Abstract 12377: Small Diameter Tissue Engineered Vascular Grafts for Arterial Bypass Applications
Objective: Synthetic grafts are currently used for aortic grafts, iliofemoral and femoral-popliteal bypasses when autologous tissue is insufficient. However, small diameter synthetic grafts are rarely used due to high rates of occlusion. Therefore, our objective is to develop a small diameter synthetic graft.
Methods: Grafts were composed of poly-(lactic acid) nanofibers (PLA-nano) (Fig. A). Grafts were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice (Fig. B), with 12 mice undergoing sham operations. Animals were followed for up to 12 months post-implantation.
Results: All synthetic grafts had an inner luminal diameter between 500 and 600μm (Fig. A). Survival in PLA-nano group was 95.3% at 12 months post-implantation (sham group: 94.4%) (Fig. C).
In vivo graft monitoring using Doppler ultrasound and microCT revealed no cases of graft stenosis or graft dilatation in PLA-nano group up to 12 month post-implantation (Fig. D, E, F).
Histologic analysis revealed grafts with an endothelial monolayer at 4, 8 and 12 months after implantation. Neo-extracellular matrix was noted at 12 months. However, PLA scaffold was still present at 12 months after implantation.
Immunohistochemistry staining showed CD 31-, and αSMA-positive cells in PLA-nano scaffold at 12 months, demonstrating presence of smooth muscle cells.
PCR analysis showed gene expressions for SMC, Collagen, MMP and macrophages were increased in PLA nano group compared to sham group.
Conclusion: We successfully implanted small diameter (0.5-0.6mm) synthetic biodegradable vascular grafts as aortic interposition conduits in mice. Long-term survival in PLA-nano group was excellent without graft stenosis or aneurysmal dilatation. Tissue remodeling by autologous cells revealed evidence of neo-vessels by 12 months. Further investigation in large animals with longer life-spans is required to fully evaluate temporal degradation characteristics of these grafts.
- © 2013 by American Heart Association, Inc.