scanning-electron-microscopy-energy-dispersive-spectroscopy

Scanning Electron Microscopy-Energy Dispersive Spectroscopy Evaluation of a Retinal Explant Model of Iron Intraocular Foreign Body Injury

Iron intraocular foreign body (IOFB) can cause retinal damage, which may be related to the release, transfer, and tissue infiltration of iron particles. ...

Joint Shantou International Eye Center of Shantou University and The Chinese University of Hong Kong

Retinal disease treatment by stem cell-based replacement relies on stem cell differentiation into retinal cells. We previously demonstrated that human periodontal ligament-derived stem cells can be directed into retinal lineage upon induction. Here, we report the transdifferentiation potential of human adipose-derived stem cells (ASCs) into retinal lineage and its enhancement by Notch signaling modulation. Human ASCs, isolated from abdominal fat, expressed mesenchymal but not hematopoietic stem cell markers, and they can differentiate into adipocytes, chondrocytes, and osteoblasts . Upon noggin/Dkk-1/IGF-1 induction, the treated ASCs showed elevated expression of retinal progenitor, retinal ganglion, and photoreceptor cell markers as well as the glutamate-evoked calcium response, which was not observed in the noninduced cells. Compared to the regular induction treatment, Notch signaling activation by JAG1 enhanced the expression of retinal progenitor and precursor markers without affecting the glutamate-evoked calcium response. In contrast, Notch signaling inhibition by DAPT showed more retinal ganglion cells, but delayed the response to glutamate stimulation. In summary, our results revealed that human ASCs possess a retinal transdifferentiation potential upon noggin/Dkk-1/IGF-1 induction, which can further be enhanced by Notch signaling activation.

Notch Signaling Activation Enhances Human Adipose-Derived Stem Cell Retinal Differentiation.

Periodontal ligament (PDL) stem cell properties are critical in the periodontal tissue regeneration for periodontitis. Previously, we have demonstrated that cigarette smoking attenuates PDL-derived stem cell (PDLSC) regenerative properties. Here, we report the findings on the regenerative properties of human PDLSCs with different donor ages and the underlying mechanisms. Human PDLSCs from 18 independent donors were divided into different age groups (≤ 20, 20-40, and > 40 years old). The proliferation of PDLSCs with donor age of ≤ 20 years old was significantly higher than that of the 20-40- and > 40-years-old groups, whereas the migration of PDLSCs with donor age of ≤ 20 and 20-40 years old was significantly higher than that of the > 40-years-old group. Moreover, the mesodermal lineage differentiation capabilities of PDLSCs were also higher in the donor age group of ≤ 20 years old than the donor age of > 40 years old. In addition, shorter telomere length and lower expression of SSEA4 were found in PDLSCs with donor age of > 40 years old, compared with those with donor age of ≤ 20-years-old group. Besides, PDLSCs with donor age of 20-40 and > 40 years old had higher IL6 and CXCL8 gene expressions. In summary, results from this study revealed the attenuated proliferation, migration, and mesodermal lineage differentiation properties in human PDLSCs with older donor ages. Donor age of PDLSCs should be considered as the selection criteria for the periodontal tissue regeneration treatment.

Attenuated regenerative properties in human periodontal ligament-derived stem cells of older donor ages with shorter telomere length and lower SSEA4 expression.

To determine the expressions of SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine protease (TMPRSS2) genes in human and mouse ocular cells and comparison to other tissue cells.

Expression of SARS-CoV-2 receptor ACE2 and TMPRSS2 in human primary conjunctival and pterygium cell lines and in mouse cornea.

Diabetic retinopathy (DR) is a significant global public health concern. Alternative, safe, and cost-effective pharmacologic approaches are warranted. We aimed to investigate the therapeutic potential of nattokinase (NK) for early DR and the underlying molecular mechanism.

Protective effects of nattokinase against microvasculopathy and neuroinflammation in diabetic retinopathy.

Long-chain fatty acids (LCFAs) are one of the main energy-supplying substances in the body. LCFAs with different lengths and saturations may have contrasting biological effects that exacerbate or alleviate progress against a variety of systemic disorders of lipid metabolism in organisms. Nonalcoholic fatty liver disease is characterized by chronic inflammation and steatosis, mainly caused by the ectopic accumulation of lipids in the liver, especially LCFAs. CD36 is a scavenger receptor that recognizes and mediates the transmembrane absorption of LCFAs and is expressed in a variety of cells throughout the body. In previous studies, our group found that 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) has the biological effect of targeting CD36 to inhibit oxidized low-density lipoprotein lipotoxicity-induced lipid metabolism disorder; it has an ω-carboxyl physiologically active center and is structurally similar to LCFAs. However, the biological mechanism of oxLig-1 binding to CD36 and competing for binding to different types of LCFAs is still not clear. In this study, molecular docking and molecular dynamics simulation were utilized to simulate and analyze the binding activity between oxLig-1 and different types of LCFAs to CD36 and confirmed by the enzyme-linked immunosorbent assay (ELISA) method. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) platform was applied to predict the drug-forming properties of oxLig-1, and HepG2 cells model of oleic acid and nonalcoholic fatty liver disease (NAFLD) model mice were validated to verify the biological protection of oxLig-1 on lipid lowering. The results showed that there was a co-binding site of LCFAs and oxLig-1 on CD36, and the binding driving forces were mainly hydrogen bonding and hydrophobic interactions. The binding abilities of polyunsaturated LCFAs, oxLig-1, monounsaturated LCFAs, and saturated LCFAs to CD36 showed a decreasing trend in this order. There was a similar decreasing trend in the stability of the molecular dynamics simulation. ELISA results similarly confirmed that the binding activity of oxLig-1 to CD36 was significantly higher than that of typical monounsaturated and saturated LCFAs. ADMET prediction results indicated that oxLig-1 had a good drug-forming property. HepG2 cells model of oleic acid and NAFLD model mice study results demonstrated the favorable lipid-lowering biological effects of oxLig-1. Therefore, oxLig-1 may have a protective effect by targeting CD36 to inhibit the excessive influx and deposition of lipotoxicity monounsaturated LCFAs and saturated LCFAs in hepatocytes.

Molecular Drug Simulation and Experimental Validation of the CD36 Receptor Competitively Binding to Long-Chain Fatty Acids by 7-Ketocholesteryl-9-carboxynonanoate.

Non-adherent culture is critical for the transdifferentiation of stem cells from mesoderm to neuroectoderm. Sphere culture has been reported to directly induce the adipose tissue cells to neural stem cells. Here we aimed to evaluate continuous non-adherent culture on the transdifferentiation potential of human adipose-derived stem cells (ASCs) into retinal lineage. Human ASCs were induced into retinal lineage by the treatment of noggin, dickkopf-related protein 1, and IGF-1 (NDI) under adherent and non-adherent culture. The NDI induction treatment with the adherent culture for 21 days promoted robust expression of retinal markers in the induced ASCs as compared to those without NDI induction on the adherent culture. With continuous non-adherent culture for 21 days, human ASCs could highly express retinal marker genes even without NDI induction treatment as compared to those on the adherent culture. The combination of continuous non-adherent culture with the NDI induction did not show a significant upregulation of the retinal marker expression as compared to either NDI induction with the adherent culture or continuous non-adherent culture without NDI induction treatment. In summary, both non-adherent culture and NDI induction medium could independently promote the transdifferentiation of human ASCs into retinal lineage. Yet, their combination did not produce an enhancement effect.

Continuous non-adherent culture promotes transdifferentiation of human adipose-derived stem cells into retinal lineage.

Deep neural network-based programs can be applied to protein structure modeling by inputting amino acid sequences. Here, we aimed to evaluate the AlphaFold2-modeled myocilin wild-type and variant protein structures and compare to the experimentally determined protein structures. Molecular dynamic and ligand binding properties of the experimentally determined and AlphaFold2-modeled protein structures were also analyzed. AlphaFold2-modeled myocilin variant protein structures showed high similarities in overall structure to the experimentally determined mutant protein structures, but the orientations and geometries of amino acid side chains were slightly different. The olfactomedin-like domain of the modeled missense variant protein structures showed fewer folding changes than the nonsense variant when compared to the predicted wild-type protein structure. Differences were also observed in molecular dynamics and ligand binding sites between the AlphaFold2-modeled and experimentally determined structures as well as between the wild-type and variant structures. In summary, the folding of the AlphaFold2-modeled MYOC variant protein structures could be similar to that determined by the experiments but with differences in amino acid side chain orientations and geometries. Careful comparisons with experimentally determined structures are needed before the applications of the in silico modeled variant protein structures.

Evaluation of Myocilin Variant Protein Structures Modeled by AlphaFold2.

: to determine the metabolomics profiles in the plasma samples of primary open-angle glaucoma (POAG) patients. : The plasma samples from 20 POAG patients under intraocular pressure (IOP)-lowering medication treatment and 20 control subjects were subjected to the untargeted metabolomics analysis, among which 10 POAG patients and 10 control subjects were further subjected to the oxylipin-targeted metabolomics analysis by liquid chromatography-mass spectrometry analysis. The prediction accuracy of the differentially abundant metabolites was assessed by the receiver operating characteristic curves. Pathway analysis and correlation analysis on the differentially abundant metabolites and clinical and biochemical parameters were also conducted. : Untargeted metabolomics profiling identified 33 differentially abundant metabolites in the POAG patients, in which the metabolism of linoleic acid, α-linolenic acid, phenylalanine, and tricarboxylic acid cycle were enriched. The correlation analysis indicated that the differentially abundant metabolites were associated with central corneal thickness, peripapillary retinal nerve fiber layer thickness, visual field defects, and lymphocytes. The oxylipin-targeted metabolomics analysis identified 15-keto-Prostaglandin F2 alpha, 13,14-Dihydro-15-keto-prostaglandin D2, 11-Dehydro-thromboxane B2, 8,9-Epoxyeicosatrienoic acid, and arachidonic acid to be significantly decreased in the POAG patients and enriched in the arachidonic acid (AA) pathway. : This study revealed that the metabolites in the arachidonic acid metabolism pathway are differentially abundant, suggesting high IOP may not be the only detrimental factor for optic nerve cell damage in this group of POAG patients. Lipid metabolism instability-mediated alterations in oxylipins and AA pathways may be important in POAG, suggesting that oxidative stress and immune-related inflammation could be valuable directions for future therapeutic strategies.

Untargeted and Oxylipin-Targeted Metabolomics Study on the Plasma Samples of Primary Open-Angle Glaucoma Patients.

To investigate the plasma lipoprotein subclasses in patients with primary open-angle glaucoma (POAG), a total of 20 Chinese POAG patients on intraocular pressure (IOP)-lowering treatment and 20 age-matched control subjects were recruited. Based on the levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), the study subjects were divided into elevated- and normal-level subgroups. The plasma lipoprotein, lipoprotein subclasses, and oxidized LDL (oxLDL) levels were quantitatively measured. The discrimination potential of the lipoproteins was evaluated using the area under the receiver operating characteristic curve (AUC), and their correlation with clinical parameters was also evaluated. Compared to the control subjects with elevated TC and/or LDL-C levels, the levels of TC, LDL-C, non-high-density lipoprotein cholesterol (non-HDL), LDL subclass LDL3 and small dense LDL (sdLDL), and oxLDL were significantly higher in POAG patients with elevated TC and/or LDL-C levels. No differences in any lipoproteins or the subclasses were found between the POAG patients and control subjects with normal TC and LDL-C levels. Moderate-to-good performance of TC, LDL-C, non-HDL, LDL3, sdLDL, and oxLDL was found in discriminating between the POAG patients and control subjects with elevated TC and/or LDL-C levels (AUC: 0.710-0.950). Significant negative correlations between LDL3 and sdLDL with retinal nerve fiber layer (RNFL) thickness in the superior quadrant and between LDL3 and average RNFL thickness were observed in POAG patients with elevated TC and/or LDL-C levels. This study revealed a significant elevation of plasma lipoproteins, especially the LDL subclasses, in POAG patients with elevated TC and/or LDL-C levels, providing insights on monitoring specific lipoproteins in POAG patients with elevated TC and/or LDL-C.

Profile of Lipoprotein Subclasses in Chinese Primary Open-Angle Glaucoma Patients.

Investigate the oxylipin profiles in the aqueous humor of primary open-angle glaucoma (POAG) patients.

Oxylipins in Aqueous Humor of Primary Open-Angle Glaucoma Patients.

Autosomal dominant optic atrophy (ADOA) caused by mutations in the nuclear-encoded OPA1 gene result in the preferential loss of retinal ganglion cells (RGCs) and progressive optic nerve degeneration. The severity of ADOA can be highly variable. This study compared the pathophysiological consequences of the c.1034 G > A OPA1 missense mutation and the c.1305+2delGT OPA1 deletion. There was a significant correlation between the severity of visual loss and the extent of macular RGC loss as determined by optical coherence tomography imaging. In cells transfected with the c.1034 G > A mutant, the percentage of fragmented mitochondria was greater than 60% with cytochrome c (cyt c) overflow, and significantly elevated levels of reactive oxygen species (ROS) and apoptosis. In contrast, the c.1305+2delGT mutant caused mitochondrial fragmentation in ~ 20% of HeLa cells, resulting in less cyt c overflow and apoptosis. The extent of mitochondrial network fragmentation and apoptosis increased with decreasing WT OPA1 mRNA expression levels. The c.1034 G > A OPA1 missense mutation is likely to induce a dominant-negative effect compared with haploinsufficiency with the c.1305+2delGT OPA1 deletion. These contrasting pathophysiological mechanisms could influence disease severity in ADOA through their differential consequences on mitochondrial structure and function. The small drug molecule Paromomycin was able to rescue the mitochondrial fragmentation induced by the c.1034 G > A mutation, providing proof-of-concept for further therapeutic validation in ADOA.

Contrasting pathophysiological mechanisms of OPA1 mutations in autosomal dominant optic atrophy.

Primary open angle glaucoma (POAG) is a major subtype of glaucoma and a leading cause of irreversible visual impairment and blindness worldwide, but with elusive pathogenesis. Here we aimed to delineate the N-glycan profile in the plasma samples of POAG patients and compare to that of the mild senile cataract subjects. Fasting peripheral whole blood was collected from 44 unrelated Han Chinese POAG patients and 39 mild senile cataract subjects. The plasma samples were isolated and subjected to the N-glycan profiling analysis by high throughput fluorophore-assisted capillary gel electrophoreses in an DNA sequencer. In total, 21 major asialo N-glycan peaks were observed in the plasma samples of the POAG patients and cataract subjects through the capillary gel electrophoresis analysis. Relative peak height proportions of Peak III, VIII, and X showed significant differences in the POAG patients as compared to the cataract subjects, and combined Peak III, VIII, and X achieved an AUC of 0.792. Linear correlation analysis revealed a negative correlation of Peak X with mean deviation of visual field in the POAG patients. Notably, sex-specific N-glycan differences were observed. Lectin blotting demonstrated higher level of core fucosylation on the plasma immunoglobulin G of the POAG patients. In summary, this study revealed the N-glycan profiles in the plasma samples of POAG patients. The plasma N-glycan signature can be a potential novel biomarker for POAG.

Article	Year
Notch Signaling Activation Enhances Human Adipose-Derived Stem Cell Retinal Differentiation. Stem cells international\| PubMed ID: 30410544	2018
Attenuated regenerative properties in human periodontal ligament-derived stem cells of older donor ages with shorter telomere length and lower SSEA4 expression. Cell and tissue research\| PubMed ID: 32043210	2020
Expression of SARS-CoV-2 receptor ACE2 and TMPRSS2 in human primary conjunctival and pterygium cell lines and in mouse cornea. Eye (London, England)\| PubMed ID: 32382146	2020
Protective effects of nattokinase against microvasculopathy and neuroinflammation in diabetic retinopathy. Journal of diabetes\| PubMed ID: 37403338	2023
Molecular Drug Simulation and Experimental Validation of the CD36 Receptor Competitively Binding to Long-Chain Fatty Acids by 7-Ketocholesteryl-9-carboxynonanoate. ACS omega\| PubMed ID: 37576668	2023
Continuous non-adherent culture promotes transdifferentiation of human adipose-derived stem cells into retinal lineage. Open life sciences\| PubMed ID: 38027227	2023
Evaluation of Myocilin Variant Protein Structures Modeled by AlphaFold2. Biomolecules\| PubMed ID: 38275755	2023
Untargeted and Oxylipin-Targeted Metabolomics Study on the Plasma Samples of Primary Open-Angle Glaucoma Patients. Biomolecules\| PubMed ID: 38540727	2024
Profile of Lipoprotein Subclasses in Chinese Primary Open-Angle Glaucoma Patients. International journal of molecular sciences\| PubMed ID: 38674129	2024
Oxylipins in Aqueous Humor of Primary Open-Angle Glaucoma Patients. Biomolecules\| PubMed ID: 39334893	2024
Contrasting pathophysiological mechanisms of OPA1 mutations in autosomal dominant optic atrophy. Cell death discovery\| PubMed ID: 40447565	2025
Plasma N-glycan signature as biomarker for primary open angle glaucoma. Experimental eye research\| PubMed ID: 41038368	2025

Chong-Bo Chen

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