Tissue-engineered stent-graft integrates with aortic wall by recruiting host tissue into graft scaffold

Abstract

To prevent postoperative migration and endoleaks after endovascular aneurysm repair, we developed a tissue-engineered vascular graft that integrates with the aortic wall by recruiting the host tissue into the graft scaffold. In the present study, we assessed the mechanical properties of the new graft and evaluated the integration between the graft and aortic wall histologically and mechanically in canine models. The tissue-engineered vascular graft was woven to be partially degradable with a double-layered fiber (core; polyethylene terephthalate [PET], and sheath; polyglycolic acid [PGA]). The mechanical properties of the graft were assessed compared with a thin-walled woven polyester graft (control; 12 mm in diameter, 30 mm long). The stent-grafts, composed of a stainless Z stent (20 mm in diameter, 25 mm long) and a PET/PGA or control graft (n=5 in each group), were implanted in the descending thoracic aorta of mongrel dogs for 2 months. We assessed the histologic findings of the explants and the degree of adhesion between the graft and aortic wall. The PET/PGA graft achieved nearly the same mechanical properties as those of the control graft in tensile strength and flexibility, with slightly greater water permeability. At 2 months after implantation, in the PET/PGA group, the PGA component had degraded and been replaced by host tissue that contained a mixture of α-smooth muscle actin-positive cells and other host cells. The graft was a unified structure with the aorta. The adhesion strength between the graft and aortic wall was significantly enhanced in the PET/PGA group. The PET/PGA stent-graft demonstrated histologic and mechanical integration with the native aorta. This next-generation stent-graft might reduce the risk of migration and endoleaks, leading to preferable long-term results of endovascular aneurysm repair.