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Intracisternal enzyme replacement therapy in lysosomal storage diseases: dispersal pathways, regional enzyme concentrations and the effect of posttreatment posture

Authors


  • R.D. Jolly was project leader who conceived and managed the research and was principally responsible for writing. N.R. Marshall was responsible for management and clinical procedures involving the experimental dogs. A. Hartman was the radiologist who managed and interpreted the CT scans. K.M. Hemsley and L.K. Winner were responsible for the assays of SGSH enzyme. J. Marshall performed the statistical analyses.

Correspondence: Robert D. Jolly, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, 4442, New Zealand. Tel: +64 6 356 9099 ext 7891; Fax: +64 6 350 5714; E-mail: R.D.Jolly@massey.ac.nz

Abstract

Aims

To investigate routes of dispersal of enzyme, its regional uptake and the effect of posture when replacement enzyme is administered directly into the cerebrospinal fluid (CSF).

Methods

Dispersal pathways of particles and solutes were investigated using intracisternal injections of india ink with visual assessment, and a contrast medium (Iohexol) with computer tomography (CT). Replacement enzyme was measured at 46 loci within the central nervous system (CNS) in four groups of dogs subjected to different post-injection postural changes.

Results

India ink and CT studies showed dispersal pathways for CSF to be mainly via cisterns and sulci. Replacement enzyme reached all areas of the CNS tested, although mean concentrations varied 49-fold over different areas of the brain. Posttreatment posture had only modest effects on enzyme uptake in limited anatomical sites.

Conclusions

Dispersal of solutes after injection is rapid and initially enhanced by the injection process. Preferential pathways for CSF flow in the subarachnoid spaces of the brain involve cisterns and sulci. The splenial and suprasplenial sulci in particular appear important conduits for dispersal to more dorsal and rostral areas of the brain. Expansion and contraction of these sulci during brain pulsation is considered important to the forward flow of solutes in CSF through these compartments. Following intracisternal enzyme replacement therapy, enzyme reached all areas of the brain, but there was considerable disparity of enzyme uptake with some areas recording much higher levels than others. Posttreatment posture made only modest differences to enzyme uptake.

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