and decellularized human umbilical vein (DHUV) scaffolds. Both human umbilical vein endothelial cells (HUVEC) and human cord blood derived endothelial progenitor cells (EPC) were seeded onto the scaffold with or without the S1P treatment. The efficacy of re-cellularization was determined by using the fluorescent marker CellTracker CMFDA and anti-CD31 immunostaining. The antithrombotic effect of S1P was examined by the anti-aggregation tests measuring platelet adherence and clotting time. Finally, we altered the expression of SDC1, a major glycocalyx protein on the endothelial cell surface, using MMP-7 digestion to explore its role using platelet adhesion tests in vitro. The result showed that S1P enhanced the attachment of HUVEC and EPC. Based on the anti-aggregation tests, S1P-treated HUVEC recellularized vessels when grafted showed reduced thrombus formation compared to controls. Our results also identified reduced SDC1 shedding from HUVEC responsible for inhibition of platelet adherence. However, no significant antithrombogenic effect of S1P was observed on EPC. In conclusion, S1P is an effective agent capable of decreasing thrombotic risk in engineered blood vessel grafts. STATEMENT OF SIGNIFICANCE:Sphingosine-1phosphate (S1P) is a low molecular-weight phospholipid mediator that regulates diverse biological activities of endothelial cell, including survival, proliferation, cell barrier integrity, and also influences the development of the vascular system. Based on these characters, we the first time to use it as an additive during the process of a small caliber blood vessel construction by decellularized human umbilical vein and endothelial cell/endothelial progenitor. We further explored the function and mechanism of S1P in promoting revascularization and protection against thrombosis in this tissue engineered vascular grafts. The results showed that S1P could not only accelerate the generation but also reduce thrombus formation of small caliber blood vessel.