Mechanical properties, drug eluting characteristics and in vivo performance of a genipin-crosslinked chitosan polymeric stent

A limitation with the use of polymers as stent matrices is their inherent mechanical weakness. In this study, a polymeric stent, made from chitosan-based films fixed by genipin which has a cyclic molecular structure, was developed (the genipin stent). The mechanical properties of the genipin stent were investigated; its counterpart fixed by a linear epoxy compound (the epoxy stent) and a commercially available metallic stent were used as controls. The results indicated that the cyclic crosslinking structures formed within the genipin stent matrix were beneficiary to the improvement of its mechanical property. Additionally, the tolerable compression load of the genipin stent was superior to that of the control metallic stent. The cytotoxicity of the genipin stent was significantly lower than the epoxy stent. The deployment of the genipin stent in rabbit infrarenal abdominal aortas was performed using a French sheath. At 3 months postoperatively, the retrieved arteries remained patent; no thrombosis was observed. A nearly intact layer of endothelial cells was seen on the stent-implanted vessel wall. To evaluate its possibility as a drug delivery vehicle, sirolimus (an anti-proliferative drug) was loaded in the genipin stent. It was found that the genipin stent with heparin coating exhibited a linear sustained-release profile and the released sirolimus still possessed its original activity in inhibiting smooth muscle cell proliferation. These findings suggest that the genipin stent with enhanced mechanical strength can be used as an attractive stent platform for local drug delivery.