标题：Impact of chemical modification of sulfamidase on distribution to brain interstitial fluid and to CSF after an intravenous administration in awake, freely-moving rats
摘要：Mucopolysaccharidosis III A (MPS IIIA) is an autosomal recessive lysosomal storage disorder caused by deficiency of the enzyme sulfamidase. The disorder results in accumulation of heparan sulfate, lysosomal enlargement and cellular and organ dysfunction. Patients exhibit progressive neurodegeneration and behavioral problems and no treatment is currently available. Enzyme replacement therapy is explored as potential treatment strategy for MPS IIIA patients and to modify the disease, sulfamidase must reach the brain. The glycans of recombinant human sulfamidase (rhSulfamidase) can be chemically modified to generate CM-rhSulfamidase. The chemical modification reduced the affinity to the cation-independent mannose-6-phosphate receptor with the aim a prolonged higher concentration in circulation and thus at the blood brain barrier. The pharmacokinetic properties in serum and the distribution to brain and to cerebrospinal fluid (CSF) of chemically modified recombinant human sulfamidase (CM-rhSulfamidase) were studied and compared to those of rhSulfamidase, after a single intravenous (i.v.) 30 mg/kg dose in awake, freely-moving male Sprague Dawley rats. Distribution to brain was studied by microdialysis of the interstitial fluid in prefrontal cortex and by repeated intra-individual CSF sampling from the cisterna magna. Push-pull microdialysis facilitated sampling of brain interstitial fluid to determine large molecule concentrations in awake, freely-moving male Sprague Dawley rats. Together with repeated serum and CSF sampling, push-pull microdialysis facilitated determination of CM-rhSulfamidase and rhSulfamidase kinetics after i.v. administration by non-compartments analysis and by a population modelling approach. Chemical modification increased the area under the concentration versus time in serum, CSF and brain interstitial fluid at least 7-fold. The results and the outcome of a population modelling approach of the concentration versus time data indicated that both compounds pass the BBB with an equilibrium established fairly rapid after administration. We suggest that prolonged high serum concentrations facilitated high brain interstitial fluid concentrations, which could be favorable to reach various target cells in the brain.
关键词：Mucopolysaccharidosis IIIA ; Sulfamidase ; Enzyme replacement therapy ; Microdialysis ; Pharmacokinetics ; CNS distribution ; aCSF artificial cerebrospinal fluid ; AUC∞ area under the concentration-time curve from t = 0 to infinity ; AUClast area under the concentration-time curve from t = 0 to the last observed concentration ; IF interstitial fluid ; CL clearance ; Cmax maximum concentration ; CM-rhSulfamidase chemically modified recombinant human sulfamidase ; CNS central nervous system ; CSF cerebrospinal fluid ; h.a.d;hours after dose ; HS heparan sulfate ; ID identifier ; i.v;intravenous ; LLOQ lower limit of quantification ; M6PR mannose-6-phosphate receptor ; MPS IIIA mucopolysaccharidosis type III A ; MSD-ECL meso scale discovery electrochemiluminescence ; PBS phosphate buffered saline ; PK pharmacokinetics ; rhSulfamidase recombinant human sulfamidase ; SD standard deviation ; SGSH N-sulfoglucosamine sulfohydrolase ; t½ terminal half-life ; V volume of distribution
