Serum eyedrops antagonize the anti(lymph)angiogenic effects of bevacizumab in vitro and in vivo.

PURPOSE: The effect of autologous serum eyedrops on the corneal vasculature is undefined. Therefore, we analyzed the corneal vascular effects of serum eyedrops in comparison with and in combination with bevacizumab eyedrops.

METHODS

In vitro, blood and lymphatic endothelial cells were treated with serum eyedrops, bevacizumab eyedrops, or a combination of both, and cell proliferation was measured. In vivo, inflammatory corneal neovascularization was induced by suture placement. Subsequently, corneal blood and lymphatic vessel progression and regression were analyzed after treatment with serum or bevacizumab eyedrops or a combination of both. Hemangiogenesis and lymphangiogenesis were quantified in whole mounts using CD31 and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1); inflammatory cell infiltration was analyzed using CD11b. Furthermore, corneal expression levels of interleukin 1β, tumor necrosis factor α, vascular endothelial growth factor (VEGF) A, VEGF-C, and VEGF-D were analyzed by real-time PCR.

RESULTS

In vitro, serum increased and bevacizumab decreased endothelial cell proliferation. In vivo, serum eyedrops had no significant effect on corneal vessel progression or regression. Bevacizumab eyedrops reduced blood and lymphatic vessel progression and promoted blood and lymphatic vessel regression. The combination of serum eyedrops and bevacizumab eyedrops attenuated the anti(lymph)angiogenic effects of bevacizumab. Inflammatory corneal cell counts were not significantly altered by serum or bevacizumab eyedrops. Serum eyedrops changed the proinflammatory and pro(lymph)angiogenic status of the cornea. Bevacizumab eyedrops significantly reduced proinflammatory and pro(lymph)angiogenic factor expression. Higher doses of bevacizumab did not restore its anti(lymph)angiogenic effects when used in combination with serum.

CONCLUSIONS

The counteracting effects of serum eyedrops and bevacizumab eyedrops on the corneal vasculature should be taken into account when combined therapeutic regimens are considered.