Vascular endothelial growth factor-D transgenic mice show enhanced blood capillary density, improved postischemic muscle regeneration, and increased susceptibility to tumor formation.

Vascular endothelial growth factor-D (VEGF-D) has angiogenic and lymphangiogenic activity, but its biologic role has remained unclear because knockout mice showed no clear phenotype. Transgenic (TG) mice expressing the mature form of human VEGF-D (hVEGF-D) were produced by lentiviral (LV) transgenesis using the perivitelline injection method. Several viable founders showed a macroscopically normal phenotype and the transgene transmitted through germ line. Expression of hVEGF-D mRNA was high in skeletal muscles, skin, pancreas, heart, and spleen. A significant increase was found in capillary density of skeletal muscles and myocardium, whereas no changes were observed in lymphatic capillary density. After induction of hindlimb ischemia, the TG mice showed enhanced capacity for muscle regeneration. However, on aging the TG mice had significantly increased mortality from malignant tumors, of which half were breast adenocarcinomas characterized with the absence of periductal muscle cells. Some tumors metastasized into the lungs. In addition, lung and skin tumors were found, but no blood- or lymphatic vessel-derived malignancies were detected. We conclude that in mice hVEGF-D is an angiogenic factor associated with improved muscle regeneration after ischemic injury but also with increased incidence of tumor formation with a preference for mammary gland tumors.