Modulation of starling forces and muscle fiber maturity permits adenovirus-mediated gene transfer to adult dystrophic (mdx) mice by the intravascularroute

Duchenne muscular dystrophy (DMD) and other inherited myopathies lead to pr ogressive destruction of most skeletal muscles in the body, including those responsible for maintaining respiration. DMD is a fatal disorder caused by defects in the dystrophin gene. Recombinant adenovirus vectors (AdV) are c onsidered a promising means for therapeutic delivery of a functional dystro phin gene to DMD muscles, If AdV-mediated dystrophin gene replacement in DM D is to be successful, development of a systemic delivery method for target ing the large number of diseased muscles will be required. In this study we investigated two major factors preventing efficient AdV-mediated gene tran sfer to skeletal muscles of adult animals after intravascular AdV administr ation: (1) an inability of AdV particles to breach the endothelial barrier and enter into contact with myofibers, and (2) a relatively nonpermissive m yofiber population for AdV infection due at least in part to insufficient l evels of the coxsackie/adenovirus attachment receptor (CAR), On the basis o f established principles governing the transendothelial flux of macromolecu les, we further hypothesized that an alteration in Starling forces (increas ed hydrostatic and decreased osmotic pressures) within the intravascular co mpartment would facilitate AdV transendothelial flux via convective transpo rt. In addition, experimental muscle regeneration was employed to increase the prevalence of immature myofibers in which CAR expression is upregulated , Here we report that by employing the above-described strategy, high-level heterologous reporter gene expression was achievable in hindlimb muscles o f normal rats as well as dystrophic (mdx) mice (genetic homolog of DMD) aft er a single intraarterial injection of AdV, Microsphere studies confirmed e nhanced transport into muscle of fluorescent tracer particles in the size r ange of AdV, and there was a high concordance between CAR upregulation and myofiber transduction after intraarterial AdV delivery, Furthermore, in mdx mice examined 10 days after intraarterial AdV delivery, the aforementioned procedures had no adverse effects on the force-generating capacity of targ eted muscles. These findings have implications for eventual AdV-mediated ge ne therapy of generalized skeletal muscle diseases such as DMD using a syst emic intraarterial delivery approach.