Three-Dimensional (3D) Bioprinted GelMA/BAMMA Tubular Scaffolds Loaded with Adipose-Derived Mesenchymal Stem Cells: Tissue Remodeling and Vascularization in Rat Omentum

Congenital malformations, iatrogenic injuries, and acquired diseases of the ureter often lead to structural or functional defects, yet tissue engineering approaches for ureteral repair and reconstruction remain limited. In this study, a photo-crosslinkable bladder acellular matrix (BAMMA) was synthesized from porcine bladder acellular matrix (BAM) through enzymatic digestion and methacrylic anhydride modification. The mechanical and biological properties of GelMA, GelMA/BAMMA, and BAMMA hydrogels were comprehensively characterized, and 3D-bioprinted tubular scaffolds were fabricated using a GelMA/BAMMA hydrogel and adipose-derived mesenchymal stem cells (ADSCs) mixture as the bioink and subsequently embedded in the rat omentum. The GelMA/BAMMA hybrid hydrogel combined the favorable mechanical properties of GelMA with the biological activity of BAMMA, supporting the growth and proliferation of ADSCs. One week after omental embedding, histological and immunohistochemical analyses revealed enhanced tissue remodelling, neovascularization and mitigated local inflammatory response in the ADSC-seeded scaffolds compared with the unseeded controls. These findings demonstrate that ADSC-loaded GelMA/BAMMA bioprinted tubular scaffolds can undergo tissue remodeling and vascularization in a rat omental model, providing a feasible hydrogel bioink for ureteral tissue engineering and a foundation for future research on ureteral repair.