Enhanced Delivery and Effects of Acid Sphingomyelinase by ICAM-1-Targeted Nanocarriers in Type B Niemann-Pick Disease Mice

Abstract

Acid sphingomyelinase deficiency in type B Niemann-Pick disease leads to lysosomal sphingomyelin storage, principally affecting lungs, liver, and spleen. Infused recombinant enzyme is beneficial, yet its delivery to the lungs is limited and requires higher dosing than liver and spleen, leading to potentially adverse reactions. Previous studies showed increased enzyme pulmonary uptake by nanocarriers targeted to ICAM-1, a protein overexpressed during inflammation. Here, using polystyrene and poly(lactic-co-glycolic acid) nanocarriers, we optimized lung delivery by varying enzyme dose and nanocarrier concentration, verified endocytosis and lysosomal trafficking in vivo, and evaluated delivered activity and effects. Raising the enzyme load of nanocarriers progressively increased absolute enzyme delivery to all lung, liver, and spleen, over the naked enzyme. Varying nanocarrier concentration inversely impacted lung versus liver and spleen uptake. Mouse intravital and postmortem examination verified endocytosis, transcytosis, and lysosomal trafficking using nanocarriers. Compared to naked enzyme, nanocarriers increased enzyme activity in organs and reduced lung sphingomyelin storage and macrophage infiltration. Although old mice with advanced disease showed reactivity (pulmonary leukocyte infiltration) to injections, including buffer without carriers, antibody, or enzyme, younger mice with mild disease did not. We conclude that anti-ICAM nanocarriers may result in effective lung enzyme therapy using low enzyme doses.

Co-coating of receptor-targeted drug nanocarriers with anti-phagocytic moieties enhances specific tissue uptake versus non-specific phagocytic clearance

“…Therefore, these data suggest that both targeting and clearance contribute to the fast removal of anti-ICAM NCs from the circulation, with the lungs representing a prime site for specific targeting. In accord to previous reports 44,47,58 and cellular data showing endothelial uptake of anti-ICAM NCs, TEM analysis showed seemingly intact capillary vessels and alveolar spaces in the lungs of mice injected with anti-ICAM NCs, with the majority of visible NCs residing within the vesicular compartment in endothelial cells (Supplementary Figure S11). …”

“…rapidly accumulate in the lungs, since this organ abundantly expresses ICAM-1 and it contains a significant fraction of body vascular endothelium. 40,44,45 This was verified here for the formulations used in this study (Figure 7). For instance, using polystyrene models we observed that, although their circulating levels were similarly low 30 min after injection (~5% of the injected dose (ID); Figure 7A), anti-ICAM NCs disappeared from the bloodstream more rapidly than control IgG NCs (9 %ID and 40 %ID, respectively, 2 min after injection).…”

“…35 We and others have reported the use of ICAM-1 targeting in drug delivery, including protein conjugates, polymer nanoparticles, dendrimers, liposomes, etc., for various therapeutic and diagnostic applications. 40,45–50 Our previous studies have characterized anti-ICAM NCs in cell culture and in mice, 38,40,44,51 providing controls for this study.…”

“…Our previous studies have shown that anti-ICAM PLGA NCs behave similarly as polystyrene models in terms of specific binding, endocytosis and intracellular effects of therapeutic cargo in cell cultures, as well circulation, biodistribution and cargo delivery in mice. 44,47,51 As shown in Table 1, coating antibodies and CD47 on PLGA NCs increased their average size, PDI and ζ-potential, resulting in formulations with parameters comparable to polystyrene models: e.g., anti-ICAM/CD47 PLGA vs. polystyrene NCs were 197 vs. 193 nm in diameter, had 0.2 vs. 0.09 polydispersity index, and displayed 138 vs. 118 anti-ICAM antibody molecules and 158 vs. 170 CD47 molecules per NC. Control formulations coated with either ICAM-1 or IgG alone, or control co-coating with IgG and CD47, were all similar for both polystyrene and PLGA counterparts (Table 1).…”

“…For this, mice were perfused under anesthesia with PBS first and then fixative, followed by collection of the lungs and processing for transmission electron microscopy, as reported. 44 …”