Directly construct microvascularization of tissue engineering trachea in orthotopic transplantation

Tissue engineering technology provides effective alternative treatments for tracheal reconstruction. The formation of a functional microvascular network is essential to support cell metabolism and ensure the long-term survival of grafts. However, given the lack of an identifiable vascular pedicle of the trachea that could be anastomosed to the blood vessels directly in the recipient's neck, successful tracheal transplantation faces significant challenges in rebuilding the adequate blood supply of the graft. Herein, we describe a one-step method to construct microvascularization of tissue-engineered trachea in orthotopic transplantation. Forty rabbit tracheae were decellularized using a vacuum-assisted decellularization (VAD) method. Histological appearance and immunohistochemical (IHC) analysis demonstrated efficient removal of cellular components and nuclear material from natural tissue, which was also confirmed by 4'-6-diamidino-2-phenylindole(DAPI) staining and DNA quantitative analysis, thus significantly reducing the antigenicity. Scanning electron microscopy (SEM), immunofluorescence (IF) analysis, GAG and collagen quantitative analysis showed that the hierarchical structures, composition and integrity of the extracellular matrix (ECM) were protected. IF analysis also demonstrated that basic fibroblast growth factor (b-FGF) was preserved during the decellularization process, and also exerted biocompatibility and proangiogenic properties by the chick chorioallantoic membrane(CAM) assay. Xenotransplantation assays indicated that the VAD tracheal matrix would no longer induced inflammatory reactions implanted in the body for 4 weeks after treated by VAD more than 16 h. Furthermore, we seeded the matrix with bone marrow-derived endothelial cells (BMECs) in vitro and performed in vivo tracheal patch repair assays to prove the biocompatibility and neovascularization of VAD-treated tracheal matrix, and the formation of a vascular network around the patch promoted the crawling of surrounding ciliated epithelial cells to the surface of the graft. We conclude that this natural VAD tracheal matrix is non-immunogenic and no inflammatory reactions in vivo transplantation. Seeding with BMECs on the grafts and then performing orthotopic transplantation can effectively promote the microvascularization and accelerate the native epithelium cells crawling to the lumen of the tracheal graft.