Imaging gene delivery in a mouse model of congenital neuronal ceroid lipofuscinosis.

Adeno-associated virus (AAV)-mediated gene replacement for lysosomal disorders have been spurred by the ability of some serotypes to efficiently transduce neurons in the brain and by the ability of lysosomal enzymes to cross-correct among cells. Here, we explored enzyme replacement therapy in a knock-out mouse model of congenital neuronal ceroid lipofuscinosis (NCL), the most severe of the NCLs in humans. The missing protease in this disorder, cathepsin D (CathD) has high levels in the central nervous system. This enzyme has the potential advantage for assessing experimental therapy in that it can be imaged using a near-infrared fluorescence (NIRF) probe activated by CathD. Injections of an AAV2/rh8 vector-encoding mouse CathD (mCathD) into both cerebral ventricles and peritoneum of newborn knock-out mice resulted in a significant increase in lifespan. Successful delivery of active CathD by the AAV2/rh8-mCathD vector was verified by NIRF imaging of mouse embryonic fibroblasts from knock-out mice in culture, as well as by ex vivo NIRF imaging of the brain and liver after gene transfer. These studies support the potential effectiveness and imaging evaluation of enzyme replacement therapy to the brain and other organs in CathD null mice via AAV-mediated gene delivery in neonatal animals.

Suicidal gene therapy in an NF-κB-controlled tumor environment as monitored by a secreted blood reporter.

The nuclear factor-κB (NF-κB) is known to be activated in many cancer types including lung, ovarian, astrocytomas, melanoma, prostate as well as glioblastoma, and has been shown to correlate with disease progression. We have cloned a novel NF-κB-based reporter system (five tandem repeats of NF-κB responsive genomic element (NF; 14 bp each)) to drive the expression cassette for both a fusion between the yeast cytosine deaminase and uracil phosphoribosyltransferase (CU) as a therapeutic gene and the secreted Gaussia luciferase (Gluc) as a blood reporter, separated by an internal ribosomal entry site (NF-CU-IGluc). We showed that malignant tumor cells have high expression of Gluc, which correlates to high activation of NF-κB. When NF-κB was further activated by tumor necrosis factor-α in these cells, we observed up to 10-fold increase in Gluc levels and therefore transgene expression in human glioma cells served to greatly enhance the sensitization of these cells to the prodrug, 5-fluorocytosine both in cultured cells and in vivo subcutaneous tumor xenograft model. This inducible system provides a tool to enhance the expression of imaging and therapeutic genes for cancer therapy.