Prefabricated tracheal prosthesis with partial biodegradable materials : a surgical and tissue engineering evaluation in vivo

Large and circumferential tracheal defects remain at this time an unsolved problem for reconstructive surgery. Many types of prosthetic and tissue grafts have been used but with limited comfortable results. Major complications are anastomotic dehiscence, graft ischemia and stenosis due to the poor vascularization of the prosthetic complex. We studied the in vivo behaviour of a prefabricated flap composed of a partially bioresorbable tracheal prosthesis and an artero-venous vascular carrier. The prosthesis was made of a tubular skeleton of knitted Dacron (20 μm porosity) embedded within a bioresorbable poly-lactic-co-glycolic acid polymer (PLA75GA25) covering both sides. Fifteen New Zealand White rabbits were divided in three groups, depending on the time of examination (30, 90 and 180 days post-implantation). The prosthesis was implanted in the visceral space of the neck using the common carotid trunk and the internal jugular vein as vascular pedicle. The histological, immunohistochemical, and ESEM analyses of collected samples, showed a time-dependent process of tissue neoformation and neovascularization on the prosthetic material with a significant increase from 30 to 90 days post-implantation. In contrast, there was no statistically significant difference in the fibrovascular connective deposition from 90 to 180 days. This finding indicated the three months time as the best period for the tissue deposition and consequent hypothetical orthotopic transplantation of the prosthesis. Further in vivo studies are intended to confirm the results.