Nonviral in vivo gene therapy for tissue engineering of articular cartilage and tendon repair

Heretofore, nonviral methods have been used primarily for in vitro transfection of cultured cell lines. These methods were substantially less efficient when compared with the use of viruses, particularly when used in vivo. Herein a three-step, highly efficient method of nonviral gene delivery is presented. Using this method, genes have been delivered successfully into tissues of orthopaedic importance with high-efficiency by nonviral means. Transforming growth factor-beta 1, parathyroid hormone related protein, and a marker gene were transferred into primary perichondrium and cartilage cells with efficiencies in excess of 70%. They overexpressed their cognate gene products showing efficacy of expression in a rabbit model of osteochondral defect repair. Using the same method, a marker gene was delivered into a canine model for intrasynovial flexor tendon injury and repair. This was achieved by direct gene delivery during surgery. An estimated 5 additional minutes were required during surgery to complete the transfection steps. High efficiency gene delivery was achieved in the flexor tendons, tendon sheaths, tendon pulleys, surrounding tissues, and skin. The efficiency of transfection approached 100% in the exposed superficial tissue layers and transfected cells were found several layers below the exposed tissue surfaces. The data show the potential of direct nonviral gene therapy in orthopaedics for ex vivo and in vivo applications.