Precise engineering of dapivirine-loaded nanoparticles for the development of anti-HIV vaginal microbicides

Polymeric nanoparticles (NPs) have the potential to provide effective and safe delivery of antiretroviral drugs in the context of prophylactic anti-HIV vaginal microbicides. Dapivirine-loaded poly(d,l-lactic-co-glycolic acid) (PLGA) NPs were produced by an emulsion-solvent evaporation method, optimized for colloidal properties using a 3-factor, 3-level Box-Behnken experimental design, and characterized for drug loading, production yield, morphology, thermal behavior, drug release, in vitro cellular uptake, cytotoxicity and pro-inflammatory potential. Also, drug permeability/membrane retention in well-established HEC-1-A and CaSki cell monolayer models as mediated by NPs was assessed in the absence or presence of mucin. Box-Behnken design allowed optimizing monodisperse 170nm drug-loaded NPs. Drug release experiments showed an initial burst effect up to 4h, followed by sustained 24h release at pH 4.2 and 7.4. NPs were readily taken up by different genital and macrophage cell lines as assessed by fluorescence microscopy. Drug-loaded NPs presented lower or at least similar cytotoxicity as compared to the free drug, with up to around one-log increase in half-maximal cytotoxic concentration values. In all cases, no relevant changes in cell pro-inflammatory cytokine/chemokine production were observed. Dapivirine transport across cell monolayers was significantly decreased when mucin was present at the donor side with either NPs or the free drug, thus evidencing the influence of this natural glycoprotein in membrane permeability. Moreover, drug retention in cell monolayers was significantly higher for NPs in comparison with the free drug. Overall, obtained dapivirine-loaded PLGA NPs possess interesting technological and biological features that may contribute to their use as novel safe and effective vaginal microbicides.