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 preparat ion as a material for small-vessel stent grafts in rabbits. MATERIALS AND METHODS: A composite nitinol-collagen endovascular stent-graf t with a 4-mm inner diameter was deployed in the abdominal aorta in nine ra bbits. 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 s tent-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 s tent-graft. At 1 month, the stent-graft was endothelialized and was infiltr ated with fibroblasts that deposited collagen within the interstices of the implanted collagen material. At 3 months, there was additional collagen de position 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 bioc ompatible for at least 3 months in rabbits. It is rapidly endothelialized a nd does not cause reactive stenosis. As a versatile and biocompatible polym er, collagen is potentially useful in the construction of endovascular sten t-grafts for use in human arteries.