Abstract No. 502 Electrospun Bioresorbable Polymer Blends as Vascular Grafts

Many vascular bypass patients lack enough healthy tissue to be used in the procedure. Current polymeric prosthetic grafts may be utilized in large-caliber vessels but can still induce stenosis and thrombosis. We aim to synthesize more biocompatible grafts with alternative bioresorbable polymers for applications in small-caliber vessels. Synthesis: PCL, PCL:PEG, PCL:PLGA (poly lactic-co-glycolic acid), and PCL:PLA—were dissolved in 3:1 ratios and electrospun at 15 kV to yield polymeric grafts. Hemolysis: The samples were incubated overnight in media, and the supernatant was used to test for hemolysis. Proliferation assay: The proliferation of RF24 or MOVAS cells on the scaffolds were also determined at 4, 24, 48, and 96 hours with an Alamar blue assay. In vitro assay: Samples were also placed in an in vitro pump system to simulate the in vivo degradation of the grafts under constant pulsatile flow. At 0, 2, and 4 weeks, the maximum stress and modulus of elasticity was measured using an MTest Quattro machine (ADMET, Shirley, NY). In vivo assay: A scaffold of each type was grafted onto the abdominal aorta of Sprague-Dawley rats under anaesthesia. A 5th control rat had their abdominal aorta severed and reconnected. After 4 weeks, rats were sacrificed, and the scaffolds were removed and imaged for analysis. All polymer combinations were shown to be non-hemolytic and non-cytotoxic. Additionally, PCL, PCL-PEG, and PCL-PLA all showed comparable values of porosity, while PCL-PLGA showed a significantly lowered porosity value. We also found that while PCL-PEG had one of the lowest maximum stresses, it was on par with PCL-PLGA with having a lower modulus of elasticity. In our cell proliferation assay, PCL-PEG demonstrated the greatest amount of proliferation at the end of the 96 hours for both RF24 cells and MOVAS cells. Finally, after analysis of our in vivo samples, we found both PCL and PCL-PLGA scaffolds induced significant stenosis of the vessel. PCL-PEG demonstrated proper cell layers and an inner endothelial monolayer and PCL-PLA also had a developing vein with appropriate cell layers, but it had some interruptions in its endothelial monolayer with a little narrowing of the vessel. PCL-PEG is the most ideal polymer combination to continue testing against for vascular graft synthesis and the inclusion of a biocompatible hydrophilic polymer enhanced polymer grafts' ability recruit cells for vascular reconstruction with a decreased incidence of stenosis and thrombosis.