Stem cell therapy has garnered much attention and application in the past decades for the treatment of diseases and injuries. Mesenchymal stem cells (MSCs) are studied most extensively for their ...therapeutic roles, which appear to be derived from their paracrine activity. Recent studies suggest a critical therapeutic role for extracellular vesicles (EV) secreted by MSCs. EV are nano-sized membrane-bound vesicles that shuttle important biomolecules between cells to maintain physiological homeostasis. Studies show that EV from MSCs (MSC-EV) have regenerative and anti-inflammatory properties. The use of MSC-EV, as an alternative to MSCs, confers several advantages, such as higher safety profile, lower immunogenicity, and the ability to cross biological barriers, and avoids complications that arise from stem cell-induced ectopic tumor formation, entrapment in lung microvasculature, and immune rejection. These advantages and the growing body of evidence suggesting that MSC-EV display therapeutic roles contribute to the strong rationale for developing EV as an alternative therapeutic option. Despite the success in preclinical studies, use of MSC-EV in clinical settings will require careful consideration; specifically, several critical issues such as (i) production methods, (ii) quantification and characterization, (iii) pharmacokinetics, targeting and transfer to the target sites, and (iv) safety profile assessments need to be resolved. Keeping these issues in mind, the aim of this mini-review is to shed light on the challenges faced in MSC-EV research in translating successful preclinical studies to clinical platforms.
Recent studies have found that extracellular vesicles (EVs) play an important role in normal and disease processes. In the present study, we isolated and characterized EVs from the brains of rhesus ...macaques, both with and without simian immunodeficiency virus (SIV) induced central nervous system (CNS) disease. Small RNA sequencing revealed increased miR-21 levels in EVs from SIV encephalitic (SIVE) brains. In situ hybridization revealed increased miR-21 expression in neurons and macrophage/microglial cells/nodules during SIV induced CNS disease. In vitro culture of macrophages revealed that miR-21 is released into EVs and is neurotoxic when compared to EVs derived from miR-21-/- knockout animals. A mutation of the sequence within miR-21, predicted to bind TLR7, eliminates this neurotoxicity. Indeed miR-21 in EV activates TLR7 in a reporter cell line, and the neurotoxicity is dependent upon TLR7, as neurons isolated from TLR7-/- knockout mice are protected from neurotoxicity. Further, we show that EVs isolated from the brains of monkeys with SIV induced CNS disease activates TLR7 and were neurotoxic when compared to EVs from control animals. Finally, we show that EV-miR-21 induced neurotoxicity was unaffected by apoptosis inhibition but could be prevented by a necroptosis inhibitor, necrostatin-1, highlighting the actions of this pathway in a growing number of CNS disorders.
Effective drug delivery to the CNS to achieve the desired therapeutic response is a significant challenge in the field of drug delivery. In central nervous system (CNS), blood brain barrier (BBB) ...restricts the desired therapeutic responses due to inefficient targeting, release kinetics, and failure to reach therapeutic concentrations in the brain. Therefore, most potentially beneficial diagnostic and therapeutic agents are not able to reach to the brain upon systemic administration. Despite the existence of many invasive techniques to promote drug deliveries across BBB, novel strategies of drug delivery system which can cross BBB effectively are required, otherwise translation of novel neurotherapeutics from bench to bedside will be difficult to achieve. In this review, we briefly outline the existing and emerging strategies for CNS drug deliveries with a focus on potential and challenges of using extracellular vesicles (EVs) in CNS drug delivery system. EVs are emerging as a promising tool for therapeutic delivery owing to its favorable intrinsic features of biocompatibility, stability, stealth capacity, ability to overcome natural barriers and inherent homing capability. EVs are nanovesicles that allow cell-cell communication. The EVs-cargo reflects the physiological as well as the pathophysiological state of a cell. EVs are shown to play a role in human immunodeficiency virus (HIV) infection and dissemination, which contributes to acquired immune deficiency syndrome (AIDS). In the context of HIV-1 infection, this review also outlines the role of EVs in dissemination, challenges faced in EVs research in HIV-1 co-morbid conditions and potential of nanotechnologies, especially EVs in Neuro-AIDS.
Graphical Abstract
EVs are used for the delivery of small molecule drugs, protein, and nucleic acid to the CNS as well as imaging molecules for in vivo tracking. For the purpose of delivery, EVs may or may not be subjected to membrane modification. The advantages of EVs, including its biocompatibility, low immunogenicity, and low toxicity profiles, can be exploited to potentially devise novel therapeutic delivery system for CNS drug targeting. This article outlines the challenges in potential EV-based therapeutic delivery.
Addiction is a chronic and relapsing brain disorder characterized by compulsive seeking despite adverse consequences. There are both heritable and epigenetic mechanisms underlying drug addiction. ...Emerging evidence suggests that non‐coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non‐coding RNAs, and circular RNAs regulate synaptic plasticity and related behaviors caused by substances of abuse. These ncRNAs modify gene expression and may contribute to the behavioral phenotypes of addiction. Among the ncRNAs, the most widely researched and impactful are miRNAs. The goal in this systematic review is to provide a detailed account of recent research involving the role of miRNAs in addiction.
This article is categorized under:
RNA Interactions with Proteins and Other Molecules > Small Molecule‐RNA Interactions
RNA in Disease and Development > RNA in Disease
Drugs of abuse impact the pathophysiology of the brain via intercellular and intracellular alterations of microRNAs. The primary glial cells of the brain, astrocytes and microglia, are responsible for inducing the majority of inflammatory cytokines that impact neurons and potentiate addiction and withdrawal symptoms. Neurons are key in forming long‐term and short‐term memories as well as conditioning through synaptic plasticity and synapto‐dendritic injury. These changes influence the majority of effects that cause the transition from recreational use to substance abuse.
Despite the success of combinational antiretroviral therapy (cART), the high pervasiveness of human immunodeficiency virus-1 (HIV)-associated neurocognitive disorders (HAND) poses a significant ...challenge for society. Methamphetamine (meth) and related amphetamine compounds, which are potent psychostimulants, are among the most commonly used illicit drugs. Intriguingly, HIV-infected individuals who are meth users have a comparatively higher rate of neuropsychological impairment and exhibit a higher viral load in the brain than infected individuals who do not abuse meth. Effectively, all cell types secrete nano-sized lipid membrane vesicles, referred to as extracellular vesicles (EVs) that can function as intercellular communication to modulate the physiology and pathology of the cells. This study shows that meth treatments on chronically HIV-infected promonocytic U1 cells induce the release of EVs that promote cellular clustering and syncytia formation, a phenomenon that facilitates HIV pathogenesis. Our analysis also revealed that meth exposure increased intercellular adhesion molecule-1 (ICAM-1) and HIV-Nef protein expression in both large (10 K) and small (100 K) EVs. Further, when meth EVs are applied to uninfected naïve monocyte-derived macrophages (MDMs), we saw a significant increase in cell clustering and syncytia formation. Furthermore, treatment of MDMs with antibodies against ICAM-1 and its receptor, lymphocyte function-associated antigen 1 (LFA1), substantially blocked syncytia formation, and consequently reduced the number of multinucleated cells. In summary, our findings reveal that meth exacerbates HIV pathogenesis in the brain through release of proadhesive EVs, promoting syncytia formation and thereby aiding in the progression of HIV infection in uninfected cells.
MicroRNA (miR)‐142 is up‐regulated in the brain in HIV and SIV encephalitis (SIVE). We identified the cell types where miR‐142 is up‐regulated and its relevant downstream target. Fluorescent in situ ...hybridization combined with immunofluorescent labeling revealed that miR‐142‐3p and ‐5p are expressed within hippocampal neurons and myeloid cells in SIVE. Sirtuin1 (SIRT1) was predicted as a potential miR‐142 target by analysis of its 3‘‐UTR and bioinformatic analysis of factors linked to altered hippocampal gene expression profile in SIVE. Overexpression of pre‐miR‐142 in HEK293T cells led to a 3.7‐fold decrease in SIRT1 protein level. Examination of the individual effects of miR‐142‐5p and miR‐142‐3p through overexpression and inhibition studies revealed that significant effects on SIRT1 occurred only with miR‐142‐5p. Luciferase reporter assays revealed a 2.3‐fold inhibition of expression due to interaction of miR‐142 with the SIRT1 3‘‐UTR, mutation analysis revealed that only the miR‐142‐5p target site was active. MiR‐142 expression in primary human neurons led to a small (1.3‐fold) but significant decrease in SIRT1 protein level. Furthermore, qRT‐PCR revealed up‐regulation of miR‐142‐3p (6.4‐fold) and ‐5p (3.9‐fold) and down‐regulation of SIRT1 (33‐fold) in macrophages/microglia from animals with SIVE. We have therefore elucidated a miR‐mediated mechanism of regulation of SIRT1 expression in SIVE.—Chaudhuri, A. D., Yelamanchili, S. V., Marcondes, M. C. G., Fox, H. S., Up‐regulation of microRNA‐142 in simian immunodeficiency virus encephalitis leads to repression of sirtuin1. FASEB J. 27, 3720–3729 (2013). www.fasebj.org
Opioid abuse has become a major public health crisis that affects millions of individuals across the globe. This widespread abuse of prescription opioids and dramatic increase in the availability of ...illicit opioids have created what is known as the opioid epidemic. Pregnant women are a particularly vulnerable group since they are prescribed for opioids such as morphine, buprenorphine, and methadone, all of which have been shown to cross the placenta and potentially impact the developing fetus. Limited information exists regarding the effect of oxycodone (oxy) on synaptic alterations. To fill this knowledge gap, we employed an integrated system approach to identify proteomic signatures and pathways impacted on mixed neuroglial cultures treated with oxy for 24 h. Differentially expressed proteins were mapped onto global canonical pathways using ingenuity pathway analysis (IPA), identifying enriched pathways associated with ephrin signaling, semaphorin signaling, synaptic long-term depression, endocannabinoid signaling, and opioid signaling. Further analysis by ClueGO identified that the dominant category of differentially expressed protein functions was associated with GDP binding. Since opioid receptors are G-protein coupled receptors (GPCRs), these data indicate that oxy exposure perturbs key pathways associated with synaptic function.
Perinatal exposure to prescription opioids pose a critical public health risk. Notably, research has found significant neurodevelopmental and behavioral deficits between
in utero
(IUO) and postnatal ...(PNO) oxycodone-exposed offspring but there is a notable gap in knowledge regarding the interaction of these groups to other drug exposure, particularly nicotine exposure. Nicotine’s widespread use represents a ubiquitous clinical interaction that current research does not address. Children often experiment with drugs and risky behavior; therefore, adolescence is a key timepoint to characterize. This study employed an integrated systems approach to investigate escalating nicotine exposure in adolescence and subsequent nicotine withdrawal in the IUO- and PNO-offspring. Western blot analysis found synaptic protein alterations, especially upregulation of synaptophysin in IUO-withdrawal animals. RT-qPCR further validated immune dysfunction in the central nervous system (CNS). Peripheral nicotine metabolism was consistent with increased catabolism of nicotine concerning IUO animals. Lastly, behavioral assays found subtle deficits to withdrawal in nociception and anxiety-like behavior. This study showed, for the first time, the vulnerabilities of PNO- and IUO-exposed groups concerning nicotine use during early adolescence and withdrawal.
Graphical Abstract
Aberrant expression of microRNAs (miRs) has been implicated in the pathogenesis of several neurodegenerative disorders. In HIV-associated neurocognitive disorders (HAND), miR-142 was found to be ...upregulated in neurons and myeloid cells in the brain. We investigated the downstream effects of chronic miR-142 upregulation in neuronal cells by comparing gene expression in stable clones of the human neuroblastoma cell line BE(2)M17 expressing miR-142 to controls. Microarray analysis revealed that miR-142 expression led to a reduction in monoamine oxidase (MAO) A mRNA, which was validated by qRT-PCR. In addition to the mRNA, the MAOA protein level and enzyme activity were also reduced. Examination of primary human neurons revealed that miR-142 expression indeed resulted in a downregulation of MAOA protein level. Although MAOA is not a direct target of miR-142, SIRT1, a key transcriptional upregulator of MAOA is, thus miR-142 downregulation of MAOA expression is indirect. MiR-142 induced decrease in MAOA expression and activity may contribute to the changes in dopaminergic neurotransmission reported in HAND.
Previous research has established sex differences associated with nicotine intake, however a significant gap in knowledge remains regarding the molecular mechanisms that govern these differences at ...the transcriptional level. One critical regulator of transcription are microRNAs (miRNAs). miRNAs are a family of non-coding RNAs that regulate an array of important biological functions altered in several disease states, including neuroadaptive changes within the brain associated with drug dependence. We examined the prefrontal cortex (PFC) from male and female Sprague-Dawley rats following self-administration (22 days) of nicotine or yoked saline controls using next generation RNA-Sequencing (RNA-Seq) technology and found an array of miRNAs to be significantly and differentially regulated by nicotine self-administration. Of these, we found the expression of miR-199a and 214, which are expressed on the same cluster of chromosome 1, to be upregulated in the female rats exposed to nicotine; upregulation in this group was further validated by real time polymerase chain reaction (RT-PCR). Bioinformatics analysis to assess common targets of miR-199/214 identified Sirtuin 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD)- dependent deacetylase that plays a role in apoptosis, neuron survival, and stress resistance. Using western-blot, we confirmed downregulation of SIRT1 and increased cleaved caspase 3 expression in the brains of nicotine-exposed female rats and no change in expression levels in the other groups. Collectively, our findings highlight a miR-199/214 regulatory network that, through SIRT1, may be associated with nicotine seeking in females which may serve as a potential therapeutic target for sex-specific treatment approaches.
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