Apoptosis of leukemia cells induced by dielectric barrier discharge plasma and its mechanism / 国际生物医学工程杂志

ABSTRACT

Objective To explore the killing effect of dielectric barrier discharge (DBD) plasma on tumor cells and to analyze the DBD-induced apoptosis mechanism.Methods Thiazolyl blue tetrazolium bromide (MTT) assay method was used to detect the killing effect of low temperature plasma on the cytotoxicity of normal spleen leukocytes and acute promyelocytic leukemia cells (LT-12) at different doses.The changes of reactive oxygen species (ROS) level were measured after plasma treatment.The cell apoptosis rate was detected by Annexin V/PI double staining at different doses.The expression of apoptosis-related genes and proteins was detected by qRT-PCR and Western Blot.Results MTT results showed that the killing effect of plasma treatment was dose-dependent and time-dependent.The cell survival rate after 8 hours of treatment decreased from 98％ to 63％ with the dose increasing from 30 s to 240 s.The survival rate decreased from 78％ (2 h) to 39％ (24 h) after the treatment with a same dose (e.g.240 s).Annexin V/PI double staining results demonstrated that the plasma effect can induce apoptosis,and the apoptosis rate was not only positively correlated with the plasma dose,but also with the post-plasma time.The longer the post-plasma time,the higher was the apoptosis rate.The apoptotic rate of the 60 s dose treatment after 12 h was 48％ that increased to 55.3％ with the dose of 120 s.The production of reactive oxygen species (ROS) detected by flow cytometry also showed a time correlation of the plasma treatment.After the plasma treatment,the ROS level immediately increased to 1.24 times,and sharply increased to 5.39 times after 20 h post-plasma.The experimental results of qRT-PCR and Western blot showed that the expression of the genes and proteins of Caspase family and Bcl-2 family was very active at 8 to 12 h post-plasma treatment.Conclusions Low-temperature plasma can effectively kill tumor cells,and apoptosis is the main mechanism of death.The molecular mechanism of apoptosis of tumor cells induced by low temperature plasma was preliminary confirmed.