Purpose: Long-circulating nanoparticles are needed for sustained systemic drug delivery, but PEGylation—the current stealth gold standard—can face anti-PEG immune responses. A top-down biomimetic approach using natural erythrocyte membranes could better mimic red blood cells (RBCs), nature’s long-circulating carriers, while retaining a biodegradable polymeric core for cargo delivery.
Hypothesis: If biodegradable PLGA nanoparticles are coated with natural erythrocyte membranes—including both membrane lipids and associated membrane proteins—then the resulting RBC-membrane-camouflaged nanoparticles will have enhanced serum stability, reduced macrophage uptake, prolonged blood circulation, and improved biodistribution compared with bare PLGA and PEGylated lipid–polymer hybrid nanoparticles.
Aims: Derive RBC-membrane vesicles from mouse erythrocytes and fuse them onto PLGA nanoparticles. - Characterize the core–shell structure, size, zeta potential, and retained membrane protein content. - Evaluate serum stability and in vivo pharmacokinetics/biodistribution in mice. - Compare performance against bare PLGA and PEGylated lipid–PLGA hybrid nanoparticles.
Delivery system:
Component: Polymeric core; Details: Carboxy-terminated 50:50 poly(lactic-co-glycolic acid) (PLGA), 0.67 dL/g
Component: Core size; Details: ~70 nm
Component: Coating; Details: Natural erythrocyte membrane-derived vesicles (bilayered lipids + associated membrane proteins)
Component: Fabrication; Details: Solvent displacement for PLGA cores; hypotonic lysis, sonication, and extrusion for RBC vesicles; vesicle–particle fusion by repeated extrusion through 100-nm pores
Component: Final size; Details: ~80 nm; lipid shell thickness 7–8 nm
Component: Zeta potential; Details: ~−10.2 mV initially; ~−12.7 mV after 2 weeks
Component: Payload; Details: Hydrophobic DiD fluorophore for tracking; DMPE-RhB for membrane labeling; no therapeutic cargo
Component: Targeting ligand; Details: None
Component: Key feature; Details: Top-down transfer of natural RBC membrane and associated proteins to a synthetic polymeric nanoparticle
Approach: In vitro: HeLa cells for endocytosis and core–shell colocalization; 100% FBS serum stability assay. - In vivo: Male ICR mice (6–8 weeks), same strain as RBC donors; n = 6 mice per group. - Injection: 150 µL of 3 mg/mL DiD-loaded nanoparticles via tail vein. - Controls: Bare PLGA nanoparticles (~75 nm); PEG 2000-functionalized lipid–PLGA hybrid nanoparticles (~80 nm). - Pharmacokinetics: Blood collected at 1, 5, 15, 30 min, and 1, 2, 4, 8, 24, 48, 72 h. - Biodistribution: Organs (liver, kidney, spleen, brain, lung, heart, blood) collected at 24, 48, and 72 h.
Key methods: Structure/size: Transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential. - Protein retention: SDS-PAGE of RBC ghosts, RBC vesicles, and purified coated nanoparticles. - Serum stability: Absorbance at 560 nm in 100% FBS over 4 h. - Cellular uptake/colocalization: Fluorescence microscopy with DiD and DMPE-RhB. - Pharmacokinetics/biodistribution: Fluorescence measurements of blood and homogenized organs; two-compartment/nonlinear model fitting. - Dye release: Dialysis method to confirm minimal DiD release (<20% over 72 h).
Key results: Core–shell structure: TEM showed ~80 nm particles with a ~70 nm polymeric core and a 7–8 nm lipid shell, consistent with RBC membrane thickness. - Protein retention: SDS-PAGE showed that most RBC membrane proteins were retained on the coated nanoparticles; some peripheral/spectrin-associated proteins were lost (band near 51 kDa fainter; ~200 kDa band missing). - Serum stability: RBC-membrane-coated and PEGylated nanoparticles showed no absorbance change in 100% FBS over 4 h; bare PLGA aggregated immediately. - Circulation: RBC-membrane-coated nanoparticles had significantly longer circulation than PEGylated and bare PLGA nanoparticles. Blood retention was 21% at 24 h, 15% at 48 h, and 11% at 72 h. - Biodistribution: Nanoparticles distributed mainly in blood and liver; as blood signal decreased, liver signal increased, indicating RES uptake. Other organs showed lower accumulation. - Comparison: RBC-membrane-coated nanoparticles circulated much longer than previously reported RBC-derived liposomes, which clear in <30 min; most published nanoparticles show negligible blood retention after 24 h.
Interpretation: The authors claim that top-down translocation of natural erythrocyte membranes—lipids and associated proteins—onto biodegradable polymeric nanoparticles provides a unique and robust biomimetic functionalization strategy. The platform enables long circulation, serum stability, and potential clinical translation, including personalized medicine using a patient’s own RBC membranes. Challenges for human translation include blood group antigen matching and removal of immunogenic proteins.
Limitations: In vivo mouse model only; no human or large-animal validation. - No therapeutic payload or disease efficacy: only dye tracking; no drug/gene delivery or therapeutic outcome. - No targeting ligand: passive circulation/biodistribution only. - Protein loss: some peripheral/spectrin-associated proteins were lost during extrusion; functional consequences not fully assessed. - Human translation challenges: human RBCs contain numerous blood group antigens; cross-matching or immunogenic protein depletion would be required. - No long-term toxicity, repeated-dose, or immune-response data. - Small sample size: n = 6 mice per group. - No direct comparison to all alternative stealth materials, only PEGylated lipid–PLGA hybrid nanoparticles. - Dye release <20% over 72 h; drug release kinetics for therapeutic cargo not characterized.
