Primitive regenerated-tissue evolution in situ after implantation of a 3D-printed tracheal graft

Robust neotissue growth including cartilage, muscle, adipose and glands was observed on the external surface of 3D-printed tracheal grafts transplanted into a 3-month-old large-scale porcine, noticeable after 7 days. This study is the first to categorize the regeneration stages in detail, aiming for a clearer understanding of the cell development process, as previously studies have not fully elucidated chondrogenesis and glandogenesis mechanisms. We’ve identified 4 stages of chondrogenesis based on chondrocyte numbers, protein expression and perichondrium presence. Muscle cells evolved from a fibroblast-like state, confirmed by αSMA and SM-MHC markers, while initial adipose tissue resembling brown fat diminished over time. Gland development, marked by a change were in MUC5B expression, paralleled the findings in native trachea epithelium and submucosal glands. TGF-β1 and type XII collagen were key indicators in the emerging neotissue post-transplant.