The antiangiogenic effects of integrin alpha5beta1 inhibitor (ATN-161) in vitro and in vivo

Purpose: Integrin α5β1 is involved in the development of choroidal neovascularization (CNV). Thus, the inhibition of Integrin α5β1 may provide an alternative to the current standard of CNV therapy, which involves inhibition of vascular endothelial growth factor (VEGF) and is not effective in all patients. This study evaluated the antiangiogenic effects of ATN-161, a small peptide inhibitor of Integrin α5β1, in human choroidal endothelial cells (hCECs) and in laser-induced CNV in rats. Furthermore, the utility of spectral-domain optical coherence tomography (SD-OCT) for dynamic observation of the development of CNV in animal models was assessed.

Methods: The antiangiogenic potential of ATN-161 was evaluated in VEFG-stimulated hCECs by MTS proliferation assays, migration assays, and synthetic matrix capillary tube formation assays. To evaluate the antiangiogenic effects of ATN-161 in vivo, CNV was induced in rats by laser photocoagulation. ATN-161, scrambled peptide, or AF564 anti-VEGF antibody, were injected intravitreally immediately after photocoagulation. Eyes were examined by SD-OCT and fluorescein angiography on days 1, 7, and 14 after injection, and the areas of CNV were measured by analysis of choroidal flatmounts at day 14.

Results: ATN-161 inhibited VEGF-induced migration and capillary tube formation in hCECs, but did not inhibit proliferation. In vivo, injection of ATN-161 after laser photocoagulation inhibited CNV leakage and neovascularization to an extent similar to AF564. Furthermore, SD-OCT and histologic examinations indicated that ATN-161 significantly decreased the size of laser-induced lesions.

Conclusions: Integrin α5β1 inhibition by ATN-161 may be a promising alternative therapy for CNV-related angiogenesis. In addition, SD-OCT technology allows excellent visualization of experimentally induced CNV in vivo.