Journal
ACS NANO
Volume 13, Issue 2, Pages 1136-1152Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acsnano.8b05482
Keywords
endosomal escape; high-throughput screening; siRNA delivery; pH-responsive drug carriers
Categories
Funding
- United States National Institutes of Health [R01HL122347, R01EB019409, R01CA224241]
- Department of Defense [CDMRP W81XWH-14-1-0298]
- National Science Foundation Graduate Research Fellowship [0909667, 1445197]
- Vanderbilt SyBBURE Searle Undergraduate Research Program
- Vanderbilt Ingram Cancer Center [P30 CA68485]
- Vanderbilt Digestive Disease Research Center [DK058404]
- NIH [CA68485, DK20593, DK58404, DK59637, EY08126]
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Endolysosome entrapment is one of the key barriers to the therapeutic use of biologic drugs that act intracellularly. The screening of prospective nanoscale endosome-disrupting delivery technologies is currently limited by methods that are indirect and cumbersome. Here, we statistically validate Galectin 8 (Ga18) intracellular tracking as a superior approach that is direct, quantitative, and predictive of therapeutic cargo intracellular bioactivity through in vitro high-throughput screening and in vivo validation. Gal8 is a cytosolically dispersed protein that, when endosomes are disrupted, redistributes by binding to glycosylation moieties selectively located on the inner face of endosomal membranes. The quantitative redistribution of a Gal8 fluorescent fusion protein from the cytosol into endosomes is demonstrated as a real-time, live cell assessment of endosomal integrity that does not require labeling or modification of either the carrier or the biologic drug and that allows quantitative distinction between closely related, endosome-disruptive drug carriers. Through screening two families of siRNA polymeric carrier compositions at varying dosages, we show that Gal8 endosomal recruitment correlates strongly (r = 0.95 and p < 10(-4)) with intracellular siRNA bioactivity. Through this screen, we gathered insights into how composition and molecular weight affect endosome disruption activity of poly[(ethylene glycol)-b-[(2-(dimethylamino)ethyl methacrylate)-co-(butyl methacrylate)]] [PEG-(DMAEMA-co-BMA)] siRNA delivery systems. Additional studies showed that Gal8 recruitment predicts intracellular bioactivity better than current standard methods such as Lysotracker colocalization (r = 0.35, not significant), pH-dependent hemolysis (not significant), or cellular uptake (r = 0.73 and p < 10(-3)). Importantly, the Gal8 recruitment method is also amenable to fully objective high throughput screening using automated image acquisition and quantitative image analysis, with a robust estimated Z' of 0.6 (whereas assays with Z' > 0 have high-throughput screening utility). Finally, we also provide measurements of in vivo endosomal disruption based on Gal8 visualization (p < 0.03) of a nanocarrier formulation confirmed to produce significant cytosolic delivery and bioactivity of siRNA within tumors (p < 0.02). In sum, this report establishes the utility of Gal8 subcellular tracking for the rapid optimization and high-throughput screening of the endosome disruption potency of intracellular delivery technologies.
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