Utilization of a novel Sendai virus vector in ex vivo gene therapy for hemophilia A

Sendai virus (SeV) vectors are being recognized as a superior tool for gene transfer. Here, we report the transfection efficacy of a novel, high-performance, replication-defective, and persistent Sendai virus (SeVdp) vector in cultured cells and in mice using a near-infrared fluorescent protein (iRFP)-mediated in vivo imaging system. The novel SeVdp vector established persistent infection, and strong expression of inserted genes was sustained indefinitely in vitro. Analysis of iRFP-expressing cells transplanted subcutaneously into NOG, nude, and ICR mice suggests that innate immunity was involved in the exclusion of the transplanted cells. We also evaluated the feasibility of this novel SeVdp vector for hemophilia A gene therapy. This system enabled insertion of full-length FVIII genes, and transduced cells secreted FVIII into the culture medium. Transient FVIII activity was detected in the plasma of mice after intraperitoneal transplantation of these FVIII-secreting cells. Further improvement in methods to evade immunity, such as simultaneous expression of immunomodulatory genes, would make this novel vector a very useful tool in regenerative medicine.