Mannose-6-Phosphate Functionalized Liposomal Nanocarrier for Lysosome-specific Delivery of β-Glucuronidase in Drosophila Model of MPS VII

Abstract

Lysosomal dysfunction leads to critical lysosomal storage disorder (LSD) conditions, and among all, Mucopolysaccharidosis VII (MPS VII), or Sly syndrome, is a rare LSD caused by the deficiency of the β-glucuronidase (β-GUS) enzyme, leading to the accumulation of glycosaminoglycans (GAGs) in tissues and organs. Since enzyme replacement therapy (ERT) lacks target-specific delivery of recombinant enzymes, targeted enzyme delivery approaches are desired to enhance the success of existing ERT methods. The effective targeted delivery of functional enzymes to lysosomes remains a significant therapeutic challenge. In this study, we report the design and development of a mannose-6-phosphate (M6P) functionalized liposomal nanocarrier for targeted lysosomal delivery of β-GUS. The liposomal nanocarriers were formulated with surface-decorated M6P ligand functionality to exploit the previously established M6P receptor-mediated endocytosis pathway, ensuring high specificity and enhanced intracellular trafficking to lysosomes. Comprehensive physicochemical characterization confirmed the stability, size uniformity, and successful surface functionalization of the liposomes. Internalization studies using HEK293 cells and hemocytes derived from the Drosophila model of MPS VII demonstrated significantly improved cellular internalization and colocalization with lysosomes. The time- and dose-dependent restoration of β-GUS activity was also studied. Furthermore, the nanocarrier exhibited minimal cytotoxicity, indicating its potential for safe and effective ERT. This targeted liposomal system represents a promising platform for lysosome-specific delivery of therapeutic enzymes and could be broadly applied to other lysosomal storage disorders.