Fig. 5: Upregulation of CCL5 in irradiated MSCs mediates increased lung metastasis.

a MSCs (1 × 10⁴) or Ccl5-deficient MSCs (1 × 10⁴) were irradiated (12 Gy) and cultured for 24 h before co-injected with 4T1 cells (5 × 10⁴) into BALB/c mice via tail vein. Metastatic nodules were counted after 14 days. n ≥ 4 for each group. b MSCs (1 × 10⁴) or irradiated (12 Gy) MSCs (1 × 10⁴) were co-injected with 4T1 cells (5 × 10⁴) into BALB/c mice via tail vein. Single-cell suspensions prepared from lung tissues were analyzed for the frequency of CCR5⁺F4/80⁺ macrophages by flow cytometry after 14 days. n = 3 for each group. c Ccl5-deficient MSCs (1 × 10⁴) or irradiated (12 Gy) Ccl5-deficient MSCs (1 × 10⁴) were co-injected with 4T1 cells (5 × 10⁴) into BALB/c mice via tail vein. Single-cell suspensions prepared from lung tissues were analyzed for the frequency of CCR5⁺F4/80⁺ macrophages by flow cytometry after 14 days. n = 4 for each group. d MSCs (1 × 10⁴) or irradiated (12 Gy) MSCs (1 × 10⁴) were co-injected with 4T1 cells (5 × 10⁴) into BALB/c mice via tail vein. Clodronate liposomes were injected (2 mg/kg, i.p.) to mice every three days. Metastasis lung tumor nodules were counted after 14 days. n ≥ 3 for each group. All experiments in this figure were repeated at least three times. *p < 0.05, **p < 0.01, ***p < 0.001; ns not significant.