Immunotherapeutic effect of photothermal-mediated exosomes secreted from breast cancer cells

Aim: Exosomal damage-associated molecular patterns can play a key role in immunostimulation and changing the cold tumor microenvironment to hot. Materials & methods: This study examined the immunostimulation effect of photothermal and hyperthermia-treated 4T1 cell-derived exosomes on 4T1 cell-induced breast tumors in BALB/c animal models. Exosomes were characterized for HSP70, HSP90 and HMGB-1 before injection into mice and tumor tissues were analyzed for IL-6, IL-12 and IL-1 beta, CD4 and CD8 T-cell permeability, and PD-L1 expression. Results: Thermal treatments increased high damage-associated molecular patterns containing exosome secretion and the permeability of T cells to tumors, leading to tumor growth inhibition. Conclusion: Photothermal-derived exosomes showed higher damage-associated molecular patterns than hyperthermia with a higher immunostimulation and inhibiting tumor growth effect. Plain language summary: This research explored the impact of using tiny dying cancer cell-derived particles known as exosomes to activate the immune system to fight against breast tumors in animal models. These exosomes contain specific molecules that can trigger the immune response and alter the environment surrounding the tumor. Researchers applied two different treatments, photothermal and hyperthermia, to kill the cancer cells and obtain these exosomes. Both treatments involved using heat to kill the cells. The study revealed that exosomes derived through the photothermal method exhibited higher levels of these immune-activating molecules compared with those obtained through hyperthermia. Upon injecting these exosomes into the animal models, they enhanced the ability of the immune cells to enter the tumors, resulting in a reduction in tumor growth. Overall, the findings indicate that using exosomes obtained through the photothermal method may be more effective in stimulating the immune system to fight against cancer and inhibiting tumor growth, as opposed to using exosomes obtained through hyperthermia. [GRAPHICS] .