Skeletal response to lentiviral mediated gene therapy in a mouse model of MPS VII.

Mucopolysaccharidosis VII (MPS VII) is an autosomal recessive, lysosomal storage disorder caused by ß-glucuronidase (GUSB) deficiency, resulting in the accumulation of glycosaminoglycans (GAGs), in a variety of cell types. Severe, progressive skeletal pathology, termed dysostosis multiplex, is a prominent clinical feature of MPS VII. We have evaluated a gene therapy protocol for its efficacy in preventing the development and progression of bone pathology in MPS VII mice treated with a lentiviral vector at birth or at 7 weeks. Two weeks after injections, high levels of vector expression were observed in liver, spleen and bone marrow and to a lesser extent in kidney, lung and heart. Widespread clearance of GAG storage was observed in somatic tissues of both groups and some clearance of neuronal storage was observed in mice treated from birth. Micro-CT analysis demonstrated a significant decrease in vertebral and femoral bone mineral volume, trabecular number, bone surface density and cortical bone thickness in both treatment groups. Lumbar and femoral bone lengths were significantly decreased in untreated MPS VII mice, while growth plate heights were increased and these parameters did not change upon treatment. Small improvements in performance in the open field and rotarod behaviour tests were noted. Overall, systemic lentiviral-mediated gene therapy results in a measurable improvement in parameters of bone mass and architecture as well as biochemical and enzymatic correction. Conversely, growth plate chondrocytes were not responsive to treatment, as evidenced by the lack of improvement in vertebral and femoral bone length and growth plate height.

Lysophosphatidylcholine as an adjuvant for lentiviral vector mediated gene transfer to airway epithelium: effect of acyl chain length.

BACKGROUND: Poor gene transfer efficiency has been a major problem in developing an effective gene therapy for cystic fibrosis (CF) airway disease. Lysophosphatidylcholine (LPC), a natural airway surfactant, can enhance viral gene transfer in animal models. We examined the electrophysiological and physical effect of airway pre-treatment with variants of LPC on lentiviral (LV) vector gene transfer efficiency in murine nasal airways in vivo. METHODS: Gene transfer was assessed after 1 week following nasal instillations of a VSV-G pseudotype LV vector pre-treated with a low and high dose of LPC variants. The electrophysiological effects of a range of LPC variants were assessed by nasal transepithelial potential difference measurements (TPD) to determine tight junction permeability. Any physical changes to the epithelium from administration of the LPC variants were noted by histological methods in airway tissue harvested after 1 hour. RESULTS: Gene transduction was significantly greater compared to control (PBS) for our standard LPC (palmitoyl/stearoyl mixture) treatment and for the majority of the other LPC variants with longer acyl chain lengths. The LPC variant heptadecanoyl also produced significantly greater LV gene transfer compared to our standard LPC mixture. LV gene transfer and the transepithelial depolarization produced by the 0.1% LPC variants at 1 hour were strongly correlated (r2 = 0.94), but at the 1% concentration the correlation was less strong (r2 = 0.59). LPC variants that displayed minor to moderate levels of disruption to the airway epithelium were clearly associated with higher LV gene transfer. CONCLUSIONS: These findings show the LPC variants effect on airway barrier function and their correlation to the effectiveness of gene expression. The enhanced expression produced by a number of LPC variants should provide new options for preclinical development of efficient airway gene transfer techniques.