Novel Protein Blocks Lymph But Not Blood Vessel Formation

Researchers have isolated a molecule that selectively blocks the formation of lymphatic vessels (lymphangiogenesis) in the cornea of the eye without effecting development of blood vessels (hemangiogenesis).

Investigators at the University of Kentucky (Lexington, USA) identified the molecule as the secreted form of the protein endothelial growth factor receptor-2 (Vegfr-2), which they named soluble Vegfr-2 (sVegfr-2).

They reported in the August 9, 2009, online edition of the journal Nature Medicine that sVegfr-2 specifically inhibited lymphatic vessel growth both during development and following injury by blocking the lymphatic growth factor Vegf-C. Loss of sVegfr-2 during development led to the spontaneous invasion of lymphatic vessels, but not blood vessels, into the cornea. Soluble Vegfr-2 was also required for normal development of lymphatics in the skin.

In tissue culture and animal experiments, the investigators found that sVegfr-2 blocked the growth of lymphangioma cells isolated from children with this tumor, and treatment of mice following corneal transplantation with the protein nearly eliminated graft rejection.

The isolation of this endogenous inhibitor of lymphangiogenesis holds great therapeutic promise for a number of diseases in which lymphatic growth is a serious complication.

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