Enhancing Biodistribution of Therapeutic Enzymes In Vivo by Modulating Surface Coating and Concentration of ICAM-1-Targeted Nanocarriers

Abstract

Coupling therapeutic proteins to targeted nanocarriers can enhance their biodistribution. This is the case for enzyme replacement therapies where intravenously injected enzymes must avoid prolonged blood exposure while reaching body organs. We have shown enhanced tissue targeting of various lysosomal enzymes by coupling to nanocarriers targeted to intercellular adhesion molecule-1 (ICAM-1). Here, we varied design parameters to modify tissue enzyme levels without affecting specific targeting and relative biodistribution. We coupled α-galactosidase (αGal; affected in Fabry disease) to model polymer nanocarriers and varied enzyme load (50 vs. 500 molecules/particle), anti-ICAM surface density (80 vs. 180 molecules/particle), and nanocarrier concentration (1.6×1013 vs. 2.4×1013 carriers/kg) to render three formulations (45, 449, 555 μg αGal/kg). Naked αGal preferentially distributed in blood vs. organs, while nanocarriers shifted biodistribution from blood to tissues. Accumulation in brain, kidneys, heart, liver, lungs, and spleen did not vary among nanocarrier formulations, with enhanced specific tissue accumulation compared to naked αGal. The highest specificity was associated with lowest antibody density and nanocarrier concentration, but highest enzyme load; possibly because of synergistic enzyme affinity toward cell-surface markers. Variation of these parameters significantly increased absolute enzyme accumulation. This strategy may help optimize delivery of lysosomal enzyme replacement and, likely, other protein delivery approaches.

ICAM-1 targeting, intracellular trafficking, and functional activity of polymer nanocarriers coated with a fibrinogen-derived peptide for lysosomal enzyme replacement

“…As per an enzyme cargo, we selected ASM (the enzyme deficient in types A-B NPD) since our previous studies on anti-ICAM/ASM NCs [9,24] provide a good historical control for new peptide-targeted NCs to be examined here. Surface-loading of lysosomal enzymes on NCs is a reasonable strategy because: (a) these enzymes are not intrinsically toxic as classical drugs are, but otherwise endogenous to the body and required ubiquitously in most tissues [1], (b) they are only active at acidic lysosomal pH and can be considered pro-drugs until the lysosome is reached [2], (c) presence of the NC surface provides fast intralysosomal activity without minute control of release required for encapsulated counterparts [8], and (d) this design has shown promising targeting, uptake, lysosomal trafficking, and enzyme activity with storage reduction in our previous works [7-9,13,24,25]. With regard to surface adsorption as a coating strategy, this results in random distribution of cargo and targeting moieties on the NC surface, which is no different from most strategies of covalent linkage where the exact position of the protein (antibody, peptide, enzyme) residue that is modified in each one protein molecule are not controlled.…”

“…Previous studies using polymer NCs coated with anti-ICAM antibody molecules have illustrated great promise of this strategy to improve the delivery of recombinant enzymes used for enzyme replacement therapy of LDs [7-9,24,25]. Nevertheless, further evaluation of the translational potential of this strategy will require optimization of these formulations to maximize their biocompatibility.…”

“…Our previous studies on lysosomal ERT applications have shown significant potential of ICAM-1-targeted polymer NCs, as illustrated in the examples of acid sphingomyelinase (ASM) used for type B Niemann-Pick disease (NPD) [9,24], α-galactosidase used for Fabry disease [8,25], and α-glucosidase used for Pompe disease [7]. ICAM-1-targeted polymer NCs (both non-degradable polystyrene models and clinically-relevant poly(lactic-co-glycolic acid) (PLGA) NCs) were shown to markedly improve targeting and biodistribution of lysosomal enzymes in mice, and enhance their endocytosis and lysosomal trafficking in cells, with attenuation of storage in both models [7-9,26].…”

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

“…These formulations have been shown to be stable, including lack of aggregation, adsorption of serum albumin, or protein detachment. 38,40,41 …”

Lysosomal enzyme replacement therapies: Historical development, clinical outcomes, and future perspectives

“…Also related to this role in transcellular (as opposed to paracellular) extravasation of leukocytes is the ability of ICAM-1 to mediate transcytosis across cellular linings, which has been shown for both endothelial and epithelial cells [444, 445]. In cellular models of these barriers, ICAM-1-targeted nanoparticles bearing enzymes (shown for alpha-galactosidase) and also direct antibody-enzyme conjugates (shown for model horseradish peroxidase) have been observed to transcytose from the apical to the basolateral surface of “barrier” cells [442, 444].…”