Research paperStudy of fluid dynamics reveals direct communications between lymphatic vessels and venous blood vessels at lymph nodes of mice

- Fluid dynamics in the lymphatic and blood vascular systems of conventional laboratory mice were clarified.
- Fluid dynamics in the lymphatic and blood vascular systems are the same as those of MXH10/Mo/lpr mice.
- Lymph nodes could be a source of systemic metastasis in MXH10/Mo/lpr mice.
- The results can be used to facilitate studies of the progression of lymphatic metastasis to hematogenous metastasis
- The findings will be relevant to future investigations aimed at developing a lymphatic drug delivery system to treat cancer.

Cancer cells metastasize to lymph nodes, with distant metastasis resulting in poor prognosis. The role of lymph node metastasis (LNM) in the spread of cancer to distant organs remain incompletely characterized. The visualization of flow dynamics in the lymphatic and blood vessels of MXH10/Mo-lpr/lpr mice, which develop systemic swelling of lymph nodes up to 10 mm in diameter, has revealed that lymph nodes have the potential to be a direct source of systemic metastasis. However, it is not known whether these fluid dynamics characteristics are universal phenomena present in other strains of laboratory mice. Here we show that the fluid dynamics observed in MXH10/Mo-lpr/lpr mice are the same as those observed in C57BL/6J, BALB/cAJcl and NOD/ShiJic-scidJcl mice. Furthermore, when fluorescent solution was injected into a tumor-bearing lymph node, the flow dynamics observed in the efferent lymphatic vessels and thoracoepigastric vein depended on the type of tumor cell. Our results indicate that fluid dynamics in the lymphatic and blood vessels of MXH10/Mo-lpr/lpr mice are generalized phenomena seen in conventional laboratory mice. We anticipate our results can facilitate studies of the progression of lymphatic metastasis to hematogenous metastasis via lymph nodes and the early diagnosis and treatment of LNM.