Dolph Houben

167 New surgical technique of whole joint VCA 8 In order to avoid the risks life-long drug therapy, we have developed a novel method to maintain bone and joint allotransplant viability by rapid development of an autologous neoangiogenic circulation [21-24] [25] [26-29] . We tested this novel method in small animal models with bone only VCAs. At the time of the transplant procedure, implantation of autogenous AV-bundles within bone results in capillary sprouting and ultimately, a new autologous neoangenic circulation within the allotransplant. Viability is maintained in the short-term by 2-weeks’ triple drug therapy. These drugs not only prevent acute rejection but also promote neo-angiogenesis from the implanted AV bundle [14, 26, 30] . Bone blood flow is maintained despite eventual nutrient vessel thrombosis, and new bone forms to heal and remodel the transplant. Osteocytes within the new bone have been found to be autogenous to the recipient animal. Similarly, whole knee joint VCA allotransplants have been studied in rat and rabbit models. Although viability was maintained, the knee allotransplants developed both arthritic changes and joint contractures [14] . The cause of the degenerative changes requires further investigation. The potentially affected by loss of proprioceptive nerve supply, as well as poor cartilage nutrition caused by a relatively fixed flexion deformity in these small animals. Joint denervation certainly could lead to joint destruction, termed Charcot arthropathy. .These findings are similar to those found in clinical experience with long-term immunosuppression [1, 7] . Future research should also focus on the role of joint denervation and subsequent development of degenerative changes. In this article, we report a new whole knee VCA model to permit future investigation of best methods used to reconstruct large bone and joint defects in a large animal model. The pig is certainly one of the best experimental VCA models for translational studies of methods showing promise in small animal models [16] . Adult pigs are of similar size to man and have bone and joints of similar anatomy. Additionally, the porcine blood type, and swine leukocyte antigens (SLA) are well known [16, 31] . This allows evaluation of transplantation in size, blood type and age matched animals but over a major mismatch in histocompatibility. The development of a larger species whole knee joint allotransplantation allows pre-clinical evaluation of functional, biomechanical, histological, immunological, radio graphical, and neo- angiogenesis analyses of joint VCAs, all in one animal. Bone healing, remodeling and neo- angiogenesis can be confirmed with the use of serial radiographs, micro-CT and quantitative histomorphometry. Biomechanical data can be obtained in measuring the range of motion of the knee during the survival period. At the final evaluation axial-compression, cyclic reference point indentation and torque force testing can be performed in the same specimen. Serial blood draws allow monitoring of blood cytology and systemic immune response over time. Local immune response and gene-expression can be evaluated by immunohistochemistry and real-time PCR. With the use of laser capture microdissection and qPCR, the cell population and re-population of the allotransplant can be determined in specific cell lineages of interest by quantification of sex- determine region of the Y-chromosome (SRY) , if a sex-mismatched set-up is used.