Purpose Familial exudative vitreoretinopathy (FEVR) and Norrie disease are examples of genetic disorders in which the retinal vasculature fails to fully form (hypovascular), leading to congenital blindness. While studying the role of a factor expressed during retinal development, T-box factor Tbx3 , we discovered that optic cup loss of Tbx3 caused the retina to become hypovascular. The purpose of this study was to characterize how loss of Tbx3 affects retinal vasculature formation. Methods Conditional removal of Tbx3 from both retinal progenitors and astrocytes was done using the optic cup-Cre recombinase driver BAC-Dkk3-Cre and was analyzed using standard immunohistochemical techniques. Results With Tbx3 loss, the retinas were hypovascular, as seen in patients with retinopathy of prematurity (ROP) and FEVR. Retinal vasculature failed to form the stereotypic tri-layered plexus in the dorsal–temporal region. Astrocyte precursors were reduced in number and failed to form a lattice at the dorsal–temporal edge. We next examined retinal ganglion cells, as they have been shown to play a critical role in retinal angiogenesis. We found that melanopsin expression and Islet1/2-positive retinal ganglion cells were reduced in the dorsal half of the retina. In previous studies, the loss of melanopsin has been linked to hyaloid vessel persistence, which we also observed in the Tbx3 conditional knockout (cKO) retinas, as well as in infants with ROP or FEVR. Conclusions To the best of our knowledge, these studies are the first demonstration that Tbx3 is required for normal mammalian eye formation. Together, the results provide a potential genetic model for retinal hypovascular diseases.

Neural tissue formation requires coordinated, interwoven development of both neural and vascular cells. Spatially distinct regions of the central nervous system (CNS) express factors that are predicted to affect vasculature in one area but not another, yet an example of this idea has not been found. Due to its accessibility, the eye is an excellent tissue to study this question. The factor TBX3 is required for frog eye development, yet its role in mammalian eye formation was not known. To determine how Tbx3 loss-of-function affected eye formation, we crossed the validated Tbx3-floxed mice with the optic cup-Cre recombinase driver, BAC-Dkk3-CRE. We confirmed earlier expression studies of Tbx3 RNA and protein in the embryonic dorsal optic vesicle and, postnatally, in sporadic clusters of cells of the inner nuclear layer. Surprisingly, we also found TBX3 in astrocyte precursors at P0. With Tbx3 loss, blood vessels were malformed throughout the retina, but with more severe effects seen in the dorsal retina. Astrocyte precursors were reduced in number and failed to form a lattice at the dorsal edge. We next examined retinal ganglion cells, as they have been shown to play a critical role in retinal angiogenesis. We found that a subset of intrinsically photosensitive retinal ganglion cells (ipRGCs) were missing melanopsin in the dorsal half of the retina. In previous studies, loss of melanopsin has been linked to hyaloid artery persistence, which we also observed in the Tbx3 cKO retina. Together, these results show that TBX3 is required for retinal angiogenesis.Summary StatementTBX3 is a multifunctional protein important for frog eye development. This is the first study showing that TBX3 is critical for mammalian eye formation, controlling the function of key cells required for angiogenesis.

Introduction: There is lack of information regarding the mortality benefits between different medications in patients with permanent atrial fibrillation (AF). Purpose: We aimed to identify if there is any difference in mortality between the use of different rate controlling medications in patients with permanent AF. Methods: We identified patients with permanent AF without history of heart failure (HF) by using the TriNetX research database which provides information from electronic medical records from several health care institutions primarily based in the United States. Patients were divided in 4 cohorts, those taking metoprolol, diltiazem, carvedilol, or atenolol. Propensity score matching (PSM) was used to equilibrate the cohorts based on past medical history and medications. The cohorts were compared amongst each other after PSM. Results: There was no difference in mortality, emergency room visits, or hospitalizations with the use of different rate-controlling medications. Conclusion: This study suggests that there is no difference in mortality with the use of metoprolol, carvedilol, atenolol, or diltiazem in patients with permanent AF without history of HF.