Cationic lipid-mediated intracellular delivery of antibodies into live cells

Abstract

The ability to introduce antibodies to live cells opens new insights to a wide range of applications, such as protein intracellular trafficking studies, protein interference studies with blocking antibodies, and live immunolabeling or protein phosphorylation states studies. Apart from single-chain format variable (scFv) antibodies, DNA transfection of eukaryotic cells is rarely used to produce antibodies in situ, mainly due to inappropriate folding of the antibody in the cytoplasm. Thus, the development of dedicated carriers is needed since antibodies, which are large, are unable to cross the plasma membrane by passive transport. As a result, intracellular delivery of antibodies represents a novel approach for cell biologists. For efficient antibody delivery, major hurdles such as crossing the plasma membrane and effective release of the antibody in the cytoplasm need to be overcome. We studied these two crucial steps using a dedicated delivery reagent in live cells and compared the results with immunocytochemistry experiments in fixed cells.