Targeting extracellular vesicles to injured tissue using membrane cloaking and surface display.

BACKGROUND: Extracellular vesicles (EVs) and exosomes are nano-sized, membrane-bound vesicles shed by most eukaryotic cells studied to date. EVs play key signaling roles in cellular development, cancer metastasis, immune modulation and tissue regeneration. Attempts to modify exosomes to increase their targeting efficiency to specific tissue types are still in their infancy. Here we describe an EV membrane anchoring platform termed "cloaking" to directly embed tissue-specific antibodies or homing peptides on EV membrane surfaces ex vivo for enhanced vesicle uptake in cells of interest. The cloaking system consists of three components: DMPE phospholipid membrane anchor, polyethylene glycol spacer and a conjugated streptavidin platform molecule, to which any biotinylated molecule can be coupled for EV decoration. RESULTS: We demonstrate the utility of membrane surface engineering and biodistribution tracking with this technology along with targeting EVs for enhanced uptake in cardiac fibroblasts, myoblasts and ischemic myocardium using combinations of fluorescent tags, tissue-targeting antibodies and homing peptide surface cloaks. We compare cloaking to a complementary approach, surface display, in which parental cells are engineered to secrete EVs with fusion surface targeting proteins. CONCLUSIONS: EV targeting can be enhanced both by cloaking and by surface display; the former entails chemical modification of preformed EVs, while the latter requires genetic modification of the parent cells. Reduction to practice of the cloaking approach, using several different EV surface modifications to target distinct cells and tissues, supports the notion of cloaking as a platform technology.

Angiotensin II-Induced End-Organ Damage in Mice Is Attenuated by Human Exosomes and by an Exosomal Y RNA Fragment.

Hypertension often leads to cardiovascular disease and kidney dysfunction. Exosomes secreted from cardiosphere-derived cells (CDC-exo) and their most abundant small RNA constituent, the Y RNA fragment EV-YF1, exert therapeutic benefits after myocardial infarction. Here, we investigated the effects of CDC-exo and EV-YF1, each administered individually, in a model of cardiac hypertrophy and kidney injury induced by chronic infusion of Ang (angiotensin) II. After 2 weeks of Ang II, multiple doses of CDC-exo or EV-YF1 were administered retro-orbitally. Ang II infusion induced an elevation in systolic blood pressure that was not affected by CDC-exo or EV-YF1. Echocardiography confirmed that Ang II infusion led to cardiac hypertrophy. CDC-exo and EV-YF1 both attenuated cardiac hypertrophy and reduced cardiac inflammation and fibrosis. In addition, both CDC-exo and EV-YF1 improved kidney function and diminished renal inflammation and fibrosis. The beneficial effects of CDC-exo and EV-YF1 were associated with changes in the expression of the anti-inflammatory cytokine IL (interleukin)-10 in plasma, heart, spleen, and kidney. In summary, infusions of CDC-exo or EV-YF1 attenuated cardiac hypertrophy and renal injury induced by Ang II infusion, without affecting blood pressure, in association with altered IL-10 expression. Exosomes and their defined noncoding RNA contents may represent potential new therapeutic approaches for hypertension-associated cardiovascular and renal damage.

Y RNA fragment in extracellular vesicles confers cardioprotection via modulation of IL-10 expression and secretion.

Cardiosphere-derived cells (CDCs) reduce myocardial infarct size via secreted extracellular vesicles (CDC-EVs), including exosomes, which alter macrophage polarization. We questioned whether short non-coding RNA species of unknown function within CDC-EVs contribute to cardioprotection. The most abundant RNA species in CDC-EVs is a Y RNA fragment (EV-YF1); its relative abundance in CDC-EVs correlates with CDC potency in vivo Fluorescently labeled EV-YF1 is actively transferred from CDCs to target macrophages via CDC-EVs. Direct transfection of macrophages with EV-YF1 induced transcription and secretion of IL-10. When cocultured with rat cardiomyocytes, EV-YF1-primed macrophages were potently cytoprotective toward oxidatively stressed cardiomyocytes through induction of IL-10. In vivo, intracoronary injection of EV-YF1 following ischemia/reperfusion reduced infarct size. A fragment of Y RNA, highly enriched in CDC-EVs, alters Il10 gene expression and enhances IL-10 protein secretion. The demonstration that EV-YF1 confers cardioprotection highlights the potential importance of diverse exosomal contents of unknown function, above and beyond the usual suspects (e.g., microRNAs and proteins).