Adeno-Associated Virus Gene Transfer Ameliorates Progression of Skeletal Lesions in Mucopolysaccharidosis IVA Mice

Mucopolysaccharidosis type IVA (MPS IVA) is an autosomal congenital metabolic lysosomal disease caused by a deficiency of the <i>N</i>-acetyl-galactosamine-6-sulfate sulfatase (GALNS) gene, leading to severe skeletal dysplasia. The available therapeutics for patients with MPS IVA, enzyme replacement therapy and hematopoietic stem cell transplantation, revealed limitations in the impact of skeletal lesions. Our previous study, a significant leap forward in MPS IVA research, showed that liver-targeted adeno-associated virus (AAV) gene transfer of human GALNS (hGALNS) restored GALNS enzymatic activity in blood and multiple tissues and partially improved the aberrant accumulation of storage materials. This promising approach was further validated in our current study, where we delivered AAV8 vectors expressing hGALNS, under the control of a liver-specific or ubiquitous promoter, into MPS IVA murine disease models. The results were highly encouraging, with both AAV8 vectors leading to supraphysiological enzymatic activity in plasma and improved cytoplasmic vacuolization of chondrocytes in bone lesions of MPS IVA mice. Notably, the ubiquitous promoter constructs, a potential game-changer, resulted in significantly greater enzyme activity levels in bone and improved pathological findings of cartilage lesions in these mice than in a liver-specific one during the 12-week monitoring period, reinforcing the positive outcomes of our research in MPS IVA treatment.