MiR-124 Promote Neurogenic Transdifferentiation of Adipose Derived Mesenchymal Stromal Cells Partly through RhoA/ROCK1, but Not ROCK2 Signaling Pathway

M2 Microglia-Derived Exosomes Protect Against Glutamate-Induced HT22 Cell Injury via Exosomal miR-124-3p

As one of the most serious complications of sepsis, sepsis-associated encephalopathy has not been effectively treated or prevented. Exosomes, as a new therapeutic method, play a protective role in neurodegenerative diseases, stroke and traumatic brain injury in recent years. The purpose of this study was to investigate the role of exosomes in glutamate (Glu)-induced neuronal injury, and to explore its mechanism, providing new ideas for the treatment of sepsis-associated encephalopathy. The neuron damage model induced by Glu was established, and its metabolomics was analyzed and identified. BV2 cells were induced to differentiate into M1 and M2 subtypes. After the exosomes from both M1-BV2 cells and M2-BV2 cells were collected, exosome morphological identification was performed by transmission electron microscopy and exosome-specific markers were also detected. These exosomes were then cocultured with HT22 cells. CCK-8 method and LDH kit were used to detect cell viability and toxicity. Cell apoptosis, mitochondrial membrane potential and ROS content were respectively detected by flow cytometry, JC-1 assay and DCFH-DA assay. MiR-124-3p expression level was detected by qRT-PCR and Western blot. Bioinformatics analysis and luciferase reporter assay predicted and verified the relationship between miR-124-3p and ROCK1 or ROCK2. Through metabolomics, 81 different metabolites were found, including fructose, GABA, 2, 4-diaminobutyric acid, etc. The enrichment analysis of differential metabolites showed that they were mainly enriched in glutathione metabolism, glycine and serine metabolism, and urea cycle. M2 microglia-derived exosomes could reduce the apoptosis, decrease the accumulation of ROS, restore the mitochondrial membrane potential and the anti-oxidative stress ability in HT22 cells induced by Glu. It was also found that the protective effect of miR-124-3p mimic on neurons was comparable to that of M2-EXOs. Additionally, M2-EXOs might carry miR-124-3p to target ROCK1 and ROCK2 in neurons, affecting ROCK/PTEN/AKT/mTOR signaling pathway, and then reducing Glu-induced neuronal apoptosis. M2 microglia-derived exosomes may protect HT22 cells against Glu-induced injury by transferring miR-124-3p into HT22 cells, with ROCK being a target gene for miR-124-3p.

Cell-derived nanovesicle-mediated drug delivery to the brain: Principles and strategies for vesicle engineering

Developing strategies toward safe and effective drug delivery into the central nervous system (CNS) with improved targeting abilities and reduced off-target effects is crucial. CNS-targeted drug carriers made of synthetic molecules raise concerns about their biodegradation, clearance, immune responses, and neurotoxicity. Cell-derived nanovesicles (CDNs) have recently been applied in CNS-targeted drug delivery, because of their intrinsic stability, biocompatibility, inherent homing capability, and the ability to penetrate through biological barriers, including the blood-brain barrier. Among these CDNs, extracellular vesicles and exosomes are the most studied because their surface can be engineered and modified to cater to brain targeting. In this review, we focus on the application of CDNs in brain-targeted drug delivery to treat neurological diseases. We cover recently developed methods of exosome derivation and engineering, including exosome-like particles, hybrid exosomes, exosome-associated adeno-associated viruses, and envelope protein nanocages. Finally, we discuss the limitations and project the future development of the CDN-based brain-targeted delivery systems, and conclude that engineered CDNs hold great potential in the treatment of neurological diseases.

Molecular Mechanisms Involved in the Regulation of Neurodevelopment by miR-124

miR-124 is a miRNA predominantly expressed in the nervous system and accounts for more than a quarter of the total miRNAs in the brain. It regulates neurogenesis, neuronal differentiation, neuronal maturation, and synapse formation and is the most important miRNA in the brain. Furthermore, emerging evidence has suggested miR-124 may be associated with the pathogenesis of various neurodevelopmental and neuropsychiatric disorders. Here, we provide an overview of the role of miR-124 in neurodevelopment and the underling mechanisms, and finally, we prospect the significance of miR-124 research to the field of neuroscience.

MicroRNA-eQTLs in the developing human neocortex link miR-4707-3p expression to brain size

Expression quantitative trait loci (eQTL) data have proven important for linking non-coding loci to protein-coding genes. But eQTL studies rarely measure microRNAs (miRNAs), small non-coding RNAs known to play a role in human brain development and neurogenesis. Here, we performed small-RNA sequencing across 212 mid-gestation human neocortical tissue samples, measured 907 expressed miRNAs, discovering 111 of which were novel, and identified 85 local-miRNA-eQTLs. Colocalization of miRNA-eQTLs with GWAS summary statistics yielded one robust colocalization of miR-4707-3p expression with educational attainment and brain size phenotypes, where the miRNA expression increasing allele was associated with decreased brain size. Exogenous expression of miR-4707-3p in primary human neural progenitor cells decreased expression of predicted targets and increased cell proliferation, indicating miR-4707-3p modulates progenitor gene regulation and cell fate decisions. Integrating miRNA-eQTLs with existing GWAS yielded evidence of a miRNA that may influence human brain size and function via modulation of neocortical brain development.

RhoA Signaling in Neurodegenerative Diseases

Ras homolog gene family member A (RhoA) is a small GTPase of the Rho family involved in regulating multiple signal transduction pathways that influence a diverse range of cellular functions. RhoA and many of its downstream effector proteins are highly expressed in the nervous system, implying an important role for RhoA signaling in neurons and glial cells. Indeed, emerging evidence points toward a role of aberrant RhoA signaling in neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. In this review, we summarize the current knowledge of RhoA regulation and downstream cellular functions with an emphasis on the role of RhoA signaling in neurodegenerative diseases and the therapeutic potential of RhoA inhibition in neurodegeneration.

Insight Into Rho Kinase Isoforms in Obesity and Energy Homeostasis

Obesity and associated complications increasingly jeopardize global health and contribute to the rapidly rising prevalence of type 2 diabetes mellitus and obesity-related diseases. Developing novel methods for the prevention and treatment of excess body adipose tissue expansion can make a significant contribution to public health. Rho kinase is a Rho-associated coiled-coil-containing protein kinase (Rho kinase or ROCK). The ROCK family including ROCK1 and ROCK2 has recently emerged as a potential therapeutic target for the treatment of metabolic disorders. Up-regulated ROCK activity has been involved in the pathogenesis of all aspects of metabolic syndrome including obesity, insulin resistance, dyslipidemia and hypertension. The RhoA/ROCK-mediated actin cytoskeleton dynamics have been implicated in both white and beige adipogenesis. Studies using ROCK pan-inhibitors in animal models of obesity, diabetes, and associated complications have demonstrated beneficial outcomes. Studies via genetically modified animal models further established isoform-specific roles of ROCK in the pathogenesis of metabolic disorders including obesity. However, most reported studies have been focused on ROCK1 activity during the past decade. Due to the progress in developing ROCK2-selective inhibitors in recent years, a growing body of evidence indicates more attention should be devoted towards understanding ROCK2 isoform function in metabolism. Hence, studying individual ROCK isoforms to reveal their specific roles and principal mechanisms in white and beige adipogenesis, insulin sensitivity, energy balancing regulation, and obesity development will facilitate significant breakthroughs for systemic treatment with isoform-selective inhibitors. In this review, we give an overview of ROCK functions in the pathogenesis of obesity and insulin resistance with a particular focus on the current understanding of ROCK isoform signaling in white and beige adipogenesis, obesity and thermogenesis in adipose tissue and other major metabolic organs involved in energy homeostasis regulation.

Mouse Neural Stem Cell Differentiation and Human Adipose Mesenchymal Stem Cell Transdifferentiation Into Neuron- and Oligodendrocyte-like Cells With Myelination Potential

Stem cell therapy is an interesting approach for neural repair, once it can improve and increase processes, like angiogenesis, neurogenesis, and synaptic plasticity. In this regard, adult neural stem cells (NSC) are studied for their mechanisms of proliferation, differentiation and functionality in neural repair. Here, we describe novel neural differentiation methods. NSC from adult mouse brains and human adipose-derived stem cells (hADSC) were isolated and characterized regarding their neural differentiation potential based on neural marker expression profiles. For both cell types, their capabilities of differentiating into neuron-, astrocyte- and oligodendrocytes-like cells (NLC, ALC and OLC, respectively) were analyzed. Our methodologies were capable of producing NLC, ALC and OLC from adult murine and human transdifferentiated NSC. NSC showed augmented gene expression of NES, TUJ1, GFAP and PDGFRA/Cnp. Following differentiation induction into NLC, OLC or ALC, specific neural phenotypes were obtained expressing MAP2, GalC/O4 or GFAP with compatible morphologies, respectively. Accordingly, immunostaining for nestin⁺ in NSC, GFAP⁺ in astrocytes and GalC/O4⁺ in oligodendrocytes was detected. Co-cultured NLC and OLC showed excitability in 81.3% of cells and 23.5% of neuron/oligodendrocyte marker expression overlap indicating occurrence of in vitro myelination. We show here that hADSC can be transdifferentiated into NSC and distinct neural phenotypes with the occurrence of neuron myelination in vitro, providing novel strategies for CNS regeneration therapy. Superior Part: Schematic organization of obtaining and generating hNSC from hADSC and differentiation processes and phenotypic expression of neuron, astrocyte and oligodendrocyte markers (MAP2, GFAP and O4, respectively) and stem cell marker (NES) of differentiating hNSC 14 days after induction. The nuclear staining in blue corresponds to DAPI. bar = 100 μm. Inferior part: Neural phenotype fates in diverse differentiation media. NES: nestin; GFAP: Glial fibrillary acidic protein. MAP2: Microtubule-associated protein 2. TUJ1: β-III tubulin. PDGFRA: PDGF receptor alpha. Two-way ANOVA with Bonferroni post-test with n = 3. * p < 0.05 and ** p < 0.01: (NSCiM1 NSC induction medium 1) vs differentiation media.

Neuronal Dynamics and miRNA Signaling Differ between SH-SY5Y APPSwe and PSEN1 Mutant iPSC-Derived AD Models upon Modulation with miR-124 Mimic and Inhibitor

Neuronal miRNA dysregulation may have a role in the pathophysiology of Alzheimer's disease (AD). miRNA(miR)-124 is largely abundant and a critical player in many neuronal functions. However, the lack of models reliably recapitulating AD pathophysiology hampers our understanding of miR-124's role in the disease. Using the classical human SH-SY5Y-APP695 Swedish neuroblastoma cells (SH-SWE) and the PSEN1 mutant iPSC-derived neurons (iNEU-PSEN), we observed a sustained upregulation of miR-124/miR-125b/miR-21, but only miR-124 was consistently shuttled into their exosomes. The miR-124 mimic reduced APP gene expression in both AD models. While miR-124 mimic in SH-SWE neurons led to neurite outgrowth, mitochondria activation and small Aβ oligomer reduction, in iNEU-PSEN cells it diminished Tau phosphorylation, whereas miR-124 inhibitor decreased dendritic spine density. In exosomes, cellular transfection with the mimic predominantly downregulated miR-125b/miR-21/miR-146a/miR-155. The miR-124 inhibitor upregulated miR-146a in the two experimental cell models, while it led to distinct miRNA signatures in cells and exosomes. In sum, though miR-124 function may be dependent on the neuronal AD model, data indicate that keeping miR-124 level strictly controlled is crucial for proper neuronal function. Moreover, the iNEU-PSEN cellular model stands out as a useful tool for AD mechanistic studies and perhaps for the development of personalized therapeutic strategies.

Exosomal microRNAs from mesenchymal stem/stromal cells: Biology and applications in neuroprotection

Mesenchymal stem/stromal cells (MSCs) are extensively studied as cell-therapy agents for neurological diseases. Recent studies consider exosomes secreted by MSCs as important mediators for MSCs’ neuroprotective functions. Exosomes transfer functional molecules including proteins, lipids, metabolites, DNAs, and coding and non-coding RNAs from MSCs to their target cells. Emerging evidence shows that exosomal microRNAs (miRNAs) play a key role in the neuroprotective properties of these exosomes by targeting several genes and regulating various biological processes. Multiple exosomal miRNAs have been identified to have neuroprotective effects by promoting neurogenesis, neurite remodeling and survival, and neuroplasticity. Thus, exosomal miRNAs have significant therapeutic potential for neurological disorders such as stroke, traumatic brain injury, and neuroinflammatory or neurodegenerative diseases and disorders. This review discusses the neuroprotective effects of selected miRNAs (miR-21, miR-17-92, miR-133, miR-138, miR-124, miR-30, miR146a, and miR-29b) and explores their mechanisms of action and applications for the treatment of various neurological disease and disorders. It also provides an overview of state-of-the-art bioengineering approaches for isolating exosomes, optimizing their yield and manipulating the miRNA content of their cargo to improve their therapeutic potential.

RVG29-modified microRNA-loaded nanoparticles improve ischemic brain injury by nasal delivery

Effective nose-to-brain delivery needs to be developed to treat neurodegenerative diseases. Regulating miR-124 can effectively improve the symptoms of ischemic brain injury and provide a certain protective effect from brain damage after cerebral ischemia. We used rat models of middle cerebral artery occlusion (t-MCAO) with ischemic brain injury, and we delivered RVG29-NPs-miR124 intranasally to treat neurological damage after cerebral ischemia. Rhoa and neurological scores in rats treated by intranasal administration of RVG29-PEG-PLGA/miRNA-124 were significantly lower than those in PEG-PLGA/miRNA-124 nasal administration and RVG29-PLGA/miRNA-124 nasal administration group treated rats. These results indicate that the nose-to-brain delivery of PLGA/miRNA-124 conjugated with PEG and RVG29 alleviated the symptoms of cerebral ischemia-reperfusion injury. Thus, nasal delivery of RVG29-PEG-PLGA/miRNA-124 could be a new method for treating neurodegenerative diseases.

Neurotrophic Factor Secretion and Neural Differentiation Potential of Multilineage-differentiating Stress-enduring (Muse) Cells Derived from Mouse Adipose Tissue

Multilineage-differentiating stress-enduring (Muse) cells are endogenous pluripotent stem cells that can be isolated based on stage-specific embryonic antigen-3 (SSEA-3), a pluripotent stem cell-surface marker. However, their capacities for survival, neurotrophic factor secretion, and neuronal and glial differentiation are unclear in rodents. Here we analyzed mouse adipose tissue-derived Muse cells in vitro. We collected mesenchymal stem cells (MSCs) from C57BL/6 J mouse adipose tissue and separated SSEA-3⁺, namely Muse cells, and SSEA-3^-, non-Muse cells, to assess self-renewability; pluripotency marker expression (Nanog, Oct3/4, Sox2, and SSEA-3); spontaneous differentiation into endodermal, mesodermal, and ectodermal lineages; and neural differentiation capabilities under cytokine induction. Neurally differentiated Muse and non-Muse cell functions were assessed by calcium imaging. Antioxidant ability was measured to assess survival under oxidative stress. Brain-derived neurotrophic factor (BDNF), vascular endothelial cell growth factor (VEGF), and hepatocyte growth factor (HGF) secretion were analyzed in enzyme-linked immunosorbent assays. SSEA-3⁺ Muse cells (6.3 ± 1.9% of mouse adipose-MSCs), but not non-Muse cells, exhibited self-renewability, spontaneous differentiation into the three germ layers, and differentiation into cells positive for Tuj-1 (27 ± 0.9%), O4 (17 ± 3.4%), or GFAP (23 ± 1.3%) under cytokine induction. Neurally differentiated Muse cells responded to KCl depolarization with greater increases in cytoplasmic Ca²⁺ levels than non-Muse cells. Cell survival under oxidative stress was significantly higher in Muse cells (50 ± 2.7%) versus non-Muse cells (22 ± 2.8%). Muse cells secreted significantly more BDNF, VEGF, and HGF (273 ± 12, 1479 ± 7.5, and 6591 ± 1216 pg/mL, respectively) than non-Muse cells (133 ± 4.0, 1165 ± 20, and 2383 ± 540 pg/mL, respectively). Mouse Muse cells were isolated and characterized for the first time. Muse cells showed greater pluripotency-like characteristics, survival, neurotrophic factor secretion, and neuronal and glial-differentiation capacities than non-Muse cells, indicating that they may have better neural-regeneration potential.

Molecular Mechanisms of Transdifferentiation of Adipose-Derived Stem Cells into Neural Cells: Current Status and Perspectives

Neurological diseases can severely compromise both physical and psychological health. Recently, adult mesenchymal stem cell- (MSC-) based cell transplantation has become a potential therapeutic strategy. However, most studies related to the transdifferentiation of MSCs into neural cells have had disappointing outcomes. Better understanding of the mechanisms underlying MSC transdifferentiation is necessary to make adult stem cells more applicable to treating neurological diseases. Several studies have focused on adipose-derived stromal/stem cell (ADSC) transdifferentiation. The purpose of this review is to outline the molecular characterization of ADSCs, to describe the methods for inducing ADSC transdifferentiation, and to examine factors influencing transdifferentiation, including transcription factors, epigenetics, and signaling pathways. Exploring and understanding the mechanisms are a precondition for developing and applying novel cell therapies.

[Research progress of miRNA regulation in differentiation of adipose-derived stem cells]

Objective

To review the research progress of miRNA regulation in the differentiation of adipose-derived stem cells (ADSCs).

Methods

The recent literature associated with miRNAs and differentiation of ADSCs was reviewed. The regulatory mechanism was analyzed in detail and summarized.

Results

The results indicate that the expression of miRNAs changes during differentiation of ADSCs. In addition, miRNAs regulate the differentiation of ADSCs into adipocytes, osteoblasts, chondrocytes, neurons, and hepatocytes by regulating the signaling pathways involved in cell differentiation.

Conclusion

Through controlling the differentiation of ADSCs by miRNAs, the suitable seed cell for tissue engineering can be established. The review will provide a theoretical basis for molecular targeted therapy and stem cell therapy in clinic.

Nogo receptor knockdown and ciliary neurotrophic factor attenuate diabetic retinopathy in streptozotocin-induced diabetic rats

Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM). We investigated whether Nogo receptor (NgR) knockdown and ciliary neurotrophic factor (CNTF) treatment, either alone or in combination, ameliorated diabetic retinopathy (DR) in diabetic rat model. STZ‑induced diabetic rats were administrated for a total of 12 weeks with 3 µM siRNA (5 µl) once every 6 weeks and/or 1 µg CNTF weekly. The retinal tissues were excised. We measured cell number in ganglion cell layer (GCL) using H&E staining and cell apoptosis using TUNEL assay. Bax, Bcl‑2, Caspase‑3, F‑actin, GAP‑43, NgR, RhoA and Rock1 levels were then analyzed by Western blotting, Immunohistochemistry or Real‑time PCR. We found that NgR siRNA or CNTF injection alone significantly increased cell count in GCL in diabetic rats, inhibited ganglion cell apoptosis, elevated Bcl‑2, F‑actin and GAP‑43, and decreased Bax, Caspase‑3, NgR, RhoA and Rock1 levels. Combination treatment further prevented retinal ganglion cell loss, enhanced growth cone cytoskeleton and axonal regeneration, and suppressed NgR/RhoA/Rock1. Our results indicate that combination therapy has therapeutic potential for the treatment of DR.

MiR124 suppresses collagen formation of human tendon derived stem cells through targeting egr1

Collagen formation is used as a crucial indicator of tenogenic differentiation of human tendon derived stem cell (hTDSC). Early growth response-1(egr1), a transcriptional factor, has been demonstrated to regulate tendon differentiation and promote tendon repair. Considering that the therapeutic options for tendon injuries remain limited, investigating the regulation of egr1 could facilitate the understanding of tendon development at molecular level so as to find a promising therapeutic target. MicroRNAs (miRNA) have been considered as epigenetic regulators to mediate multiple biological activities including stem cell differentiation. In the present study, biological experiments confirmed the prediction that miR124-3p (miR124) could have direct binding with egr1. We also found that miR124 suppressed collagen formation during the tendon differentiation of hTDSC while anti-miR124 promoted it. Furthermore, egr1 knockdown abolished the promotive effect of anti-miR124, suggesting that miR124 prevents tendon differentiation via suppressing egr1 expression. Therefore, miR124 may be a promising therapeutic target for tendon injury.