Bovine type I collagen as an endovascular stent-graft material: Biocompatibility study in rabbits

PURPOSE: To study the biocompatibility of a bovine type I collagen preparation as a material for small-vessel stent-grafts in rabbits. MATERIALS AND METHODS: A composite nitinol-collagen endovascular stent-graft with a 4- mm inner diameter was deployed in the abdominal aorta in nine rabbits. Angiography was performed, and the rabbits were sacrificed at 1, 2, and 7 days and at 1 and 3 months. The portion of the aorta containing the stent- graft was excised and was histologically evaluated. RESULTS: All stent-grafts were patent at all time points. On days 1, 2, and 7 after implantation, scattered red and white blood cells adhered to the stent-graft. At 1 month, the stent-graft was endothelialized and was infiltrated with fibroblasts that deposited collagen within the interstices of the implanted collagen material. At 3 months, there was additional collagen deposition within the interstices of the stent-graft that did not narrow the lumen of the stent-grafts. CONCLUSION: Type I collagen as a intravascular stent-graft material is biocompatible for at least 3 months in rabbits. It is rapidly endothelialized and does not cause reactive stenosis. As a versatile and biocompatible polymer, collagen is potentially useful in the construction of endovascular stent-grafts for use in human arteries.