VEGF‐D deficiency in mice does not affect embryonic or postnatal lymphangiogenesis but reduces lymphatic metastasis

Abstract Vascular endothelial growth factor‐D (VEGF‐D) is one of the two ligands of the VEGFR‐3 receptor on lymphatic endothelial cells. Gene‐silencing studies in mice and Xenopus tadpoles recently showed that the role of endogenous VEGF‐D in lymphatic development is moderate. By contrast, exogenous VEGF‐D is capable of stimulating lymphangiogenesis. Nonetheless, its endogenous role in pathological conditions remains largely unknown. Hence, we reassessed its role in disease, using Vegf‐d null mice. Vegf‐d null mice were generated that, under physiological conditions, displayed normal embryonic and postnatal lymphangiogenesis and lymphatic remodelling, efficient lymphatic functioning and normal health. Vegf‐d null mice also reponded normally in models of skin wound healing and healing of infarcted myocardium, despite enhanced expression of VEGF‐D in these models in wild‐type mice. In contrast, Vegf‐d null mice displayed reduced peritumoral lymphangiogenesis and lymph node metastasis in an orthotopic pancreatic tumour model. Together, our data indicate that endogenous VEGF‐D in mice is dispensible for lymphangiogenesis during development, in postnatal and adult physiology and in several pathological conditions, but significantly contributes to lymphatic metastasis. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.