De novo cartilage growth after implantation of a 3-D-printed tracheal graft in a porcine model.

Background: Experiments were conducted on the assumption that vivid chondrogenesis would be boosted in vivo following previously preliminary chondrogenesis in a mesenchymal stem cell (MSC)-rich entire umbilical cord (UC) in vitro. Methods: Virtual 3-D tracheal grafts were generated by using a profile obtained by scanning the native trachea of the listed porcine. Although the ultimate goal was the acquisition of a living specimen beyond a 3-week survival period, the empirical results did not meet our criteria until the 10th experiment, ending with the sacrifice of the animal. The categories retrospectively evolved from post-transplant modification due to porcine death using 4 different methods of implantation in chronological order. For each group, we collected details on graft construction, clinical outcomes, and results from both gross and histology examinations. Results: Three animals died due to tracheal complications: one died from graft crush, and two died secondary to erosion of the larger graft into the great vessels. It appeared that the remaining 7 died of tracheal stenosis from granulation tissue. Ectopic de novo growth of neocartilage was found in three porcine subjects. In the nearby tissues, we detected neocartilage near the anastomosis containing interim vesicles of the vascular canals (VCs), perichondrial papillae (PPs) and preresorptive layers (PRLs), which were investigated during the infancy of cartilage development and were first unveiled in the tracheal cartilage. Conclusions: 3-D-printed anatomically precise grafts could not provide successful transplantation with stent-sparing anastomosis; nonetheless, de novo cartilage regeneration in situ appears to be promising for tracheal graft adaptability. Further graft refinement and strategies for managing granulated tissues are still needed to improve graft outcomes.