Targeting regenerative exosomes to myocardial infarction using cardiac homing peptide

Vandergriff, Adam; Huang, Ke; Shen, Deliang; Hu, Shiqi; Hensley, Michael Taylor; Caranasos, Thomas G.; Qian, Li; Cheng, Ke

To determine proper isolation of hCDC-XOs without cellular contamination, exosomes were characterized using both Western blotting, NTA, and TEM. Western blots confirmed exosome presence with the exosome marker CD81, and a lack of cellular contamination was verified using the nuclear protein PCNA (Figure 1B) . Exosome size was confirmed to be 95 nm via NTA and TEM imaging confirmed the round morphology of exosomes (Figure 1C-D) . It was not possible to directly determine the exosome labelling; NTA was not able to differentiate between labelled and unlabeled exosomes ( Figure 1C) . Instead we used indirect methods to test whether the addition of a targeting peptide would increase retention of exosomes. To do so, exosomes were incubated on slide sections of rat kidney, liver, lung, spleen, and infarcted heart. Exosomes were tracked and quantified by DiI labelling. It has been shown that exosomes demonstrate innate homing abilities [35] . Based upon the fluorescence integrated density taken from a series of images, CHP-tagged exosomes exhibited improved targeting to the infarcted heart ( Figure 1E-F) . In the other organs, the liver showed a decreased signal of CHP-XOs when compared to Scr-XOs. These data indicate that CHP conjugation is able to increase on-target and decreases off-target delivery of systemically administered exosomes.