Nanoparticle-mediated miR200-b delivery for the treatment of diabetic retinopathy

The role of metal nanocarriers, liposomes and chitosan-based nanoparticles in diabetic retinopathy treatment: A review study

Diabetic Retinopathy (DR) is a significant and progressive eye complication associated with diabetes mellitus, leading to potential vision loss. The pathophysiology of DR involves complex neurovascular changes due to prolonged hyperglycemia, resulting in microangiopathy and neurodegeneration. Current treatment modalities come with limitations such as low bioavailability of therapeutic agents, risk of side effects, and surgical complications. Consequently, the prevention and management of DR, particularly in its advanced stages, present ongoing challenges. This review investigates recent advancements in nanotechnology as a novel approach to enhance the treatment of DR. A comprehensive literature review of recent studies focusing on nanocarriers for drug delivery in DR treatment and an analysis of their efficacy compared to traditional methods was conducted for this study. The findings indicate that nanotechnology can significantly enhance the bioavailability of therapeutic agents while minimizing systemic exposure and associated side effects. The novelty of this study lies in its focus on the intersection of nanotechnology and ophthalmology, exploring innovative solutions that extend beyond existing literature on DR treatments. By highlighting recent advancements in this field, the study paves the way for future research aimed at developing more effective therapeutic strategies for managing DR.

Roles of noncoding RNAs in diabetic retinopathy: Mechanisms and therapeutic implications

Diabetic retinopathy (DR) is a microvascular complication of diabetes that leads to vision loss. The striking features of DR are hard exudate, cotton-wool spots, hemorrhage, and neovascularization. The dysregulated retinal cells, encompassing microvascular endothelial cells, pericytes, Müller cells, and adjacent retinal pigment epithelial cells, are involved in the pathological processes of DR. According to recent research, oxidative stress, inflammation, ferroptosis, pyroptosis, apoptosis, and angiogenesis contribute to DR. Recent advancements have highlighted that noncoding RNAs could regulate diverse targets in pathological processes that contribute to DR. Noncoding RNAs, including long noncoding RNAs, microRNAs (miRNA), and circular RNAs, are dysregulated in DR, and interact with miRNA, mRNA, or proteins to control the pathological processes of DR. Hence, modulation of noncoding RNAs may have therapeutic effects on DR. Small extracellular vesicles may be valuable tools for transferring noncoding RNAs and regulating the genes involved in progression of DR. However, the roles of noncoding RNA in developing DR are not fully understood; it is critical to summarize the mechanisms for noncoding RNA regulation of pathological processes and pathways related to DR. This review provides a fundamental understanding of the relationship between noncoding RNAs and DR, exploring the mechanism of how noncoding RNA modulates different signaling pathways, and pave the way for finding potential therapeutic strategies for DR.

Functional nucleic acids for the treatment of diabetic complications

In recent decades, diabetes mellitus (DM) has become a major global health problem owing to its high prevalence and increased incidence of diabetes-associated complications, including diabetic wounds (DWs), diabetic nephropathy, metabolic syndrome, diabetic retinopathy, and diabetic neuropathy. In both type 1 and type 2 diabetes, tissue damage is organ-specific, but closely related to the overproduction of reactive oxygen species (ROS) and hyperglycaemia-induced macrovascular system damage. However, existing therapies have limited effects on complete healing of diabetic complications. Fortunately, recent advances in functional nucleic acid materials have provided new opportunities for the treatment and diagnosis of diabetic complications. Functional nucleic acids possess independent structural functions that can replace traditional proteases and antibodies and perform specific biological non-genetic functions. This review summarises the current functional nucleic acid materials reported for the treatment of diabetic complications, including tetrahedral framework nucleic acids (tFNAs), short interfering RNA (siRNA), micorRNA (miRNA), locked nucleic acids, antisense oligonucleotides (ASOs), and DNA origami, which may assist in the development of novel nucleic acids with new functions and capabilities for better healing of diabetic complications.

LncRNA SNHG4 sponges miR-200b to inhibit cell apoptosis in diabetic retinopathy

This study aimed to investigate the role of long non-coding RNA (lncRNA) small nucleolar RNA host gene 4 (SNHG4) in diabetic retinopathy (DR). We found that SNHG4 was downregulated in DR. SNHG4 could directly interact with miR-200b, while overexpression of miR-200b did not affect the expression of SNHG4 in human retinal pigment epithelial cells ARPE-19. In contrast, overexpression of SNHG4 led to the upregulation of oxidation resistance 1 (Oxr1), a target of miR-200b. Cell apoptosis analysis showed that overexpression of miR-200b increased the apoptotic rate of ARPE-19 cells under high glucose treatment. Oxr1 and SNHG4 played opposite roles and reduced the effects of overexpression of miR-200b. In conclusion, SNHG4 may sponge miR-200b to inhibit cell apoptosis in DR by upregulating Oxr1.

Gene augmentation for autosomal dominant retinitis pigmentosa using rhodopsin genomic loci nanoparticles in the P23H+/- knock-in murine model

Gene therapy for autosomal dominant retinitis pigmentosa (adRP) is challenged by the dominant inheritance of the mutant genes, which would seemingly require a combination of mutant suppression and wild-type replacement of the appropriate gene. We explore the possibility that delivery of a nanoparticle (NP)-mediated full-length mouse genomic rhodopsin (gRho) or human genomic rhodopsin (gRHO) locus can overcome the dominant negative effects of the mutant rhodopsin in the clinically relevant P23H+/--knock-in heterozygous mouse model. Our results demonstrate that mice in both gRho and gRHO NP-treated groups exhibit significant structural and functional recovery of the rod photoreceptors, which lasted for 3 months post-injection, indicating a promising reduction in photoreceptor degeneration. We performed miRNA transcriptome analysis using next generation sequencing and detected differentially expressed miRNAs as a first step towards identifying miRNAs that could potentially be used as rhodopsin gene expression enhancers or suppressors for sustained photoreceptor rescue. Our results indicate that delivering an intact genomic locus as a transgene has a greater chance of success compared to the use of the cDNA for treatment of this model of adRP, emphasizing the importance of gene augmentation using a gDNA that includes regulatory elements.

Efficiency co-delivery of ellagic acid and oxygen by a non-invasive liposome for ameliorating diabetic retinopathy

Diabetic retinopathy (DR) is one of the serious complications of diabetes, which has become the fourth leading cause of vision loss worldwide. Current treatment of DR relies on intravitreal injections of antiangiogenic agents, which has made considerable achievements in reducing visual impairment. However, long-term invasive injections require advanced technology and can lead to poor patient compliance as well as the incidence of ocular complications including bleeding, endophthalmitis, retinal detachment and others. Hence, we developed non-invasive liposomes (EA-Hb/TAT&isoDGR-Lipo) for efficiency co-delivery of ellagic acid and oxygen, which can be administered intravenously or by eye drops. Among that, ellagic acid (EA), as an aldose reductase inhibitor, could remove excessive reactive oxygen species (ROS) induced by high glucose for preventing retinal cell apoptosis, as well as reduce retinal angiogenesis through the blockage of VEGFR2 signaling pathway; carried oxygen could ameliorate DR hypoxia, and further enhanced the anti-neovascularization efficacy. Our results showed that EA-Hb/TAT&isoDGR-Lipo not only effectively protected retinal cells from high glucose-induced damage, but also inhibited VEGF-induced vascular endothelial cells migration, invasion, and tube formation in vitro. In addition, in a hypoxic cell model, EA-Hb/TAT&isoDGR-Lipo could reverse retinal cell hypoxia, thereby reducing the expression of VEGF. Significantly, after being administered as an injection or eye drops, EA-Hb/TAT&isoDGR-Lipo obviously ameliorated the structure (central retinal thickness and retinal vascular network) of retina by eliminating ROS and down-regulating the expression of GFAP, HIF-1α, VEGF and p-VEGFR2 in a DR mouse model. In summary, EA-Hb/TAT&isoDGR-Lipo holds great potentials in improvement of DR, which provides a novel approach for the treatment of DR.

Improved Melatonin Delivery by a Size-Controlled Polydopamine Nanoformulation Attenuates Preclinical Diabetic Retinopathy

Oxidative stress, reactive oxygen species generation, and overexpression of VEGF are signatory events in diabetic retinopathy. The downregulation of VEGF and anti-inflammatory action pave the way for diabetic retinopathy (DR) therapy. In that, lower absorption kinetics of melatonin limits its immense therapeutic potential. Hence, we have demonstrated a reverse microemulsion method to synthesize melatonin-loaded polydopamine nanoparticles to replenish both at a single platform with an improved melatonin delivery profile. The study has evaluated in vitro and in vivo protection efficiency of biocompatible melatonin-loaded polydopamine nanoparticles (MPDANPs). The protection mechanism was explained by downregulation of VEGF, CASPASE3, and PKCδ against high-glucose/streptozotocin (STZ)-induced insults, in vitro and in vivo. The anti-inflammatory and antiangiogenic effect and potential of MPDANPs to enhance melatonin in vivo stability with prolonged circulation time have proved MPDANPs as a potential therapeutic candidate in DR management. The DR therapeutic potential of MPDANPs has been arbitrated by improving the bioavailability of melatonin and inhibition of VEGF-PKCδ crosstalk in vivo.

Polymer- and lipid-based nanocarriers for ocular drug delivery: Current status and future perspectives

Ocular diseases seriously affect patients' vision and life quality, with a global morbidity of over 43 million blindness. However, efficient drug delivery to treat ocular diseases, particularly intraocular disorders, remains a huge challenge due to multiple ocular barriers that significantly affect the ultimate therapeutic efficacy of drugs. Recent advances in nanocarrier technology offer a promising opportunity to overcome these barriers by providing enhanced penetration, increased retention, improved solubility, reduced toxicity, prolonged release, and targeted delivery of the loaded drug to the eyes. This review primarily provides an overview of the progress and contemporary applications of nanocarriers, mainly polymer- and lipid-based nanocarriers, in treating various eye diseases, highlighting their value in achieving efficient ocular drug delivery. Additionally, the review covers the ocular barriers and administration routes, as well as the prospective future developments and challenges in the field of nanocarriers for treating ocular diseases.

Emerging Theranostic Nanomaterials in Diabetes and Its Complications

Diabetes mellitus (DM) refers to a group of metabolic disorders that are characterized by hyperglycemia. Oral subcutaneously administered antidiabetic drugs such as insulin, glipalamide, and metformin can temporarily balance blood sugar levels, however, long-term administration of these therapies is associated with undesirable side effects on the kidney and liver. In addition, due to overproduction of reactive oxygen species and hyperglycemia-induced macrovascular system damage, diabetics have an increased risk of complications. Fortunately, recent advances in nanomaterials have provided new opportunities for diabetes therapy and diagnosis. This review provides a panoramic overview of the current nanomaterials for the detection of diabetic biomarkers and diabetes treatment. Apart from diabetic sensing mechanisms and antidiabetic activities, the applications of these bioengineered nanoparticles for preventing several diabetic complications are elucidated. This review provides an overall perspective in this field, including current challenges and future trends, which may be helpful in informing the development of novel nanomaterials with new functions and properties for diabetes diagnosis and therapy.

Preparation of Targeted Mitochondrion Nanoscale-Release Peptides and Their Efficiency on Eukaryotic Cells

We established a self-decomposable SiO₂ encapsulated mitochondrial targeting short peptide SS31 drug loading system (SiO₂@SS31) to determine its nano-sustained release characteristics in eukaryotic cells. We explored the protection of SiO₂@SS31 on the 661W cells after oxidative injury by H₂O₂. After the drug loading, we detected the morphology of SiO₂@SS31 by transmission electron microscopy (TEM). Moreover, high-pressure liquid chromatography (HPLC) was used to determine the drug capacity and encapsulation efficiency of the nanoparticles. Then, the release curve in vitro was drawn. The 661W cells were cultured in vitro to allow the detection of cytotoxicity by the MTT assay. The SS31loaded nanoscale microspheres labeled with fluorescein isothiocyanate (SiO₂@FITC-SS31) were prepared, and their sustained release effect was detected with intracellular endocytosis, using confocal microscopy and flow cytometry. Within 15 days, the SiO2@SS31 nanoparticles were completely decomposed and simultaneously released the SS31 peptide in deionized water and normal saline. Nonetheless, the process was faster in simulated body fluid and serum. The MTT assay suggested that SiO₂@SS31 has sustained protection compared with SS31 in the 661W cells at 48 h. Flow cytometry proved SiO₂@FITC-SS31 could maintain a high level and last longer after 24 h. The SS31 peptide, which has excellent medical application prospects, can be slowly and continuously released from self-decomposable SiO₂ and targeted to concentrate on mitochondria.

Distribution of polymeric nanoparticles in the eye: implications in ocular disease therapy

Advantages of polymeric nanoparticles as drug delivery systems include controlled release, enhanced drug stability and bioavailability, and specific tissue targeting. Nanoparticle properties such as hydrophobicity, size, and charge, mucoadhesion, and surface ligands, as well as administration route and suspension media affect their ability to overcome ocular barriers and distribute in the eye, and must be carefully designed for specific target tissues and ocular diseases. This review seeks to discuss the available literature on the biodistribution of polymeric nanoparticles and discuss the effects of nanoparticle composition and administration method on their ocular penetration, distribution, elimination, toxicity, and efficacy, with potential impact on clinical applications.

MicroRNA-148a-3p alleviates high glucose-induced diabetic retinopathy by targeting TGFB2 and FGF2

AIMS

Diabetic retinopathy (DR), a common complication of type 1 or type 2 diabetes mellitus, has become the leading cause of blindness among adults in working age. The dysregulation of microRNA has been reported to be strongly related to the initiation or progression of DR. However, neither the biological role nor the molecular mechanism of miR-148a-3p has been researched in DR. This study is designed to investigate the function and mechanism of miR-148a-3p in DR.

METHODS

The bioinformatics analysis (Targetscan: https://www.targetscan.org/vert_72/ ) and numerous experiments including real-time quantitative polymerase chain reaction, terminal deoxynucleotidyltransferase dUTP nick end labeling, CCK-8, western blot, vasculogenesis and luciferase reporter assays were used to research the function and mechanism of miR-148a-3p in DR.

RESULTS

We constructed DR cell model by treating human retinal microvascular endothelial cells (HRECs) with different concentration gradients of high glucose (HG). Additionally, HG treatment reduced miR-148a-3p level in HRECs. In function, overexpression of miR-148a-3p caused an increase in cell viability and a decrease in cell apoptosis. Besides, miR-148a-3p overexpression led to a damage on blood-retinal barrier (BRB) and suppressed angiogenesis. In mechanism, miR-148a-3p specifically bound to 3' untranslated region of TGFB2 and FGF2. At least, rescue assays demonstrated that the inhibitive influence of miR-148a-3p mimics on BRB injury was offset by overexpression of TGFB2 and the attenuation of angiogenesis resulting from miR-148a-3p mimics was abrogated by overexpression of FGF2 CONCLUSIONS: In a word, we discovered that miR-148a-3p alleviated HG-induced DR by targeting TGFB2 and FGF2. This novel discovery indicated miR-148a-3p as a potential target for DR diagnosis or treatment.

Glucose-induced microRNA-218 suppresses the proliferation and promotes the apoptosis of human retinal pigment epithelium cells by targeting RUNX2

OBJECTIVE

MicroRNA-218 (miR-218) critical for preventing the progression of numerous diseases, including diseases of the retinal pigment epithelium (RPE). However, the mechanism by which miR-218 regulates the PRE in humans remains largely unknown. Our study investigated the effects of glucose-induced miR-218 expression on human RPE cells (ARPE-19), as well as its targeted regulatory effect.

METHODS

The levels of miR-218 and runt-related transcription factor 2 (RUNX2) expression were investigated by RT-qPCR or Western blot assays. Cell viability and apoptosis were assessed by CCK-8 assays, flow cytometry, and Hoechst staining. A luciferase reporter assay was performed to determine whether Runx2 is a target gene of miR-218.

RESULTS

Our results showed that glucose up-regulated miR-218 expression, suppressed proliferation, and induced the apoptosis of ARPE-19 cells. We verified that miR-218 could inhibit the proliferation and facilitate the apoptosis of ARPE-19 cells, while inhibition of miR-218 expression produced the opposite effects. In terms of mechanism, we demonstrated that RUNX2 was a direct target of miR-218. Functional experiments showed that Runx2 served as a miR-218 target to help inhibit the proliferation and induction of apoptosis in ARPE-19 cells.

CONCLUSION

Our findings suggest the miR-218/Runx2 axis as a potential target for treating diabetic retinopathy (DR).

Silencing circ_0001879 inhibits the proliferation and migration of human retinal microvascular endothelial cells under high-glucose conditions via modulating miR-30-3p

BACKGROUND AND AIM

Diabetic retinopathy is a severe diabetic complication and a major cause of blindness. In this study, we explored the role of circ_0001879 in retinal vascular dysfunction under diabetic conditions.

METHODS

Human retinal microvascular endothelial cells (HRMECs) were divided into normal glucose group (NG, 5.5 mmol/L d-glucose), high glucose group (HG, 25 mmol/L d-glucose), and osmotic control group (5.5 mmol/L d-glucose + 19.5 mmol/L mannitol). The expression of circ_0001879 and miR-30-3p was assessed via qRT-PCR. The circ_0001879/miR-30-3p roles in retinal vascular dysfunction were investigated through Cell Counting Kit-8 and Transwell assay. Bioinformatics analysis and luciferase reporter assays were applied to examine interactions between circ_0001879 and miR-30-3p in HRMECs.

RESULTS

The relative circ_0001879 expression was remarkably increased in diabetic retinas group than that in the control group. Silencing circ_0001879 suppressed the proliferation and migration of HRMECs under high-glucose conditions. In addition, circ_0001879 acted as a binding platform and miRNA sponge for miR-30-3p. Circ_0001879 modulated the function of HRMECs via targeting miR-30-3p.

CONCLUSION

Silencing circ_0001879 inhibited the proliferation and migration of HRMECs under high-glucose conditions via modulating miR-30-3p, which might shed new light on a novel potentially marker and molecular therapeutic target for diabetic retinopathy.

Rhodopsin Genomic Loci DNA Nanoparticles Improve Expression and Rescue of Retinal Degeneration in a Model for Retinitis Pigmentosa

The use of gene therapy may allow replacement of the defective gene. Minigenes, such as cDNAs, are often used. However, these may not express normal physiological genetic profiles due to lack of crucial endogenous regulatory elements. We constructed DNA nanoparticles (NPs) that contain either the mouse or human full-length rhodopsin genomic locus, including endogenous promoters, all introns, and flanking regulatory sequences of the 15-16 kb genomic rhodopsin DNA inserts. We transduced the NPs into primary retinal cell cultures from the rhodopsin knockout (RKO) mouse in vitro and into the RKO mouse in vivo and compared the effects on different functions to plasmid cDNA NP counterparts that were driven by ubiquitous promoters. Our results demonstrate that genomic DNA vectors resulted in long-term high levels of physiological transgene expression over a period of 5 months. In contrast, the cDNA counterparts exhibited low levels of expression with sensitivity to the endoplasmic reticulum (ER) stress mechanism using the same transgene copy number both in vitro and in vivo. This study demonstrates for the first time the transducing of the rhodopsin genomic locus using compacted DNA NPs.

A cerium oxide loaded glycol chitosan nano-system for the treatment of dry eye disease

Dry eye (DE) disease is an uprising health epidemic that directly affects the surface of the eye. We developed a water soluble cerium oxide loaded glycol chitosan nanoparticle as a new type of eye drop, namely GCCNP (glycol chitosan cerium oxide nanoparticles). GCCNP is capable of scavenging cellular reactive oxygen species (ROS) for the treatment of DE disease. The antioxidative effects of GCCNP were assessed in mice primary corneal and conjunctival cells in vitro and in a DE murine model in vivo. GCCNP's effect on the DE models was assessed via histological evaluations, migration assays, cell viability assays, cellular uptake analyses, intracellular ROS scavenging assays, wound healing assays, mitochondrial membrane potential readings, corneal fluorescein staining, tear volume concentrations, tear film break up time analyses, and lastly, analytical/spectroscopic analyses of GCCNP eye drop formulations. Spectroscopic analysis showed that cerium oxide was entrapped into the glycol chitosan (GC). The solubility of cerium in GC (GCCNP) increased to 709.854±24.3μg/ml compared to its original solubility in cerium oxide, which was measured as 0.020±0.002μg/ml. GCCNP had no cytotoxic effect and showed improvements on dry eye disease models by stabilizing the tear film, scavenging ROS, up-regulating SOD, promoting and maintaining corneal and conjunctival cell growth and integrity. We provided convincing evidence that GCCNP is an effective treatment for DE and may represent a potential new class of drug for DE disease.

Internal Ribosome Entry Site Dramatically Reduces Transgene Expression in Hematopoietic Cells in a Position-Dependent Manner

Bicistronic transgene expression mediated by internal ribosome entry site (IRES) elements has been widely used. It co-expresses heterologous transgene products from a message RNA driven by a single promoter. Hematologic gene delivery is a promising treatment for both inherited and acquired diseases. A combined strategy was recently documented for potential genome editing in hematopoietic cells. A transduction efficiency exceeding ~90% can be achieved by capsid-optimized recombinant adeno-associated virus serotype 6 (rAAV6) vectors. In this study, to deliver an encephalomyocarditis virus (EMCV) IRES-containing rAAV6 genome into hematopoietic cells, we observed that EMCV IRES almost completely shut down the transgene expression during the process of mRNA–protein transition. In addition, position-dependent behavior was observed, in which only the EMCV IRES element located between a promoter and the transgenes had an inhibitory effect. Although further studies are warranted to evaluate the involvement of cellular translation machinery, our results propose the use of specific IRES elements or an alternative strategy, such as the 2A system, to achieve bicistronic transgene expression in hematopoietic cells.

Poly(lactic-co-glycolic acid) nanoparticle-mediated interleukin-12 delivery for the treatment of diabetic retinopathy

Background

Diabetic retinopathy (DR) is a complication of diabetes that affects the eyes and vision. It is a leading cause of visual impairment and blindness in working-age people. Vascular endothelial growth factor-A (VEGF-A) is a primary initiator and potential mediator of DR. Matrix metalloproteinase-9 (MMP-9) plays a progressive role in the onset and severity of DR. Interleukin-12 (IL-12) is a cytokine of the chemokine family that could reduce the levels of MMP-9 and VEGF-A and suppress tumor angiogenesis. We hypothesize that IL-12 may also have superior therapeutic efficacy against DR. However, protein drugs are prone to degradation by various proteases after drug injection. Therefore, they have short half-lives and low blood concentrations. The objective of this study was to develop IL-12-loaded nanoparticles for long-term and sustained DR treatment.

Methods

IL-12-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (IL-12-PNP) were developed by double emulsion. The characteristics, anti-DR activity, and mechanisms of IL-12-PNP were examined in vitro and in vivo.

Results

The nanoparticles had suitable particle size (~132.8 nm), drug encapsulation efficiency (~34.7%), and sustained drug release profile. Compared with IL-12 and blank nanoparticles, IL-12-PNP showed better inhibitory efficacy against VEGF-A and MMP-9 expression in rat endothelial cells and DR mouse retina. Intraocular IL-12-PNP administration significantly reduced retinal damage in DR mice as they presented with increased thickness and decreased neovascularization after treatment.

Conclusion

These data indicate that IL-12-PNP is an effective drug delivery platform for DR therapy. It restores the thickness and reduces neovascularization of the retinas of DR mice.

Identification of miRNAs-genes regulatory network in diabetic nephropathy based on bioinformatics analysis

MicroRNAs (miRNAs) play a great contribution to the development of diabetic nephropathy (DN). The aim of this study was to explore potential miRNAs-genes regulatory network and biomarkers for the pathogenesis of DN using bioinformatics methods.Gene expression profiling data related to DN (GSE1009) was obtained from the Gene Expression Omnibus (GEO) database, and then differentially expressed genes (DEGs) between DN patients and normal individuals were screened using GEO2R, followed by a series of bioinformatics analyses, including identifying key genes, conducting pathway enrichment analysis, predicting and identifying key miRNAs, and establishing regulatory relationships between key miRNAs and their target genes.A total of 600 DEGs associated with DN were identified. An additional 7 key DEGs, including 6 downregulated genes, such as vascular endothelial growth factor α (VEGFA) and COL4A5, and 1 upregulated gene (CCL19), were identified in another dataset (GSE30528) from glomeruli samples. Pathway analysis showed that the down- and upregulated DEGs were enriched in 14 and 6 pathways, respectively, with 7 key genes mainly involved in extracellular matrix-receptor interaction, PI3K/Akt signaling, focal adhesion, and Rap1 signaling. The relationships between miRNAs and target genes were constructed, showing that miR-29 targeted COL4A and VEGFA, miR-200 targeted VEGFA, miR-25 targeted ITGAV, and miR-27 targeted EGFR.MiR-29 and miR-200 may play important roles in DN. VEGFA and COL4A5 were targeted by miR-29 and VEGFA by miR-200, which may mediate multiple signaling pathways leading to the pathogenesis and development of DN.

Increased Extracellular Matrix Protein Production in Chronic Diabetic Complications: Implications of Non-Coding RNAs

Management of chronic diabetic complications remains a major medical challenge worldwide. One of the characteristic features of all chronic diabetic complications is augmented production of extracellular matrix (ECM) proteins. Such ECM proteins are deposited in all tissues affected by chronic complications, ultimately causing organ damage and dysfunction. A contributing factor to this pathogenetic process is glucose-induced endothelial damage, which involves phenotypic transformation of endothelial cells (ECs). This phenotypic transition of ECs, from a quiescent state to an activated dysfunctional state, can be mediated through alterations in the synthesis of cellular proteins. In this review, we discussed the roles of non-coding RNAs, specifically microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), in such processes. We further outlined other epigenetic mechanisms regulating the biogenesis and/or function of non-coding RNAs. Overall, we believe that better understanding of such molecular processes may lead to the development of novel biomarkers and therapeutic strategies in the future.

Plasma levels of miR-29b and miR-200b in type 2 diabetic retinopathy

MicroRNAs (miRNAs/miRs) are involved in the pathogenesis of diabetes mellitus and its chronic complications, and their circulating levels have emerged as potential biomarkers for the development and progression of diabetes. However, few studies have examined the expression of miRNAs in diabetic retinopathy (DR) in humans. This case-control study aimed to investigate whether the plasma levels of miR-29b and miR-200b are associated with DR in 186 South Brazilians with type 2 diabetes (91 without DR, 46 with non-proliferative DR and 49 with proliferative DR). We also included 20 healthy blood donors to determine the miRNA expression in the general population. Plasma levels of miR-29b and miR-200b were quantified by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Proliferative DR was inversely associated with plasma levels of miR-29b (unadjusted OR = 0.694, 95% CI: 0.535-0.900, P = 0.006) and miR-200b (unadjusted OR = 0.797, 95% CI: 0.637-0.997, P = 0.047). However, these associations were lost after controlling for demographic and clinical covariates. In addition, patients with type 2 diabetes had lower miR-200b levels than blood donors. Our findings reinforce the importance of addressing the role of circulating miRNAs, including miR-29 and miR-200b, in DR.

MicroRNA-200a/200b Modulate High Glucose-Induced Endothelial Inflammation by Targeting O-linked N-Acetylglucosamine Transferase Expression

Background and Aims: Increased O-linked N-acetylglucosamine (O-GlcNAc) modification of proteins by O-GlcNAc transferase (OGT) is associated with diabetic complications. Furthermore, oxidative stress promotes endothelial inflammation during diabetes. A previous study reported that microRNA-200 (miR-200) family members are sensitive to oxidative stress. In this study, we examined whether miR-200a and miR-200b regulate high-glucose (HG)-induced OGT expression in human aortic endothelial cells (HAECs) and whether miRNA-200a/200b downregulate OGT expression to control HG-induced endothelial inflammation.

Methods: HAECs were stimulated with high glucose (25 mM) for 12 and 24 h. Real-time polymerase chain reaction (PCR), western blotting, THP-1 adhesion assay, bioinformatics predication, transfection of miR-200a/200b mimic or inhibitor, luciferase reporter assay, and transfection of siRNA OGT were performed. The aortic endothelium of db/db diabetic mice was evaluated by immunohistochemistry staining.

Results: HG upregulated OGT mRNA and protein expression and protein O-GlcNAcylation levels (RL2 antibody) in HAECs, and showed increased intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and E-selectin gene expression; ICAM-1 expression; and THP-1 adhesion. Bioinformatics analysis revealed homologous sequences between members of the miR-200 family and the 3′-untranslated region (3′-UTR) of OGT mRNA, and real-time PCR analysis confirmed that members of miR-200 family were significantly decreased in HG-stimulated HAECs. This suggests the presence of an impaired feedback restraint on HG-induced endothelial protein O-GlcNAcylation levels because of OGT upregulation. A luciferase reporter assay demonstrated that miR-200a/200b mimics bind to the 3′-UTR of OGT mRNA. Transfection with miR-200a/200b mimics significantly inhibited HG-induced OGT mRNA expression, OGT protein expression; protein O-GlcNAcylation levels; ICAM-1, VCAM-1, and E-selectin gene expression; ICAM-1 expression; and THP-1 adhesion. Additionally, siRNA-mediated OGT depletion reduced HG-induced protein O-GlcNAcylation; ICAM-1, VCAM-1, and E-selectin gene expression; ICAM-1 expression; and THP-1 adhesion, confirming that HG-induced endothelial inflammation is partially mediated via OGT-induced protein O-GlcNAcylation. These results were validated in vivo: tail-vein injection of miR-200a/200b mimics downregulated endothelial OGT and ICAM-1 expression in db/db mice.

Conclusion: miR-200a/200b are involved in modulating HG-induced endothelial inflammation by regulating OGT-mediated protein O-GlcNAcylation, suggesting the therapeutic role of miR-200a/200b on vascular complications in diabetes.

A Naturally Fluorescent Mgp Transgenic Mouse for Angiogenesis and Glaucoma Longitudinal Studies

Purpose

Our goal was to generate and characterize a new mouse model in which only angiogenesis- and glaucoma-relevant tissues would be naturally fluorescent. The Matrix Gla (MGP) gene is highly expressed in vascular smooth muscle cells (VSMC) and trabecular meshwork (TM). We sought to direct our Mgp-Cre.KI mouse recombinase to VSMC/TM cells to produce their longitudinal fluorescent profiles.

Methods

Homozygous Mgp-Cre.KI mice were crossed with Ai9 homozygous reporter mice harboring a loxP-flanked STOP cassette preventing transcription of a DsRed fluorescent protein (tdTomato). The F1 double-heterozygous (Mgp-tdTomato) was examined by direct fluorescence, whole mount, histology, and fundus photography. Custom-made filters had 554/23 emission and 609/54 exciter nanometer wavelengths. Proof of concept of the model's usefulness was conducted by inducing guided imaging laser burns. Evaluation of a vessel's leakage and proliferation was followed by noninvasive angiography.

Results

The Mgp-tdTomato mouse was viable, fertile, with normal IOP and ERG. Its phenotype exhibited red paws and snout (cartilage expression), which precluded genotyping. A fluorescent red ring was seen at the limbus and confirmed to be TM expression by histology. The entire retinal vasculature was red fluorescent (VSMC) and directly visualized by fundus photography. Laser burns on the Mgp-tdTomato allowed separation of leakiness and neovascularization evaluation parameters.

Conclusions

The availability of a transgenic mouse naturally fluorescent in glaucoma-relevant tissues and retinal vasculature brings the unique opportunity to study a wide spectrum of single and combined glaucomatous conditions in vivo. Moreover, the Mgp-tdTomato mouse provides a new tool to study mechanisms and therapeutics of retinal angiogenesis longitudinally.

Nanoparticles as Delivery Vehicles for the Treatment of Retinal Degenerative Diseases

Over the last few years, huge progress has been made in the understanding of molecular mechanisms underlying the pathogenesis of retinal degenerative diseases. Such knowledge has led to the development of gene therapy approaches to treat these devastating disorders. Non-viral gene delivery has been recognized as a prospective treatment for retinal degenerative diseases. In this review, we will summarize the constituent characteristics and recent applications of three representative nanoparticles (NPs) in ocular therapy.

Genomic form of rhodopsin DNA nanoparticles rescued autosomal dominant Retinitis pigmentosa in the P23H knock-in mouse model

Retinitis pigmentosa (RP) is a group of inherited retinal degenerative conditions and a leading cause of irreversible blindness. 25%-30% of RP cases are caused by inherited autosomal dominant (ad) mutations in the rhodopsin (Rho) protein of the retina, which impose a barrier for developing therapeutic treatments for this genetically heterogeneous disorder, as simple gene replacement is not sufficient to overcome dominant disease alleles. Previously, we have explored using the genomic short-form of Rho (sgRho) for gene augmentation therapy of RP in a Rho knockout mouse model. We have shown improved gene expression and fewer epigenetic modifications compared with the use of a Rho cDNA expression construct. In the current study, we altered our strategy by delivering a codon-optimized genomic form of Rho (co-sgRho) (for gene replacement) in combination with an RNAi-based inactivation of endogenous Rho alleles (gene suppression of both mutant Rho alleles, but mismatched with the co-sgRho) into a homozygous Rho^P23H/P23H knock-in (KI) RP mouse model, which has a severe phenotype of adRP. In addition, we have conjugated a cell penetrating TAT peptide sequence to our previously established CK30PEG10 diblock co-polymer. The DNAs were compacted with CK30PEG10-TAT diblock co-polymer to form DNA nanoparticles (NPs). These NPs were injected into the sub-retinal space of the KI mouse eyes. As a proof of concept, we demonstrated the efficiency of this strategy in the partial improvement of visual function in the Rho^P23H/P23H KI mouse model.

MicroRNA-21 inhibits mitochondria-mediated apoptosis in keloid

MicroRNA-21 acts as an oncogene by promoting cell proliferation and migration, whereas inhibiting apoptosis in majority of cancers. MicroRNA-21 is upregulated in human keloid fibroblasts. We hypothesized that microRNA-21 may contribute to pathogenesis of keloid fibroblasts. First, enhanced miR-21 but reduced mitochondrial-mediated apoptosis observed in keloid tissues indicated its importance in keloids development. Second, upregulation of microRNA-21 induced a decrease in the ratio of BAX to BCL-2 and suppressed mitochondrial fission in keloid fibroblasts. Third, by attenuating the decline in cellular mitochondrial membrane potential, overexpression of miR-21 suppressed cytochrome c release to the cytoplasm, followed by a decrease in the activity of intracellular caspase-9 and caspase-3, suggesting that mitochondrial-mediated proapoptotic pathway was impaired. Simultaneously, intracellular reactive oxygen species were decreased, indicating microRNA-21 undermined oxidative stress. This phenotype was reversed by miR-21 inhibition. Therefore, our study demonstrates that inhibition of microRNA-21 induces mitochondrial-mediated apoptosis in keloid fibroblasts, proposing microRNA-21 as a potential therapeutic target in keloid fibroblasts.

Glycol Chitosan Engineered Autoregenerative Antioxidant Significantly Attenuates Pathological Damages in Models of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the foremost cause of irreversible blindness in people over the age of 65 especially in developing countries. Therefore, an exploration of effective and alternative therapeutic interventions is an unmet medical need. It has been established that oxidative stress plays a key role in the pathogenesis of AMD, and hence, neutralizing oxidative stress is an effective therapeutic strategy for treatment of this serious disorder. Owing to autoregenerative properties, nanoceria has been widely used as a nonenzymatic antioxidant in the treatment of oxidative stress related disorders. Yet, its potential clinical implementation has been greatly hampered by its poor water solubility and lack of reliable tracking methodologies/processes and hence poor absorption, distribution, and targeted delivery. The water solubility and surface engineering of a drug with biocompatible motifs are fundamental to pharmaceutical products and precision medicine. Here, we report an engineered water-soluble, biocompatible, trackable nanoceria with enriched antioxidant activity to scavenge intracellular reactive oxygen species (ROS). Experimental studies with in vitro and in vivo models demonstrated that this antioxidant is autoregenerative and more active in inhibiting laser-induced choroidal neovascularization by decreasing ROS-induced pro-angiogenic vascular endothelial growth factor (VEGF) expression, cumulative oxidative damage, and recruitment of endothelial precursor cells without exhibiting any toxicity. This advanced formulation may offer a superior therapeutic effect to deal with oxidative stress induced pathogeneses, such as AMD.

Synthetic nanocarriers for the delivery of polynucleotides to the eye

This review is a comprehensive analysis of the progress made so far on the delivery of polynucleotide-based therapeutics to the eye, using synthetic nanocarriers. Attention has been addressed to the capacity of different nanocarriers for the specific delivery of polynucleotides to both, the anterior and posterior segments of the eye, with emphasis on their ability to (i) improve the transport of polynucleotides across the different eye barriers; (ii) promote their intracellular penetration into the target cells; (iii) protect them against degradation and, (iv) deliver them in a long-term fashion way. Overall, the conclusion is that despite the advantages that nanotechnology may offer to the area of ocular polynucleotide-based therapies (especially AS-ODN and siRNA delivery), the knowledge disclosed so far is still limited. This fact underlines the necessity of more fundamental and product-oriented research for making the way of the said nanotherapies towards clinical translation.

Targeting noncoding RNAs in disease

Many RNA species have been identified as important players in the development of chronic diseases, including cancer. Over the past decade, numerous studies have highlighted how regulatory RNAs such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) play crucial roles in the development of a disease state. It is clear that the aberrant expression of miRNAs promotes tumor initiation and progression, is linked with cardiac dysfunction, allows for the improper physiological response in maintaining glucose and insulin levels, and can prevent the appropriate integration of neuronal networks, resulting in neurodegenerative disorders. Because of this, there has been a major effort to therapeutically target these noncoding RNAs. In just the past 5 years, over 100 antisense oligonucleotide-based therapies have been tested in phase I clinical trials, a quarter of which have reached phase II/III. Most notable are fomivirsen and mipomersen, which have received FDA approval to treat cytomegalovirus retinitis and high blood cholesterol, respectively. The continued improvement of innovative RNA modifications and delivery entities, such as nanoparticles, will aid in the development of future RNA-based therapeutics for a broader range of chronic diseases. Here we summarize the latest promises and challenges of targeting noncoding RNAs in disease.