Herpes simplex virus vector-mediated gene transfer of kynurenine aminotransferase improves detrusor overactivity in spinal cord-injured rats.

Detrusor overactivity threatens the renal function of patients with spinal cord injury. Suppressing N-methyl-D-aspartate receptors is known to improve detrusor overactivity in rats with spinal cord injury, whereas kynurenic acid, the endogenous antagonist of N-methyl-D-aspartate receptors, is irreversibly synthesized by kynurenine aminotransferases (KATs). In this study, we investigated whether replication-defective herpes simplex virus vector-mediated gene transfer of human KAT II could treat detrusor overactivity by injecting the vectors into the rat bladder wall 1 week after spinal cord injury. Three weeks after injection, we evaluated the cystometry and gene expression of KAT II in L6-S1 dorsal root ganglia. The results showed that the vectors are transported to L6-S1 dorsal root ganglia and upregulate the expression of KAT II, and that they also improve the detrusor overactivity and voiding efficiency. We also proved that N-methyl-D-aspartate receptors were blocked by kynurenic acid in the extracellular solution or the vector-mediated gene transfer of KAT II in cultured rat neurons of L6-S1 dorsal root ganglia by whole-cell patch clamp to explore the mechanisms of gene therapy. Therefore, replication-defective herpes simplex virus vector-mediated KAT II inhibits detrusor overactivity in spinal cord-injured rats, possibly by suppressing N-methyl-D-aspartate receptors in bladder afferent pathways.