Nanosecond pulse ablation of hepatocellular carcinoma effect on the immune cells in the liver region of mice

Objective To analyze the changes of local immune cells in liver of mice caused by nanosecond pulse therapy for hepatocellular carcinoma. Methods Forty C57BL-6J of mice were randomly divided into four groups: negative control group (n=10), tumor group (n=10), surgical resection group (n=10) and nanosecond pulse group (n=10). Hepa 1-6 cells were injected into the left hepatic lobe of mice in tumor group, resection group and nanosecond pulse group to construct the orthotopic xenograft tumor model. Left hepatic lobectomy was performed in the surgical excision group and nanosecond pulse was performed in the nanosecond pulse group 7 days after the construction. All mice were sacrificed 7 days after the treatment. CD3＋ was detected by flow cytometry in the left hepatic lobe lesion, the nanosecond pulse group and the normal liver tissue of the right hepatic lobe in the liver and tumor groups of the blank control group. T, CD4＋T, CD8＋T, regulatory T cells (Treg), myeloid-derived suppressor cells (MDSC), natural killer cells (NK), B cells, and the ratio of CD4＋T to CD8＋T. Results In the blank control group, the tumor group the number of lesion in the mice and the pulse area of the nanosecond pulse group CD4＋T cells in blank control group (normal liver)>nanosecond pulse group>tumor group [(25.77±3.76)% vs. (15.72±2.70)% vs. (12.68±3.13)%, P blank control group>nanosecond pulse group [(14.01±2.75)% vs. (13.99±1.41)% vs. (8.42±2.21)%, P blank control group > tumor group [(1.90±0.17) vs. (1.86±0.32) vs. (0.93±0.21), P blank control group > tumor group [(47.65±3.77)% vs. (33.74±3.91)% vs. (15.94±6.10)%, P nanosecond pulse group > blank control group [(18.49±2.74)% vs. (8.41±3.05)% vs. (2.15±0.69)%, P 0.05). Normal liver tissue in right lobe of liver in 4 groups the ratio of CD4＋T to CD8＋T in blank control group >nanosecond pulse group >surgical resection group >tumor group [(1.86±0.32) vs. (1.85±0.43) vs. (1.52±0.16) vs. (1.36±0.29), P surgical resection group >blank control group> Tumor group [(46.85±8.30)% vs. (34.23±6.17)% vs. (33.74±3.91)% vs. (27.64±2.20)%, P resection group>nanosecond pulse group>blank control group [(26.34±6.23)% vs. (7.01±2.04)% vs. (3.63±1.59)% vs. (3.19±1.50)% , P resection group>nanosecond pulse group>blank control group [(12.22±2.02)% vs. (5.00±0.73)% vs. (2.87±0.96)% vs. (2.15±0.69)%, P 0.05). Conclusion Nanosecond pulse ablation of primary hepatocellular carcinoma of mice can induce immune response in ablation area and other hepatic lobes, which may be due to the anti-tumor immunity induced by nanosecond pulse. Key words: Liver Neoplasms; Nanosecond pulse; Ablation; Immune response; Tumor microenvironment