Surface-Attached Model Lipid Membranes Derived from Human Red Blood Cells.

Red blood cells (RBCs) are the most abundant human cell type, and interactions with the RBC membrane are at the heart of many processes relevant for human health, such as immune system modulation, as well as binding by foreign pathogens and pharmacological drugs. To better study such membrane interface interactions, it would be useful to employ surface-attached model lipid membranes derived from RBCs to enable surface-sensitive biophysical and biochemical measurements. Here, we present approaches to prepare two such types of RBC-derived model lipid membranes─tethered RBC liposomes and supported lipid bilayers (RBC-SLBs)─as well as characterization and validation data. Both model membranes are prepared from liposomes formed by extrusion from RBC ghosts. Tethered RBC liposomes are assembled by incorporating small amounts of biotinylated lipids into the liposomes and then binding to a polymer/avidin-coated glass coverslip. RBC-SLBs are formed from RBC liposomes by the vesicle fusion method but require mixing with synthetic "rupture vesicles" containing polyethylene glycol (PEG) lipids to induce successful merger, producing hybrid RBC-rupture vesicle SLBs. Lipid mobility is retained in these SLBs at low fraction of RBCs but decreases substantially at higher fractions >0.5. The glycophorin A membrane protein is well-distributed in the SLBs but is largely immobile. The functionality of both model membranes is demonstrated by acetylcholinesterase enzyme activity, and the RBC-SLBs are shown to be functional binding targets for viral pathogens. We anticipate that our results and methodologies will be of interest to researchers studying molecular interactions with RBC membranes, as well as those interested in the engineering of model membrane platforms derived from other physiological membranes.