Introduction: VEGF-C156S, a lymphangiogenesis-specific form of vascular endothelial growth factor C (VEGF-C), has been considered as a promising candidate for the experimental pro-lymphangiogenic treatment, as it lacks potential angiogenic effects. As a precursor to future clinical trials, the therapeutic efficacy and blood vascular side effects of VEGF-C and VEGF-C156S were compared in a large animal model of secondary lymphedema. Combination of lymphatic growth factor treatment and autologous lymph node transfer was used to normalize the lymphatic anatomy after surgical excision of lymphatic tissue.
Methods: Lymph vessels around the inguinal lymph node of female domestic pigs were destroyed in order to impair the normal lymphatic drainage from the hind limb. Local injections of adenoviruses (Ad) encoding VEGF-C or VEGF-C156S were used to enhance the regrowth of the lymphatic vasculature. AdLacZ (β-galactosidase) and saline injections served as controls.
Results: Both VEGF-C and VEGF-C156S induced growth of new lymphatic vessels in the area of excision, although lymphangiogenesis was notably stronger after VEGF-C treatment. Also the transferred lymph nodes were best-preserved in the VEGF-C-treated pigs. Despite the enlargement of blood vessels following the VEGF-C therapy, no signs of sprouting angiogenesis or increased blood vascular permeability in the form of increased wound exudate volumes were observed.
Conclusions: Our results show that VEGF-C provides the preferred alternative for growth factor therapy of lymphedema when compared to VEGF-C156S, due to the superior lymphangiogenic response and minor blood vessel effects. Furthermore, these observations suggest that activation of both VEGFR-2 and VEGFR-3 might be needed for efficient lymphangiogenesis.