PEGylated and targeted extracellular vesicles display enhanced cell specificity and circulation time.

Extracellular vesicles (EVs) are increasingly being recognized as candidate drug delivery systems due to their ability to functionally transfer biological cargo between cells. However, the therapeutic applicability of EVs may be limited due to a lack of cell-targeting specificity and rapid clearance of exogenous EVs from the circulation. In order to improve EV characteristics for drug delivery to tumor cells, we have developed a novel method for decorating EVs with targeting ligands conjugated to polyethylene glycol (PEG). Nanobodies specific for the epidermal growth factor receptor (EGFR) were conjugated to phospholipid (DMPE)-PEG derivatives to prepare nanobody-PEG-micelles. When micelles were mixed with EVs derived from Neuro2A cells or platelets, a temperature-dependent transfer of nanobody-PEG-lipids to the EV membranes was observed, indicative of a 'post-insertion' mechanism. This process did not affect EV morphology, size distribution, or protein composition. After introduction of PEG-conjugated control nanobodies to EVs, cellular binding was compromised due to the shielding properties of PEG. However, specific binding to EGFR-overexpressing tumor cells was dramatically increased when EGFR-specific nanobodies were employed. Moreover, whereas unmodified EVs were rapidly cleared from the circulation within 10min after intravenous injection in mice, EVs modified with nanobody-PEG-lipids were still detectable in plasma for longer than 60min post-injection. In conclusion, we propose post-insertion as a novel technique to confer targeting capacity to isolated EVs, circumventing the requirement to modify EV-secreting cells. Importantly, insertion of ligand-conjugated PEG-derivatized phospholipids in EV membranes equips EVs with improved cell specificity and prolonged circulation times, potentially increasing EV accumulation in targeted tissues and improving cargo delivery.

The pathology of alcohol hangover.

Research on human subjects analyzing blood and urine samples determined biological correlates that may explain the pathology of alcohol hangover. These analyses showed that concentrations of various hormones, electrolytes, free fatty acids, triglycerides, lactate, ketone bodies, cortisol, and glucose were not significantly correlated with reported alcohol hangover severity. Also, markers of dehydration (e.g., vasopressin) were not significantly related to hangover severity. Some studies report a significant correlation between blood acetaldehyde concentration and hangover severity, but most convincing is the significant relationship between immune factors and hangover severity. The latter is supported by studies showing that hangover severity may be reduced by inhibitors of prostaglandin synthesis. Several factors do not cause alcohol hangover but can aggravate its severity. These include sleep deprivation, smoking, congeners, health status, genetics and individual differences. Future studies should more rigorously study these factors as well as biological correlates to further elucidate the pathology of alcohol hangover.