MicroRNA Let-7f-5p Promotes Bone Marrow Mesenchymal Stem Cells Survival by Targeting Caspase-3 in Alzheimer Disease Model

In vivo and ex vivo gene therapy for neurodegenerative diseases: a promise for disease modification

Neurodegenerative diseases (NDDs), including AD, PD, HD, and ALS, represent a growing public health concern linked to aging and lifestyle factors, characterized by progressive nervous system damage leading to motor and cognitive deficits. Current therapeutics offer only symptomatic management, highlighting the urgent need for disease-modifying treatments. Gene therapy has emerged as a promising approach, targeting the underlying pathology of diseases with diverse strategies including gene replacement, gene silencing, and gene editing. This innovative therapeutic approach involves introducing functional genetic material to combat disease mechanisms, potentially offering long-term efficacy and disease modification. With advancements in genomics, structural biology, and gene editing tools such as CRISPR/Cas9, gene therapy holds significant promise for addressing the root causes of NDDs. Significant progress in preclinical and clinical studies has demonstrated the potential of in vivo and ex vivo gene therapy to treat various NDDs, offering a versatile and precise approach in comparison to conventional treatments. The current review describes various gene therapy approaches employed in preclinical and clinical studies for the treatment of NDDs, including AD, PD, HD, and ALS, and addresses some of the key translational challenges in this therapeutic approach.

Mesenchymal Stem Cells from Familial Alzheimer's Patients Express MicroRNA Differently

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the predominant form of dementia globally. No reliable diagnostic, predictive techniques, or curative interventions are available. MicroRNAs (miRNAs) are vital to controlling gene expression, making them valuable biomarkers for diagnosis and prognosis. This study examines the transcriptome of olfactory ecto-mesenchymal stem cells (MSCs) derived from individuals with the PSEN1(A431E) mutation (Jalisco mutation). The aim is to determine whether this mutation affects the transcriptome and expression profile of miRNAs and their target genes at different stages of asymptomatic, presymptomatic, and symptomatic conditions. Expression microarrays compare the MSCs from mutation carriers with those from healthy donors. The results indicate a distinct variation in the expression of miRNAs and mRNAs among different symptomatologic groups and between individuals with the mutation. Using bioinformatics tools allows us to identify target genes for miRNAs, which in turn affect various biological processes and pathways. These include the cell cycle, senescence, transcription, and pathways involved in regulating the pluripotency of stem cells. These processes are closely linked to inter- and intracellular communication, vital for cellular functioning. These findings can enhance our comprehension and monitoring of the disease's physiological processes, identify new disorder indicators, and develop innovative treatments and diagnostic tools for preventing or treating AD.

Epigenetics of Alzheimer’s Disease: Past, Present and Future

Alzheimer’s disease (AD) exemplifies a looming epidemic lacking effective treatment and manifests with the accumulation of neurofibrillary tangles, amyloid-β plaques, neuroinflammation, behavioral changes, and acute cognitive impairments. It is a complex, multifactorial disorder that arises from the intricate interaction between environment and genetic factors, restrained via epigenetic machinery. Though the research progress has improved the understanding of clinical manifestations and disease advancement, the causal mechanism of detrimental consequences remains undefined. Despite the substantial improvement in recent diagnostic modalities, it is challenging to distinguish AD from other forms of dementia. Accurate diagnosis is a major glitch in AD as it banks on the symptoms and clinical criteria. Several studies are underway in exploring novel and reliable biomarkers for AD. In this direction, epigenetic alterations have transpired as key modulators in AD pathogenesis with the impeding inferences for the management of this neurological disorder. The present chapter aims to discuss the significance of epigenetic modifications reported in the pathophysiology of AD such as DNA methylation, hydroxy-methylation, methylation of mtDNA, histone modifications, and noncoding RNAs. Additionally, the chapter also describes the possible therapeutic avenues that target epigenetic modifications in AD.

BDNF-enriched small extracellular vesicles protect against noise-induced hearing loss in mice

Noise-induced hearing loss (NIHL) is one of the most prevalent acquired sensorineural hearing loss etiologies and is characterized by the loss of cochlear hair cells, synapses, and nerve terminals. Currently, there are no agents available for the treatment of NIHL because drug delivery to the inner ear is greatly limited by the blood-labyrinth barrier. In this study, we used mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) as nanoscale vehicles to deliver brain-derived neurotrophic factor (BDNF) and evaluated their protective effects in a mouse model of NIHL. Following intravenous administration, BDNF-loaded sEVs (BDNF-sEVs) efficiently increased the expression of BDNF protein in the cochlea. Systemic application of sEVs and BDNF-sEVs significantly attenuated noise-induced cochlear hair cell loss and NIHL in CBA/J mice. BDNF-sEVs also alleviated noise-induced loss of inner hair cell ribbon synapses and cochlear nerve terminals. In cochlear explants, sEVs and BDNF-sEVs effectively protected hair cells against H2O2-induced cell loss. Additionally, BDNF-sEVs remarkably ameliorated H2O2-induced oxidative stress, cell apoptosis, and cochlear nerve terminal degeneration. Transcriptomic analysis revealed that many mRNAs and miRNAs were involved in the protective actions of BDNF-sEVs against oxidative stress. Collectively, our findings reveal a novel therapeutic strategy of MSC-sEVs-mediated BDNF delivery for the treatment of NIHL.

The microRNAs (miRs) overexpressing mesenchymal stem cells (MSCs) therapy in neurological disorders; hope or hype

Altered expression of multiple miRNAs was found to be extensively involved in the pathogenesis of different neurological disorders including Alzheimer's disease, Parkinson's disease, stroke, epilepsy, multiple sclerosis, amyotrophic lateral sclerosis, and Huntington's disease. One of the biggest concerns within gene-based therapy is the delivery of the therapeutic microRNAs to the intended place, which is obligated to surpass the biological barriers without undergoing degradation in the bloodstream or renal excretion. Hence, the delivery of modified and unmodified miRNA molecules using excellent vehicles is required. In this light, mesenchymal stem cells (MSCs) have attracted increasing attention. The MSCs can be genetically modified to express or overexpress a particular microRNA aimed with promote neurogenesis and neuroprotection. The current review has focused on the therapeutic capabilities of microRNAs-overexpressing MSCs to ameliorate functional deficits in neurological conditions.

The microRNomes of Chinese hamster ovary (CHO) cells and their extracellular vesicles, and how they respond to osmotic and ammonia stress

A new area of focus in Chinese hamster ovary (CHO) biotechnology is the role of small (exosomes) and large (microvesicles or microparticles) extracellular vesicles (EVs). CHO cells in culture exchange large quantities of proteins and RNA through these EVs, yet the content and role of these EVs remain elusive. MicroRNAs (miRs or miRNA) are central to adaptive responses to stress and more broadly to changes in culture conditions. Given that EVs are highly enriched in miRs, and that EVs release large quantities of miRs both in vivo and in vitro, EVs and their miR content likely play an important role in adaptive responses. Here we report the miRNA landscape of CHO cells and their EVs under normal culture conditions and under ammonia and osmotic stress. We show that both cells and EVs are highly enriched in five miRs (among over 600 miRs) that make up about half of their total miR content, and that these highly enriched miRs differ significantly between normal and stress culture conditions. Notable is the high enrichment in miR-92a and miR-23a under normal culture conditions, in contrast to the high enrichment in let-7 family miRs (let-7c, let-7b, and let-7a) under both stress conditions. The latter suggests a preserved stress-responsive function of the let-7 miR family, one of the most highly preserved miR families across species, where among other functions, let-7 miRs regulate core oncogenes, which, depending on the biological context, may tip the balance between cell cycle arrest and apoptosis. While the expected-based on their profound enrichment-important role of these highly enriched miRs remains to be dissected, our data and analysis constitute an important resource for exploring the role of miRs in cell adaptation as well as for synthetic applications.

Mechanisms of analgesic effect of mesenchymal stem cells in osteoarthritis pain

Osteoarthritis (OA) is the most common musculoskeletal disease, and it is a major cause of pain, disability and health burden. Pain is the most common and bothersome presentation of OA, but its treatment is still suboptimal, due to the short-term action of employed analgesics and their poor adverse effect profile. Due to their regenerative and anti-inflammatory properties, mesenchymal stem cells (MSCs) have been extensively investigated as a potential therapy for OA, and numerous preclinical and clinical studies found a significant improvement in joint pathology and function, pain scores and/or quality of life after administration of MSCs. Only a limited number of studies, however, addressed pain control as the primary end-point or investigated the potential mechanisms of analgesia induced by MSCs. In this paper, we review the evidence reported in literature that support the analgesic action of MSCs in OA, and we summarize the potential mechanisms of these antinociceptive effects.

Stem Cell Therapy for Alzheimer's Disease: A Scoping Review for 2017-2022

Alzheimer's disease (AD) has been a major causal factor for mortality among elders around the world. The treatments for AD, however, are still in the stage of development. Stem cell therapy, compared to drug therapies and many other therapeutic options, has many advantages and is very promising in the future. There are four major types of stem cells used in AD therapy: neural stem cells, mesenchymal stem cells, embryonic stem cells, and induced pluripotent stem cells. All of them have applications in the treatments, either at the (1) cellular level, in an (2) animal model, or at the (3) clinical level. In general, many more types of stem cells were studied on the cellular level and animal model, than the clinical level. We suggest for future studies to increase research on various types of stem cells and include cross-disciplinary research with other diseases. In the future, there could also be improvements in the timeliness of research and individualization for stem cell therapies for AD.

Mechanism of acteoside-activated let-7g-5P attenuating Aβ-induced increased permeability and apoptosis of brain microvascular endothelial cells based on experimental and network pharmacology

OBJECTIVES

Amyloid β-protein (Aβ)-induced apoptosis and oxidative stress of human brain microvascular endothelial cells(BMECs) are contributors to the development of Alzheimer's disease (AD). Acteoside has shown its therapeutic potential for AD treatment. Therefore, this study investigated the effect of acteoside on Aβ-induced blood-brain barrier damage, oxidative stress and apoptosis as well as to explore the underlying mechanisms through network pharmacology.

METHODS

The study used Aβ to induce human BMECs to construct an in-vitro injury model. Following treatment with acteoside, transendothelial electrical resistance (TEER), RT-qPCR and Western blot were used to evaluate the permeability of BMECs. The apoptosis level was detected by TUNEL and Western blot, ROS assay kit was used for the detection of reactive oxygen species (ROS) expression. The let-7g-5p expression level was detected by RT-qPCR. After additional treatment with let-7g-5p inhibitor, corresponding assays were performed again. Finally, network pharmacology was used to verify the mechanism.

RESULTS

Acteoside decreased the permeability, oxidative stress and cell apoptosis of Aβ-stimulated cells. More importantly, acteoside-activated let-7g-5p and additional treatment with let-7g-5p inhibitor abated the effects of acteoside on Aβ-induced permeability, oxidative stress and apoptosis of Aβ-stimulated BMECs. According to network pharmacology, 233 targeted genes of acteoside and 122 potential targets of let-7g-5p were determined by screening several databases, and two targets called Casp-3 and ITGB3 were obtained after taking the intersection.

CONCLUSION

In conclusion, these results reveal that acteoside-activated let-7g-5p attenuating Aβ-induced increased permeability and apoptosis of human BMECs.

Methionine Restriction Improves Cognitive Ability by Alleviating Hippocampal Neuronal Apoptosis through H19 in Middle-Aged Insulin-Resistant Mice

LncRNA H19 has been reported to regulate apoptosis and neurological diseases. Hippocampal neuron apoptosis damages cognitive ability. Methionine restriction (MR) can improve cognitive impairment. However, the effect of MR on hippocampal neuronal apoptosis induced by a high-fat diet (HFD) in middle-aged mice remains unclear. For 25 weeks, middle-aged mice (C57BL/6J) were given a control diet (CON, 0.86% methionine + 4.2% fat), a high-fat diet (HFD, 0.86% methionine + 24% fat), or an HFD + MR diet (HFMR, 0.17% methionine + 24% fat). The HT22 cells were used to establish the early apoptosis model induced by high glucose (HG). In vitro, the results showed that MR significantly improved cell viability, suppressed the generation of ROS, and rescued HT22 cell apoptosis in a gradient-dependent manner. In Vivo, MR inhibited the damage and apoptosis of hippocampal neurons caused by a high-fat diet, reduced hippocampal oxidative stress, improved hippocampal glucose metabolism, relieved insulin resistance, and enhanced cognitive ability. Furthermore, MR could inhibit the overexpression of H19 and caspase-3 induced by HFD, HG, or H2O2 in vivo and in vitro, and promoted let-7a, b, e expression. These results indicate that MR can protect neurons from HFD-, HG-, or H2O2-induced injury and apoptosis by inhibiting H19.

miRNA-Based Early Healing Mechanism of Extraction Sockets: miR-190a-5p, a Potential Enhancer of Bone Healing

Objective

Tooth extraction causes a wound with hard and soft tissue defects in the alveolar ridge. Few studies have reported the function of microRNAs (miRNAs) in the healing of extraction sockets. This study used bioinformatics analysis to reveal the possible relevance and role of miRNAs during the early stages following tooth extraction.

Materials and Methods

Socket tissues from beagle dogs (Canis familiaris; two males and two females) were collected 1 and 12 hours after extraction of premolars on both sides of the mandible. miRNA expression was profiled through miRNA sequencing, and hub miRNAs showing characteristic expression patterns were selected and subjected to target enrichment analysis. Alkaline phosphatase (ALP) activity analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) were performed to verify the effect of hub miRNA on osteoblast differentiation and bone regeneration in vivo.

Results

Five miRNAs were identified to have consistently high expression levels, with cfa-miR-451 showing the highest expression. Additionally, 20 hub miRNAs were selected as candidates expected to play an important role in the healing process. Pathways, such as the MAPK, axon guidance, TGF-β, and Wnt signaling, were significantly enriched. Among hub miRNAs, miR-190a-5p increased ALP activity and mRNA expression of osteogenic markers and increased new bone formation in vivo.

Conclusions

Our findings suggest that miRNAs may be involved in the earliest stages of socket healing after tooth extraction and can play an important role in moderating the entire socket healing mechanism in the extraction socket.

Circulating extracellular vesicle-containing microRNAs reveal potential pathogenesis of Alzheimer’s disease

The pathogenesis of Alzheimer’s disease (AD) remains unknown till today, hindering the research and development of AD therapeutics and diagnostics. Circulating extracellular vesicles (EVs) can be utilized as a new window to spy upon AD pathogenesis. Altered microRNA profiles were noted in both the cerebrospinal fluid (CSF)- and blood-isolated EVs of AD patients, implying the outstanding potential of circulating EV-containing miRNAs (CEmiRs) to serve as important regulators in AD pathogenesis. Although several CEmiRs were found to play a part in AD, the association of globally altered miRNA profiles in patients’ serum-derived EVs with AD pathogenesis remains unclear. In this study, we first investigated the miRNA profile in serum-derived EVs from AD, mild cognitive impairment (MCI) patients, and healthy individuals. We observed differential expression patterns of CEmiRs and classified them into 10 clusters. We identified the predicted targets of these differentially expressed CEmiRs (DECEmiRs) and analyzed their biological functions and interactions. Our study revealed the temporal regulation of complex and precise signaling networks on AD pathogenesis, shedding light on the development of novel therapeutic strategies, including multi-target drug combination for AD treatment.

Mesenchymal stromal cells for the treatment of Alzheimer’s disease: Strategies and limitations

Alzheimer’s disease (AD) is a major cause of age-related dementia and is characterized by progressive brain damage that gradually destroys memory and the ability to learn, which ultimately leads to the decline of a patient’s ability to perform daily activities. Although some of the pharmacological treatments of AD are available for symptomatic relief, they are not able to limit the progression of AD and have several side effects. Mesenchymal stem/stromal cells (MSCs) could be a potential therapeutic option for treating AD due to their immunomodulatory, anti-inflammatory, regenerative, antioxidant, anti-apoptotic, and neuroprotective effects. MSCs not only secret neuroprotective and anti-inflammatory factors to promote the survival of neurons, but they also transfer functional mitochondria and miRNAs to boost their bioenergetic profile as well as improve microglial clearance of accumulated protein aggregates. This review focuses on different clinical and preclinical studies using MSC as a therapy for treating AD, their outcomes, limitations and the strategies to potentiate their clinical translation.

Therapeutic utility of mesenchymal stromal cell (MSC)-based approaches in chronic neurodegeneration: a glimpse into underlying mechanisms, current status, and prospects

Recently, mesenchymal stromal cell (MSC)-based therapy has become an appreciated therapeutic approach in the context of neurodegenerative disease therapy. Accordingly, a myriad of studies in animal models and also some clinical trials have evinced the safety, feasibility, and efficacy of MSC transplantation in neurodegenerative conditions, most importantly in Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington’s disease (HD). The MSC-mediated desired effect is mainly a result of secretion of immunomodulatory factors in association with release of various neurotrophic factors (NTFs), such as glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF). Thanks to the secretion of protein-degrading molecules, MSC therapy mainly brings about the degradation of pathogenic protein aggregates, which is a typical appearance of chronic neurodegenerative disease. Such molecules, in turn, diminish neuroinflammation and simultaneously enable neuroprotection, thereby alleviating disease pathological symptoms and leading to cognitive and functional recovery. Also, MSC differentiation into neural-like cells in vivo has partially been evidenced. Herein, we focus on the therapeutic merits of MSCs and also their derivative exosome as an innovative cell-free approach in AD, HD, PD, and ALS conditions. Also, we give a brief glimpse into novel approaches to potentiate MSC-induced therapeutic merits in such disorders, most importantly, administration of preconditioned MSCs.

Immunomodulatory Properties of Human Breast Milk: MicroRNA Contents and Potential Epigenetic Effects

Infants who are exclusively breastfed in the first six months of age receive adequate nutrients, achieving optimal immune protection and growth. In addition to the known nutritional components of human breast milk (HBM), i.e., water, carbohydrates, fats and proteins, it is also a rich source of microRNAs, which impact epigenetic mechanisms. This comprehensive work presents an up-to-date overview of the immunomodulatory constituents of HBM, highlighting its content of circulating microRNAs. The epigenetic effects of HBM are discussed, especially those regulated by miRNAs. HBM contains more than 1400 microRNAs. The majority of these microRNAs originate from the lactating gland and are based on the remodeling of cells in the gland during breastfeeding. These miRNAs can affect epigenetic patterns by several mechanisms, including DNA methylation, histone modifications and RNA regulation, which could ultimately result in alterations in gene expressions. Therefore, the unique microRNA profile of HBM, including exosomal microRNAs, is implicated in the regulation of the genes responsible for a variety of immunological and physiological functions, such as FTO, INS, IGF1, NRF2, GLUT1 and FOXP3 genes. Hence, studying the HBM miRNA composition is important for improving the nutritional approaches for pregnancy and infant's early life and preventing diseases that could occur in the future. Interestingly, the composition of miRNAs in HBM is affected by multiple factors, including diet, environmental and genetic factors.

The functional mechanism of bone marrow-derived mesenchymal stem cells in the treatment of animal models with Alzheimer's disease: crosstalk between autophagy and apoptosis

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer's disease. However, the underlying mechanism remains undefined. Based on meta-analysis and comprehensive review, high-profile studies support the theory that transplanted BMMSCs activate autophagy, as evidenced by the expression levels of signal molecules such as Beclin-1, Atg5, LC3-II, and mTOR. Functional autophagy mitigates neuronal apoptosis, which is reflected by the alterations of IAPs, Bcl-2, caspase-3, and so forth. Moreover, the transplantation of BMMSCs can decrease aberrant amyloid-beta peptides as well as tau aggregates, inhibit neuroinflammation, and stimulate synaptogenesis. There is a signal crosstalk between autophagy and apoptosis, which may be regulated to produce synergistic effect on the preconditioning of stem cells. Forasmuch, the therapeutic effect of transplanted BMMSCs can be enhanced by autophagy and/or apoptosis modulators.

Role of miRNAs in Neurodegeneration: From Disease Cause to Tools of Biomarker Discovery and Therapeutics

Neurodegenerative diseases originate from neuronal loss in the central nervous system (CNS). These debilitating diseases progress with age and have become common due to an increase in longevity. The National Institute of Environmental Health Science’s 2021 annual report suggests around 6.2 million Americans are living with Alzheimer’s disease, and there is a possibility that there will be 1.2 million Parkinson’s disease patients in the USA by 2030. There is no clear-cut universal mechanism for identifying neurodegenerative diseases, and therefore, they pose a challenge for neurobiology scientists. Genetic and environmental factors modulate these diseases leading to familial or sporadic forms. Prior studies have shown that miRNA levels are altered during the course of the disease, thereby suggesting that these noncoding RNAs may be the contributing factor in neurodegeneration. In this review, we highlight the role of miRNAs in the pathogenesis of neurodegenerative diseases. Through this review, we aim to achieve four main objectives: First, we highlight how dysregulation of miRNA biogenesis led to these diseases. Second, we highlight the computational or bioinformatics tools required to identify the putative molecular targets of miRNAs, leading to biological molecular pathways or mechanisms involved in these diseases. Third, we focus on the dysregulation of miRNAs and their target genes leading to several neurodegenerative diseases. In the final section, we highlight the use of miRNAs as potential diagnostic biomarkers in the early asymptomatic preclinical diagnosis of these age-dependent debilitating diseases. Additionally, we discuss the challenges and advances in the development of miRNA therapeutics for brain targeting. We list some of the innovative strategies employed to deliver miRNA into target cells and the relevance of these viral and non-viral carrier systems in RNA therapy for neurodegenerative diseases. In summary, this review highlights the relevance of studying brain-enriched miRNAs, the mechanisms underlying their regulation of target gene expression, their dysregulation leading to progressive neurodegeneration, and their potential for biomarker marker and therapeutic intervention. This review thereby highlights ways for the effective diagnosis and prevention of these neurodegenerative disorders in the near future.

Stem cell therapy for Alzheimer's disease: An overview of experimental models and reality

Alzheimer's disease (AD) is a neurodegenerative disorder. The pathology of AD is characterized by extracellular amyloid beta (Aβ) plaques, neurofibrillary tangles composed of hyperphosphorylated tau, neuronal death, synapse loss, and brain atrophy. Many therapies have been tested to improve or at least effectively modify the course of AD. Meaningful data indicate that the transplantation of stem cells can alleviate neuropathology and significantly ameliorate cognitive deficits in animal models with Alzheimer's disease. Transplanted stem cells have shown their inherent advantages in improving cognitive impairment and memory dysfunction, although certain weaknesses or limitations need to be overcome. This review recapitulates rodent models for AD, the therapeutic efficacy of stem cells, influencing factors, and the underlying mechanisms behind these changes. Stem cell therapy provides perspective and challenges for its clinical application in the future.

Identification of let-7f and miR-338 as plasma-based biomarkers for sporadic amyotrophic lateral sclerosis using meta-analysis and empirical validation

Amyotrophic lateral sclerosis (ALS) is a lethal neurodegenerative disease that in most cases occurs sporadic (sALS). The disease is not curable, and its pathogenesis mechanisms are not well understood yet. Given the intricacy of underlying molecular interactions and heterogeneity of ALS, the discovery of molecules contributing to disease onset and progression will open a new avenue for advancement in early diagnosis and therapeutic intervention. Here we conducted a meta-analysis of 12 circulating miRNA profiling studies using the robust rank aggregation (RRA) method, followed by enrichment analysis and experimental verification. We identified miR-451a and let-7f-5p as meta-signature miRNAs whose targets are involved in critical pathogenic pathways underlying ALS, including ‘FoxO signaling pathway’, ‘MAPK signaling pathway’, and ‘apoptosis’. A systematic review of 7 circulating gene profiling studies elucidated that 241 genes up-regulated in sALS circulation with concomitant being targets of the meta-signature miRNAs. Protein–protein interaction (PPI) network analysis of the candidate targets using MCODE algorithm revealed the main subcluster is involved in multiple cascades eventually leads apoptosis, including ‘positive regulation of neuron apoptosis. Besides, we validated the meta-analysis results using RT-qPCR. Indeed, relative expression analysis verified let-7f-5p and miR-338-3p as significantly down-regulated and up-regulated biomarkers in the plasma of sALS patients, respectively. Receiver operating characteristic (ROC) analysis also highlighted the let-7f-5p and miR-338-3p potential as robustness plasma biomarkers for diagnosis and potential therapeutic targets of sALS disease.

Characterization of Differentially Expressed miRNAs by CXCL12/SDF-1 in Human Bone Marrow Stromal Cells

Stromal cell-derived factor 1 (SDF-1) is known to influence bone marrow stromal cell (BMSC) migration, osteogenic differentiation, and fracture healing. We hypothesize that SDF-1 mediates some of its effects on BMSCs through epigenetic regulation, specifically via microRNAs (miRNAs). MiRNAs are small non-coding RNAs that target specific mRNA and prevent their translation. We performed global miRNA analysis and determined several miRNAs were differentially expressed in response to SDF-1 treatment. Gene Expression Omnibus (GEO) dataset analysis showed that these miRNAs play an important role in osteogenic differentiation and fracture healing. KEGG and GO analysis indicated that SDF-1 dependent miRNAs changes affect multiple cellular pathways, including fatty acid biosynthesis, thyroid hormone signaling, and mucin-type O-glycan biosynthesis pathways. Furthermore, bioinformatics analysis showed several miRNAs target genes related to stem cell migration and differentiation. This study's findings indicated that SDF-1 induces some of its effects on BMSCs function through miRNA regulation.

Anticancer roles of let-7f-1-3p in non-small cell lung cancer via direct targeting of integrin β1

Lung cancer is one of the most common types of cancer, with the highest mortality rate worldwide. MicroRNAs play notable roles in the chemotherapeutic effects of anticancer drugs. The present study used reverse transcription-quantitative PCR, western blotting and cell migration and invasion assays to reveal the role of let-7f-1-3p in non-small cell lung cancer (NSCLC) and explore the effect of let-7f-1-3p on doxorubicin (DOX) treatment. It was demonstrated that the levels of let-7f-1-3p in carcinoma tissues were lower compared with those in paracarcinoma tissues. Thus, let-7f-1-3p may act as a suppressor gene. The present study also explored the role of let-7f-1-3p in A549 and NCI-H1975 cells. Results revealed that let-7f-1-3p could inhibit the viability, migration and invasion of NSCLC cells and induce their apoptosis. Integrin β1 acted as a target gene regulated by let-7f-1-3p. This suggested that let-7f-1-3p could enhance DOX-inhibited cell viability, migration and invasion in vitro. Overall, the present study demonstrated that let-7f-1-3p may act as a target for drug design and lung cancer therapy.

Functional Mechanism of Bone Marrow-Derived Mesenchymal Stem Cells in the Treatment of Animal Models with Alzheimer's Disease: Inhibition of Neuroinflammation

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer’s disease. However, the underlying mechanisms remain to be determined. Available data demonstrate transplanted BMMSCs can inhibit neuroinflammation, which may be related to microglial M1/M2 polarization and is regulated by the secretion of autocrine and paracrine cytokines. BMMSCs also mitigate Aβ plaques and Tau tangles in the brain, which may be associated with the recruitment of peripheral blood monocytes and the subsequent comprehensive effects. The therapeutic effects of stem cells involve potential mechanisms such as immunomodulation, apoptosis, and proliferation. BMMSC-mediated functional reconstruction through dynamic remodeling develops a novel balance. Herein, present review recapitulates the molecular basis of BMMSC-assisted biological processes and summarizes the possible mechanisms related to the interaction between BMMSCs and microglia. The transplanted BMMSCs can suppress neuroinflammation that plays a key role in the pathogenesis of Alzheimer’s disease.

The Therapeutic Potential of Mesenchymal Stromal Cells for Regenerative Medicine: Current Knowledge and Future Understandings

In recent decades, research on the therapeutic potential of progenitor cells has advanced considerably. Among progenitor cells, mesenchymal stromal cells (MSCs) have attracted significant interest and have proven to be a promising tool for regenerative medicine. MSCs are isolated from various anatomical sites, including bone marrow, adipose tissue, and umbilical cord. Advances in separation, culture, and expansion techniques for MSCs have enabled their large-scale therapeutic application. This progress accompanied by the rapid improvement of transplantation practices has enhanced the utilization of MSCs in regenerative medicine. During tissue healing, MSCs may exhibit several therapeutic functions to support the repair and regeneration of injured tissue. The process underlying these effects likely involves the migration and homing of MSCs, as well as their immunotropic functions. The direct differentiation of MSCs as a cell replacement therapeutic mechanism is discussed. The fate and behavior of MSCs are further regulated by their microenvironment, which may consequently influence their repair potential. A paracrine pathway based on the release of different messengers, including regulatory factors, chemokines, cytokines, growth factors, and nucleic acids that can be secreted or packaged into extracellular vesicles, is also implicated in the therapeutic properties of MSCs. In this review, we will discuss relevant outcomes regarding the properties and roles of MSCs during tissue repair and regeneration. We will critically examine the influence of the local microenvironment, especially immunological and inflammatory signals, as well as the mechanisms underlying these therapeutic effects. Importantly, we will describe the interactions of local progenitor and immune cells with MSCs and their modulation during tissue injury. We will also highlight the crucial role of paracrine pathways, including the role of extracellular vesicles, in this healing process. Moreover, we will discuss the therapeutic potential of MSCs and MSC-derived extracellular vesicles in the treatment of COVID-19 (coronavirus disease 2019) patients. Overall, this review will provide a better understanding of MSC-based therapies as a novel immunoregenerative strategy.

An Overview of Mesenchymal Stem Cell-based Therapy Mediated by Noncoding RNAs in the Treatment of Neurodegenerative Diseases

Mesenchymal stem cells (MSCs) have become a promising tool for neurorestorative therapy of neurodegenerative diseases (NDDs), which are mainly characterized by the progressive and irreversible loss of neuronal structure and function in the central or peripheral nervous system. Recently, studies have reported that genetic manipulation mediated by noncoding RNAs (ncRNAs) can increase survival and neural regeneration of transplanted MSCs, offering a new strategy for clinical translation. In this review, we summarize the potential role and regulatory mechanism of two major types of ncRNAs, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), during the neurogenesis of MSCs with gene expression profile analyses. We also overview the realization of MSC-based therapy mediated by ncRNAs in the treatment of spinal cord injury, stroke, Alzheimer's disease and peripheral nerve injury. It is expected that ncRNAs will become promising therapeutic targets for NDD on stem cells, while the underlying mechanisms require further exploration.

Circ_0085289 Alleviates the Progression of Periodontitis by Regulating let-7f-5p/SOCS6 Pathway

Periodontitis is a common chronic inflammation that often occurs in adults. Circular RNAs (circRNAs) play a vital role in inflammation-related diseases. However, the role and potential basis of hsa_circ_0085289 in periodontitis remain unknown. Periodontal ligament cells (PDLCs) were exposed to lipopolysaccharide (LPS) to mimic periodontitis. The levels of circ_0085289, let-7f-5p, and suppressor of cytokine signaling 6 (SOCS6) were determined using qRT-PCR and western blot. The release of inflammatory cytokines was measured via enzyme-linked immunosorbent assay (ELISA). Cell viability and apoptosis were determined using Cell Counting Kit-8, flow cytometry, Caspase-3 Assay Kit, and western blot assays. The association between let-7f-5p and circ_0085289/SOCS6 was validated via dual-luciferase reporter, RNA pull-down, and RIP assays. Circ_0085289 and SOCS6 levels were reduced, and let-7f-5p level was increased in periodontitis patients and LPS-treated PDLCs. LPS stimulation caused PDLC injury and circ_0085289 downregulation. Moreover, circ_0085289 upregulation or let-7f-5p downregulation diminished LPS-triggered PDLC injury. Besides, circ_0085289 promoted SOCS6 expression by absorbing let-7f-5p. Circ_0085289 alleviated LPS-stimulated PDLC injury via targeting let-7f-5p. Moreover, let-7f-5p targeted SOCS6 to affect LPS-resulted PDLC injury. Circ_0085289 alleviated PDLC injury induced by LPS stimulation via modulating let-7f-5p/SOCS6 axis, suggesting a promising biomarker for periodontitis treatment.

The let-7f-5p-Nme4 pathway mediates tumor necrosis factor α-induced impairment in osteogenesis of bone marrow-derived mesenchymal stem cells

Although tumor necrosis factor α (TNF-α)-mediated inflammation significantly impacts osteoporosis, the mechanisms underlying the osteogenic differentiation defects of bone marrow-derived mesenchymal stem cells (BM-MSCs) caused by TNF-α remain poorly understood. We found that TNF-α stimulation of murine BM-MSCs significantly upregulated the expression levels of several microRNAs (miRNAs), including let-7f-5p, but this increase was significantly reversed by treatment with the kinase inhibitor BAY 11-7082. To study gain- or loss of function, we transfected cells with an miRNA inhibitor or miRNA mimic. We then demonstrated that let-7f-5p impaired osteogenic differentiation of BM-MSCs in the absence and presence of TNF-α, as evidenced by alkaline phosphatase and alizarin red staining as well as quantitative assays of the mRNA levels of bone formation marker genes in differentiated BM-MSCs. Moreover, let-7f-5p targets the 3' untranslated region of Nucleoside diphosphate kinase 4 (Nme4) mRNA and negatively regulates Nme4 expression in mouse BM-MSCs. Ectopic expression of Nme4 completely reversed the inhibitory effects of the let-7f-5p mimic on osteogenic differentiation of mouse BM-MSCs. Furthermore, inhibition of let-7f-5p or overexpression of Nme4 in BM-MSCs restored in-vivo bone formation in an ovariectomized animal model. Collectively, our work indicates that let-7f-5p is involved in TNF-α-mediated reduction of BM-MSC osteogenesis via targeting Nme4.

Let-7f miRNA regulates SDF-1α- and hypoxia-promoted migration of mesenchymal stem cells and attenuates mammary tumor growth upon exosomal release

Bone marrow-derived human mesenchymal stem cells (hMSCs) are recruited to damaged or inflamed tissues where they contribute to tissue repair. This multi-step process involves chemokine-directed invasion of hMSCs and on-site release of factors that influence target cells or tumor tissues. However, the underlying molecular mechanisms are largely unclear. Previously, we described that microRNA let-7f controls hMSC differentiation. Here, we investigated the role of let-7f in chemotactic invasion and paracrine anti-tumor effects. Incubation with stromal cell-derived factor-1α (SDF-1α) or inflammatory cytokines upregulated let-7f expression in hMSCs. Transfection of hMSCs with let-7f mimics enhanced CXCR4-dependent invasion by augmentation of pericellular proteolysis and release of matrix metalloproteinase-9. Hypoxia-induced stabilization of the hypoxia-inducible factor 1 alpha in hMSCs promoted cell invasion via let-7f and activation of autophagy. Dependent on its endogenous level, let-7f facilitated hMSC motility and invasion through regulation of the autophagic flux in these cells. In addition, secreted let-7f encapsulated in exosomes was increased upon upregulation of endogenous let-7f by treatment of the cells with SDF-1α, hypoxia, or induction of autophagy. In recipient 4T1 tumor cells, hMSC-derived exosomal let-7f attenuated proliferation and invasion. Moreover, implantation of 3D spheroids composed of hMSCs and 4T1 cells into a breast cancer mouse model demonstrated that hMSCs overexpressing let-7f inhibited tumor growth in vivo. Our findings provide evidence that let-7f is pivotal in the regulation of hMSC invasion in response to inflammation and hypoxia, suggesting that exosomal let-7f exhibits paracrine anti-tumor effects.

RETRACTED: Hepatocellular carcinoma cells-derived exosomal microRNA-378b enhances hepatocellular carcinoma angiogenesis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figs. 2D/G/H, 4C, 5F and 6D, which appear to have the same eyebrow shaped phenotype as many other publications tabulated here (https://docs.google.com/spreadsheets/d/149EjFXVxpwkBXYJOnOHb6RhAqT4a2llhj9LM60MBffM/edit#gid=0). The journal requested the corresponding author comment on these concerns and provide the raw data. However the authors were not able to satisfactorily fulfil this request and therefore the Editor-in-Chief decided to retract the article.

The Eminent Role of microRNAs in the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is an irrevocable neurodegenerative condition characterized by the presence of senile plaques comprising amassed β-amyloid peptides (Aβ) and neurofibrillary tangles mainly comprising extremely phosphorylated Tau proteins. Recent studies have emphasized the role of microRNAs (miRNAs) in the development of AD. A number of miRNAs, namely, miR-200a-3p, miR-195, miR-338-5p, miR-34a-5p, miR-125b-5p, miR-132, miR-384, miR-339-5p, miR-135b, miR-425-5p, and miR-339-5p, have been shown to participate in the development of AD through interacting with BACE1. Other miRNAs might affect the inflammatory responses in the course of AD. Aberrant expression of several miRNAs in the plasma samples of AD subjects has been shown to have the aptitude for differentiation of AD subjects from healthy subjects. Finally, a number of AD-modifying agents affect miRNA profile in cell cultures or animal models. We have performed a comprehensive search and summarized the obtained data about the function of miRNAs in AD in the current review article.

The insect peptide CopA3 blocks programmed cell death by directly binding caspases and inhibiting their proteolytic activation

Caspases play essential roles in apoptotic processes, which is necessary for cellular homeostasis. However, over-activation of caspases and subsequent excessive apoptosis is considered a main cause of Parkinson's disease and liver diseases. Here, we found that the insect-derived peptide, CopA3, which has shown antiapoptotic effects in many apoptosis models, directly binds to caspases. The resulting complexes do not dissociate during denaturing polyacrylamide gel electrophoresis, as evidenced by a distinct shift in the migration of caspase reflecting an increase in their molecular weight. Surface plasmon resonance and experiment using cysteine-substituted mutants of CopA3 collectively revealed that binding of CopA3 to caspases is dependent on an internal cysteine residue. Notably, CopA3 binding significantly inhibited proteolytic activation of downstream caspases by upstream caspases. In summary, the demonstration that CopA3 directly binds to caspases and inhibits their activating cleavage suggests a possible therapeutic approach for treating human diseases resulting from uncontrolled apoptosis.

Stem cell-based therapy as a promising approach in Alzheimer's disease: current perspectives on novel treatment

Alzheimer's disease (AD) is a neuronal disorder with insidious onset and slow progression, leading to growing global concern with huge implications for individuals and society. The occurrence of AD has been increased and has become an important health issue throughout the world. In recent years, the care of more than 35 million patients with AD costs over $ 600 billion per year, it is approximately 1 percent of the global Gross Domestic Product. Currently, the therapeutic approach is not effective for neurological deficits especially after the development of these major neurological disorders. The discovery of the technique called cell-based therapy has shown promising results and made important conclusions beyond AD using the stem cells approach. Here we review recent progress on stem cell-based therapy in the context of AD.

Modulation of MicroRNAs as a Potential Molecular Mechanism Involved in the Beneficial Actions of Physical Exercise in Alzheimer Disease

Alzheimer disease (AD) is one of the most common neurodegenerative diseases, affecting middle-aged and elderly individuals worldwide. AD pathophysiology involves the accumulation of beta-amyloid plaques and neurofibrillary tangles in the brain, along with chronic neuroinflammation and neurodegeneration. Physical exercise (PE) is a beneficial non-pharmacological strategy and has been described as an ally to combat cognitive decline in individuals with AD. However, the molecular mechanisms that govern the beneficial adaptations induced by PE in AD are not fully elucidated. MicroRNAs are small non-coding RNAs involved in the post-transcriptional regulation of gene expression, inhibiting or degrading their target mRNAs. MicroRNAs are involved in physiological processes that govern normal brain function and deregulated microRNA profiles are associated with the development and progression of AD. It is also known that PE changes microRNA expression profile in the circulation and in target tissues and organs. Thus, this review aimed to identify the role of deregulated microRNAs in the pathophysiology of AD and explore the possible role of the modulation of microRNAs as a molecular mechanism involved in the beneficial actions of PE in AD.

Mesenchymal stromal cells (MSCs) for neurodegenerative disease: A promising frontier

Neurodegenerative disorders are a variety of diseases including Alzheimer's (AD), Parkinson's (PD), and Huntington's diseases (HD), multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) along with some other less common diseases generally described by the advanced deterioration of central or peripheral nervous system, structurally or functionally. In the last two decades, mesenchymal stromal cells (MSCs) due to their unique assets encompassing self-renewal, multipotency and accessibility in association with low ethical concern open new frontiers in the context of neurodegenerative diseases therapy. Interestingly, MSCs can be differentiated into endodermal and ectodermal lineages (e.g., neurons, oligodendrocyte, and astrocyte), and thus could be employed to advance cell-based therapeutic strategy. Additionally, as inflammation ordinarily ensues as a local response provoked by microglia in the neurodegenerative diseases, MSCs therapy because of their pronounced immunomodulatory properties is noticed as a rational approach for their treatment. Recently, varied types of studies have been mostly carried out in vitro and rodent models using MSCs upon their procurement from various sources and expansion. The promising results of the studies in rodent models have motivated researchers to design and perform several clinical trials, with a speedily rising number. In the current review, we aim to deliver a brief overview of MSCs sources, expansion strategies, and their immunosuppressive characteristics and discuss credible functional mechanisms exerted by MSCs to treat neurodegenerative disorders, covering AD, PD, ALS, MS, and HD.

Expression profiling of microRNAs and isomiRs in conventional central chondrosarcoma

Conventional central chondrosarcoma (CCC) is a malignant bone tumor that is characterized by the production of chondroid tissue. Since radiation therapy and chemotherapy have limited effects on CCC, treatment of most patients depends on surgical resection. This study aimed to identify the expression profiles of microRNAs (miRNAs) and isomiRs in CCC tissues to highlight their possible participation to the regulation of pathways critical for the formation and growth of this type of tumor. Our study analyzed miRNAs and isomiRs from Grade I (GI), Grade II (GII), and Grade III (GIII) histologically validated CCC tissue samples. While the different histological grades shared a similar expression profile for the top abundant miRNAs, we found several microRNAs and isomiRs showing a strong different modulation in GII + GIII vs GI grade samples and their involvement in tumor biology could be consistently hypothesized. We then in silico validated these differently expressed miRNAs in a larger chondrosarcoma public dataset and confirmed the expression trend for 17 out of 34 miRNAs. Our results clearly suggests that the contribution of miRNA deregulation, and their targeted pathways, to the progression of CCC could be relevant and strongly indicates that when studying miRNA deregulation in tumors, not only the canonical miRNAs, but the whole set of corresponding isomiRs should be taken in account. Improving understanding of the precise roles of miRNAs and isomiRs over the course of central chondrosarcoma progression could help identifying possible targets for precision medicine therapeutic intervention.

Transplantation of bone marrow mesenchymal stem cells improves cognitive deficits and alleviates neuropathology in animal models of Alzheimer's disease: a meta-analytic review on potential mechanisms

BACKGROUND

Alzheimer's disease is a neurodegenerative disorder. Therapeutically, a transplantation of bone marrow mesenchymal stem cells (BMMSCs) can play a beneficial role in animal models of Alzheimer's disease. However, the relevant mechanism remains to be fully elucidated.

MAIN BODY

Subsequent to the transplantation of BMMSCs, memory loss and cognitive impairment were significantly improved in animal models with Alzheimer's disease (AD). Potential mechanisms involved neurogenesis, apoptosis, angiogenesis, inflammation, immunomodulation, etc. The above mechanisms might play different roles at certain stages. It was revealed that the transplantation of BMMSCs could alter some gene levels. Moreover, the differential expression of representative genes was responsible for neuropathological phenotypes in Alzheimer's disease, which could be used to construct gene-specific patterns.

CONCLUSIONS

Multiple signal pathways involve therapeutic mechanisms by which the transplantation of BMMSCs improves cognitive and behavioral deficits in AD models. Gene expression profile can be utilized to establish statistical regression model for the evaluation of therapeutic effect. The transplantation of autologous BMMSCs maybe a prospective therapy for patients with Alzheimer's disease.

MicroRNA Let-7i Is a Promising Serum Biomarker for Post-stroke Cognitive Impairment and Alleviated OGD-Induced Cell Damage in vitro by Regulating Bcl-2

Background

The mechanism of post-stroke cognitive impairment (PSCI) has not been explained. We aimed to investigate whether miR-let-7i participates in the PSCI and illuminates its underlying role in oxygen–glucose deprivation (OGD)-induced cell apoptosis.

Methods

Blood samples from 36 subjects with PSCI and 38 with post-stroke cognitive normality (Non-PSCI) were collected to evaluate the differential expression of miR-let-7 family members, using qRT-PCT analysis. Spearman correlation was performed to estimate the correlation between the miR-1et-7i level and Montreal Cognitive Assessment (MoCA) score. Treatment of SH-SY5Y cells with OGD was used to induce cell apoptosis in vitro. Effects of miR-let-7i on OGD-induced cell apoptosis was estimated after transfection. The target gene of miR-let-7i was analyzed by dual luciferase reporter gene assay.

Results

The expression of miR-let-7i was up-regulated in PSCI patients compared with Non-PSCI (p < 0.001) and negatively correlated with MoCA score (r = −0.643, p < 0.001). When exposed to OGD, SH-SY5Y cells showed significant apoptosis accompanied by miR-let-7i up-regulation. In OGD-treated cells, miR-let-7i up-regulation was accompanied by cell apoptosis, while down-regulation showed the opposite effect. Luciferase reporter assay showed that Bcl-2 was a target gene of miR-let-7i. Western blot showed that miR-let-7i up-regulation promoted Bcl-2 expression, while qRT-PCR showed that miR-let-7i had no effect on Bcl-2 expression.

Conclusion

miR-let-7i was overexpressed in PSCI patients and it could be used as a diagnostic biomarker for PSCI. We illuminated the potential mechanism that miR-let-7i alleviated OGD-induced cell damage by targeting Bcl-2 at the post-transcriptional level.

Molecular Pathogenesis and Interventional Strategies for Alzheimer's Disease: Promises and Pitfalls

Alzheimer's disease (AD) is a debilitating disorder characterized by age-related dementia, which has no effective treatment to date. β-Amyloid depositions and hyperphosphorylated tau proteins are the main pathological hallmarks, along with oxidative stress, N-methyl-d-aspartate (NMDA) receptor-mediated excitotoxicity, and low levels of acetylcholine. Current pharmacotherapy for AD only provides symptomatic relief and limited improvement in cognitive functions. Many molecules have been explored that show promising outcomes in AD therapy and can regulate cellular survival through different pathways. To have a vivid approach to strategize the treatment regimen, AD physiopathology should be better explained considering diverse etiological factors in conjunction with biochemical disturbances. This Review attempts to discuss different disease modification approaches and address the novel therapeutic targets of AD that might pave the way for new drug discovery using the well-defined targets for therapy of the disease.

Circulating RNAs as Potential Biomarkers in Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a complex multi-system neurodegenerative disorder with currently limited diagnostic and no therapeutic options. Despite the intense efforts no clinically applicable biomarkers for ALS are yet established. Most current research is thus focused, in particular, in identifying potential non-invasive circulating biomarkers for more rapid and accurate diagnosis and monitoring of the disease. In this review, we have focused on messenger RNA (mRNA), non-coding RNAs (lncRNAs), micro RNAs (miRNAs) and circular RNA (circRNAs) as potential biomarkers for ALS in peripheral blood serum, plasma and cells. The most promising miRNAs include miR-206, miR-133b, miR-27a, mi-338-3p, miR-183, miR-451, let-7 and miR-125b. To test clinical potential of this miRNA panel, a useful approach may be to perform such analysis on larger multi-center scale using similar experimental design. However, other types of RNAs (lncRNAs, circRNAs and mRNAs) that, together with miRNAs, represent RNA networks, have not been yet extensively studied in blood samples of patients with ALS. Additional research has to be done in order to find robust circulating biomarkers and therapeutic targets that will distinguish key RNA interactions in specific ALS-types to facilitate diagnosis, predict progression and design therapy.

Accumulation of kynurenine elevates oxidative stress and alters microRNA profile in human bone marrow stromal cells

Kynurenine, a metabolite of tryptophan breakdown, has been shown to increase with age, and plays a vital role in a number of age-related pathophysiological changes, including bone loss. Accumulation of kynurenine in bone marrow stromal cells (BMSCs) has been associated with a decrease in cell proliferation and differentiation, though the exact mechanism by which kynurenine mediates these changes is poorly understood. MiRNAs have been shown to regulate BMSC function, and accumulation of kynurenine may alter the miRNA expression profile of BMSCs. The aim of this study was to identify differentially expressed miRNAs in human BMSCs in response to treatment with kynurenine, and correlate miRNAs function in BMSCs biology through bioinformatics analysis. Human BMSCs were cultured and treated with and without kynurenine, and subsequent miRNA isolation was performed. MiRNA array was performed to identify differentially expressed miRNA. Microarray analysis identified 50 up-regulated, and 36 down-regulated miRNAs in kynurenine-treated BMSC cultures. Differentially expressed miRNA included miR-1281, miR-330-3p, let-7f-5p, and miR-493-5p, which are important for BMSC proliferation and differentiation. KEGG analysis found up-regulated miRNA targeting glutathione metabolism, a pathway critical for removing oxidative species. Our data support that the kynurenine dependent degenerative effect is partially due to changes in the miRNA profile of BMSCs.

Mesenchymal stem cells: Cell therapy and regeneration potential

Rapid advances in the isolation of multipotent progenitor cells, routinely called mesenchymal stromal/stem cells (MSCs), from various human tissues and organs have provided impetus to the field of cell therapy and regenerative medicine. The most widely studied sources of MSCs include bone marrow, adipose, muscle, peripheral blood, umbilical cord, placenta, fetal tissue, and amniotic fluid. According to the standard definition of MSCs, these clonal cells adhere to plastic, express cluster of differentiation (CD) markers such as CD73, CD90, and CD105 markers, and can differentiate into adipogenic, chondrogenic, and osteogenic lineages in vitro. However, isolated MSCs have been reported to vary in their potency and self-renewal potential. As a result, the MSCs used for clinical applications often lead to variable or even conflicting results. The lack of uniform characterization methods both in vitro and in vivo also contributes to this confusion. Therefore, the name "MSCs" itself has been increasingly questioned lately. As the use of MSCs is expanding rapidly, there is an increasing need to understand the potential sources and specific potencies of MSCs. This review discusses and compares the characteristics of MSCs and suggests that the variations in their distinctive features are dependent on the source and method of isolation as well as epigenetic changes during maintenance and growth. We also discuss the potential opportunities and challenges of MSC research with the hope to stimulate their use for therapeutic and regenerative medicine.

MicroRNAs in Alzheimer's Disease: Diagnostic Markers or Therapeutic Agents?

MicroRNAs (miRNAs) are small non-coding nucleic acids able to post-transcriptionally regulate gene expression by binding to complementary sequences of target messenger RNA (mRNA). It has been estimated that at least 1% of the human genome encodes miRNA and every miRNA can regulate up to 200 mRNAs. These findings suggest that dysregulation of miRNA expression could be associated with several human pathological conditions including central neurological disorders. Alzheimer’s disease (AD) is a neurodegenerative disorder and the most common cause of dementia in the elderly. The characteristic symptoms are a progressive loss of memory and other cognitive functions due to the impairment of particular types of neurons and synapses, leading to neuronal death. At present, the available symptomatic treatments can only slow down disease progression without stopping it. miRNAs are widely found within the nervous system where they are key regulators of functions such as neurite outgrowth, dendritic spine morphology, neuronal differentiation, and synaptic plasticity. This has been the clue for considering miRNAs crucial molecules to be studied in AD, and nowadays, dysfunction of miRNAs in AD is increasingly recognized. In this review, we summarized existing evidence about miRNAs as biomarkers or therapeutic agents. The field of miRNAs as biomarkers is more advanced in terms of human data, and it is likely that miRNAs will be used successfully in the near future. Given the huge number of miRNAs potentially involved in diagnostics, miRNA panels will be used for specific tasks such as the stage of the disease, the risk prediction, and disease progression. The field of miRNAs as therapeutics is rapidly developing, and it offers a huge variety of solutions. These include positive effects related to beta-amyloid or tau reduction, increased number of neurons, inhibition of apoptosis, protection of synapses, transformation of other cellular elements into missing/deficient neurons in AD, and so on. It is predictable that both areas of research will be carried forward. However, given the absence of an AD therapy able to stop or reverse the disease, it is desirable to accelerate research on miRNAs as therapeutic agents.

MicroRNA in Brain pathology: Neurodegeneration the Other Side of the Brain Cancer

The mammalian brain is made up of billions of neurons and supporting cells (glial cells), intricately connected. Molecular perturbations often lead to neurodegeneration by progressive loss of structure and malfunction of neurons, including their death. On the other side, a combination of genetic and cellular factors in glial cells, and less frequently in neurons, drive oncogenic transformation. In both situations, microenvironmental niches influence the progression of diseases and therapeutic responses. Dynamic changes that occur in cellular transcriptomes during the progression of developmental lineages and pathogenesis are controlled through a variety of regulatory networks. These include epigenetic modifications, signaling pathways, and transcriptional and post-transcriptional mechanisms. One prominent component of the latter is small non-coding RNAs, including microRNAs, that control the vast majority of these networks including genes regulating neural stemness, differentiation, apoptosis, projection fates, migration and many others. These cellular processes are also profoundly dependent on the microenvironment, stemness niche, hypoxic microenvironment, and interactions with associated cells including endothelial and immune cells. Significantly, the brain of all other mammalian organs expresses the highest number of microRNAs, with an additional gain in expression in the early stage of neurodegeneration and loss in expression in oncogenesis. However, a mechanistic explanation of the concept of an apparent inverse correlation between the odds of cancer and neurodegenerative diseases is only weakly developed. In this review, we thus will discuss widespread de-regulation of microRNAome observed in these two major groups of brain pathologies. The deciphering of these intricacies is of importance, as therapeutic restoration of pre-pathological microRNA landscape in neurodegeneration must not lead to oncogenesis and vice versa. We thus focus on microRNAs engaged in cellular processes that are inversely regulated in these diseases. We also aim to define the difference in microRNA networks between pro-survival and pro-apoptotic signaling in the brain.