This study aimed to compare the microstructure and nanomechanical properties of single trabecular bone in different regions of osteonecrosis of the femoral head. Osteonecrotic femoral heads were taken from 20 patients undergoing total hip arthroplasties between 2011 and 2014. Following incision, resin was embedded and polished, and divided into four regions according to the type of pathologic change; i.e., subchondral bone, and necrotic, sclerotic, and healthy regions. Indents from a single trabecular bone of each region were randomly selected to undergo nanoindentation. The results are (1) The elastic modulus and degree of hardness were significantly elevated in the sclerotic region, but there were no differences in necrotic and subchondral bone regions compared with healthy regions. (2) The elastic modulus and hardness of the single trabecular bone were significantly greater in central versus edge regions (for all regions). The conclusions are (1) The mechanical properties of single bone trabeculae were not markedly altered in the necrotic region. (2) The elastic modulus and degree of hardness increased significantly between the edge and central regions, regardless of whether the bone was normal or osteonecrotic.

Gene therapy constitutes a promising strategy for the treatment of osteoarthritis (OA). We assessed the use of electroporation (EP) of non-viral gene vectors, and compared its efficacy with that of adeno-associated virus (AAV) vectors. EP-and AAV-mediated delivery of human interleukin-1 receptor antagonist (hIL-1Ra) was localized performed in the joints of rats following induction of OA. mRNA levels for hIL-1Ra, IL-1β, TNF-α, MMP-13 and ADAMTS-4 in the cartilage and synovial tissues were analyzed. Structural analyses of the subchondral bone at the medial femoral condyle were performed by Micro-CT after treatment. Knee joint specimens were staining with hematoxylin and eosin and Saffron O. Induction of hIL-1Ra by both EP and AAV inhibited inflammatory-induced subchondral bone reconstruction, and effectively suppressed IL-1β activity, as evidenced by decreased expression of MMP-13 and ADAMTS-4. Histological analyses revealed significant protection of cartilage, proteoglycan by EP and AAV. hIL-1Ra expression was similar in both the EP and AAV groups. Notably, this gene is not easier degraded transduced by EP compared with AAV. Taken together, these results show that EP offers transfection efficiency comparable to that of AAV, with the potential for longer gene expression, making EP a promising candidate for efficient non-viral delivery of OA gene therapy.

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