Browsing by Author "Rangan, Rajiv S."
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Item miRNA Profiling of Human Optic Nerve Head Astrocytes Exposed to Cyclic Stretch(2021-05) Rangan, Rajiv S.; Tovar-Vidales, Tara; Clark, Abbot F.; Liu, YangGlaucoma is a leading cause of irreversible blindness. Vision loss results from the degeneration and death of retinal ganglion cells (RGCs) and their axons. The primary risk factor for glaucoma is increased intraocular pressure (IOP) (2). Elevated IOP results in aberrations in the biomechanical properties of ocular tissues - including the transmission of biomechanical stretch through the reticulated, fibroelastic region of the optic nerve head (ONH) known as the lamina cribrosa (LC) (6). Cells of the LC are sensitive to biomechanical stretch and respond to increased stretch and pressure to promote the excessive synthesis of extracellular matrix (ECM) proteins and ECM remodeling (15,17). These responses promote a fibrotic environment within the LC that can cause mechanical damage to the axons of RGCs. ONH astrocytes represent one of the major cell types of the LC and are believed to contribute significantly to pathological ECM remodeling at the LC during glaucoma (11). ONH astrocytes also demonstrate a dysregulated pattern of protein expression when exposed to stretch (17). The mechanism that underlies this stretch-induced, aberrant dysregulation is unknown. MicroRNA (miRNA) dysregulation may represent one of the mechanisms contributing to the differential protein expression patterns seen in ONH astrocytes exposed to stretch. In this study we examine the miRNA profiles of ONH astrocytes exposed to cyclic stretch.Item Neuroprotection of Rodent and Human Retinal Ganglion Cells In Vitro/Ex Vivo by the Hybrid Small Molecule SA-2(MDPI, 2022-12-12) Pham, Jennifer H.; Johnson, Gretchen A.; Rangan, Rajiv S.; Amankwa, Charles E.; Acharya, Suchismita; Stankowska, Dorota L.The mechanisms underlying the neuroprotective effects of the hybrid antioxidant-nitric oxide donating compound SA-2 in retinal ganglion cell (RGC) degeneration models were evaluated. The in vitro trophic factor (TF) deprivation model in primary rat RGCs and ex vivo human retinal explants were used to mimic glaucomatous neurodegeneration. Cell survival was assessed after treatment with vehicle or SA-2. In separate experiments, tert-Butyl hydroperoxide (TBHP) and endothelin-3 (ET-3) were used in ex vivo rat retinal explants and primary rat RGCs, respectively, to induce oxidative damage. Mitochondrial and intracellular reactive oxygen species (ROS) were assessed following treatments. In the TF deprivation model, SA-2 treatment produced a significant decrease in apoptotic and dead cell counts in primary RGCs and a significant increase in RGC survival in ex vivo human retinal explants. In the oxidative stress-induced models, a significant decrease in the production of ROS was observed in the SA-2-treated group compared to the vehicle-treated group. Compound SA-2 was neuroprotective against various glaucomatous insults in the rat and human RGCs by reducing apoptosis and decreasing ROS levels. Amelioration of mitochondrial and cellular oxidative stress by SA-2 may be a potential therapeutic strategy for preventing neurodegeneration in glaucomatous RGCs.