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AIM: To observe the effect of low oxygen concentration on the neural retina in human induced pluripotent stem cell (hiPSC)-derived retinal organoids (ROs). METHODS: The hiPSC and a three-dimensional culture method were used for the experiments. Generated embryoid bodies (EBs) were randomly and equally divided into hypoxic and normoxic groups. Photographs of the EBs were taken on days 38, 45, and 52, and the corresponding volume of EBs was calculated. Simultaneously, samples were collected at these three timepoints, followed by fixation, sectioning, and immunofluorescence. RESULTS: The proportion of Ki67-positive proliferating cells increased steadily on day 38; this proliferation-promoting effect tended to increase tissue density rather than tissue volume. On days 45 and 52, the two groups had relatively similar ratios of Ki67-positive cells. Further immunofluorescence analysis showed that the ratio of SOX2-positive cells significantly increased within the neural retina on day 52 (P<0.05). In contrast, the percentage of PAX6- and CHX10-positive cells significantly decreased following hypoxia treatment at all three timepoints (P<0.01), except for CHX10 at day 45 (P>0.05). Moreover, the proportion of PAX6-/TUJ1+ cells within the neural retinas increased considerably (P<0.01, <0.05, <0.05 respectively). CONCLUSION: Low oxygen promotes stemness and proliferation of neural retinas, suggesting that hypoxic conditions can enlarge the retinal progenitor cell pool in hiPSC-derived ROs.
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AIM: To quantitatively evaluate the risk of anxiety and depression in patients with uveitis via performing a Meta-analysis. METHODS: Three electronic database (PubMed, Embase, and Cochrane Library databases) were searched for studies recording data about uveitis and anxiety as well as depression simultaneously up to January 2021. The incidence rate and standard mean difference (SMD) with a 95% confidence interval (95%CI) were calculated to analyse the association using random-effects models based on heterogeneity tests. RESULTS: In total, 12 observational studies containing 874 patients with uveitis were included. The results showed that there was a significant association between uveitis and anxiety (SMD=0.97, 95%CI: 0.39 to 1.54, P=0.0009) and depression (SMD=0.79, 95%CI: 0.51 to 1.07, P<0.00001). The overall morbidities of anxiety and depression in patients with uveitis were 39% and 17%, respectively. With subgroup analysis, the heterogeneity actually came from different kinds of uveitis. Specifically, the incidence rates of both anxiety and depression were relatively low in patients with anterior uveitis (33% and 15%), moderate in patients with infectious uveitis (46% and 22%), and high in patients with unspecified uveitis (59% and 35%). CONCLUSION: It is preliminarily indicated that patients with uveitis may have a high risk of anxiety and depression. Ophthalmologists and psychologists should pay more attention to the psychological state when dealing with patients with uveitis. Further high-quality studies with detailed direct data are needed to draw more precise conclusions.
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The biosafety and efficiency of transplanting retinal pigment epithelial (RPE) cells derived from both human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) have been evaluated in phase I and phase II clinical trials. For further large-scale application, cryopreserved RPE cells must be used; thus, it is highly important to investigate the influence of cryopreservation and thawing on the biological characteristics of hESC-RPE cells and their post-transplantation vision-restoring function. Here, via immunofluorescence, qPCR, transmission electron microscopy, transepithelial electrical resistance, and enzyme-linked immunosorbent assays (ELISAs), we showed that cryopreserved hESC-RPE cells retained the specific gene expression profile, morphology, ultrastructure, and maturity-related functions of induced RPE cells. Additionally, cryopreserved hESC-RPE cells exhibited a polarized monolayer, tight junction, and gap junction structure and an in vitro nanoparticle phagocytosis capability similar to those of induced hESC-RPE cells. However, the level of pigment epithelium-derived factor (PEDF) secretion was significantly decreased in cryopreserved hESC-RPE cells. Royal College of Surgeons rats with cryopreserved hESC-RPE cells engrafted into the subretinal space exhibited a significant decrease in the b-wave amplitude compared with rats engrafted with induced hESC-RPE cells at 4 weeks post transplantation. However, the difference disappeared at 8 weeks and 12 weeks post operation. No significant difference in the outer nuclear layer (ONL) thickness was observed between the two groups. Our data showed that even after cryopreservation and thawing, cryopreserved hESC-RPE cells are still qualified as a donor cell source for cell-based therapy of retinal degenerative diseases.
