Strategies of gene transfer to the kidney

Kidney targeted gene transfer has been a realistic goal for many researchers since 1991, but unfortunately, to date there is no reliable gene transfer technique for gene therapy of renal diseases. However, at the experimental level, several in vivo gene transfer methods have attempted to target certain renal structures, for example, the HVJ-liposome method and renal perfusion of adenovirus for glomerular cells, intravenous injection of oligonucleotides (ODNs) for proximal tubule, intra-arterial injection of adenovirus followed by cold incubation with a vasodilator for interstitial vasculature of the outer medulla, and adenoviral injection into the renal pelvis for the inner medullary collecting duct. As an ex vivo gene transfer method targeting the glomerulus, the transfusion of genetically-modified mesangial cells has been attempted. Implantation of genetically-modified tubular epithelial cells into the subcapsular region has been employed for ex vivo transfection to the interstitium. Gene therapy has focused particularly on the transplanted kidney, where an exogenous gene can transferred in advance. In the future, an inducible system and individual cell targeting strategy should be developed. The improvement of gene transfer techniques, especially vectors for delivering genes, is crucial. The potential application of gene transfer technologies is enormous while the therapeutic approaches have just begun to be explored. Therapeutic interventions of the process of progression of glomerulonephritis in the rat have been directed towards inhibiting the actions of growth factors. Obviously, molecular biological intervention is coming of age and there is a tremendous excitement over its potential. We believe that gene transfer techniques will become common tools for the dissection of molecular aspects of diseases and possibly for gene therapy in the field of nephrology.