Construction of Exosomes that Overexpress CD47 and Evaluation of Their Immune Escape

Abstract

Our general purpose was to provide a theoretical and practical foundation for the use of exosomes (EXOs) that have high levels of CD47 as stable and efficient drug carriers. Thus, we prepared EXOs from adipose tissue-derived mesenchymal stromal cells (ADMSCs) that had high levels of CD47 (EXOs^CD47) and control EXOs (without CD47), and then compared their immune escape <i>in vivo</i> and their resistance to phagocytosis <i>in vitro</i>. Nanoflow cytometry was used to determine the CD47 level in these EXOs, and the amount of EXOs^CD47 that remained in rat plasma at 3 h after intraperitoneal injection. Phagocytosis of the EXOs was also determined using <i>in vitro</i> rat macrophage bone marrow (RMA-BM) experiments. Our <i>in vitro</i> results showed that macrophages ingested significantly more control EXOs than EXOs^CD47 (<i>p</i> < 0.01), with confirmation by ultra-high-definition laser confocal microscopy. Consistently, our <i>in vivo</i> results showed that rats had 1.377-fold better retention of EXOs^CD47 than control EXOs (<i>p</i> < 0.01). These results confirmed that these engineered EXOs^CD47 had improved immune escape. Our results therefore verified that EXOs^CD47 had increased immune evasion relative to control EXOs, and have potential for use as drug carriers.