Engineered Extracellular Vesicles for Tumor-Targeted Delivery of Therapeutic siRNA for Lung Cancer Therapy.

RNAi-based technologies offer the potential to treat cancer effectively, but safe and efficient RNA administration remains a barrier to their clinical adoption. In this study, we developed extracellular vesicles (EVs) and a gold nanoparticle (GNP)-based hybrid system for the targeted delivery of therapeutic siRNA. We used siRNA to silence the B7-H4 encoding gene (a B7 family immune checkpoint protein, gene ). The knockdown of B7-H4 inhibits proliferation, invasion, and migration in cancer cell lines and increases apoptosis levels. The standardized nanocomplex of GNPs and B7-H4 siRNA (GNPs-siR) was hybridized with EVs by a heat shock technique in the presence of CaCl to form the EV-siR hybrid system. Furthermore, the system's ability to selectively deliver siRNA was examined in two Non-Small Cell Lung Cancer (NSCLC) cell lines, viz., H1299 and A549, as well as in a normal lung fibroblast cell line (MRC9). We found that the standard dose of EV-siR effectively knocked down B7-H4 in cancer cells H1299 and A549 and their spheroids. However, it was less effective in normal lung cells (MRC9). Finally, we demonstrated the antitumor therapeutic effect of the EV-siR complex in NSCLC xenograft models. The results from this study highlight the effectiveness of the hybrid EV-siR system in delivering therapeutic siRNA to tumor cells and open an avenue to explore the efficacy of the system in patient-derived NSCLC and other solid tumor models.