A Mutation-Agnostic Hematopoietic Stem Cell Gene Therapy for Metachromatic Leukodystrophy

Area of Science:

• Genetics
• Neuroscience
• Biotechnology

Background:

• Metachromatic leukodystrophy (MLD) is a rare genetic disorder caused by Arylsulfatase-A (ARSA) deficiency, leading to progressive neurodegeneration.
• Current treatment options for MLD are limited, highlighting the need for innovative therapeutic strategies.
• ARSA enzyme is crucial for sulfatide metabolism in the central nervous system.

Purpose of the Study:

• To develop and evaluate a mutation-agnostic gene therapy for MLD using CRISPR-Cas9.
• To assess the efficacy of gene editing in restoring ARSA enzyme activity in patient-derived hematopoietic stem and progenitor cells (HSPCs).
• To demonstrate the potential for clinical translation of this gene therapy approach.

Main Methods:

• Utilized CRISPR-Cas9 gene editing with an AAV6 repair template for mutation-agnostic gene therapy.
• Targeted the ARSA locus in human bone marrow-derived HSPCs.
• Quantified gene insertion/deletion efficiency, gene integration rates, and off-target editing.
• Assessed ARSA enzyme activity restoration in patient-derived HSPCs.

Main Results:

• Achieved high efficiency of insertions and deletions (>87%) and gene integration (>47%) at the ARSA locus.
• Demonstrated no detectable off-target editing in treated HSPCs.
• Restored ARSA enzyme activity by over 30-fold in HSPCs from MLD patients, reaching levels comparable to healthy adults.
• Validated the therapy in HSPCs from patients with distinct ARSA mutations.

Conclusions:

• The developed mutation-agnostic gene therapy is effective in restoring ARSA enzyme activity in MLD patient-derived HSPCs.
• The approach shows high efficiency and specificity, with significant potential for clinical application in MLD treatment.
• This study provides a strong proof of concept for a novel therapeutic strategy for MLD patients.