Acute toxicities of intravenous, intraperitoneal, or intratumoral injection of natural killer cells in human pancreatic adenocarcinoma-bearing mice: Randomized study

•In this study, intravenous injection appeared the safest way to give NK cells to human pancreatic adenocarcinoma-bearing mice.•Intra-peritoneal/tumoral NK cell injection most often affected spleen, liver, and lung, with mostly mild pathological changes.•NK cells demonstrated preliminary anticancer efficacies in mice subcutaneously engrafted with human pancreatic adenocarcinoma. To investigate the possible acute toxicities and pathological changes associated with intravenous, intraperitoneal, or intratumoral injection of natural killer (NK) cells in mice subcutaneously bearing human pancreatic adenocarcinoma (PaC). 100 NPG tumor-bearing mice (50/sex) were engrafted subcutaneously with human PaC BXPC-3 cells 9 days before administration. They were randomly divided into 10 groups with 5 males and 5 females in each group. Mice in Group 1 were given sodium chloride intravenously as vehicle control, and mice in Groups 2–4 human peripheral blood-derived NK cells intravenously at doses of 2 × 107, 1 × 108, and 5 × 108 cells/kg, respectively; mice in Groups 5–7 were injected with NK cells intraperitoneally at doses of 2 × 107, 1 × 108, and 5 × 108 cells/kg, respectively, and mice in Groups 8–10 with NK cells intratumorally at doses of 4 × 103, 2 × 104, and 1 × 105 cells/mm3, respectively. Each group was given a single dose; the mice were observed clinically, and body weight, food intake, blood biochemistry, and tumor volume were measured. On Day 15, the mice were euthanized for gross anatomy and histopathology. On planned euthanasia, in Groups 2–4 no gross or microscopic pathological changes related to cells injection were found; in Groups 5–7 mice of both sexes showed a decrease in extramedullary hematopoiesis of spleen, and at the dose of 5 × 108 cells/kg, mice of both sexes showed an increase in the composition of spleen white pulp cells. In Groups 8–10, mice of both sexes at doses of 4 × 103 and 1 × 105 cells/mm3 and female mice at the dose of 2 × 104 cells/mm3 showed a decrease in extramedullary hematopoiesis of spleen, and female mice at a dose of 4 × 103 cells/mm3 and mice of both sexes at doses of ≥ 2 × 104 cells/mm3 showed an increase in the composition of spleen white pulp cells; perivascular/peribronchiolar inflammatory cell infiltration in lung and bronchus was observed in mice of both sexes at doses of ≥ 2 × 104 cells/mm3, and inflammatory cell infiltration in liver was observed in mice of both sexes at a dose of 1 × 105 cells/mm3. No other abnormal c