Abstract
Purpose :
The mechanisms by which ocular vascular networks refine and remodel their connections to reach their final form is not well understood. In this study, we have used the the zebrafish hyaloidal vasculature as a model system to study vascular pruning.
Methods :
Zebrafish hyaloidal vasculature was visualized using the fli-1:GFP and flk-1:mcherry ras transgenic lines and imaged using a Leica M205FA stereo fluorescence scope. Morpholinos against PU.1 were injected into single cell embryos using standard techniques. 2x tricaine and 15 mM BDM were added to the fish water from 80 hours post fertilization to 110 hours post fertilization.
Results :
Time lapse imaging of fli-l:GFP embryos showed pruning of the hyaloidal vasculature from 3 days post fertilization to 5 days fertilization. To determine whether cell death was a primary mechanism of vascular pruning, we used Acridine orange staining as well as TUNEL staining of embryos from 3 days to 5 days post fertilization, the time period of pruning. Minimal staining occurred that colocalized with vessels, suggesting cell death was not the primary mechanism of pruning. Additionally , preventing development of macrophages by injecting PU.1 antisense morpholinos, a gene required for macrophage differentiation, also did not affect vascular development, suggesting macrophages were not required for pruning. Interestingly, addition of 2x Tricaine or 15 uM BDM, drugs which affect blood flow by decreasing heart rate from days 3-5 post fertilization caused defects in vascular pruning.
Conclusions :
This results suggest that blood flow may play an important role in modulating vascular pruning during hyaloidal vasculature development. Further studies are needed to investigate this process.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.