Cell Seeding of a Novel Electrospun Vascular Graft Prevents Stenosis in a Mouse Model

Objective: Nanofiber graft creation using electrospinning technology has been proposed as a highly tunable and reproducible method for tissue engineered vascular graft scaffold fabrication; however, the role of cell seeding... [ view full abstract ]

Objective: Nanofiber graft creation using electrospinning technology has been proposed as a highly tunable and reproducible method for tissue engineered vascular graft scaffold fabrication; however, the role of cell seeding for neotissue formation of nanofiber graft is controversial. The purpose of the present study is to determine the effect of bone marrow mononuclear cell (BM-MNC) seeding in a novel electrospun vascular graft.
Methods: Electrospun scaffolds were fabricated from a copolymer solution of poly-glycolic acid (PGA) and poly(L-lactide-co-caprolactone) (PLCL). Platelet activation and cell seeding efficiency were assessed by ATP secretion and DNA assays respectively. Cell-free and BM-MNC seeded electrospun scaffolds were implanted in mice (n = 10 per group) as IVC interposition conduits. Animals were followed with serial ultrasonography for 6 months, after which grafts were harvested for evaluation of patency and neotissue formation by immunohistochemical and PCR analyses.
Results: Cell-seeding of electrospun scaffolds prevented stenosis compared to unseeded scaffolds (seeded: 9/10 vs. unseeded: 1/10, p = 0.0011) over 6 months. The patent vascular graft demonstrated concentric laminated smooth muscle cells, a confluent endothelial monolayer, and collagen rich extracellular matrix. Platelet derived ATP, a marker of platelet activation, was significantly reduced after incubating thrombin activated platelets in the presence of BM-MNC seeded electrospun scaffolds compared to unseeded scaffolds (p < 0.0001). Non-inflammatory M2 macrophage infiltration into the cell-seeded scaffolds was significantly higher than unseeded scaffolds.
Conclusions: BM-MNC seeding on electrospun vascular graft attenuated stenosis through the prevention of platelet attachment and M2 macrophage infiltration, which led to well-organized neotissue formation.