Development of immunoliposomes with E-Selectin affinity to target endothelial inflammation: direct comparison of antibody types.

Abstract

Inflamed endothelium targeting via E-Selectin is a promising strategy for drug delivery across the neurovascular interface, however, exploitation of the strategy by immunoliposomes remains limited. Furthermore, the high cost of antibodies poses a practical barrier for iterative formulation optimization. In this study, we developed two E-Selectin-targeted immunoliposome types incorporating either a commercially available monoclonal antibody (mAb) or a mAb produced in-house from a proprietary hybridoma line. Pre-formed liposomes were functionalized through maleimide-PEG conjugation and characterized for size distribution (by DLS), zeta potential (electrophoretic mobility), and Mab attachment (%). Immunoliposome targeting efficacy was assessed on brain microvascular endothelial cells under basal conditions and also after LPS-induced inflammation (to mimic pathological E-Selectin upregulation), by flow cytometry. Both immunoliposome formulations had similar characteristics and demonstrated significantly enhanced binding to endothelial cells relative to non-targeted liposomes, under both conditions studied. Furthermore, uptake by inflamed cells was always significantly higher than by non-inflamed cells. No differences in (in vitro) targeting magnitude between the commercial and hybridoma-derived Mab's were quantified, proving their comparable performance despite substantial differences in mAb cost. The current findings highlight the feasibility of substituting commercial mAbs with hybridoma-derived ones during preclinical development of targeted nanocarriers, as a strategy to reduce expenses while preserving their specificity and functional performance. Furthermore, it is demonstrated that E-Selectin targeted immunoliposomes are promising drug delivery systems for treatment of inflamed vasculature, justifying further in vitro and in vivo exploitation.