Developing targeted extracellular vesicles for therapeutic delivery in cardiovascular disease.  

Background: Extracellular vesicles (EVs) are lipid-bound particles released from cells that are implicated in health and disease, including cardiovascular diseases (CVD). EVs can be exogenously loaded with therapeutic agents and modified with targeting peptides for targeted therapeutic delivery.  

Methods: EVs were isolated using size exclusion chromatography from the serum of spontaneously hypertensive stroke-prone rats (SHRSP) and characterised by NanoSight. EVs were fluorescently labelled with PHK-67 or Licor NHS-800 dye and modified with one of five candidate cardiomyocyte or endothelial targeting peptides. EVs (control and targeted) were incubated with rat microvascular endothelial cells (MVECs) or rat H9c2 cardiomyoblasts to assess cell-selective uptake via confocal microscopy. For in vivo investigation, we intravenously injected modified EVs into male and female SHRSP rats and after 24 hours, animals were culled, and organs were imaged via Pearl Imaging.  

Results: In H9c2 cardiomyoblasts, peptides 1 (DDTRHWG), 3 (CSTSMLKAC) and 5 (APWHLSSQYSRT) significantly increased EV uptake compared to untargeted EVs (p=0.01). In MVECs, peptides 2 (CSGMARTKC) and 4 (WLSEAGPVVTVRALRGTGSW) suggested a trend in increased EV uptake, compared to untargeted EVs. In vivo, although peptide 1 did not modify cardiac uptake, a significant increased uptake was seen in the kidneys while also detargeting the liver and spleen when compared to untargeted EVs (n=6; p = 0.01; 2.38-fold increase).  

Summary: These initial data provide insight into the utility of targeting EVs as therapeutic delivery vectors for CVD however require further investigation and optimisation for future therapeutic studies.