Histology (toluidine blue staining) of chondrocytes seeded to chitosan-only scaffolds, GAM embedding empty plasmid nanoparticles, and GAM embedding HA/CS/pTGF-β1 nanoparticles for 7 and 21 days of culture.

Toluidine blue stains ECM, therefore cell clusters intensely stained by toluidine blue indicate newly synthesized proteoglycans. Cell clusters were much denser and evenly distributed in GAM embedding HA/CS/pTGF-β1 nanoparticles than the other two control groups. Panels A, B, C: ×100; D, E, F: ×400; G, H, I: ×40; J, K, L: ×200.