Scheme of the in vitro model. For embedding of the cartilage-BNC constructs, hot liquid agarose (2%) was added to the cavities of a 48-well plate (A). Cylinders of defined size (5.8 mm) were created by inserting a metal-pin plate into the hot agarose and removing it after polymerization of the agarose (B). The central defects of the cartilage discs were filled with the BNC material using forceps (C) and, after embedding the constructs into the agarose (D), culture medium was added (E). One part of the samples was stimulated with TGF-β1 at a concentration of 10 ng/ml. After in vitro culture, cartilage/BNC constructs were subjected to histological characterization. In addition, gene expression of chondrocytes isolated either from the BNC implant, the cartilage surface or the cartilage matrix was analyzed. At the protein level, the amount of cartilage components released into the supernatant as well as the remaining content in cartilage samples was quantified. BNC, bacterial nana-cellulose; TGF-β1, transforming growth factor-β1.
Pretzel et al. Arthritis Research & Therapy 2013 15:R59 doi:10.1186/ar4231