Time-Lapse Imaging of Retinal Angiogenesis Reveals Decreased Development and Progression of Neovascular Sprouting by Anecortave Desacetate

Abstract

To elucidate the effects of anecortave desacetate (AD) treatment on the kinetics of neovascular sprouting and its molecular mechanisms in retinal explants and during retinal vascular development in mice. The antiangiogenic effects of AD on retinal angiogenesis were evaluated using two different models: a retinal explant model treated with vascular endothelial growth factor (VEGF) and a mouse model of postnatal retinal vascular development. Time-sequential observation was followed by the quantification of movements in neovascular sprouts and microglia. Real time-PCR was performed for the measurement of mRNA levels. AD treatment significantly reduced the number of neovascular sprouts in retinal explants in a dose-dependent manner. Time-lapse imaging demonstrated that AD suppressed the new development and elongation of neovascular sprouts and the motility of tip cells. Moreover, AD treatment disturbed the filopodial extension and significantly decreased the transcriptional levels of KDR and platelet-derived growth factor-B, which are highly expressed in tip cells. In addition, it was confirmed that AD inhibited postnatal development of the retinal vasculature in mice, including filopodial extension in tip cells. These data suggest that AD suppresses both the development and the progression of sprouting angiogenesis. Interestingly, VEGF-induced microglial movements were also reduced in the retinal explants treated with AD. These changes were consistent with decreased mRNA levels of SDF-1 and Flt-1, which regulate the activation of inflammatory cells. AD inhibited both the development and the progression of VEGF-induced retinal angiogenesis mediated, in part, by the suppression of tip cell motility in two angiogenic models.