Tissue engineering of articular cartilage using nasal chondrocytes on alginate-chitosan-based composite scaffolds

Articular cartilage defects present a significant clinical challenge due to the tissue’s limited self-repair capacity. Tissue-engineered scaffolds that support cell survival, phenotype maintenance, and extracellular matrix (ECM) formation offer a promising strategy for restoring hyaline cartilage. In this study, we synthesized a composite scaffold composed of naturally derived biomaterials alginate and chitosan (AC), and a variant supplemented with type II collagen (CAC), and evaluated their pro-chondrogenic potential. Rabbit nasal septal chondrocytes (NSCs) were selected as the cellular component because of their high proliferative capacity and phenotypic stability. NSCs were seeded on to AC and CAC scaffolds and cultured for up to six weeks. Cell presence and distribution, histological morphology, ECM deposition, chondrogenic marker expression, and mechanical properties were assessed. Live/Dead imaging demonstrated sustained live-cell presence in both scaffold-types across all time-points. Histological analysis confirmed cellular infiltration into the scaffold interior, and Safranin-O staining showed pericellular red staining at later time -points, suggestive of early matrix deposition. Immunohistochemistry revealed increased staining over time of Sox9, aggrecan, and type II collagen, with CAC scaffolds exhibiting earlier temporal changes in aggrecan and type II collagen expression. Mechanical testing of cellular AC scaffolds showed a 15-fold increase in stiffness post-culture, suggesting ECM-associated reinforcement. These findings suggest that AC scaffolds, particularly when supplemented with type II collagen provide a supportive microenvironment for NSCs to infiltrate and express key chondrogenic markers. This composite system represents a simple and adaptable platform with potential utility for engineering cartilage.