# Bovine Cartilage-Derived Type II Collagen Composite Scaffolds: Collagen Characterization, Physicochemical Properties, and In Vitro Chondrocyte Responses

## TL;DR

Researchers developed a collagen-based scaffold from bovine cartilage that supports cartilage cell growth and maintains cell function in the lab.

## Contribution

A novel composite scaffold using bovine type II collagen, silk fibroin, and chitosan is proposed for cartilage tissue engineering.

## Key findings

- CII-based scaffolds supported chondrocyte growth and extracellular matrix deposition.
- The CII:SF:CS ratio of 7:3:1 showed highest GAG/DNA content and upregulated cartilage-related genes.
- The scaffold with 7:3:1 ratio maintained cell phenotype and reduced dedifferentiation marker expression.

## Abstract

Type II collagen (CII), the major structural protein in the cartilage extracellular matrix, is a promising biomaterial for scaffold design in cartilage tissue engineering. In this study, high-purity CII was successfully extracted from bovine cartilage, an abundant by-product of cattle slaughter, and its amino acid composition, triple-helical conformation, and thermal stability were verified. CII was subsequently combined with silk fibroin (SF) and chitosan (CS) to fabricate three-dimensional (3D) porous scaffolds via freeze-drying. The pore structure, porosity, swelling behavior, mechanical properties and in vitro degradation characteristics were systematically evaluated. Scaffolds with favorable structural integrity, mechanical performance, and degradation rates were further evaluated biologically using human primary chondrocytes. All CII-based composite scaffolds supported chondrocyte growth and promoted early extracellular matrix deposition. Notably, the scaffold with a CII:SF:CS ratio of 7:3:1 showed the highest GAG/DNA content, accompanied by upregulated gene expression related to the cartilage phenotype (COL2A1, ACAN, and SOX9) and reduced expression of the dedifferentiation marker COL1A1, indicating improved phenotype maintenance. Overall, within the tested range, CII70 (CII:SF:CS = 7:3:1) represents a practical compromise between scaffold stability and in vitro chondrocyte-related outcomes, providing a basis for selecting CII/SF/CS formulations for cartilage tissue engineering.