PCL-PLA blends for electrospun vascular grafts with enhanced cellular activity and long-term biodegradability

Abstract

Small-diameter tissue-engineered vascular grafts face challenges such as mechanical instability, poor endothelialization, stenosis, thrombosis, and intimal hyperplasia. In this study, novel bilayer fibrous vascular graft designs were developed that structurally and biologically mimic native vessels. The grafts were fabricated by electrospinning PLA, PCL, and PLCL polymers, featuring randomly distributed fibers (_R) in the inner layer and radially oriented fibers (_O) in the outer layer. Human umbilical vein endothelial cells (HUVECs) and human aortic vascular smooth muscle cells (HA-VSMCs) were cultured on the inner and outer layers, respectively. Scaffold morphology, fiber diameter, wall thickness, water contact angle, cell viability (MTS assay), cell morphology (SEM and fluorescence microscopy), gene expression (PECAM1, PCDH12, TGF-beta 1), and long-term biodegradation profiles were assessed. The results showed that all scaffolds demonstrated suitable fiber morphology and wall thickness (250-400 mu m). Cell viability significantly increased by Day 14 for both HUVECs and HA-VSMCs, with PCLPLA80_R and PCL100_R scaffolds showing enhanced endothelial proliferation, while PLCL100_O exhibited superior cytoskeletal organization in smooth muscle cells. Gene expression analysis revealed a significant increase in PECAM1 on PLCL100_R at Day 3 and in TGF-beta 1 on PLCL100_O (Day 7) and PCLPLA80_O (Day 14). Biodegradation results indicated that PLCL scaffolds disintegrated by month 3, whereas PCL and PCL/PLA-based scaffolds retained over 30% of their initial mass after 12 months. Radially aligned fibers slowed degradation compared to randomly distributed fibers. Overall, the developed bilayer fibrous grafts effectively support cell proliferation, functional gene expression, and controlled biodegradation, suggesting that the strategic combination of fiber orientation and material composition can enhance scaffold performance and hold promise for small-diameter vascular tissue engineering applications.