Loading Rapamycin Improves the Patency of Vascular Grafts in a Mouse Model of Atherosclerosis

Improving the patency rate of small-diameter vascular grafts in a pathological environment is the key to achieving their clinical translation and application. The current approach to in vivo implantation evaluations of small-diameter vascular grafts is predominantly based on healthy animal models. However, the majority of patients who undergo vascular transplantation are afflicted with vascular diseases, such as hyperlipidaemia or atherosclerosis. In this study, we constructed an ApoE gene knockout atherosclerotic mouse model and investigated the patency and regenerative performance of small-diameter vascular grafts in a diseased environment. We prepared heparinized Poly (ε-caprolactone) (PCL) vascular grafts (PCL-Hep) using electrospinning technology. By taking advantage of the physical adsorption of heparin, rapamycin (RM) was loaded onto the surface of grafts to obtain PCL-Hep-RM vascular grafts, which exhibited exceptional mechanical properties and drug sustained-release characteristics. Subsequently, the PCL-Hep-RM vascular grafts were implanted into the carotid arteries of atherosclerotic mice. The results demonstrated that PCL-Hep-RM significantly enhanced the patency rate and suppressed intimal hyperplasia in comparison with the PCL control group. This study offers novel concepts and methodologies for addressing challenges such as the low long-term patency rate and luminal stenosis of vascular grafts in a diseased environment, thereby promoting the translational medicine research of small-diameter vascular grafts.