Neural stem cells transplanted to the subretinal space of rd1 mice delay retinal degeneration by suppressing microglia activation.

BACKGROUND AIMS: Retinal degeneration (RD) is an inherited eye disease characterized by irreversible photoreceptor loss. Conventionally, the activation of the resident microglia is secondary to the disease. Stem cell-based therapy has recently made rapid progress in treating RD. Although it has been demonstrated that the effect of stem cell therapy may include immunomodulation, the specific mechanisms have not been clarified. METHODS: Immunocytochemistry, terminal deoxynucleotidyl transferase UTP nick end labelling (TUNEL) assay and Western blot were used to analyze the microglia activation and photoreceptor apoptosis in the retina of rd1 mice. GFP-C17.2 neural stem cells (NSCs) were transplanted into the subretinal space to study the immunomodulatory and neuroprotective effects. The transwell co-culture of BV2 cells with GFP-C17.2 was performed to study the proliferation, apoptosis and secretion levels of inflammatory factors. Real time-quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) were performed to explore the gene and protein level of factors secreted by NSCs and microglia. RESULTS: TUNEL-positive cells were primarily distributed in the inner nuclear layer (INL) of rd1 mice on P8d, appeared in the outer nuclear layer (ONL) on P10d and peaked on P14d. Meanwhile, microglia migrated to the ONL and reached the maximum level, accompanied by the changes in the levels of fractalkine and its unique receptor CX3CR1 protein. After transplantation of NSCs on P7d into the subretinal space of rd1 mice, the activated microglia were inhibited and the degeneration of ONL was delayed. In addition, microglia activation was suppressed by co-cultured NSCs in vitro. The gene and protein level of tissue inhibitor of metalloproteinase (TIMP1) in NSCs was elevated, whereas that of matrix metalloproteinase (MMP9) in BV2 microglia was markedly suppressed in this co-culture system. CONCLUSIONS: Transplanted NSCs in the retina exerted immunomodulatory effects on microglia, thus delaying the degeneration of photoreceptors.

The effects of China's urban basic medical insurance schemes on the equity of health service utilisation: evidence from Shaanxi Province.

INTRODUCTION: In order to alleviate the problem of "Kan Bing Nan, Kan Bing Gui" (medical treatment is difficult to access and expensive) and improve the equity of health service utilisation for urban residents in China, the Urban Employee Basic Medical Insurance scheme (UEBMI) and Urban Resident Basic Medical Insurance scheme (URBMI) were established in 1999 and 2007, respectively. This study aims to analyse the effects of UEBMI and URBMI on the equity of outpatient and inpatient utilisation in Shaanxi Province, China. METHODS: Using the data from the fourth National Health Services Survey in Shaanxi Province, the method of Propensity Score Matching was employed to generate comparable samples between the insured and uninsured residents, through a one-to-one match algorithm. Next, based on the matched data, the method of decomposition of the concentration index was employed to compare the horizontal inequity indexes of health service utilisation between the UEBMI/URBMI insured and the matched uninsured residents. RESULTS: For the UEBMI insured and matched uninsured residents, the horizontal inequity indexes of outpatient visits are 0.1256 and -0.0511 respectively, and the horizontal inequity indexes of inpatient visits are 0.1222 and 0.2746 respectively. Meanwhile, the horizontal inequity indexes of outpatient visits are -0.1593 and 0.0967 for the URBMI insured and matched uninsured residents, and the horizontal inequity indexes of inpatient visits are 0.1931 and 0.3199 respectively. CONCLUSIONS: The implementation of UEBMI increased the pro-rich inequity of outpatient utilisation (rich people utilise outpatient facilities more than the poor people) and the implementation of URBMI increased the pro-poor inequity of outpatient utilisation. Both of these two health insurance schemes reduced the pro-rich inequity of inpatient utilisation.

Transplanted olfactory ensheathing cells restore retinal function in a rat model of light-induced retinal damage by inhibiting oxidative stress.

There is still not an effective treatment for continuous retinal light exposure and subsequent photoreceptor degeneration. Olfactory ensheathing cell (OEC) transplantation has been shown to be neuroprotective in spinal cord, and optic nerve injury and retinitis pigmentosa. However, whether OECs protect rat photoreceptors against light-induced damage and how this may work is unclear. Thus, to elucidate this mechanism, purified rat OECs were grafted into the subretinal space of a Long-Evans rat model with light-induced photoreceptor damage. Light exposure decreased a- and b- wave amplitudes and outer nuclear layer (ONL) thickness, whereas the ONL of rats exposed to light for 24 h after having received OEC transplants in their subretinal space was thicker than the PBS control and untreated groups. A- and b- wave amplitudes from electroretinogram of OEC-transplanted rats were maintained until 8 weeks post OEC transplantation. Also, transplanted OECs inhibited formation of reactive oxygen species in retinas exposed to light. In vitro experiments showed that OECs had more total antioxidant capacity in a co-cultured 661W photoreceptor cell line, and cells were protected from damage induced by hydrogen-peroxide. Thus, transplanted OECs preserved retinal structure and function in a rat model of light-induced degeneration by suppressing retinal oxidative stress reactions.

Features specific to retinal pigment epithelium cells derived from three-dimensional human embryonic stem cell cultures - a new donor for cell therapy.

Retinal pigment epithelium (RPE) transplantation is a particularly promising treatment of retinal degenerative diseases affecting RPE-photoreceptor complex. Embryonic stem cells (ESCs) provide an abundant donor source for RPE transplantation. Herein, we studied the time-course characteristics of RPE cells derived from three-dimensional human ESCs cultures (3D-RPE). We showed that 3D-RPE cells possessed morphology, ultrastructure, gene expression profile, and functions of authentic RPE. As differentiation proceeded, 3D-RPE cells could mature gradually with decreasing proliferation but increasing functions. Besides, 3D-RPE cells could form polarized monolayer with functional tight junction and gap junction. When grafted into the subretinal space of Royal College of Surgeons rats, 3D-RPE cells were safe and efficient to rescue retinal degeneration. This study showed that 3D-RPE cells were a new donor for cell therapy of retinal degenerative diseases.

Grafted c-kit+/SSEA1- eye-wall progenitor cells delay retinal degeneration in mice by regulating neural plasticity and forming new graft-to-host synapses.

BACKGROUND: Despite diverse pathogenesis, the common pathological change observed in age-related macular degeneration and in most hereditary retinal degeneration (RD) diseases is photoreceptor loss. Photoreceptor replacement by cell transplantation may be a feasible treatment for RD. The major obstacles to clinical translation of stem cell-based cell therapy in RD remain the difficulty of obtaining sufficient quantities of appropriate and safe donor cells and the poor integration of grafted stem cell-derived photoreceptors into the remaining retinal circuitry. METHODS: Eye-wall c-kit+/stage-specific embryonic antigen 1 (SSEA1)- cells were isolated via fluorescence-activated cell sorting, and their self-renewal and differentiation potential were detected by immunochemistry and flow cytometry in vitro. After labeling with quantum nanocrystal dots and transplantation into the subretinal space of rd1 RD mice, differentiation and synapse formation by daughter cells of the eye-wall c-kit+/SSEA1- cells were evaluated by immunochemistry and western blotting. Morphological changes of the inner retina of rd1 mice after cell transplantation were demonstrated by immunochemistry. Retinal function of rd1 mice that received cell grafts was tested via flash electroretinograms and the light/dark transition test. RESULTS: Eye-wall c-kit+/SSEA1- cells were self-renewing and clonogenic, and they retained their proliferative potential through more than 20 passages. Additionally, eye-wall c-kit+/SSEA1- cells were capable of differentiating into multiple retinal cell types including photoreceptors, bipolar cells, horizontal cells, amacrine cells, Müller cells, and retinal pigment epithelium cells and of transdifferentiating into smooth muscle cells and endothelial cells in vitro. The levels of synaptophysin and postsynaptic density-95 in the retinas of eye-wall c-kit+/SSEA1- cell-transplanted rd1 mice were significantly increased at 4 weeks post transplantation. The c-kit+/SSEA1- cells were capable of differentiating into functional photoreceptors that formed new synaptic connections with recipient retinas in rd1 mice. Transplantation also partially corrected the abnormalities of inner retina of rd1 mice. At 4 and 8 weeks post transplantation, the rd1 mice that received c-kit+/SSEA1- cells showed significant increases in a-wave and b-wave amplitude and the percentage of time spent in the dark area. CONCLUSIONS: Grafted c-kit+/SSEA1- cells restored the retinal function of rd1 mice via regulating neural plasticity and forming new graft-to-host synapses.