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

TL;DR

The paper describes methods to create model lipid membranes from human red blood cells for studying membrane interactions with pathogens and drugs.

Contribution

The novel contribution is the development and validation of two RBC-derived model membranes: tethered RBC liposomes and RBC-supported lipid bilayers.

Findings

Tethered RBC liposomes and RBC-SLBs were successfully prepared and characterized.

RBC-SLBs retain lipid mobility at low RBC fractions but show reduced mobility at higher fractions.

RBC-SLBs are functional for enzyme activity and can bind viral pathogens.

Abstract

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.

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