Biomaterial Mesh Seeded with Vascular Remnants from a Quail Embryo Has a Significant and Fast Vascular Templating Effect on Host Implant Tissue

Seeding biomaterial implants with vascular remnants has the potential to facilitate host vessel ingrowth via a vascular templating effect. Vessels from quail embryo were grown into a polyurethane fibroporous mesh and the samples were frozen–thawed and then implanted in rat subcutaneous dorsum. Results show that the process of revascularization, using the quail vessel remnants, occurred over the first 3 days after implantation and resulted in functional vessels. Rat endothelial cells were found in the quail templates on day 1. On day 2 the endothelial cells formed a confluent layer and started producing laminin. By this time approximately 70% of the rat vessel tissue in the implant had grown into quail vascular remnants, indicating that the quail vessels were extensively used as templates for host vessel ingrowth. Laminin production was increased and collagen production started by day 3, at which time the vessels were functional in that rat blood flowed through them. At 2 weeks host vessel density was approximately twice that of control samples; thus the implant substantially enhanced the size of the vascular network. For meshes that additionally received vascular endothelial growth factor (VEGF) seeding before implantation, vessel density at 2 weeks was enhanced over samples with quail embryo alone. However, the quail was found to have the greatest angiogenic effect above any of the implant components—quail, VEGF, and collagen. Tissue engineering of vessel templates may thus be a realistic solution to effective fast vascularization of biomaterials.