Human monoclonal natural IgG antibodies can penetrate MDA-MB-231 cells and transport intracellularly paclitaxel-loaded gold nanorods

Abstract

BackgroundPrevious studies of our laboratory have shown the cell penetrating ability of polyclonal human IgGs present in Intravenous Immunoglobulin (IVIg) therapeutic preparations; those IgGs possessed Natural Antibodies (NAbs) activities, namely reactivity against several structurally unrelated self and non-self antigens (polyreactivity), due to which they can enter living cells. In this work, we isolated human monoclonal IgG Abs (h-mIgGs), derived from Multiple Myeloma patients’ sera with high mIgG concentration, exhibiting polyreactivity, and studied their penetration ability in triple negative, highly aggressive, metastatic MDA-MB-231 breast cancer cell line and their potential role as intracellular carriers of paclitaxel (PTX)-loaded gold nanorods (GNRs). Materials and methodsThe isolated h-mIgGs were tested regarding purity by SDS-PAGE, monoclonality by IsoElectric Focusing electrophoresis (IEF) and polyreactivity by ELISA. The cell–penetrating ability of h-mIgGs, alone or conjugated with GNRs and GNRs loaded with PTX, were tested by immunofluorescence (IF), and their effect on apoptosis and cell viability by FACS and MTT assay, respectively. ResultsAmong six isolated h-mIgGs, five were cell-penetrating antibodies (CPAbs) showing cytoplasmic localization in living MDA-MB-231 cells, with no effect on cell viability. In comparison to unconjugated CPAbs, CPAbs conjugates exhibited significantly augmented intracytoplasmic IF signal. One out of the five CPAbs exhibited optimum characteristics as far as antibody conjugation and cell penetration performance are concerned. The selected CPAb35-GNRs-PTX conjugate displayed a significant decrease on MDA-MB-231 cell viability when compared to GNRs-PTX conjugates and PTX alone. ConclusionsMonoclonal IgG antibodies isolated from Multiple Myeloma patients’ sera can penetrate cancer cells and transport intracellularly the chemotherapeutic agent PTX conjugated to gold nanorods. Extended screening of such h-mIgGs as potential drug-carriers might be an effective approach for their exploitation in biomedicine.