The Role of the miR-21/SPRY2 Axis in Modulating Proangiogenic Factors, Epithelial Phenotypes, and Wound Healing in Corneal Epithelial Cells

Tetrahedral DNA-Based Functional MicroRNA-21 Delivery System: Application to Corneal Epithelial Wound Healing

Corneal injury occurs frequently which may lead to serious visual impairment. Rapid and efficient re-epithelialization after corneal epithelial injury is the key issue for maintaining corneal homeostasis. Among various treatment strategies, microRNA (miR)-based therapy shows great potential. However, structural limitations of miRNAs hinder its biomedical functionality. Nucleic acid nanotechnology is an appealing candidate for gene delivery because of its flexible modification and excellent biocompatibility. Herein, modified 3D tetrahedral framework nucleic acids (tFNAs) utilized as gene carriers for miR-21 delivery are constructed. TFNAs-miR-21 (T-21) shows great enzymatic resistance in extracellular environment and payload delivery into human corneal epithelial cells (HCECs) via clathrin-mediated endocytosis. T-21 facilitates proliferation and migration in HCECs via activating PI3K/AKT and ERK1/2 signaling pathways in vitro. In vivo studies, T-21 can be internalized by corneal epithelium in mice. In the mice corneal scratch model, T-21 ophthalmic solutions used as eye drops show no apparent side effects on the ocular surface histologically and exert great potential in accelerating corneal wound healing. These findings demonstrate that modified tFNAs are promising candidates for miRNA delivery for corneal wound healing. The convenient administration and great biocompatibility of tetrahedral DNA nanoparticles highlight its potential as gene transporter in solving ocular problems.

Sodium hyaluronate promotes proliferation, autophagy, and migration of corneal epithelial cells by downregulating miR-18a in the course of corneal epithelial injury

Corneal epithelium can resist the invasion of external pathogenic factors to protect the eye from external pathogens. Sodium hyaluronate (SH) has been confirmed to promote corneal epithelial wound healing. However, the mechanism by which SH protects against corneal epithelial injury (CEI) is not fully understood. CEI model mice were made by scratching the mouse corneal epithelium, and in vitro model of CEI were constructed via curettage of corneal epithelium or ultraviolet radiation. The pathologic structure and level of connective tissue growth factor (CTGF) expression were confirmed by Hematoxylin and Eosin staining and immunohistochemistry. CTGF expression was detected by an IHC assay. The levels of CTGF, TGF-β, COLA1A, FN, LC3B, Beclin1, and P62 expression were monitored by RT-qPCR, ELISA, Western blotting or immunofluorescence staining. Cell proliferation was detected by the CCK-8 assay and EdU staining. Our results showed that SH could markedly upregulate CTGF expression and downregulate miR-18a expression in the CEI model mice. Additionally, SH could attenuate corneal epithelial tissue injury, and enhance the cell proliferation and autophagy pathways in the CEI model mice. Meanwhile, overexpression of miR-18a reversed the effect of SHs on cell proliferation and autophagy in CEI model mice. Moreover, our data showed that SH could induce the proliferation, autophagy, and migration of CEI model cells by downregulating miR-18a. Down-regulation of miR-18a plays a significant role in the ability of SH to promote corneal epithelial wound healing. Our results provide a theoretical basis for targeting miR-18a to promote corneal wound healing.

Targeting exosomes enveloped EBV-miR-BART1-5p-antagomiRs for NPC therapy through both anti-vasculogenic mimicry and anti-angiogenesis

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a type of head and neck cancer with high incidence in China. The molecular mechanisms of vasculogenic mimicry (VM) and angiogenesis are not fully elucidated in NPC. More specially, it has seldomly been reported that Epstein-Barr virus-encoded miRNA can regulate VM and angiogenesis in NPC. The aim of this study was to investigate the function and molecular mechanism of a targeting exosome system (iRGD-exo-antagomiR) against VM and angiogenesis in NPC, and to provide new approaches for improving the comprehensive treatment of NPC.

METHODS

Exosomes were isolated by differential ultracentrifugation. Dynamic light scattering, transmission electron microscopy and western blotting were performed to characterize the exosomes. The 3D-Culture assay, tube formation assay, chicken chorioallantoic membrane assay, Matrigel plug assay, mouse xenograft tumor modeling and immunohistochemical staining were applied to evaluate the anti-VM and anti-angiogenic effects of the targeting exosome system in vitro and in vivo. Western blot was performed to detect the changes of downstream regulated networks following interference and recovery of the target gene.

RESULTS

In vitro or in vivo treatment with iRGD-tagged exosome containing antagomiR-BART1-5p specifically suppressed VM and angiogenesis in NPC. EBV-miR-BART1-5p promoted VM and angiogenesis in vitro and in vivo by regulating VEGF, PI3K, Akt, mTOR and HIF1-α in a Spry2-dependent manner.

CONCLUSIONS

Our findings demonstrated that targeting exosomes enveloped EBV-miR-BART1-5p-antagomiRs in a Spry2-dependent manner for NPC therapy through both anti-VM and anti-angiogenesis in vitro and in vivo.

Proteomic profiling of human corneal stroma from long-term contact lens wearers reveals activation of inflammatory responses

PURPOSE

To investigate the association between proteomic changes and potential pathogenesis in the human cornea with respect to the duration of wearing soft contact lenses (SCLs).

METHODS

A total of 96 corneal stroma samples, obtained via small incision lenticule extraction (SMILE), were equally grouped according to the duration of wearing SCL: 0Y, did not wear SCL; 5Y, wore SCL for<5 years; 5-10Y, wore SCL for 5-10 years; O10Y, wore SCL for>10 years. Liquid chromatography-tandem mass spectrometry was used to identify and quantify protein profiles in the corneal stroma. Expression levels of CO1A1, CO4A1, NFKB1, and IL6RB were determined using western blot and immunohistochemistry analysis.

RESULTS

This study quantified a total of 5,668 proteins across samples and identified 2,379 differentially expressed proteins (DEPs) with significantly increased abundance in the three SCL-wearing groups compared with that in the non-SCL-wearing group. Compared with those in the 0Y group, the molecular functions of DEPs in the 5Y, 5-10Y, and O10Y groups were mainly related to translation regulator activity, antigen binding, peptidase inhibitor activity, participation in extracellular matrix (ECM) production, complement activation, and inflammatory responses. Pathway enrichment analysis of DEPs showed that the sphingolipid, phosphatidylinositol 3-kinase-protein kinase B, and hypoxia-inducible factor-1 signaling pathways were activated in the human corneal stroma after long-term SCL use.

CONCLUSIONS

Inflammation-related proteomic components in human corneal stroma increased after long-term use of SCL and may act as an essential factor in the molecular pathogenesis of corneal stroma damage.

Molecular Mediators and Regulators of Retinal Angiogenesis

BACKGROUND

Retinal neovascularization is the major cause of vision loss that affects both adults and young children including premature babies. It has been a major pathology in several retinal diseases like age-related macular degeneration (AMD), diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Current treatment modalities such as anti-VEGF therapy, laser are not suitable for every patient and response to these therapies is highly variable. Thus, there is a need to investigate newer therapeutic targets for DR, ROP and AMD, based on a clear understanding of disease pathology and regulatory mechanisms involved.

METHOD

Appropriate articles published till February 2021 were extracted from PUBMED using keywords like ocular angiogenesis, DR, ROP, AMD, miRNA, mRNA, and cirMiRNA and containvaluable information regarding the involvement of miRNA in causing neovascularization. After compiling the list of miRNA regulating mRNA expression in angiogenesis and neovascularaization, their interactions were studied using online available tool MIENTURNET (http://userver.bio.uniroma1.it/apps/mienturnet/). The pathways involved in these processes were also predicted using the same tool.

RESULTS

Most of the studies have explored potential targets like HIF1-α, PDGF, TGFβ, FGF, etc., for their involvement in pathological angiogenesis in different retinal diseases. The regulatory role of microRNA (miRNA) has also been explored in various retinal ocular pathologies. This review highlights regulatory mechanism of cellular and circulatory miRNAs and their interactions with the genes involved in retinal neovascularization. The role of long noncoding RNA (ncRNA) in the regulation of genes involved in different pathways is also noteworthy and discussed in this review.

CONCLUSION

This review highlights the potential regulatory mechanism/pathways involved in retinal neovascularization and its implications in retinal diseases and for identifying new drug targets.

Non-coding RNAs in immunoregulation and autoimmunity: Technological advances and critical limitations

Immune cell function is critically dependent on precise control over transcriptional output from the genome. In this respect, integration of environmental signals that regulate gene expression, specifically by transcription factors, enhancer DNA elements, genome topography and non-coding RNAs (ncRNAs), are key components. The first three have been extensively investigated. Even though non-coding RNAs represent the vast majority of cellular RNA species, this class of RNA remains historically understudied. This is partly because of a lag in technological and bioinformatic innovations specifically capable of identifying and accurately measuring their expression. Nevertheless, recent progress in this domain has enabled a profusion of publications identifying novel sub-types of ncRNAs and studies directly addressing the function of ncRNAs in human health and disease. Many ncRNAs, including circular and enhancer RNAs, have now been demonstrated to play key functions in the regulation of immune cells and to show associations with immune-mediated diseases. Some ncRNAs may function as biomarkers of disease, aiding in diagnostics and in estimating response to treatment, while others may play a direct role in the pathogenesis of disease. Importantly, some are relatively stable and are amenable to therapeutic targeting, for example through gene therapy. Here, we provide an overview of ncRNAs and review technological advances that enable their study and hold substantial promise for the future. We provide context-specific examples by examining the associations of ncRNAs with four prototypical human autoimmune diseases, specifically rheumatoid arthritis, psoriasis, inflammatory bowel disease and multiple sclerosis. We anticipate that the utility and mechanistic roles of these ncRNAs in autoimmunity will be further elucidated in the near future.

Perfluorodecalin-based oxygenated emulsion as a topical treatment for chemical burn to the eye

Chemical injuries to the eye are emergencies with limited acute treatment options other than prompt irrigation and can cause permanent vision loss. We developed a perfluorodecalin-based supersaturated oxygen emulsion (SSOE) to topically deliver high concentration of oxygen to the eye. SSOE is manufactured in hyperbaric conditions and stored in a ready-to-use canister. Upon dispensation, SSOE rapidly raises partial oxygen pressure 3 times over atmospheric level. SSOE is biocompatible with human corneal cells and safe on mouse eyes in vivo. A single topical application of SSOE to the eye after alkali injury significantly promotes corneal epithelial wound healing, decreases anterior chamber exudation, and reduces optical opacity and cataract formation in mice. SSOE treatment reduces intraocular hypoxia, cell death, leukocyte infiltration, production of inflammatory mediators, and hypoxia-inducible factor 1-alpha signaling, thus hastening recovery of normal tissue integrity during the wound healing process. Here, we show that SSOE is an effective topical therapeutic in the acute treatment of ocular chemical injuries.

Umbilical Cord Mesenchymal Stem Cell-Derived Small Extracellular Vesicles Deliver miR-21 to Promote Corneal Epithelial Wound Healing through PTEN/PI3K/Akt Pathway

Objective

Rapid restoration of corneal epithelium integrity after injury is particularly important for preserving corneal transparency and vision. Mesenchymal stem cells (MSCs) can be taken into account as the promising regenerative therapeutics for improvement of wound healing processes based on the variety of the effective components. The extracellular vesicles form MSCs, especially exosomes, have been considered as important paracrine mediators though transferring microRNAs into recipient cell. This study investigated the mechanism of human umbilical cord MSC-derived small extracellular vesicles (HUMSC-sEVs) on corneal epithelial wound healing.

Methods

HUMSC-sEVs were identified by transmission electron microscopy, nanoparticle tracking analysis, and Western blot. Corneal fluorescein staining and histological staining were evaluated in a corneal mechanical wound model. Changes in HCEC proliferation after HUMSC-sEVs or miR-21 mimic treatment were evaluated by CCK-8 and EdU assays, while migration was assessed by in vitro scratch wound assay. Full-length transcriptome sequencing was performed to identify the differentially expressed genes associated with HUMSC-sEVs treatment, followed by validation via real-time PCR and Western blot.

Results

The sEVs derived from HUMSCs can significantly promote corneal epithelial cell proliferation, migration in vitro, and corneal epithelial wound healing in vivo. Similar effects were obtained after miR-21 transfection, while the beneficial effects of HUMSC-sEVs were partially negated by miR-21 knockdown. Results also show that the benefits are associated with decreased PTEN level and activated the PI3K/Akt signaling pathway in HCECs.

Conclusion

HUMSC-sEVs could enhance the recovery of corneal epithelial wounds though restraining PTEN by transferring miR-21 and may represent a promising novel therapeutic agent for corneal wound repair.

MiR-335 promotes corneal neovascularization by Targeting EGFR

Background

Corneal neovascularization (CRNV) is a severe threat to the vision of people. MicroRNA-335 (miR-335) has the function of facilitating angiogenesis. However, whether miR-335 regulates the progression of CRNV remains unclear.

Methods

The miR-335 expressions in CRNV rats induced by corneal suture and HUVECs induced by b-FGF were detected by quantitative real-time PCR. For the miR-335 function, wound healing and tube formation assays were performed. For the miR-335 mechanism, a dual-luciferase reporter gene assay was conducted. Besides, for the epidermal growth factor receptor (EGFR) function, Cell Counting Kit-8 and wound healing assays were performed. Meanwhile, the rescue assay was used to assess the miR-335/EGFR function in the migration and angiogenesis of b-FGF-treated HUVECs.

Results

Functionally, the miR-335 knockdown weakened the migration and angiogenesis of b-FGF-treated HUVECs, while the miR-335 overexpression showed an opposite trend. Mechanistically, miR-335 interacted with EGFR and negatively regulated the expression of EGFR. The rescue assay illustrated that miR-335 regulated the migration and angiogenesis of b-FGF-treated HUVECs through EGFR.

Conclusions

In general, our data confirmed that miR-335 facilitated the process of CRNV by targeting EGFR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02481-0.

Targeting HMGB1-NFκb Axis and miR-21 by Glycyrrhizin: Role in Amelioration of Corneal Injury in a Mouse Model of Alkali Burn

Corneal neovascularization (CNV) is a sight-threatening condition usually associated with various inflammatory settings including chemical injury. High mobility group box 1 (HMGB1) is identified as an inflammatory alarmin in diverse tissue damage. Here, we evaluate the expression of HMGB1 and the consequences of its inhibition through its selective inhibitor glycyrrhizin (GLY) in alkali burn-induced corneal inflammation and neovascularization. GLY effectively attenuated alkali burn-induced HMGB1 expression at both mRNA and protein levels. Furthermore, slit-lamp analysis, ink perfusion, H&amp;E staining, and CD31 histochemical staining showed that GLY relieved corneal neovascularization, while GLY attenuated VEGF expression via inhibiting HMGB1/NF-κB/HIF-1α signal pathway. In addition, GLY treatment decreased the cytokine expression of CCL2 and CXCL5, accompanied by the reduction of their receptors of CCR2 and CXCR2. GLY diminished the inflammatory cell infiltration of the cornea, as well as reduced the expression of IL-1β, IL-6, and TNF-α. Moreover, treatment with GLY reduced the degree of cornea opacity through inactivating extracellular HMGB1 function, which otherwise induces TGF-β1 release and myofibroblast differentiation. Furthermore, we found that GLY treatment attenuated the upregulation of miR-21 levels in alkali burned cornea; while inhibition of miR-21in keratocytes in vitro, significantly inhibited TGF-β1-induced myofibroblast differentiation. Collectively, our results suggested that targeting HMGB1-NFκb axis and miR-21 by GLY could introduce a therapeutic approach to counter CNV.

Overexpression of Renin-B Induces Warburg-like Effects That Are Associated with Increased AKT/mTOR Signaling

The classical secretory renin-a is known to be involved in angiotensin generation, thereby regulating not only blood pressure, but also promoting oxidative stress as well as apoptotic and necrotic cell death. In contrast, another cytosolic renin isoform named renin-b has been described, exerting protective effects under ischemia-related conditions in H9c2 cardiomyoblasts. Using microarray-based transcriptome analyses, we aimed to identify the signaling pathways involved in mediating cardioprotection in H9c2 cells overexpressing renin-b. By transcriptome profiling, we identified increased gene expression of several genes encoding glycolytic enzymes and glucose transporters, while the transcript levels of TCA-cycle enzymes were decreased. Complementing data from metabolic analyses revealed enhanced glucose consumption and lactate accumulation due to renin-b overexpression. Renin-b overexpression further stimulated AKT/mTOR signaling, where numerous genes involved in this pathway showed altered transcript levels. For AKT, we also detected enhanced phosphorylation levels by means of Western blotting, suggesting an activation of this kinase. Moreover, analysis of the ROS levels identified an increase in ROS accumulation in renin-b-overexpressing cells. Altogether, our data demonstrate that renin-b overexpression induces the metabolic remodeling of H9c2 cells similar to that seen under oxygen deprivation. This metabolic phenotype exerting so-called aerobic glycolysis is also known as the Warburg effect.

Roles of MicroRNA-21 in Skin Wound Healing: A Comprehensive Review

MicroRNA-21 (miR-21), one of the early mammalian miRNAs identified, has been detected to be upregulated in multiple biological processes. Increasing evidence has demonstrated the potential values of miR-21 in cutaneous damage and skin wound healing, but lack of a review article to summarize the current evidence on this issue. Based on this review, relevant studies demonstrated that miR-21 played an essential role in wound healing by constituting a complex network with its targeted genes (i.e., PTEN, RECK. SPRY1/2, NF-κB, and TIMP3) and the cascaded signaling pathways (i.e., MAPK/ERK, PI3K/Akt, Wnt/β-catenin/MMP-7, and TGF-β/Smad7-Smad2/3). The treatment effectiveness developed by miR-21 might be associated with the promotion of the fibroblast differentiation, the improvement of angiogenesis, anti-inflammatory, enhancement of the collagen synthesis, and the re-epithelialization of the wound. Currently, miRNA nanocarrier systems have been developed, supporting the feasibility clinical feasibility of such miR-21-based therapy. After further investigations, miR-21 may serve as a potential therapeutic target for wound healing.

CHIR99021 balance TGFβ1 induced human corneal endothelial-to-mesenchymal transition to favor corneal endothelial cell proliferation

Corneal endothelial cells (CECs) play a major role in the maintenance of stromal hydration via the barrier and pump function for clear vision. Adult CEC cannot regenerate after injury. CECs cultured in vitro can undergo mitosis but may undergo corneal endothelial-to-mesenchymal transition (EnMT) and lose their endothelial characteristics. In this study, we examined the effects of CHIR99201 on transforming growth factor beta-1(TGFβ1)-induced EnMT in human CEC (hCECs) lines. CHIR99021 kept hCECs in the hexagonal shape and could downregulate the EnMT markers alpha-smooth muscle actin (α-SMA) and fibronectin (FN1), meanwhile maintained the hCECs function markers Na⁺/K⁺-ATPase and zonula occludens-1 (ZO-1) at levels comparable to those in the normal control. Interestingly, we found that the combination of CHIR99021 and TGFβ1 at appropriate concentrations would significantly promote the proliferation and migration of hCECs. These effects may be related to the inhibition of RhoA or Rac1, as well as the activation of Wnt and Erk pathway, with a calcium homeostasis. Our findings indicate that CHIR99021 inhibit EnMT and that the combination of CHIR99021 and TGFβ1 may provide new ideas for corneal endothelial regeneration and wound healing.

Hypoxia adaptation in the cornea: Current animal models and underlying mechanisms

The cornea is an avascular, transparent tissue that is essential for visual function. Any disturbance to the corneal transparency will result in a severe vision loss. Due to the avascular nature, the cornea acquires most of the oxygen supply directly or indirectly from the atmosphere. Corneal tissue hypoxia has been noticed to influence the structure and function of the cornea for decades. The etiology of hypoxia of the cornea is distinct from the rest of the body, mainly due to the separation of cornea from the atmosphere, such as prolonged contact lens wearing or closed eyes. Corneal hypoxia can also be found in corneal inflammation and injury when a higher oxygen requirement exceeds the oxygen supply. Systemic hypoxic state during lung diseases or high altitude also leads to corneal hypoxia when a second oxygen consumption route from aqueous humor gets blocked. Hypoxia affects the cornea in multiple aspects, including disturbance of the epithelium barrier function, corneal edema due to endothelial dysfunction and metabolism changes in the stroma, and thinning of corneal stroma. Cornea has also evolved mechanisms to adapt to the hypoxic state initiated by the activation of hypoxia inducible factor (HIF). The aim of this review is to introduce the pathology of cornea under hypoxia and the mechanism of hypoxia adaptation, to discuss the current animal models used in this field, and future research directions.

m(6)A demethylase ALKBH5 inhibits cell proliferation and the metastasis of colorectal cancer by regulating the FOXO3/miR-21/SPRY2 axis

OBJECTIVE

Colorectal cancer is a common malignancy worldwide. This research aimed to investigate the role of α-ketoglutarate-dependent dioxygenase alkB homologue 5 (ALKBH5), a N6-methyladenosine (m(6)A) demethylase, on the cell proliferation and metastasis of colorectal cancer.

METHODS

The interaction relationship between FOXO3, miR-21, and SPRY2 were predicted by starBase 2.0 and determined using RIP, CHIP, and dual-luciferase reporter assays. Quantitative reverse transcription PCR (RT-qPCR) and western blot were used to measure the gene and miRNA expressions of ALKBH5, FOXO3, miR-21, and SPRY2. The cell proliferation was determined using CCK8 and colony formation assays. The metastatic abilities were measured using wound healing and transwell assays.

RESULTS

In colorectal cancer, downregulated ALKBH5 is related to poor prognosis. Rescued ALKBH5 suppresses the proliferation and metastasis of colorectal cancer cells. The role of ALKBH5 is achieved by reducing the m(6)A modification of forkhead box O3 (FOXO3), which enhances its stability. FOXO3 targets miR-21 and increases the SPRY2 expressions. The antitumor effects of ALKBH5 can be blocked by FOXO3 knockdown, which is reversed by the miR-21 inhibitor.

CONCLUSION

ALKBH5 plays an antitumor role in colorectal cancer by regulating the FOXO3/miR-21/SPRY2 axis, providing a new direction for colorectal cancer therapy.

Oncologic feasibility for negative pressure wound therapy application in surgical wounds: A meta-analysis

Negative pressure wound therapy (NPWT) decreases postoperative complications of various surgeries. However, the use of NPWT for oncological surgical wounds remains controversial. To evaluate the association of NPWT with oncologic recurrence in surgical wounds without residual malignancy, we analysed studies that compared NPWT with conventional non‐pressure dressings for cancer surgical wounds without residual tumour by August 12, 2020. We compared tumour recurrence rates and postoperative complications between the two procedures. The six studies included 118 patients who received NPWT, and 149 patients who received conventional non‐pressure wound care. The overall quality of the included studies was high based on the Newcastle–Ottawa scale score of 7.5. Tumour recurrence after NPWT was not significantly different compared with conventional non‐negative pressure wound care (9.3% versus 11.4%, P = 0.40). There was no significant heterogeneity between the studies (I² = 3%). Although NTWT was associated with a lower complication rate compared with the control group, the result was non‐significant (P = 0.15). Application of NPWT in oncologic resection wounds without residual malignancy revealed no difference in local recurrence and may reduce the risk of postoperative complications compared with conventional non‐negative pressure dressings. NPWT can be considered an alternative method for reconstruction in challenging cases.

MicroRNA-124 facilitates lens epithelial cell apoptosis by inhibiting SPRY2 and MMP-2

Age-related cataract (ARC) is the primary cause of blindness worldwide. Abnormal expression of microRNAs (miRNAs/miRs) has been reported to be associated with multiple diseases, including ARC. However, the potential role of miR-124 in ARC remains unclear. The present study used the human lens epithelial cell line, SRA01/04, to investigate the potential role of miR-124 in ARC. Reverse transcription-quantitative PCR analysis was performed to detect the expression levels of miR-124, protein sprouty homolog 2 (SPRY2) and matrix metalloproteinase-2 (MMP-2) in ARC tissues, while western blotting was performed to detect the protein levels of SPRY2 and MMP-2. Cell viability and apoptosis of SRA01/04 cells were assessed via Cell Counting Kit-8 and TUNEL assays, respectively. The interaction between miR-124 and SPRY2 or MMP-2 was confirmed via the dual-luciferase reporter and RNA immunoprecipitation assays. The results of the present study demonstrated that miR-124 expression was significantly upregulated in ARC tissues, and knockdown of miR-124 increased SRA01/04 cell viability and suppressed apoptosis. In addition, SPRY2 and MMP-2 expression was decreased in ARC tissues, and were demonstrated to directly bind to miR-124. Overexpression of SPRY2 or MMP-2 increased SRA01/04 cell viability and repressed apoptosis, the effects of which were reversed following overexpression of miR-124. Taken together, these results suggested that miR-124 facilitates lens epithelial cell apoptosis by modulating SPRY2 or MMP-2 expression, providing a novel treatment approach for ARC.

Crosstalk between MicroRNA and Oxidative Stress in Primary Open-Angle Glaucoma

Reactive oxygen species (ROS) plays a key role in the pathogenesis of primary open-angle glaucoma (POAG), a chronic neurodegenerative disease that damages the trabecular meshwork (TM) cells, inducing apoptosis of the retinal ganglion cells (RGC), deteriorating the optic nerve head, and leading to blindness. Aqueous humor (AH) outflow resistance and intraocular pressure (IOP) elevation contribute to disease progression. Nevertheless, despite the existence of pharmacological and surgical treatments, there is room for the development of additional treatment approaches. The following review is aimed at investigating the role of different microRNAs (miRNAs) in the expression of genes and proteins involved in the regulation of inflammatory and degenerative processes, focusing on the delicate balance of synthesis and deposition of extracellular matrix (ECM) regulated by chronic oxidative stress in POAG related tissues. The neutralizing activity of a couple of miRNAs was described, suggesting effective downregulation of pro-inflammatory and pro-fibrotic signaling pathways, including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), transforming growth factor-beta 2 (TGF-β2), Wnt/β-Catenin, and PI3K/AKT. In addition, with regards to the elevated IOP in many POAG patients due to increased outflow resistance, Collagen type I degradation was stimulated by some miRNAs and prevented ECM deposition in TM cells. Mitochondrial dysfunction as a consequence of oxidative stress was suppressed following exposure to different miRNAs. In contrast, increased oxidative damage by inhibiting the mTOR signaling pathway was described as part of the action of selected miRNAs. Summarizing, specific miRNAs may be promising therapeutic targets for lowering or preventing oxidative stress injury in POAG patients.

Exosomal miR-27 negatively regulates ROS production and promotes granulosa cells apoptosis by targeting SPRY2 in OHSS

Ovarian hyperstimulation syndrome (OHSS) is one of the most dangerous iatrogenic complications in controlled ovarian hyperstimulation (COH). The exact molecular mechanism that induces OHSS remains unclear. In recent years, accumulating evidence found that exosomal miRNAs participate in many diseases of reproductive system. However, the specific role of miRNAs, particularly the follicular fluid-derived exosomal miRNAs in OHSS remains controversial. To identify differentially expressed follicular fluid exosomal miRNAs from OHSS and non-OHSS patients, the analysis based on miRNA-sequence was conducted. The levels of 291 miRNAs were significantly differed in exosomes from OHSS patients compared with normal control, and exosomal miR-27 was one of the most significantly down-regulated miRNAs in the OHSS group. By using MiR-27 mimic, we found it could increase ROS stress and apoptosis by down-regulating the expression of p-ERK/Nrf2 pathway by negatively regulating SPRY2. These data demonstrate that exosomal miRNAs are differentially expressed in follicular fluid between patients with and without OHSS, and follicular fluid exosomal miR-27 may involve in the pathological process of OHSS development.

An update: mechanisms of microRNA in primary open-angle glaucoma

Glaucoma is a disease with characteristic optic neuropathy and loss of vision, leading to blindness, and primary open-angle glaucoma (POAG) is the most common glaucoma type throughout the world. Genetic susceptibility is the main factor in POAG, and most susceptibility genes cause changes in microRNA expression and function, thereby leading to POAG occurrence and development. Increasing evidence indicates that many microRNAs are involved in the regulation of intraocular pressure (IOP) and play an important role in the increase in IOP in POAG. Additionally, microRNA is closely related to optic nerve damage factors (mechanical stress, hypoxia and inflammation). This review discusses the effect of single-nucleotide polymorphisms in POAG-related genes on microRNA and the value of microRNA in the diagnosis and treatment of POAG.

Exosomes Derived from Bone Mesenchymal Stem Cells with the Stimulation of Fe3O4 Nanoparticles and Static Magnetic Field Enhance Wound Healing Through Upregulated miR-21-5p

Background

Both magnetic nanoparticles (MNPs) and exosomes derived from bone mesenchymal stem cells (BMSC-Exos) have been reported to improve wound healing. In this study, novel exosomes (mag-BMSC-Exos) would be fabricated from BMSCs with the stimulation of MNPs and a static magnetic field (SMF) to further enhance wound repair.

Methods

Mag-BMSC-Exos, namely, exosomes derived from BMSCs preconditioned with Fe₃O₄ nanoparticles and a SMF, together with BMSC-Exos were both first isolated by ultracentrifugation, respectively. Afterwards, we conducted in vitro experiments, including scratch wound assays, transwell assays, and tube formation assays, and established an in vivo wound healing model. The miRNA expression profiles were compared between BMSC-Exos and mag-BMSC-Exos to detect the potential mechanism of improving wound healing. At last, the function of exosomal miR-21-5p during wound healing was confirmed by utilizing a series of gain- and loss-of-function experiments in vitro.

Results

The optimal working magnetic condition was 50 µg/mL Fe₃O₄ nanoparticles combined with 100 mT SMF. In vitro, mag-BMSC-Exo administration promoted proliferation, migration and angiogenesis to a greater extent than BMSC-Exo administration. Local transplantation of mag-BMSC-Exos into rat skin wounds resulted in accelerated wound closure, narrower scar widths and enhanced angiogenesis compared with BMSC-Exo transplantation. Notably, miR-21-5p was found to be highly enriched in mag-BMSC-Exos and served as a critical mediator in mag-BMSC-Exo-induced regulatory effects through inhibition of SPRY2 and activation of the PI3K/AKT and ERK1/2 signaling pathways.

Conclusion

Mag-BMSC-Exos can further enhance wound healing than BMSC-Exos by improving angiogenesis and fibroblast function, and miR-21-5p upregulation in mag-BMSC-Exos might be the potential mechanism. This work offers an effective and promising protocol to improve wound healing in clinic.

Stabilization of HIF-1α in Human Retinal Endothelial Cells Modulates Expression of miRNAs and Proangiogenic Growth Factors

Retinal hypoxia is one of the causative factors of diabetic retinopathy and is also one of the triggers of VEGF release. We hypothesized that specific dysregulated miRNAs in diabetic retinopathy could be linked to hypoxia-induced damage in human retinal endothelial cells (HRECs). We investigated in HRECs the effects of chemical (CoCl₂) hypoxia on the expression of HIF-1α, VEGF, PlGF, and of a focused set of miRNAs. We found that miR-20a-5p, miR-20b-5p, miR-27a-3p, miR-27b-3p, miR-206-3p, miR-381-3p correlated also with expression of TGFβ signaling pathway genes in HRECs, challenged with chemical hypoxic stimuli. In conclusion, our data suggest that retinal angiogenesis would be promoted, at least under HIF-1α activation, by upregulation of PlGF and other factors such as miRNAs, VEGFA, and TGFβ1.

Engineered Human Adipose Stem-Cell-Derived Exosomes Loaded with miR-21-5p to Promote Diabetic Cutaneous Wound Healing

Diabetic wounds are a worldwide health problem causing extremely heavy public health burden and require effective treatment. Optimal strategies for treating nonhealing diabetic wounds include stem-cell-based therapy and delivery of novel drug substances, such as functional microRNAs (miRNAs); however, miRNA easily degrades in the wound microenvironment. Herein, we developed a human adipose stem-cell-derived exosome (hASC-exos)-based miRNA delivery strategy to enhance its therapeutic efficacy. The miR-21-5p mimics, as novel therapeutic candidates for diabetic wounds, were loaded into hASC-exos by electroporation, taking advantage of natural availability and biocompatibility of exosomes as extracellular miRNA transporting particles. The engineered exosomes (E-exos) exhibited excellent effects on promoting proliferation and migration of keratinocytes via Wnt/β-catenin signaling in vitro and accelerating diabetic wound healing by increasing re-epithelialization, collagen remodeling, angiogenesis, and vessel maturation in vivo. Results from this study would set the fundamentals of applying hASC-exos to deliver future drug substances and to develop cell-free therapy for wound-healing treatments.

G9a Suppression Alleviates Corneal Neovascularization through Blocking Nox4-Mediated Oxidative Stress

Background

G9a, a well-known methyltransferase, plays a vital role in biological processes. However, its role in corneal neovascularization (CoNV) remains unclear. Methods. In vitro and in vivo models were assessed in hypoxia-stimulated angiogenesis and in a mouse model of alkali burn-induced CoNV. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions and different reoxygenation times to identify the molecular mechanisms involved in this process.

Results

In this study, we found that G9a was positively related to corneal alkali burn-induced injury. Inhibition of G9a with BIX 01294 (BIX) alleviated corneal injury, including oxidative stress and neovascularization in vivo models were assessed in hypoxia-stimulated angiogenesis and in a mouse model of alkali burn-induced CoNV. Human umbilical vein endothelial cells (HUVECs) were cultured under hypoxic conditions and different reoxygenation times to identify the molecular mechanisms involved in this process.

The regulatory effect of microRNA-21a-3p on the promotion of telocyte angiogenesis mediated by PI3K (p110α)/AKT/mTOR in LPS induced mice ARDS

Background

Telocytes (TCs) are newly identified interstitial cells that participate in tissue protection and repair. The present study investigated the mechanisms underlying the protective effect of TCs in a mouse model of respiratory distress.

Methods

The mouse model of acute respiratory distress syndrome (ARDS) was established by intratracheal instillation of lipopolysaccharide (LPS). After instillation of TCs culture medium, lung injury was assessed, and angiogenesis markers, including CD31 and endothelial nitric oxide synthase (eNOS), were detected by immunofluorescence. Bioinformatics analysis was used to screen significantly differentially expressed microRNAs (miRNAs) in cultured TCs stimulated with LPS, and the regulation of downstream angiogenesis genes by these miRNAs was analysed and verified. PI3K subunits and pathways were evaluated by using a PI3K p110α inhibitor to study the involved mechanisms.

Results

In ARDS mice, instillation of TCs culture medium ameliorated LPS-induced inflammation and lung injury and increased the protein levels of CD31 and eNOS in the injured lungs. A total of 7 miRNAs and 1899 mRNAs were differentially regulated in TCs stimulated with LPS. Functional prediction analysis showed that the differentially expressed mRNAs were enriched in angiogenesis-related processes, which were highly correlated with miR-21a-3p. Culture medium from TCs with miR-21a-3p inhibition failed to promote angiogenesis in mouse models of LPS-induced ARDS. In cultured TCs, LPS stimulation upregulated the expression of miR-21a-3p, which further targeted the transcription factor E2F8 and decreased Notch2 protein expression. TCs culture medium enhanced hemangioendothelioma endothelial cells (EOMA cells) proliferation, which was blocked by the miR-21a-3p inhibitor. The PI3K p110α inhibitor decreased vascular endothelial growth factor levels in LPS-stimulated TCs and reversed the enhancing effect of TCs culture medium on EOMA cells proliferation.

Conclusions

TCs exerted protective effects under inflammatory conditions by promoting angiogenesis via miR-21a-3p. The PI3K p110α subunit and transcriptional factor E2F8 could be involved in this process.