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

## TL;DR

A new scaffold mimics the layered structure of cartilage and bone to better repair joint injuries and maintain cartilage cell function.

## Contribution

A bio-customized gradient scaffold with five anatomically distinct layers and KGN-loaded hydrogels for enhanced osteochondral repair.

## Key findings

- The scaffold successfully mimics five distinct layers of native osteochondral tissue.
- KGN-loaded hydrogels improve stem cell homing and chondrogenic differentiation.
- Gradient porosity prevents chondrogenic dedifferentiation and supports integrated repair.

## Abstract

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.

Graphical abstract This study presents a comprehensive approach for osteochondral repair through gradient scaffold construction. The process begins with 3D printing technology to fabricate gradient scaffolds, followed by incorporating CS as the primary component mixed with and KGN to fill the chondral layer pores. After composite scaffold assembly, the therapeutic efficacy was evaluated through both ectopic experiments and orthotopic experiments.Image 1

•Mimics the five-layer microstructure of native osteochondral tissue, reproducing its gradient spatial heterogeneity.•Integrates KGN-loaded hydrogel in cartilage zone to direct stem cell homing and chondrogenic differentiation.•Employs gradient porosity to preserve chondrogenic phenotype and prevent dedifferentiation.•Utilizes accessible materials and scalable fabrication for reproducible clinical translation.

Mimics the five-layer microstructure of native osteochondral tissue, reproducing its gradient spatial heterogeneity.

Integrates KGN-loaded hydrogel in cartilage zone to direct stem cell homing and chondrogenic differentiation.

Employs gradient porosity to preserve chondrogenic phenotype and prevent dedifferentiation.

Utilizes accessible materials and scalable fabrication for reproducible clinical translation.