Mucopolysaccharidosis type I (MPS I) is a lysosomal disease caused by α-L-iduronidase (IDUA) deficiency and accumulation of glycosaminoglycans (GAG). Lentiviral vector encoding correct IDUA cDNA could be used for treating MPS I. To optimize the lentiviral vector design, 9 constructs were designed by combinations of various promoters, enhancers, and codon optimization. After in vitro transfection into 293FT cells, 5 constructs achieved the highest IDUA activities (5613 to 7358 nmol/h/mg protein). These 5 candidate vectors were then tested by injection (1 × 107 TU/g) into neonatal MPS I mice. After 30 days, one vector, CCEoIDW, achieved the highest IDUA levels: 2.6% of wildtype levels in the brain, 9.9% in the heart, 200% in the liver and 257% in the spleen. CCEoIDW achieved the most significant GAG reduction: down 49% in the brain, 98% in the heart, 100% in the liver and 95% in the spleen. Further, CCEoIDW had the lowest transgene frequency, especially in the gonads (0.03 ± 0.01 copies/100 cells), reducing the risk of insertional mutagenesis and germ-line transmission. Therefore, CCEoIDW is selected as the optimal lentiviral vector for treating MPS I disease and will be applied in large animal preclinical studies. Further, taken both in vitro and in vivo comparisons together, codon optimization, use of EF-1α promoter and woodchuck hepatitis virus posttranscriptional response element (WPRE) could enhance transgene expression. These results provided a better understanding of factors contributing efficient transgene expression in lentiviral gene therapies.
Bibliographical noteFunding Information:
Paul Score, Ph.D. constructed the lentiviral plasmids used in this study. The authors would like to thank Brenda Diethelm-Okita (University of Minnesota) for managing IACUC protocols, Bryan Hall (University of Minnesota) for advising on QPCR experiments, the University of Iowa Vector Core for vector production and in vitro transfection, and Aldevron (Fargo, ND) for sequencing and plasmid manufacturing services. This work was supported by NIH grant “Gene Therapy for Metabolic Diseases” 5P01HD032652 . The authors have no conflicts of interest to declare. Dr. Ou is a fellow of the Lysosomal Disease Network.
- Gene therapy
- Hurler syndrome
- Lysosomal disease