Daniela Mayr1, Julia Preishuber-Pflügl1, Andreas Koller1, Susanne M Brunner1, Christian Runge1, Anja-Maria Ladek1, Francisco J Rivera2,3,4, Herbert A Reitsamer1,5, Andrea Trost1. 1. Research Program for Experimental Ophthalmology and Glaucoma Research, Department of Ophthalmology and Optometry, University Hospital of the Paracelsus Medical University Salzburg, Salzburg, Austria. 2. Spinal Cord Injury and Tissue Regeneration Center, Salzburg, Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria. 3. Laboratory of Stem Cells and Neuroregeneration, Faculty of Medicine, Institute of Anatomy, Histology and Pathology, Universidad Austral de Chile, Valdivia, Chile. 4. Center for Interdisciplinary Studies on the Nervous System (CISNe), Universidad Austral de Chile, Valdivia, Chile. 5. Director of the Research Program for Experimental Ophthalmology and Glaucoma Research, Paracelsus Medical University, Salzburg, Austria.
Abstract
PURPOSE: Pericytes (PCs), located abluminal of endothelial cells on capillaries, are essential for vascular development and stability. They display a heterogeneous morphology depending on organ localization, differentiation state, and function. Consequently, PCs show a diverse gene expression profile, impeding the usage of a unique PC marker and therefore the distinct identification of PCs. Inducible reporter mouse models represent an important tool for investigating the fate of PCs under physiological and pathophysiological conditions. PC-specific expression efficiency of the fluorescence reporter tdTomato following tamoxifen induction was analyzed and compared in two inducible Cre recombinase-expressing mouse models under control of the NG2 and PDGFRb promotor. METHODS: The NG2-CreER™-tdTomato and the PDGFRb-P2A-CreERT2-tdTomato mice were treated with tamoxifen at three defining time points of retinal vascular development: post-natal days (P)5, P10/11/12, and P48/49/50/51. TdTomato reporter induction efficiency was determined by analyzing retinal whole mounts utilizing confocal microscopy, using the antibodies Anti-neural/glial antigen 2 (PCs), Anti-Collagen IV (basement membrane), and Anti-Glutamine Synthetase (Müller glial cells). RESULTS: Tamoxifen induction at the three different time points resulted in PC-specific expression of tdTomato in both reporter models. In the NG2-CreER™-tdTomato mouse, the induction efficiency ranged from 21.9 to 35.5%. In the PDGFRb-P2A-CreERT2-tdTomato mouse, an induction efficiency between 78.9 and 94.1% was achieved. TdTomato expression in the retina was restricted to PCs and vascular smooth muscle cells in the NG2-CreER™-tdTomato mouse, however, in the PDGFRb-P2A-CreERT2-tdTomato mouse, tdTomato was also expressed in Müller glial cells. CONCLUSION: Both reporter mouse models represent promising tools for fate-mapping studies of PCs. While the NG2-CreER™-tdTomato mouse reveals very specific labeling of PCs in the retina, its induction efficiency is lower compared to the PDGFRb-P2A-CreERT2-tdTomato mouse. Although the latter revealed a high percentage of tdTomato-positive PCs in the retina, additional labeling of Müller cells potentially hampers analysis of reporter-positive PCs.
PURPOSE: Pericytes (PCs), located abluminal of endothelial cells on capillaries, are essential for vascular development and stability. They display a heterogeneous morphology depending on organ localization, differentiation state, and function. Consequently, PCs show a diverse gene expression profile, impeding the usage of a unique PC marker and therefore the distinct identification of PCs. Inducible reporter mouse models represent an important tool for investigating the fate of PCs under physiological and pathophysiological conditions. PC-specific expression efficiency of the fluorescence reporter tdTomato following tamoxifen induction was analyzed and compared in two inducible Cre recombinase-expressing mouse models under control of the NG2 and PDGFRb promotor. METHODS: The NG2-CreER™-tdTomato and the PDGFRb-P2A-CreERT2-tdTomato mice were treated with tamoxifen at three defining time points of retinal vascular development: post-natal days (P)5, P10/11/12, and P48/49/50/51. TdTomato reporter induction efficiency was determined by analyzing retinal whole mounts utilizing confocal microscopy, using the antibodies Anti-neural/glial antigen 2 (PCs), Anti-Collagen IV (basement membrane), and Anti-Glutamine Synthetase (Müller glial cells). RESULTS: Tamoxifen induction at the three different time points resulted in PC-specific expression of tdTomato in both reporter models. In the NG2-CreER™-tdTomato mouse, the induction efficiency ranged from 21.9 to 35.5%. In the PDGFRb-P2A-CreERT2-tdTomato mouse, an induction efficiency between 78.9 and 94.1% was achieved. TdTomato expression in the retina was restricted to PCs and vascular smooth muscle cells in the NG2-CreER™-tdTomato mouse, however, in the PDGFRb-P2A-CreERT2-tdTomato mouse, tdTomato was also expressed in Müller glial cells. CONCLUSION: Both reporter mouse models represent promising tools for fate-mapping studies of PCs. While the NG2-CreER™-tdTomato mouse reveals very specific labeling of PCs in the retina, its induction efficiency is lower compared to the PDGFRb-P2A-CreERT2-tdTomato mouse. Although the latter revealed a high percentage of tdTomato-positive PCs in the retina, additional labeling of Müller cells potentially hampers analysis of reporter-positive PCs.
Authors: Nils Korte; Zeki Ilkan; Claire L Pearson; Thomas Pfeiffer; Prabhav Singhal; Jason R Rock; Huma Sethi; Dipender Gill; David Attwell; Paolo Tammaro Journal: J Clin Invest Date: 2022-05-02 Impact factor: 19.456