Abstract
Purpose :
Retinal vascular inflammation is a common characteristic of diabetes. It is marked by upregulation of retinal endothelial ICAM-1 that promotes leukocyte adhesion to retinal vessels. The adherent leukocytes are strongly implicated in the development of vascular lesions associated with early diabetic retinopathy (DR). Past studies have shown that blocking ICAM-1-dependent leukocyte adhesion prevents vascular defects associated with early DR. Yet, systemic administration of anti-ICAM1 agents often cause adverse off-target effects. To address this major limitation, we here report the development and in vitro assessment of red blood cell-derived biomimetic nanoparticles (NPs) for selective delivery of anti-inflammatory salicylate to ICAM-1-expressing retinal endothelial cells (ECs) and inhibition of leukocyte-endothelial adhesion.
Methods :
The biomimetic NPs were derived from bovine red blood cell membranes, surface modified with an ICAM-1-targeting single chain variable fragment (scFv), and loaded with sodium salicylate. Size distribution of NPs was measured using dynamic light scattering while the efficiency of scFv conjugation was determined by fluorometric quantification of anti-scFv-labeled NPs. Salicylate incorporation within NPs was quantified analytically and the anti-inflammatory effect of free- and NP-incorporated sodium salicylate was determined by adding them to TNF-treated human retinal ECs (HRECs) and assessing subsequent leukocyte-HREC adhesion.
Results :
Detailed physicochemical characterization of the NPs revealed that they are ~160±35 nm in diameter, successfully conjugate anti-ICAM-1 scFv on their surface, and exhibit ~45% incorporation of sodium salicylate. Importantly, in vitro studies show that salicylate-loaded scFv-conjugated NPs undergo preferential (~2-fold greater; p<0.01) uptake in ICAM-1-expressing HRECs when compared with non-modified NPs. Further, and perhaps crucially, these ICAM-1-targeting NPs exhibit a remarkable 700-fold greater efficacy (p<0.0001) of sodium salicylate in blocking leukocyte-HREC adhesion that their non-modified counterparts.
Conclusions :
These promising in vitro findings lay the foundation for more detailed assessment of this ICAM-targeting anti-inflammatory nanotherapeutic as a more effective treatment strategy for inflammation-dependent vascular lesions of early DR.
This is a 2020 ARVO Annual Meeting abstract.