Abstract: Objective    To establish a pig articular cartilage explant model and explore its role in drug delivery evaluation to repair osteoarthritis articular cartilage lesion, thus providing a simple and economical strategy for ex vivo study.   Methods   The pig knee joint cartilage was aseptically dissected ex vivo. The cylindric cartilage in diameter of 40 mm was taken using a biopsy tissue puncher. Then, the explants were cultured in a serum-free medium. The penetration study of small molecule compounds was performed using the Rhodamine B labeled- Kartogenin(KGN). After penetration for 12 h, 24 h, and 48 h, each time point was set up for three repeat groups , the explants were obtained for frozen section. The structure of the explants and the penetration process of small molecule drugs in the cartilage of explants were observed by laser confocal microscope, and the fluorescence intensity was analyzed by Image J.   Results   The cartilage explants can maintain the normal morphology and structure in the serum-free culture for 12 h, 24 h, and 48 h ex vivo. The small molecule drug Rhodamine B-KGN emitted red fluorescence under laser confocal microscope. The fluorescence signal in the 48 h group significantly enhanced (P<0.01). The amount and depth of drugs entrance into the explants were gradually increasing.   Conclusions    An evaluation model is successfully established to trace the penetration and distribution of the small molecule compound KGN in the cartilage explant. This study can provide a simple and economical model to evaluate the effect of drug delivery on osteoarthritis cartilage repair.

Key words: Cartilage explant; ,  ,  Small molecule drug delivery; ,  ,  Drug penetration