Microsphere-adenoviral complexes target and transduce the glomerulus in vivo

Background. Developing new treatments for glomerulonephritis makes the glomerulus a logical target for gene therapy. Microspheres may lodge in the glomerulus, and replication-deficient recombinant adenoviruses are potent mediators of gene transfer. We postulated that adenoviral-microsphere complexes could result in DNA transfer (transduction) into glomerular cells in vivo. Methods. Two adenoviruses, each one containing a luciferase or β-galactosidase (β-gal) transgene expression cassette, were complexed to polystyrene microspheres. To assess in vivo glomerular transduction with this tool, male Sprague-Dawley rats underwent aortic injections with adenovirus linked to 11 or 16 μm diameter microspheres. Results. After 48 hours, adenoviral-microsphere complexes resulted in transduction of up to 19% of glomeruli per kidney section. Endothelial and mesangial cells were transduced with this approach, and transprotein expression persisted for 21 days. Transduction efficiency was greater in the 16 μm group. For all rats, there was a strong correlation between kidney luciferase levels and the number of β-gal-positive glomeruli (r = 0.87), indicating that transgene expression was primarily glomerular in location. This was supported by reverse transcriptase in situ polymerase chain reaction, which demonstrated glomerular localization of the β-gal transgene. Conclusions. The aortic injection of adenoviral-microsphere complexes transduces the glomerulus in vivo and may be a useful tool in developing approaches to gene therapy of glomerular disease.