Study on B16 Cell Cytotoxicity by High Frequency Reversible Electroporation With Bleomycin That Induces Hallmarks of Immunogenic Death

Hundreds of high frequency bipolar pulse bursts with ∼1 μs have been suggested to alleviate muscle contractions and pain during the irreversible electroporation (IRE) tumor treatment. This study is performed to verify whether eight bursts of high frequency reversible electroporation pulses (HFREs) with bleomycin could be used for electrochemotherapy (ECT) tumor treatment. Firstly, in vitro experiments on B16 cells are performed to determine the cytotoxicity of the HFREs with bleomycin. The result indicates that the protocol of HFREs with bleomycin has a significant killing effect compared with only bleomycin, in which the used HFRE pulses are set to induce high membrane permeabilization while maintaining high cell viability. The immunogenic cell death (ICD) that generates danger associated molecular patterns (DAMPs) could trigger an adaptive immune response against tumors. We demonstrated that HFREs with bleomycin could trigger the hallmarks of ICD with obvious up-regulation of DAMPs, including ATP, HMGB1, and CRT. The ICD process may begin at 3 h but perform at 6 h after HFREs with bleomycin stimulation. The in vivo experiment on mice tumor treatment also showed that the protocol of HFREs with bleomycin could inhibit tumor growth with more cytotoxic CD8+ T cells infiltration. The results obtained from in vitro and in vitro experiments preliminary confirmed that the HFREs with bleomycin could be used for ECT tumor treatment associated with the hallmarks of ICD and preliminary trigger the adaptive immune response.