Purpose
Percutaneous transcatheter implantation of porcine small intestine submucosa (SIS) bioprosthetic valves has been reported as a treatment for chronic deep venous insufficiency. Endothelial progenitor outgrowth cells (EOCs), isolated from whole ovine blood, were evaluated as a source of in vitro autologous seeding for SIS endothelialization. Retention of the EOC monolayer was evaluated to test the feasibility of delivering an endothelialized SIS valve.
Materials and Methods
20 bioprosthetic venous valves were constructed from SIS sutured onto collapsible square stent frames and were seeded with ovine EOCs in vitro. Retention of the endothelial monolayer through valve loading and delivery (3 valves), in vitro flow (3), and ex vivo flow (4) was evaluated with immunofluorescent staining and histology compared to paired unmanipulated control valves. In the ex vivo shunt loop, venous blood was pulled from an implanted dialysis catheter, through the valve, and returned to the sheep.
Results
Immunofluorescent staining of the EOCs on the valves after in vitro seeding revealed a confluent monolayer (95.6 ±2.3% confluent) on each side of the valve. When examined by immunofluorescent staining, the endothelial monolayer remained intact after loading and delivery (97.1 ±1.7%) and when subjected to flow in the in vitro loop (96.0 ±3.0%). Histology of the valves subjected to the ex vivo shunt loop revealed retention of the endothelial monolayer.
Conclusion
Endothelial monolayers seeded on SIS were retained under loading and delivery, in vitro flow, and ex vivo flow. EOCs are a promising cell source for autologous endothelialization of bioprosthetic valves for the treatment of chronic deep venous insufficiency.
