Extraction techniques for the decellularization of tissue engineered articular cartilage constructs

Several prior studies have been performed to determine the feasibility of tissue decellularization to create a non-immunogenic xenogenic tissue replacement for bladder, vasculature, heart valves, knee meniscus, temporomandibular joint disc, ligament, and tendon. However, limited work has been performed with articular cartilage, and no studies have examined the decellularization of tissue engineered constructs. The objective of this study was to assess the effects of different decellularization treatments on articular cartilage constructs, engineered using a scaffoldless approach, after 4 wks of culture, using a two-phased approach. In the first phase, five different treatments were examined: 1) 1% SDS, 2) 2% SDS, 3) 2% Tributyl Phosphate, 4) 2% Triton X-100, and 5) Hypotonic followed by hypertonic solution. These treatments were applied for either 1 h or 8 h, followed by a 2 h wash in PBS. Following this wash, the constructs were assessed histologically, biochemically for cellularity, GAG, and collagen content, and biomechanically for compressive and tensile properties. In phase II, the best treatment from phase I was applied for 1, 2, 4, 6, or 8 h in order to optimize the application time. Treatment with 2% SDS for 1 h or 2 h significantly reduced the DNA content of the tissue, while maintaining the biochemical and biomechanical properties. On the other hand, 2% SDS for 6 h or 8 h resulted in complete histological decellularization, with complete elimination of cell nuclei on histological staining, although GAG content and compressive properties were significantly decreased. Overall, 2% SDS, for 1 or 2 h, appeared to be the most effective agent for cartilage decellularization, as it resulted in decellularization while maintaining the functional properties. The results of this study are exciting as they indicate the feasibility of creating engineered cartilage that may be non-immunogenic as a replacement tissue.