Towards the development of osteochondral allografts with reduced immunogenicity

Nowadays, repair and replacement of hyaline articular cartilage still challenges orthopedic surgery. Using a graft of decellularized articular cartilage as a structural scaffold is considered as a promising therapy. So far, successful cell removal has only been possible for small samples with destruction of the macrostructure or loss of biome-chanics. Our aim was to develop a mild, enzyme-free chemical decellularization procedure while preserving the biomechanical properties of cartilage. Porcine osteochondral cylinders (diameter: 12 mm; height: 10 mm) were divided into four groups: Native plugs (NA), decellularized plugs treated with PBS, Triton-X-100 and SDS (DC), and plugs additionally treated with freeze-thaw-cycles of-20 degrees C,-80 degrees C or shock freezing in nitrogen (N2) before decellularization. In a non -decalcified HE stain the decellularization efficiency (cell removal, cell size, depth of decellularization) was calculated. For biomechanics the elastic and compression modulus, transition and failure strain as well as transition and failure stress were evaluated. The-20 degrees C,-80 degrees C, and N2 groups showed a complete decellularization of the superficial and middle zone. In the deep zone cells could not be removed in any experimental group. The biomechanical analysis showed only a reduced elastic modulus in all decellularized samples. No significant differences were found for the other biomechanical parameters.

Automated summary

The study aimed to develop a mild, enzyme-free chemical decellularization method while preserving the biomechanical properties of cartilage. Through experiments on porcine osteochondral tissue, it was found that freezing treatment could effectively decellularize the superficial and middle zones, but not the deep zone. Biomechanical analysis showed that decellularization had an impact on the elastic modulus, but not on other parameters.