The authors examined the protective effects of adipose‐derived stem cells and adipose‐derived stem cell‐conditioned medium (ASC‐CM) against retinal damage and identified the neuroprotective factors in ASC‐CM. The findings suggest that ASC‐CM and progranulin have neuroprotective effects in the light‐induced retinal‐damage model. Progranulin may be a potential target for the treatment of the degenerative diseases of the retina.

The retina is highly sensitive to oxidative stress because of its high consumption of oxygen associated with the phototransductional processes. Recent findings have suggested that oxidative stress is involved in the pathology of age-related macular degeneration, a progressive degeneration of the central retina. A well-known environmental risk factor is light exposure, as excessive and continuous light exposure can damage photoreceptors. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional factor that controls antioxidative responses and phase 2 enzymes. Thus, we hypothesized that RS9, a specific activator of Nrf2, decreases light-induced retinal cell death in vivo and in vitro. Nrf2 was detected in the nucleus of the 661W cells exposed to RS9 and also after light exposure, and the Nrf2-antioxidant response element binding was increased in 661W cells after exposure to RS9. Consequentially, the expression of the phase 2 enzyme's mRNAs of Ho-1, Nqo-1, and Gclm genes was increased in 661W cells after exposure to RS9. Furthermore, RS9 decreased the light-induced death of 661W cells (2500 lux, 24 h), and also reduced the functional damages and the histological degeneration of the nuclei in the outer nuclear layer or the retina in the in vivo studies (8000 lux, 3 h). Heme oxygenase-1 was increased after light exposure, and Nrf2 was translocated into the nucleus after light exposure in vivo. Silencing of Ho-1 reduced the protective effects of RS9 against light-induced death of 661W cells. These findings indicate that RS9 has therapeutic potential for retinal diseases that are aggravated by light exposure.

Collectively, these results indicate that astaxanthin inhibits ischemia-induced retinal cell death via its antioxidant effect. Hence, astaxanthin might be effective in treating retinal ischemic pathologies.

Abstract. Dietary carotenoids exhibit various biological activities, including antioxidative activity. In particular, astaxanthin, a type of carotenoid, is well known as a powerful antioxidant. We investigated whether astaxanthin would protect against light-induced retinal damage. In an in vivo study, ddY male mice were exposed to white light at 8,000 lux for 3 h to induce retinal damage. Five days after light exposure, retinal damage was evaluated by measuring electroretinogram (ERG) amplitude and outer nuclear layer (ONL) thickness. Furthermore, expression of apoptotic cells, 8-hydroxy-deoxyguanosine (8-OHdG), was measured. In an in vitro study, retinal damage was induced by white light exposure at 2,500 lux for 24 h, and propidium iodide (PI)-positive cells was measured and intracellular reactive oxygen species (ROS) activity was examined. Astaxanthin at 100 mg/kg inhibited the retinal dysfunction in terms of ERG and ONL loss and reduced the expression of apoptotic and 8-OHdG-positive cells induced by light exposure. Furthermore, astaxanthin protected against increases of PI-positive cells and intracellular reactive oxygen species (ROS) activity in 661W cells. These findings suggest that astaxanthin has protective effects against light-induced retinal damage via the mechanism of its antioxidative effect.

We evaluated the use of quantitative MRI relaxometry, including the dispersion of spin‐lock relaxation with different locking fields, for detecting and assessing tubular dilation and fibrosis in a mouse model of unilateral ureter obstruction (UUO). C57BL/6 J and BALB/c mice that exhibit different levels of tubular dilation and renal fibrosis after UUO were subjected to MR imaging at 7 T. Mice were imaged before UUO surgery, and at 5, 10 and 15 days after surgery. We acquired maps of relaxation rates and fit the dispersion of spin‐lock relaxation rates R1ρ at different locking fields (frequencies) to a model of exchanging water pools, and assessed the sensitivity of the derived quantities for detecting tubular dilation and fibrosis in kidney. Histological scores for tubular dilation and fibrosis, based on luminal space and positive fibrotic areas in sections, were obtained for comparison. Histology detected extensive tubular dilation and mild to moderate fibrosis in the UUO kidneys, in which enlargement of luminal space, deposition of collagen, and reductions in capillary density were observed in the cortex and outer stripe of the outer medulla. Relaxation rates R1, R2 and R1ρ clearly decreased in these regions of UUO kidneys longitudinally. While R1 showed the highest detectability to tubular dilation and overall changes in UUO kidneys, Sρ, a parameter derived from R1ρ dispersion data, showed the highest correlation with renal fibrosis in UUO. While relaxation parameters are sensitive to tubular dilation in UUO kidneys, Sρ depends primarily on the average exchange rate between water and other chemically shifted resonances such as hydroxyls and amides, and provides additional specific information for evaluating fibrosis in kidney disease.