Gene therapy: how to target the kidney. Promises and pitfalls.

The success of gene therapy strongly depends on an efficient delivery system to allow local transfer and expression of the therapeutic gene in the target organ or tissue. Vector systems have been improved and many show promise. There are two different categories of delivery vehicles: non-viral and viral vectors, both with advantages and disadvantages that must be taken into consideration in view of the final aim. Compared to other solid organs, the kidney offers the main advantage of access by different routes that dictate different sites of transfection. Thus, the choice of the delivery vehicle and administration route has to take account which cells are to be specifically targeted by the gene transfer approach. This concept will be discussed in the first part of the review. Using a gene therapy approach, improvements of renal function and interstitial inflammation have been achieved in experimental models of glomerulonephritis and tubulo-interstitial damage. Gene therapy applied to renal transplantation has shown promising results in rodents, almost controlling acute rejection. Finally, the development of animal models resembling the clinical features of human genetic renal disorders offers a first step towards new treatments among which gene therapy could become reality in the near future. The main findings concerning the suitability of gene therapy for slowing the progression of kidney diseases, and preventing acute renal graft rejection, or treating genetic disorders, are discussed.