Abstract
Purpose: :
Neovascularization is a dynamic mechanism, whereas the kinetics of retinal angiogenesis remains poorly understood. Here we evaluated the dynamics of neovascular sprouting and its molecular mechanisms in the retinal angiogenesis treated with an angiostatic steroid, anecortave desacetate (AD).
Methods: :
Retinas were isolated from C57BL6/J and cultured for 96 hours in the presence or absence of AD, followed with each additional experiment. For in vivo experiments, AD was injected intraperitoneally into C57BL6/J mice on postnatal day 2 (P2), and the retinas were isolated on P4. After the fixation and permeation, immunohistochemistry was performed with fluorescent 2nd antibodies. Real time PCR was performed for the measurements of mRNA levels. Time-sequential images were obtained using confocal microscopy, and the movements of tip cells were quantified.
Results: :
AD treatment presented the significant reduction in the number of neovascular sprouts in retinal explants in a dose dependent manner. Time-lapse imaging demonstrated that AD suppressed both the development and the elongation of sprouts, and the motility of the leading edges in tip cells. AD treatment further disturbed the filopodial extension and significantly decreased the transcriptional levels of KDR and platelet-derived growth factor-B (PDGFB), which are highly expressed in tip cells. These data suggest the tip cell dysfunction. The transcriptional level of stromal derived factor-1 (SDF-1), which regulates tip cell motility, was also reduced by AD, whereas AD did not alter the expression of its receptor, CXCR4. It was additionally confirmed that AD inhibited the in vivo neovascularization and filopodial extension in tip cells in retinal vascular development. These data suggest that AD suppresses both development and progression of sprouting angiogenesis.
Conclusions: :
AD inhibits both the development and progression of VEGF-induced retinal angiogenesis, mediated via the suppression of tip cell motility at least partially.
Keywords: neovascularization • retinal neovascularization • imaging/image analysis: non-clinical