Abstract
Drug-eluting vascular prostheses represent a new direction in vascular surgery to reduceearly thrombosis and late intimal hyperplasia for small calibre grafts. Subcutaneous implantation inrats is a rapid and cost-effective screening model to assess the drug-elution effect and could, to someextent, be useful to forecast results for vascular prostheses. We compared biological and histologicalresponses to scaffolds in different implantation sites. Polycaprolactone (PCL), paclitaxel-loadedPCL (PCL-PTX) and dexamethasone-loaded PCL (PCL-DXM) electrospun scaffolds were implantedsubcutaneously and in an infrarenal abdominal aortic model in rats for up to 12 weeks. At theconclusion of the study, a histological analysis was performed. Cellular graft invasion revealeddifferences in the progression of cellular infiltration between PCL-PTX and PCL/PCL-DXM groups inboth models. Cell infiltration increased over time in the aortic model compared to the subcutaneousmodel for all groups. Cell counting revealed major differences in fibroblast, macrophage andgiant cell graft colonisation in all groups and models over time. Macrophages and giant cellsincreased in the PCL aortic model; whereas in the subcutaneous model these cell types increasedonly after three weeks or even decreased in the drug-eluting PCL groups. Other major findings wereobserved only in the aortic replacement such as extracellular matrix deposition and neo-angiogenesis.The subcutaneous implant model can be used for screening, especially when drug-eluting effects arestudied. However, major histological differences were observed in cell type reaction and depth ofcell penetration compared to the aortic model. Our results demonstrate that the implantation site isa critical determinant of the biological response.