Systematic Review of the Preclinical Technology Readiness of Orthopedic Gene Therapy and Outlook for Clinical Translation

Bone defects and improper healing of fractures are an increasing public health burden, and there is an unmet clinical need in their successful repair. Gene therapy has been proposed as a possible approach to improve or augment bone healing with the potential to provide true functional regeneration. While large numbers of studies have been performed in vitro or in vivo in small animal models that support the use of gene therapy for bone repair, these systems do not recapitulate several key features of a critical or complex fracture environment. Larger animal models are therefore a key step on the path to clinical translation of the technology. Herein, the current state of orthopedic gene therapy research in preclinical large animal models was investigated based on performed large animal studies. A summary and an outlook regarding current clinical studies in this sector are provided. It was found that the results found in the current research literature were generally positive but highly methodologically inconsistent, rendering a comparison difficult. Additionally, factors vital for translation have not been thoroughly addressed in these model systems, and the risk of bias was high in all reviewed publications. These limitations directly impact clinical translation of gene therapeutic approaches due to lack of comparability, inability to demonstrate non-inferiority or equivalence compared with current clinical standards, and lack of safety data. This review therefore aims to provide a current overview of ongoing preclinical and clinical work, potential bottlenecks in preclinical studies and for translation, and recommendations to overcome these to enable future deployment of this promising technology to the clinical setting

Gene Therapy Strategies in Bone Tissue Engineering and Current Clinical Applications

Gene therapy provides a promising approach for regeneration and repair of injured bone. Application of gene therapy has displayed increased efficiency in various animal models and preclinical trials in comparison with traditional bone grafting methods. The objective of this review is to highlight fundamental principles of gene therapy strategies in bone tissue engineering and solutions of their current limitations for the healing of bone injury. Vector types are debated for the repair of defected site due to demonstration of constraints and applications of the protocols. In recent years, the combination of gene therapy strategies and bone tissue engineering has highly gained attention. We discussed viral and non-viral mediated delivery of therapeutic protein by using scaffolds for bone tissue engineering. Although pre-clinical studies have showed that gene therapy has very promising results to heal injured bone, there are several limitations regarding with the usage of gene delivery methods into clinical applications. Choice of suitable vector, selection of transgene and gene delivery protocols are the most outstanding questions. This article also addresses current state of gene delivery strategies in bone tissue engineering for their potential applications in clinical considerations