Poly (ɛ-Caprolactone-co-l,l-Lactide) Vascular External Sheath Carrying Prednisone for Improving Patency Rate of the Vein Graft

Coronary artery bypass graft (CABG) surgery is an impactful treatment for coronary heart disease. Intimal hyperplasia is the central reason for the restenosis of vein grafts (VGs) after CABG. The introduction of external vascular sheaths around VGs can effectively inhibit intimal hyperplasia and ensure the patency of VGs. In this study, the well-known biodegradable copolymer poly (ɛ-caprolactone-co-l,l-lactide) (PLCL) was electrospun into high porosity external sheaths. The prednisone loaded in the PLCL sheath was slowly released during the degradation process of PLCL. Under the combined effects of sheath and prednisone, intimal hyperplasia was inhibited. For the cell experiments, all sheaths show low cytotoxicity to L929 cells at different concentrations at different time intervals. The ultrasonography and histological results showed prominent dilation and intimal hyperplasia of VG without sheath after 2 months of surgery. But there was no dilation in PLCL and PLCLPrednisone groups. Of note, the prednisone-loaded sheath group exhibited efficacy in inhibiting intimal hyperplasia and ensured graft patency. To inhibit intimal hyperplasia after coronary artery bypass graft, the use of external vascular sheaths can prevent vein graft (VG) dilatation, then reduce turbulent blood flow shear stress to vessel wall, and lower the stimulation of shear stress to smooth muscle cells (SMCs), so as to prevent the proliferation and migration of vascular SMC. We provide a biodegradable sheath electrospun by poly (ɛ-caprolactone-co-l,l-lactide) (PLCL) loading prednisone and utilize it around VG in animal models. Vascular ultrasound examinations show strong evidence of vascular patency. The histological alterations of VGs in PLCLPrednisone group gave a narrower intima layer owing to the inhibition effect of prednisone.