Early natural history of neotissue formation in tissue-engineered vascular grafts in a murine model.

To characterize early events in neotissue formation during the first 2 weeks after vascular scaffold implantation. Biodegradable polymeric scaffolds were implanted as abdominal inferior vena cava interposition grafts in wild-type mice. All scaffolds explanted at day 1 contained a platelet-rich mural thrombus. Within the first few days, the majority of cell infiltration appeared to be from myeloid cells at the peritoneal surface with modest infiltration along the lumen. Host reaction to the graft was distinct between the scaffold and mural thrombus; the scaffold stimulated an escalating foreign body reaction, whereas the thrombus was quickly remodeled into collagen-rich neotissue. Mural thrombi remodel into neotissue that persistently occludes the lumen of vascular grafts.