Characterization and pharmacokinetic study of recombinant human N-acetylgalactosamine-6-sulfate sulfatase

Mucopolysaccharidosis IVA (NIPS IVA) is an autosomal recessive disorder caused by a deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS). The aims of this study were to establish Chinese hamster ovary (CHO) cells overexpressing recombinant human GALNS (rhGALNS) and to assess pharmacokinetics and tissue distribution of purified enzymes by using NIPS IVA knockout mouse (Galas(-/-)). The CHO-cell derived rhGALNS was purified from the media by a two-step affinity chromatography procedure. The rhGALNS was administered intravenously to 3-month-old Galas(-/-) mice at a single dose of 250 U/g of body weight. The treated mice were examined by assaying the GALNS activity at baseline and up to 240 min to assess clearance of the enzyme from blood circulation. The mice were sacrificed 4 h after infusion of the enzyme to study the enzyme distribution in tissues. The rhGALNS was purified 1317-fold with 71% yield. The enzyme was taken up by Galas(-/-) chondrocytes (150 U/mg/15 h). The uptake was inhibited by mannose-6-phosphate. The enzyme activity disappeared from circulation with a half-life of 2.9 min. After enzyme infusion, the enzyme was taken up and detected in multiple tissues (40.7% of total infused enzymes in liver). Twenty-four hours after a single infusion of the fluorescence-labeled enzymes into NIPS IVA mice, biodistribution pattern showed the amount of tagged enzyme retained in bone, bone marrow, liver, spleen, kidney, and heart. In conclusion, we have shown that the phosphorylated rhGAI.NS is delivered to multiple tissues, including bone, and that it functions bioactively in Gains(-/-) chondrocytes implying a potential enzyme replacement treatment. (C) 2007 Elsevier Inc. All rights reserved.