Speaker
Description
Introduction
Osteoarthritis (OA) of articular cartilage is a progressive and debilitating disease, often necessitating a total joint replacement. Between 2005 and 2015 the worldwide prevalence of OA increased by 32.9 % (from 17.9 to 23.7 million cases) [1]. There is therefore a demand for early stage interventions to stave off or delay replacement surgery. A potential treatment is a decellularised osteochondral (OC) graft. Such biological scaffolds should retain their histoarchitecture, biochemical and biomechanical properties, and should not induce negative immune responses when implanted. It is proposed that whole human condyles can be decellularised to produce large, non-immunogenic scaffolds which are then shaped to fit the size and contours of OC lesions.
Methods
Whole medial and lateral femoral condyles (FCs) from were dissected (N=4). The underlying bone was reamed to a total depth of 1 cm. Two medial and two lateral FCs from four separate donors were decellularised and the corresponding lateral and medial FCs retained as in-tissue cellular controls. The decellularisation method applied utilised low concentration sodium dodecyl sulphate (0.1 % w/v), sonication and protease inhibitors. Samples were analysed biochemically (quantitative DNA and glycosaminoglycan (GAG) assays) and histologically to stain for the presence of nuclear material and GAGs (haematoxylin and eosin (H&E), 4′,6-diamidino-2-phenylindole (DAPI) and Safranin O staining).
Results
The total DNA concentration of decellularised bone and cartilage was below the suggested maximum limit of 50 ng.mg-1 dry tissue weight (35.8 ± 12.2 and 4.3 ± 2.3 ng.mg-1 ± SD respectively). GAGs were retained in decellularised cartilage (193.5 ± 37.3 µg.mg-1 (± SD) dry tissue weight; 163.5 ± 42.7 native cartilage). These results were supported by Safranin O staining, which showed GAG retention in the cartilage over the whole sagittal section of the FCs. H&E and DAPI staining showed a reduction in nuclei in decellularised samples; cartilage and bone was largely devoid of visible nuclei. There were occasional nuclei in the calcified tidemark region between the cartilage and bone and the rare occurrence of nuclei in the bone.
Conclusion
FCs were adequately decellularised with excellent GAG retention in the cartilage. As cellular bone allografts are routinely and successfully used in orthopaedic surgery, the presence of the occasional nucleus in the decellularised product should not be of detriment to the immune compatibility of the graft. It is expected that the removal of cells from an autograft tissue through decellularisation will accelerate healing post implantation, as macrophage mediated removal of necrotic allogeneic cells is not required prior to remodelling of the implanted graft. Future work will seek to explore if the retention of GAGs is accompanied by a retention of mechanical and functional properties, through indentation and friction testing. Decellularised condyles may provide an easily stored, off-the-shelf alternative to viable cellular allografts for the repair of cartilage defects.
[1] Vos, T., Allen, C., Arora, M., et al., 2016. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015. The lancet, 388(10053), pp.1545-1602.
41883659229
