Kartogenin-loaded chitosan composite scaffold with cartilage-mimetic microstructure for layered osteochondral repair and cartilage phenotype maintenance.

Osteochondral defects represent a formidable clinical challenge due to their distinctive stratified architecture and limited intrinsic healing capacity. However, conventional tissue engineering scaffolds exhibit significant limitations in replicating the gradient properties of native osteochondral tissue while maintaining chondrogenic phenotypes. This study presents a novel bio-customized gradient scaffold CSK@G inspired by natural osteochondral architecture, developed through strategic material composition control and graduated porosity design techniques, for integrated repair of osteochondral defects. Through precise biomimetic design, the scaffold successfully recapitulates the spatial heterogeneity of native tissue by accurately mimicking five anatomically distinct layers-superficial cartilage, middle cartilage, deep cartilage, calcified cartilage, and subchondral bone. Additionally, Kartogenin (KGN)-loaded Chitosan (CS) hydrogels are strategically incorporated within cartilaginous zones to facilitate stem cell homing and create optimal cellular microenvironments that provide region-specific biochemical cues for enhanced chondrogenic differentiation. Comprehensive experimental results, both in vitro and in vivo, demonstrate that this bio-customized gradient scaffold significantly facilitates integrated osteochondral repair while effectively maintaining chondrogenic phenotypes. This work proposes a novel bio-customized strategy for osteochondral tissue engineering, resulting in a bio-customized scaffold that closely mimics the hierarchical properties of natural osteochondral tissue.