Profile of biological characterizations and clinical application of corneal stem/progenitor cells.

Corneal stem/progenitor cells are typical adult stem/progenitor cells. The human cornea covers the front of the eyeball, which protects the eye from the outside environment while allowing vision. The location and function demand the cornea to maintain its transparency and to continuously renew its epithelial surface by replacing injured or aged cells through a rapid turnover process in which corneal stem/progenitor cells play an important role. Corneal stem/progenitor cells include mainly corneal epithelial stem cells, corneal endothelial cell progenitors and corneal stromal stem cells. Since the discovery of corneal epithelial stem cells (also known as limbal stem cells) in 1971, an increasing number of markers for corneal stem/progenitor cells have been proposed, but there is no consensus regarding the definitive markers for them. Therefore, the identification, isolation and cultivation of these cells remain challenging without a unified approach. In this review, we systematically introduce the profile of biological characterizations, such as anatomy, characteristics, isolation, cultivation and molecular markers, and clinical applications of the three categories of corneal stem/progenitor cells.

Effect of image-guided systems in phacoemulsification with intraocular lens (IOL) implantation: a systematic review and meta-analysis.

PURPOSE: To explore the effect of image-guided systems in phacoemulsification with intraocular lens (IOL) implantation. METHODS: We searched Pubmed, Embase and China National Knowledge Infrastructure (inception to January 20, 2021). Two researchers extracted data and assessed paper quality independently. Uncorrected distance visual acuity (UDVA) before and after surgery, best corrected visual acuity (BCVA) before and after surgery, preoperative cylinder, postoperative residual refractive cylinder, postoperative corneal cylinder, IOL misalignment, and intraocular pressure (IOP) were compared. RESULTS: We included 14 studies with 885 cataract eyes. All data were performed using Review Manager 5.3 (RevMan 5.3) (https://revman.cochrane.org/). Cases of all preoperative outcomes showed no significant difference between image-guided group and manual group. There was no significant difference in postoperative UDVA (Standard mean difference (SMD: -0.11, 95% CI: -0.32 to 0.11, I2 = 59%, p = 0.33)), BCVA (SMD: 0.03, 95% CI: -0.12 to 0.18, I2 = 36%, p = 0.72), corneal cylinder (Weighted mean difference WMD: 0.13, 95% CI: -0.06 to -0.32, I2 = 0%, p = 0.17), IOP (WMD: -0.37, 95% CI: -1.36 to -0.62, I2 = 9%, p = 0.46) between two groups. There was less residual refractive cylinder in image-guided group than in manual group (WMD: -0.20, 95% CI: -0.26 to -0.14, I2 = 59%, p＜0.00001). It is more accurate in IOL alignment when combined with image-guided systems (WMD: -1.20, 95% CI: -1.43 to -0.96, I2 = 14%, p < 0.00001). CONCLUSION: Image-guided systems can improve the effect in phacoemulsification with intraocular lens (IOL) implantation.

Protective effect of histatin 1 against ultraviolet-induced damage to human corneal epithelial cells.

The aim of the present study was to investigate the role of histatin 1 (Hst1) in human corneal epithelial cells (HCECs) exposed to ultraviolet (UV) radiation. Prior to UV irradiation for various durations, HCECs were pre-treated with different concentrations of Hst1 and the effect on cell apoptosis and cell viability were examined by flow cytometry, alamarBlue® and MTT assays to determine the optimal concentration of Hst1 and UV dose. Cells were then subjected to quantitative PCR, ELISA and western blot analysis to determine the expression of cell damage-associated genes. HCECs exposed to UV light for 1 h displayed decreased viability when compared to that of control cells, and a 3 h UV exposure markedly increased the apoptotic rate of HECEs, while apoptosis was inhibited by pre-treatment with Hst1. UV radiation downregulated expression of insulin-like growth factor (IGF)-1 and B-cell lymphoma 2 (Bcl-2), while it upregulated Bcl-2-associated X protein (Bax) expression. Hst1 protected HCECs against UV-induced damage by upregulating the expression of IGF-1 protein and increasing the Bcl-2/Bax ratio. In conclusion, Hst1 may prevent UV-induced damage to corneal epithelial tissue injury and promote its healing.

Protein kinase B (akt) promotes pathological angiogenesis in murine model of oxygen-induced retinopathy.

Akt, or protein kinase B, is an important signaling molecule that modulates many cellular processes such as cell growth, survival, and metabolism. However, the vivo roles and effectors of Akt in retinal angiogenesis are not explicitly clear. We therefore detected the expression of Akt using Western blotting or RT-PCR technologies in an animal model of oxygen-induced retinopathy, and investigated the effects of recombinant Akt on inhibiting vessels loss and Akt inhibitor on suppressing experimental retinal neovascularization in this model. We showed that in the hyperoxic phase of oxygen-induced retinopathy, the expression of Akt was greatly suppressed. In the hypoxic phase, the expression of Akt was increased dramatically. No significant differences were found in normoxic groups. Compared with control groups, administration of the recombinant Akt in the first phase of retinopathy markedly reduced capillary-free areas, while the administration of the Akt inhibitor in the second phase of retinopathy significantly decreased retinal neovascularization but capillary-free areas. These results indicate that Akt play a critical role in the pathological process (vessels loss and neovascularization) of mouse model of oxygen-induced retinopathy, which may provide a valubale therapeutic tool for ischemic-induced retinal diseases.