Reconstruction of pulmonary artery with porcine small intestinal submucosa in a lamb surgical model: Viability and growth potential

Objectives: This study investigated the time-dependent remodeling and growth potential of porcine small intestine submucosa as a biomaterial for the reconstruction of pulmonary arteries in a lamb model. Methods: Left pulmonary arteries were partially replaced with small intestine submucosal biomaterial in 6 lambs. Two animals each were humanely killed at 1, 3, and 6 months. Computed tomographic angiography, macroscopic examination of the implanted patch, and microscopic analysis of tissue explants were performed. Results: All animals survived without complications. Patency and arborization of the pulmonary arteries were detected 6 months after implantation. There was no macroscopic narrowing or aneurysm formation in the patch area. The luminal appearance of the patch was similar to the intimal layer of the adjacent native pulmonary artery. Scanning electron microscopy showed that the luminal surface of the patch was covered by confluent cells. Immunohistochemical examination confirmed endothelialization of the luminal side of the patch in all of the explanted patches. The presence of smooth muscle cells in the medial layer was confirmed at all time points; however, expression of elastin, growth of the muscular layer, and complete degradation of patch material were detectable only after 6 months. The presence of c-Kit-positive cells suggests migration of multipotent cells into the patch, which may play a role in remodeling the small intestine submucosal biomaterial. Conclusions: Our data confirmed that remodeling and growth potential of the small intestine submucosal biomaterial are time dependent. Additional experiments are required to investigate the stability of the patch material over a longer period.