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Molecular biological advances have allowed the use of gene therapy in a clinical setting. In addition, numerous reports have indicated the existence of inducible osteoprogenitor cells in skeletal muscle. Because of this, we hypothesized that skeletal muscle cells might be ideal vehicles for delivery of bone-inductive factors. Using ex vivo gene transfer methods, we genetically engineered freshly isolated human skeletal muscle cells with adenovirus and retrovirus to express human bone morphogenetic protein 2 (BMP-2). These cells were then implanted into nonhealing bone defects (skull defects) in severe combined immune deficiency (SCID) mice. The closure of the defect was monitored grossly and histologically. Mice that received BMP-2-producing human muscle-derived cells experienced a full closure of the defect by 4 to 8 weeks posttransplantation. Remodeling of the newly formed bone was evident histologically during the 4- to 8-week period. When analyzed by fluorescence in situ hybridization, a small fraction of the transplanted human muscle-derived cells was found within the newly formed bone, where osteocytes normally reside. These results indicate that genetically engineered human muscle-derived cells enhance bone healing primarily by delivering BMP-2, while a small fraction of the cells seems to differentiate into osteogenic cells.

At the time we prefer OCT instead of ACT given the correct indication.

Rotator cuff lesions are one of the most common causes of upper extremity disability. Surgical therapy addresses mostly the extrinsic etiology, but not intrinsic factors such as aging, structural changes, low vascularity, and inflammatory processes. In this study, genetically engineered, highly purified muscle-derived cells (MDCs) were characterized and injected into the supraspinatus tendons of nude rats. The injected cells were monitored for 3 weeks. In vitro, the engineered, highly purified MDCs do not express vimentin; 98% of them are positive for the beta-galactosidase marker gene, and 99% hybridize with the specific pancentromeric mouse probe. beta-Galactosidase marker gene expression of the injected cells was detected up to 21 days. From day 7 after injection, the cell nuclei became spindle shaped, cells were integrated into the tendon collagen bundles, and the cells showed differentiation into vimentin-expressing fibroblastic cells. The results indicate that the rotator cuff tendon matrix and its original cellular components modulated the injected MDCs toward a fibroblastic phenotype. The compatibility and ability of MDCs to differentiate into other cell lineages, such as fibroblasts, might have high potential utility in tissue-engineering applications for tendon healing. This approach facilitates the application of muscle-derived progenitor cells and ex vivo gene therapy for the treatment of rotator cuff lesions.

Allograft meniscal transplantation represents one of the few available treatment options after menisectomy. Despite acceptable early results, a considerable controversy exists with regard to poor graft regeneration, shrinkage and biomechanical failure of transplanted menisci. Transfer of specific growth factor genes may improve the regeneration process of meniscal allografts. The aim of this study was to investigate the feasibility of gene transfer in meniscal allografts in rabbits. Four different viral vectors encoding marker genes, including lacZ, luciferase, and green fluorescence protein were used to investigate viral transduction in 50 lapine menisci for 4 weeks in vitro. Subsequently, 16 unilateral meniscus replacements were performed with ex vivo retrovirally transduced meniscal allografts, and the expression of the lacZ gene was examined histologically at 2, 4, 6, and 8 weeks after transplantation. Gene expression in the superficial cell layers of the menisci can be detected for up to 4 weeks in vitro, but the level of gene transfer declined over time. The transduction with retrovirus showed better persistence and deep penetration of the menisci with infected cells. In vivo, declining numbers of beta-galactosidase-positive cells were also detected in retrovirally transduced allografts up to 8 weeks. Consistently, transduced cells were found at the menisco-synovial junction of the transplants and in deeper layers of the menisci. There was no evidence of cellular immune response in the transduced transplants. This investigation showed a prospective for growth factor delivery in auto- and allografts. In further experiments, vectors expressing therapeutic proteins such as growth factors will be investigated to assess their potential to improve remodeling and healing of meniscal allografts.

Pure robot-assisted laparoscopic ureteral reimplantation is a safe and feasible approach to the management of ureteral stricture disease.