Viral vector-mediated transgenic cell therapy in regenerative medicine: safety of the process.

INTRODUCTION: There are safety concerns regarding viral vectors in regenerative medicine research because of adverse experiences in conventional gene therapy with systemic delivery of recombinant virus. Transgenic cell therapy emerges as an attractive strategy, in which the genes of interest are delivered in vitro into isolated cells first; instead of transgene vectors, these transgenic cells are then implanted back to the host. This ex vivo strategy enables the examination of cell viability and phenotype before subsequent transplantation and prevents to the most extent the potential delivery-related hazards caused by exposure of viral components to the host. The transgenic implants are often localized, thus traceable for safety monitoring except those cases involving systemic distribution of transgenic cells. AREAS COVERED: The safety of ex vivo process used in viral vector-mediated transgenic cell therapy for regenerative medicine purpose. EXPERT OPINION: Safety concerns related to viral vector delivery can be dispelled in the majority of regenerative medicine applications by transgenic cell therapy. The ex vivo process executes in vitro transfection before subsequent transplantation of transgenic cells so that it avoids the exposure of viral components (particularly capsids or envelops) to the host, while this exposure is inevitable in conventional in vivo gene therapy. Besides, the practice of localized cell implantation and in vitro manipulation also reinforce the safety of transgenic cell therapy. Given the significantly reduced delivery-related hazard, viral vector-mediated transgenic cell therapy can be generally considered as a safe approach for most regenerative medicine applications.