Improved Method of Recombinant AAV2 Delivery for Systemic Targeted Gene Therapy

A major hurdle in most current gene therapy modalities is the ability to transduce target tissues at very high efficiencies that ultimately lead to therapeutic levels of transgene expression. We have developed a novel method of recombinant adeno-associated virus 2 (rAAV) delivery that results in increased vector transduction efficiencies using microspheres reversibly conjugated to rAAV vectors. We hypothesize that conjugation to microspheres should result in a higher effective concentration of vector as well as longer relative exposure time of vector to target cells as it moves through the tissue vasculature. In vitro experiments demonstrate that the same level of transduction seen with free vector can be achieved using 1% of vector when conjugated to microspheres. In addition, using magnetic microspheres, the region of infection can be targeted. In vivo, we demonstrate that microsphere-mediated delivery of rAAV vector results in higher transduction efficiencies than delivery with free vector alone when administered either intramuscularly or intravenously. Furthermore, we demonstrate targeting of transgene expression to specific tissues by retention of microsphere-bound vector in the capillary bed. These studies demonstrate a novel method to deliver rAAV vectors more effectively that could prove to be a successful alternative mode of virus-mediated human gene therapy.