Histological/immunohistolpogical characterization of high-density pellet cultures of chondrocytes originating from BNC, cartilage surface or enzymatically digested cartilage. Samples were obtained from cartilage/BNC constructs cultured for eight weeks with continuous TGF-β1 stimulation (identical results for non-stimulated samples). Chondrocytes were then propagated by 'outgrowth-cultures' from isolated BNC inserts or isolated cartilage cylinders, or after enzymatic digestion of isolated cartilage cylinders. After reaching the required amount of cells for the three preparations, high-density cultures of chondrocytes were generated by pellet centrifugation. High-density pellet cultures of chondrocytes originating from BNC (A1, B1, C1), cartilage surface (A2, B2, C2) or enzymatically digested cartilage (A3, B3, C3) were then subjected to two weeks of culture in chondrogenic (with TGF-β1) or basal medium (without TGF-β1). Sections of high-density pellets were then stained for the appearance of proteoglycans using alcian blue (A1-A3); in addition, collagen type II (B1-B3) and type I (C1-C3) were identified immunohistologically. Inserts represent the histology of pellets cultured in basal medium. Magnifications: 40 x. BNC, bacterial nana-cellulose; TGF-β1, transforming growth factor-β1.
Pretzel et al. Arthritis Research & Therapy 2013 15:R59 doi:10.1186/ar4231