Enhanced endothelial delivery and biochemical effects of α-galactosidase by ICAM-1-targeted nanocarriers for Fabry disease.

Fabry disease, due to the deficiency of α-galactosidase A (α-Gal), causes lysosomal accumulation of globotriaosylceramide (Gb3) in multiple tissues and prominently in the vascular endothelium. Although enzyme replacement therapy (ERT) by injection of recombinant α-Gal improves the disease outcome, the effects on the vasculopathy associated with life-threatening cerebrovascular, cardiac and renal complications are still limited. We designed a strategy to enhance the delivery of α-Gal to organs and endothelial cells (ECs). We targeted α-Gal to intercellular adhesion molecule 1 (ICAM-1), a protein expressed on ECs throughout the vasculature, by loading this enzyme on nanocarriers coated with anti-ICAM (anti-ICAM/α-Gal NCs). In vitro radioisotope tracing showed efficient loading of α-Gal on anti-ICAM NCs, stability of this formulation under storage and in model physiological fluids, and enzyme release in response to lysosome environmental conditions. In mice, the delivery of (125)I-α-Gal was markedly enhanced by anti-ICAM/(125)I-α-Gal NCs in brain, kidney, heart, liver, lung, and spleen, and transmission electron microscopy showed anti-ICAM/α-Gal NCs attached to and internalized into the vascular endothelium. Fluorescence microscopy proved targeting, endocytosis and lysosomal transport of anti-ICAM/α-Gal NCs in macro- and micro-vascular ECs and a marked enhancement of Gb3 degradation. Therefore, this ICAM-1-targeting strategy may help improve the efficacy of therapeutic enzymes for Fabry disease.