iPSC-Derived Chondroprogenitors as a Promising Cell Source for Cartilage Engineering: A Comparison with MSCs in Unmodified and Peptide-Functionalized Alginate Hydrogels

Articular cartilage degeneration is a hallmark of degenerative joint diseases, yet its limited regenerative capacity poses significant challenges for tissue engineering. While mesenchymal stem cells (MSCs) are the most commonly employed cell type in cartilage tissue engineering, they exhibit donor variability, restricted expansion capacity, and tendencies toward fibrocartilage formation and hypertrophic differentiation. Human induced pluripotent stem cell-derived chondroprogenitors (iCPs) represent a promising alternative, offering scalable production of developmentally relevant cells with intrinsic chondrogenic commitment. However, their performance within three-dimensional biomaterial scaffolds remains largely unexplored. Here, we compared chondrogenic differentiation of iCPs and MSCs within alginate hydrogels of varying stiffness (0.37 - 4.55 kPa) exhibiting physiologically relevant stress relaxation properties. Intermediate stiffness (2% alginate, ~2.17 kPa) optimally supported chondrogenesis for both cell types. While MSCs differentiated as single cells, iCPs spontaneously self-organized into cartilaginous aggregates without requiring a separate pellet pre-culture step, showing significantly higher hyaline indices and reduced COL10 expression, despite initial low viability in hydrogels. To further enhance chondrogenesis, we functionalized 2% alginate gels with RGD and HAVDI peptides mimicking integrin- and cadherin-mediated signaling. HAVDI/RGD functionalization significantly enhanced hyaline cartilage marker expression in both cell types, with iCPs exhibiting superior matrix composition characterized by elevated aggrecan and SOX9 expression and reduced COL10 and MMP13 compared to MSCs. These findings establish iCPs as a promising cell source for cartilage tissue engineering and disease modeling, particularly within biomaterials integrating mechanical and bioactive cues that recapitulate the native cartilage microenvironment.