Abstract
Purpose: :
To elucidate the expression patterns of various secreted angiogenic factors during anterior eye development. The cornea is avascular, however, it is surrounded by highly vascularized pericorneal tissue. We hypothesize that factors are expressed in the anterior eye that promote angiogenesis in the pericorneal region while maintaining corneal avascularity.
Methods: :
Reverse Transcription PCR (RT-PCR) and RNA in situ hybridization were used to identify spatiotemporal expression patterns of proangiogenic and antiangiogenic factors in the anterior eye region during critical time points in chicken corneal development (E3, E5, E6, and E7).
Results: :
Our data shows that secreted proangiogenic and antiangiogenic factors are expressed in the developing cornea and adjacent tissues, such as the lens, iris, etc. Assayed factors represent several gene families known to affect angiogenesis, for example, semaphorin, netrin, and growth factor families. Many of these genes are weakly expressed by E3, then strengthen and localize to specific regions of developing tissues in the anterior eye by E7. Respective angiogenic factor receptors have been found localized to blood vessels and their precursors. Receptors expressed by blood vessel precursors are present in the anterior eye by E3, while receptors expressed only by mature blood vessels were not found until E5.
Conclusions: :
Our data suggests that many proangiogenic and antiangiogenic factors are expressed in patterns that suggest their roles in maintaining corneal avascularity, while retaining vascularization throughout the rest of the anterior eye. Our results will provide insight into how blood vessel growth is regulated during development and disease progression.
Keywords: cornea: basic science • development • blood supply