Morphologic features of biocompatibility and neoangiogenesis onto a biodegradable tracheal prosthesis in an animal model

We evaluated a new designed bioresorbable polymer (Degrapol®) tracheal prostesis in an in-vivo angiogenesis-inducing animal model focusing on the specific tissue reaction, the neo-angiogenesis and also the eventual cathepsin B role during the polymer degradation. Fifteen rabbits were divided into three groups (2, 6 and 8 weeks) and our tube-shaped porous prosthesis was implanted using the common carotid artery and the internal jugular vein as vascular pedicle. Optical and electron microscopy, immunohistochemestry and immunocitochemestry were performed at the end of each period, showing cells and fibrils, in direct contact with the Degrapol® scaffold, strongly increased with time. Blood vessel neoformation was visible with CD31 expression localized at the endothelial cells forming the neovascular walls. Over time many of them differentiate in muscle fibres as validate by the expression of -smooth muscle actin (SMA). Few inflammatory cells, expressing CD14, were visible while most cells adopting a pronounced spreading phenotype showed a strong positivity for cathepsin B. We concluded that this bioresorbable polymer provided a good substrate for fibrous tissue deposition with an excellent degree of neo-angiogenesis. Also cathepsin B seems to contribute to the polymer degradation and particularly to neovascularization by stimulating capillary-like tubular structures and cell proliferation.