Modulation of Schlemm's canal endothelial cell stiffness via latrunculin loaded block copolymer micelles

Abstract

Increased stiffness of Schlemm's canal endothelial cells (SC cells) is a major contributing factor to the increased pressure characteristic of primary open-angle glaucoma. New treatments for glaucoma are being developed using actin depolymerizers and rho kinase inhibitors to address this increased stiffness. However, these agents have off-target effects and are not as potent as had been hoped. We have developed a micellar nanocarrier assembled from poly(ethylene glycol)-bl-poly(propylene sulfide) copolymers capable of encapsulating latrunculin A (Lat A) with the goal of modulating SC cell stiffness. Lat A-loaded nanocarriers were similar in size and morphology to unloaded poly (ethylene glycol)-bl-poly(propylene sulfide) (PEG-bl-PPS) micelles, loaded Lat A at 62% encapsulation efficiency, and retained loaded Lat A for at least 22 days. The continued functional activity of Lat A following encapsulation within micelles was verified in murine macrophages, which are known to display decreased endocytosis in response to Lat A-dependent cytoskeletal disruption. Endocytic inhibition remained unchanged when comparing equal concentrations of micelle-loaded versus free form Lat A. Uptake of Lat A-loaded micelles by human SC cells was verified in vitro with no sign of cytotoxicity, and modulation of SC cell stiffness was measured by atomic force microscopy. Lat A-loaded micelles significantly decreased SC cell stiffness, which resulted in visible changes in cell morphology as observed by confocal microscopy. Our results demonstrate that PEG-bl-PPS micelles represent a tunable platform for the controlled intracellular delivery of latrunculin. These self-assembled polymeric nanobiomaterials may support the rational design and engineering of delivery systems for the treatment of glaucoma. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1771-1779, 2018.

Co-administration of macropinocytosis inhibitory nanoparticles (MiNP) for enhanced nanoparticle circulation time and target tissue accumulation following subcutaneous injection

“…Confirmation of the micelle structure was obtained using cryogenic transmission electron microscopy and small angle X-ray scattering (SAXS) studies (Figure 2a Table S2. LatA quantification and loading within the micelles was determined by HPLC-UV as previously reported [24] and allowed for all formulations to be referenced based on their LatA content (Table S1). These data are consistent with our previous findings that encapsulation of LatA by PEG-b-PPS micelles does not alter their physical structure or polydispersity.…”

“…Furthermore, LatA is hydrophobic and thus not amenable to direct administration via SC or IV routes. We have previously shown that LatA retains its inhibitory effects by disrupting the cell cytoskeleton when encapsulated in PEG-b-PPS micelles but without toxicity [23,24] .…”

High Density Display of an Anti-Angiogenic Peptide on Micelle Surfaces Enhances Their Inhibition of αvβ3 Integrin-Mediated Neovascularization In Vitro

“…PEG-b-PPS block co-polymer was synthesized according to a previously established protocol [45]. Briefly, initiation of anionic ring-opening polymerization of PPS was facilitated by PEG thioacetate deprotected by sodium methoxide.…”

“…PEG-b-PPS self-assembles into a diverse range of nanocarrier morphologies that possess dense PEG coronas to inhibit nonspecific protein adsorption as well as hydrophobic PPS domains for retention of lipophilic payloads [41][42][43][44]. Recently, Stack et al employed PEG-b-PPS micelles for targeted intracellular delivery of latrunculin A as a treatment for glaucoma [45]. Furthermore, Yi et al demonstrated that lipidated peptides could be stably incorporated into PEG-b-PPS nanocarriers for in vivo applications and that the surface density of these peptides could be optimized using in vitro cell culture systems for enhanced binding to specific cell membrane receptors [46].…”

YAP and TAZ, the conductors that orchestrate eye development, homeostasis, and disease

“…Each of them has its own advantages and disadvantages, but to minimize potential side‐effects and increase the efficacy of the treatment is the primary principle for choosing appropriate delivery route. Taken Verteporfin and Lat‐B as examples, Verteporfin is widely used as a photosensitizer intravenously, therefore, intravenous injection would be the first choice for regulating YAP in eye unless further needs or concerns turn out; a cellar nanocarrier assembled from poly(ethylene glycol)‐bl‐poly(propylene sulfide) copolymers is capable of encapsulating and delivering latrunculin‐A (another isomer of Lat), which would be a rational design for releasing Lat‐B to modulate trabecular meshwork stiffness (Stack, Vahabikashi, Johnson, & Scott, ).…”