Long-term results of cell-free biodegradable scaffolds for in situ tissue engineering of pulmonary artery in a canine model.

We previously developed a cell-free, biodegradable scaffold for in-situ tissue-engineering vasculature (iTEV) in a canine inferior vena cava (IVC) model. In this study, we investigated application of this scaffold for iTEV of the pulmonary artery (iTEV-PA) in a canine model. In vivo experiments were conducted to determine scaffold characteristics and long-term efficacy. Biodegradable scaffolds comprised polyglycolide knitted fibers and an l-lactide and ε-caprolactone copolymer sponge, with an outer glycolide and ε-caprolactone copolymer monofilament reinforcement. Tubular scaffolds (8 mm diameter) were implanted into the left pulmonary artery of experimental animals (n = 7) and evaluated up to 12 months postoperatively. Angiography of iTEV-PA after 12 months showed a well-formed vasculature without marked stenosis, aneurysmal change or thrombosis of iTEV-PA. Histological analysis revealed a vessel-like vasculature without calcification. However, vascular smooth muscle cells were not well-developed 12 months post-implantation. Biochemical analyses showed no significant difference in hydroxyproline and elastin content compared with native PA. Our long-term results of cell-free tissue-engineering of PAs have revealed the acceptable qualities and characteristics of iTEV-PAs. The strategy of using this cell-free biodegradable scaffold to create relatively small PAs could be applicable in pediatric cardiovascular surgery requiring materials.