Therapeutic responses to exogenous VEGF-C administration in experimental lymphedema: immunohistochemical and molecular characterization.

BACKGROUND: In a widely employed murine tail model of human acquired lymphedema, we have previously observed that, distal to the site of experimental lymphatic ablation, there is immunohistochemical evidence of a profound increase in cutaneous lymphatic vessel number and size that normalizes after VEGF-C administration.
OBJECTIVE: In order to investigate the mechanistic basis of the lymphatic microvascular remodeling, we have studied the lymphedematous responses to VEGF-C after co-administration of systemic VEGFR-3 neutralizing antibody. We have also undertaken genome-wide whole-tissue transcriptional profiling of lymphedematous tissues before and after exogenous VEGF-C administration. STUDY
DESIGN: We provoked postsurgical lymphedema in the mouse tail model and assessed the effects of exogenously administered human recombinant VEGF-C in the presence of a monoclonal anti-VEGFR-3 antibody. Polyclonal IgG was administered to a series of control subjects. Microvascular lymphatic remodeling was assessed through quantitative and qualitative anti-LYVE1 immunohistochemistry. Genome-wide transcriptional profiling was performed in whole skin derived from lymphedema with and without exogenous VEGF-C administration. Normal mice and surgical shams served as controls.
RESULTS: In the presence of the monoclonal anti-VEGFR-3 neutralizing antibody, positive lymphatic microvascular remodeling in lymphedematous skin is nearly completely abrogated. Furthermore, the therapeutic impact of added VEGF-C is markedly attenuated, as is the ability of the growth factor to ameliorate tissue edema. Transcriptional profiling of the VEGF-C responses in treated lymphedema reveals a very restricted list of genes whose expression is upregulated in lymphedema and re-normalized following VEGF-C treatment.
CONCLUSION: The postsurgical murine tail model of lymphedema closely simulates attributes of human lymphedema. The current series of investigations underscores the utility of the murine tail model to the preclinical and translational investigation of lymphedema. The derived insights continue to focus favorably upon the central role of the VEGFR-3 receptor and its ligands in the development and therapeutic resolution of lymphedema. Whole tissue transcriptional profiling continues to shed light on disease mechanisms and potential future targets for therapeutic intervention.