Targeting Myd88 using peptide-loaded mesenchymal stem cell membrane-derived synthetic vesicles to treat systemic inflammation.

Mesenchymal stem cells (MSC) secrete extracellular vesicles (EV) with a regenerative profile, and an increasing number of studies have focused on the utilization of MSC-EV for therapeutic drug delivery. However, EV are usually produced by cells in low quantities and are packed with numerous cytoplasmic components, which may be unfavorable for further drug loading. In this study, we developed a simple process for generating membrane vesicles directly from the cells, which we refer to as synthetic eukaryotic vesicles (SyEV). We hypothesized that MSC-derived SyEV can be efficiently loaded with an anti-inflammatory drug and the loaded vesicles can strongly suppress the systemic inflammation induced by bacterial outer membrane vesicles (OMV). SyEV were generated from MSC membranes through serial extrusion of the cells, ionic stress, and subsequent vesiculation of the membrane sheets, leading to high yield and purity of the SyEV with few cytosolic components remaining. When these SyEV were given to macrophages or mice exposed to OMV, the release of pro-inflammatory cytokines was similarly attenuated comparable to treatment with natural EV. We then loaded the SyEV with large numbers of peptides targeting Myd88 and observed enhanced therapeutic potential of the loaded vesicles in OMV-induced macrophages. Further, in vivo experiments showed that the peptide-encapsulated MSC-SyEV suppressed cytokine production synergistically. Taken together, these findings suggest that SyEV-based therapeutics is a highly interesting platform for delivering an advanced therapeutic drug for the treatment of systemic inflammation without severe side effects.