Abstract
Purpose :
We recently generated a Matrix-Gla.Knock-In.Cre mouse which specifically directs Cre to tissues of Mgp expression (trabecular meshwork, peripapillary sclera, cartilage and vascular systems). We crossed this mouse with a loxP fluorescent reporter mice. Our purpose was to characterize the F1 fluorescent mouse and to present proof of concept of potential applications for the study of angiogenesis and glaucoma in vivo using this mouse strain.
Methods :
Our homozygous strain Mgp.KI-Cre (Mgp.KI-Cre/Mgp.KI-Cre) was crossed with homozygous Rosa26.loxP-td.tomato (Jackson labs) mice. The F1 double heterozygous Mgp.KI-Cre/ wt; Rosa26.floxed-td.tomato/ wt (Mgp-td.tomato) was examined for the presence of direct fluorescence by whole mounts, histology and fundus photography. Custom-made filters for the Phoenix Micron IV had 554 emission and 609 exciter wavelengths. Laser burns were induced by guiding imaging in the Micron IV. Evaluation of vessels leakage was conducted by non invasive angiography.
Results :
The Mgp-td.tomato mouse is naturally red fluorescent in the tissues where the Mgp gene is expressed. Because of the cartilage expression of Mgp, this mouse exhibited red paws and snout and was thereafter termed the “red mouse”. A fluorescent red ring around the limbus region of the enucleated eye marked the high expression of Mgp in the mouse trabecular meshwork, which was confirmed by histology. Interestingly, the entire retinal vasculature is also naturally fluorescent red and was visualized by fundus photography without the injection of fluorescein. For a first proof of concept of the new model, guided laser burns were performed and followed by direct angiography.
Conclusions :
The availability of a transgenic mouse naturally red fluorescent in the glaucoma relevant tissues and retinal vasculature, brings the unique opportunity to study in vivo and longitudinally, a wide spectrum of glaucoma conditions and effects on the vascular system. Most important, the red mouse would be also very useful for numerous studies of retinal angiogenesis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.