Mast‐cell‐deficient W/W v mice exhibit A decreased rate of tumor angiogenesis

The role of host mast cells in tumor‐associated angiogenesis was investigated by comparing the angiogenic response of genetically mast‐cell‐deficient W/W v mice and mast‐cell‐sufficient +/+ littermate mice to s.c. growing B16‐BL6 tumors. The angiogenic response was found to be slower and initially less intense in W/W v mice than in +/+ mice. Fewer W/W v mice than +/+ mice developed spontaneous lung metastases and W/W v mice exhibited fewer lung metastases per mouse. Bone‐marrow repair of the mast‐cell deficiency restored the angiogenic response of W/W v mice and also restored the incidence of hematogenous metastases to approach that of +/+ mice. Differences in lymphatic metastasis were not detected between W/W v and +/+ mice. These results demonstrate a role for mast cells in vivo during tumor angiogenesis, and suggest a role also for host mast cells in hematogenous metastasis.