King's College London

Research portal

An Improved Adeno-Associated Virus Vector for Neurological Correction of the Mouse Model of Mucopolysaccharidosis IIIA

Research output: Contribution to journalArticle

Anna L. Gray, Claire O'Leary, Aiyin Liao, Leticia Agúndez, Amir S. Youshani, Hélène F. Gleitz, Helen Parker, Jessica T. Taylor, Olivier Danos, Michaël Hocquemiller, Nuria Palomar, R. Michael Linden, Els Henckaerts, Rebecca J. Holley, Brian W. Bigger

Original languageEnglish
Pages (from-to)1052-1066
Number of pages15
JournalHuman Gene Therapy
Volume30
Issue number9
DOIs
Published1 Sep 2019

King's Authors

Abstract

Patients with the lysosomal storage disease mucopolysaccharidosis IIIA (MPSIIIA) lack the lysosomal enzyme N-sulfoglucosamine sulfohydrolase (SGSH), one of the many enzymes involved in degradation of heparan sulfate. Build-up of un-degraded heparan sulfate results in severe progressive neurodegeneration for which there is currently no treatment. Experimental gene therapies based on gene addition are currently being explored. Following preclinical evaluation in MPSIIIA mice, an adeno-associated virus vector of serotype rh10 designed to deliver SGSH and sulfatase modifying factor 1 (SAF301) was trialed in four MPSIIIA patients, showing good tolerance and absence of adverse events with some improvements in neurocognitive measures. This study aimed to improve SAF301 further by removing sulfatase modifying factor 1 (SUMF1) and assessing if expression of this gene is needed to increase the SGSH enzyme activity (SAF301b). Second, the murine phosphoglycerate kinase (PGK) promotor was exchanged with a chicken beta actin/CMV composite (CAG) promotor (SAF302) to see if SGSH expression levels could be boosted further. The three different vectors were administered to MPSIIIA mice via intracranial injection, and SGSH expression levels were compared 4 weeks post treatment. Removal of SUMF1 resulted in marginal reductions in enzyme activity. However, promotor exchange significantly increased the amount of SGSH expressed in the brain, leading to superior therapeutic correction with SAF302. Biodistribution of SAF302 was further assessed using green fluorescent protein (GFP), indicating that vector spread was limited to the area around the injection tract. Further modification of the injection strategy to a single depth with higher injection volume increased vector distribution, leading to more widespread GFP distribution and sustained expression, suggesting this approach should be adopted in future trials.

View graph of relations

© 2020 King's College London | Strand | London WC2R 2LS | England | United Kingdom | Tel +44 (0)20 7836 5454