Chronic wounds represent a major therapeutic challenge. Lymphatic vessel function is impaired in chronic ulcers but the role of lymphangiogenesis in wound healing has remained unclear. We found that lymphatic vessels are largely absent from chronic human wounds as evaluated in patient biopsies. Excisional wound healing studies were conducted using transgenic mice with or without an increased number of cutaneous lymphatic vessels, as well as antibody-mediated inhibition of lymphangiogenesis. We found that a lack of lymphatic vessels mediated a proinflammatory wound microenvironment and delayed wound closure, and that the VEGF-C/VEGFR3 signaling axis is required for wound lymphangiogenesis. Treatment of diabetic mice (db/db mice) with the F8–VEGF-C fusion protein that targets the alternatively spliced extra domain A (EDA) of fibronectin, expressed in remodeling tissue, promoted wound healing, and potently induced wound lymphangiogenesis. The treatment also reduced tissue inflammation and exerted beneficial effects on the wound microenvironment, including myofibroblast density and collagen deposition. These findings indicate that activating the lymphatic vasculature might represent a new therapeutic strategy for treating chronic non-healing wounds.

The lymphatic vascular system plays a fundamental role in inflammation by draining interstitial fluid, immune cells, antigens, and inflammatory mediators from peripheral tissues. Site-specific delivery of the lymphangiogenic growth factor VEGF-C alleviates acute inflammation in mouse models of psoriasis and chronic colitis by enhancing local drainage. However, it is unclear whether therapeutically induced lymphangiogenesis is transient or long-lasting and whether it might prevent relapses of inflammation. Here, we investigated the long-term effects of targeted VEGF-C delivery in a chronic dermatitis model in mice. Congruent with our previous results, intravenous injection with a VEGF-C fusion protein targeted to the EDA domain of fibronectin initially resulted in reduced inflammation. Importantly, we found that targeted VEGF-C-mediated expansion of lymphatic vessels in the skin persisted for more than 170 days, long after primary inflammation had resolved. Furthermore, the treatment markedly decreased tissue swelling upon inflammatory re-challenge at the same site. Simultaneously, infiltration of leukocytes, including CD4+ T cells, macrophages, and dendritic cells, was significantly reduced in the previously treated group. In conclusion, our data show that targeted delivery of VEGF-C leads to long-lasting lymphatic expansion and long-term protection against repeated inflammatory challenge, suggesting that it is a promising new approach for the treatment of chronic, recurrent inflammatory diseases.