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Parkinson's disease (PD) is the second most common neurodegenerative disorder. The etiology of the disease remains largely unknown, but evidence have suggested that the overexpression and aggregation of alpha-synuclein (α-syn) play key roles in the pathogenesis and progression of PD. Mesenchymal stromal cells (MSCs) have been earning attention in this field, mainly due to their paracrine capacity. The bioactive molecules secreted by MSCs, i.e. their secretome, have been associated with enhanced neuronal survival as well as a strong modulatory capacity of the microenvironments where the disease develops. The selection of the appropriate animal model is crucial in studies of efficacy assessment. Given the involvement of α-syn in the pathogenesis of PD, the evidence generated from the use of animal models that develop a pathologic phenotype due to the action of this protein is extremely valuable. Therefore, in this work, we established an animal model based on the viral vector-mediated overexpression of A53T α-syn and studied the impact of the secretome of bone marrow mesenchymal stromal cells MSC(M) as a therapeutic strategy. Adult male rats were subjected to α-syn over expression in the nigrostriatal pathway to model dopaminergic neurodegeneration. The impact of locally administered secretome treatment from MSC(M) was studied. Motor impairments were assessed throughout the study coupled with whole-region (striatum and substantia nigra) confocal microscopy evaluation of histopathological changes associated with dopaminergic neurodegeneration and glial cell reactivity. Ten weeks after lesion induction, the animals received secretome injections in the substantia nigra pars compacta (SNpc) and striatum (STR). The secretome used was produced from bone marrow mesenchymal stromal cells MSC(M) expanded in a spinner flask (SP) system. Nine weeks later, animals that received the viral vector containing the gene for A53T α-syn and treated with vehicle (Neurobasal-A medium) presented dopaminergic cell loss in the SNpc and denervation in the STR. The treatment with secretome significantly reduced the levels of α-syn in the SNpc and protected the dopaminergic neurons (DAn) within the SNpc and STR. Our results are aligned with previous studies in both α-syn Caenorhabditis elegans models, as well as 6-OHDA rodent model, revealing that secretome exerted a neuroprotective effect. Moreover, these effects were associated with a modulation of microglial reactivity supporting an immunomodulatory role for the factors contained within the secretome. This further supports the development of new studies exploring the effects and the mechanism of action of secretome from MSC(M) against α-syn-induced neurotoxicity. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is the most common movement disorder, characterized by the progressive loss of dopaminergic neurons from the nigrostriatal system. Currently, there is no treatment that retards disease progression or reverses damage prior to the time of clinical diagnosis. Mesenchymal stem cells (MSCs) are one of the most extensively studied cell sources for regenerative medicine applications, particularly due to the release of soluble factors and vesicles, known as secretome. The main goal of this work was to address the therapeutic potential of the secretome collected from bone-marrow-derived MSCs (BM-MSCs) using different models of the disease. Firstly, we took advantage of an optimized human midbrain-specific organoid system to model PD in vitro using a neurotoxin-induced model through 6-hydroxydopamine (6-OHDA) exposure. In vivo, we evaluated the effects of BM-MSC secretome comparing two different routes of secretome administration: intracerebral injections (a two-site single administration) against multiple systemic administration. The secretome of BM-MSCs was able to protect from dopaminergic neuronal loss, these effects being more evident in vivo. The BM-MSC secretome led to motor function recovery and dopaminergic loss protection; however, multiple systemic administrations resulted in larger therapeutic effects, making this result extremely relevant for potential future clinical applications. [ABSTRACT FROM AUTHOR]

Neural injuries in cerebral malaria patients are a significant cause of morbidity and mortality. Nevertheless, a comprehensive research approach to study this issue is lacking, so herein we propose an in vitro system to study human cerebral malaria using cellular approaches. Our first goal was to establish a cellular system to identify the molecular alterations in human brain vasculature cells that resemble the blood–brain barrier (BBB) in cerebral malaria (CM). Through transcriptomic analysis, we characterized specific gene expression profiles in human brain microvascular endothelial cells (HBMEC) activated by the Plasmodium falciparum parasites. We also suggest potential new genes related to parasitic activation. Then, we studied its impact at brain level after Plasmodium falciparum endothelial activation to gain a deeper understanding of the physiological mechanisms underlying CM. For that, the impact of HBMEC-P. falciparum-activated secretomes was evaluated in human brain organoids. Our results support the reliability of in vitro cellular models developed to mimic CM in several aspects. These systems can be of extreme importance to investigate the factors (parasitological and host) influencing CM, contributing to a molecular understanding of pathogenesis, brain injury, and dysfunction. [ABSTRACT FROM AUTHOR]

Over 90% of chronic pain (CP) patients receive opioids-based treatments, which led to a public health crisis with lasting impacts on social and economic wellbeing based on opioid addiction. Opioids act through activation of μ (MOR), δ (DOR), and κ (KOR) opioid receptors, which are broadly and differentially distributed throughout the brain. Chronic opioid consumption leads to brain changes such as alterations on neurotransmission, dendritic branching, and spine density, as well as an increase in apoptosis. To overcome opioid-related issues, extensive efforts have been made to search for an alternative treatment. Bioactive molecules secreted by stem cells, collectively known as secretome, have shown a positive impact in different pain models. However, there is a lack of studies on the role of secretome in modulating opioid receptors. By using cerebral organoids (CeO), a self-organized, functional, and multicellular 3D structure that resemble the brain, we were able to identify MOR, DOR, and KOR at different stages of maturation. Treatment with secretome increased MOR expression highlighting a possible role in pain signaling mechanisms. Opioid treatments did not impact the expression of neuronal maturation markers but together with secretome, they increased astrogliogenesis. Opioid-treated organoids presented higher dopamine secretion recapitulating an important physiological event after opioid exposure. This work demonstrates that CeO is an important model system for the study of opioid signaling with potential implications to the understanding of basic mechanisms related to pain physiology. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) is a debilitating condition that leads to motor, sensory, and autonomic impairments. Its intrinsic pathophysiological complexity has hindered the establishment of effective treatments for decades. Nutritional interventions (NIs) for SCI have been proposed as a route to circumvent some of the problems associated with this condition. Results obtained in animal models point to a more holistic effect, rather than to specific modulation, of several relevant SCI pathophysiological processes. Indeed, published data have shown NI improves energetic imbalance, oxidative damage, and inflammation, which are promoters of improved proteostasis and neurotrophic signaling, leading ultimately to neuroprotection and neuroplasticity. This review focuses on the most well-documented Nis. The mechanistic implications and their translational potential for SCI are discussed. [ABSTRACT FROM AUTHOR]

• hBM-MSC's secretome increases in-vivo hippocampal proliferation in mice; • Astrocyte signaling through exocytosis is important to sustain the proliferative response induced by hBM-MSCs secretome; • Astrocyte signaling is important for the morphological response induced by the administration of hBM-MSCs secretome. The central nervous system (CNS) has a limited auto-regeneration capacity, which makes it challenging for the development of new therapies. Previous studies from our lab have demonstrated the applicability of human bone marrow mesenchymal stem cells (hBM-MSCs) secretome as a possible therapeutic tool for CNS. Astrocytes, glial cells present in all brain regions, are important players in brain function through their vast influence in extracellular homeostasis, neuro-vascular regulation, synaptic modulation and neurogenesis. Thus, in the present work, we aimed to evaluate the specific impact of MSCs secretome on hippocampal proliferation and astrocyte morphology, in both WT and dnSNARE mice, a transgenic model that presents impaired astrocytic exocytosis and consequently impaired astrocytic function. Results demonstrated increased levels of proliferation for WT when treated with secretome. Additionally, it was possible to observe that dnSNARE animals injected with hBM-MSCs secretome disclosed increased levels of proliferating GFAP stained cells at the SGZ. Morphometrical evaluation found increased process hypertrophy and branching of dnSNARE astrocytes when treated with secretome. These results are closely related with the trophic factors present in the secretome, namely FGF-2, BDNF, GDNF, IGF-1, VEGF, CADH2, PEDF and miR-16. Moreover, the impaired exocytosis of astrocytes may also have implications for the response to the proliferative stimulus, given the established autocrine signaling through this mechanism. [ABSTRACT FROM AUTHOR]

Spinocerebellar ataxia type 3 (SCA3) is an adult-onset neurodegenerative disease caused by a polyglutamine expansion in the ataxin-3 (ATXN3) gene. No effective treatment is available for this disorder, other than symptom-directed approaches. Bile acids have shown therapeutic efficacy in neurodegenerative disease models. Here, we pinpointed tauroursodeoxycholic acid (TUDCA) as an efficient therapeutic, improving the motor and neuropathological phenotype of SCA3 nematode and mouse models. Surprisingly, transcriptomic and functional in vivo data showed that TUDCA acts in neuronal tissue through the glucocorticoid receptor (GR), but independently of its canonical receptor, the farnesoid X receptor (FXR). TUDCA was predicted to bind to the GR, in a similar fashion to corticosteroid molecules. GR levels were decreased in disease-affected brain regions, likely due to increased protein degradation as a consequence of ATXN3 dysfunction being restored by TUDCA treatment. Analysis of a SCA3 clinical cohort showed intriguing correlations between the peripheral expression of GR and the predicted age at disease onset in presymptomatic subjects and FKBP5 expression with disease progression, suggesting this pathway as a potential source of biomarkers for future study. We have established a novel in vivo mechanism for the neuroprotective effects of TUDCA in SCA3 and propose this readily available drug for clinical trials in SCA3 patients. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cell-based therapies have been studied for spinal cord injury (SCI) treatment due to their paracrine action upon damaged tissues. MSCs neuroregenerative role may relate to the contents of their secretome in anti-inflammatory cytokines and growth-permissive factors. We propose using the secretome of MSCs isolated from the adipose tissue—adipose tissue-derived stem cells (ASCs) as a cell-free based therapy for SCI. In vivo studies were conducted in two SCI models, Xenopus laevis and mice, after complete spinal cord transection. Our results on both models demonstrated positive impacts of ASC secretome on their functional recovery which were correlated with histopathological markers of regeneration. Furthermore, in our mice study, secretome induced white matter preservation together with modulation of the local and peripheral inflammatory response. Altogether, these results demonstrate the neuroregenerative and potential for inflammatory modulation of ASC secretome suggesting it as a good candidate for cell-free therapeutic strategies for SCI. [ABSTRACT FROM AUTHOR]

The failure of axons to regenerate after a spinal cord injury (SCI) remains one of the greatest challenges in neuroscience. The initial mechanical trauma is followed by a secondary injury cascade, creating a hostile microenvironment, which not only is not permissive to regeneration but also leads to further damage. One of the most promising approaches for promoting axonal regeneration is to maintain the levels of cyclic adenosine monophosphate (cAMP), specifically by a phosphodiesterase-4 (PDE4) inhibitor expressed in neural tissues. Therefore, in our study, we evaluated the therapeutic effect of an FDA-approved PDE4 inhibitor, Roflumilast (Rof), in a thoracic contusion rat model. Results indicate that the treatment was effective in promoting functional recovery. Rof-treated animals showed improvements in both gross and fine motor function. Eight weeks post-injury, the animals significantly recovered by achieving occasional weight-supported plantar steps. Histological assessment revealed a significant decrease in cavity size, less reactive microglia, as well as higher axonal regeneration in treated animals. Molecular analysis revealed that IL-10 and IL-13 levels, as well as VEGF, were increased in the serum of Rof-treated animals. Overall, Roflumilast promotes functional recovery and supports neuroregeneration in a severe thoracic contusion injury model and may be important in SCI treatment. [ABSTRACT FROM AUTHOR]

Traumatic spinal cord injury (SCI) leads to severe motor and sensory functional impairments that affect personal and social behaviors. Medical advancements have improved supportive therapeutic measures for SCI patients, but no effective neuroregenerative therapeutic options exist to date. Deficits in motor function are the most visible consequence of SCI. However, other complications, as spasticity, produce a significant impact on SCI patient's welfare. Baclofen, a GABA agonist, is the most effective drug for spasticity treatment. Interestingly, emerging data reveals that baclofen can also play a role on neuroprotection and regeneration after SCI. The goal of this study was to understand the potential of baclofen as a treatment to promote recovery after SCI. We used a pre-clinical SCI mouse model with the administration of baclofen 1 mg/Kg at different time-points after injury. Behavior analysis (locomotor and bladder function) were performed during nine weeks of the in vivo experiment. Afterwards, spinal cords were collected and processed for histological and molecular analysis. Our data showed that baclofen leads to locomotor improvements in mice when its administered acutely after SCI. Moreover, baclofen administration also led to improved bladder function control in all experimental groups. Interestingly, acute baclofen administration modulates microglia activation state and levels of circulating chemokines and cytokines, suggesting a putative role of baclofen in the modulation of the immune response. Although further studies must be performed to understand the mechanisms that underlie the functional improvements produced by baclofen, our data shed light into the pharmacological potential of baclofen to promote recovery after SCI. Our outcomes revealed that baclofen, a well-known drug used for spasticity management, improves the motor performance after SCI in a pre-clinical animal model. Our data opens new avenues for pharmacological strategies design to promote SCI recovery. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSCs) hold promising therapeutic potential in several clinical applications, mainly due to their paracrine activity. The implementation of future secretome-based therapeutic strategies requires the use of easily accessible MSCs sources that provide high numbers of cells with homogenous characteristics. MSCs obtained from induced pluripotent stem cells (iMSCs) have been put forward as an advantageous alternative to the gold-standard tissue sources, such as bone marrow (BM-MSCs). In this study, we aimed at comparing the secretome of BM-MSCs and iMSCs over long-term culture. For that, we performed a broad characterization of both sources regarding their identity, proteomic secretome analysis, as well as replicative senescence and associated phenotypes, including its effects on MSCs secretome composition and immunomodulatory action. Our results evidence a rejuvenated phenotype of iMSCs, which is translated into a superior proliferative capacity before the induction of replicative senescence. Despite this significant difference between iMSCs and BM-MSCs proliferation, both untargeted and targeted proteomic analysis revealed a similar secretome composition for both sources in pre-senescent and senescent states. These results suggest that shifting from the use of BM-MSCs to a more advantageous source, like iMSCs, may yield similar therapeutic effects as identified over the past years for this gold-standard MSC source. [ABSTRACT FROM AUTHOR]

Machado–Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is an autosomal dominant neurodegenerative disorder (ND). While most research in NDs has been following a neuron-centric point of view, microglia are now recognized as crucial in the brain. Previous work revealed alterations that point to an increased activation state of microglia in the brain of CMVMJD135 mice, a MJD mouse model that replicates the motor symptoms and neuropathology of the human condition. Here, we investigated the extent to which microglia are actively contributing to MJD pathogenesis and symptom progression. For this, we used PLX3397 to reduce the number of microglia in the brain of CMVMJD135 mice. In addition, a set of statistical and machine learning models were further implemented to analyze the impact of PLX3397 on the morphology of the surviving microglia. Then, a battery of behavioral tests was used to evaluate the impact of microglial depletion on the motor phenotype of CMVMJD135 mice. Although PLX3397 treatment substantially reduced microglia density in the affected brain regions, it did not affect the motor deficits seen in CMVMJD135 mice. In addition to reducing the number of microglia, the treatment with PLX3397 induced morphological changes suggestive of activation in the surviving microglia, the microglia of wild-type animals becoming similar to those of CMVMJD135 animals. These results suggest that microglial cells are not key contributors for MJD progression. Furthermore, the impact of PLX3397 on microglial activation should be taken into account in the interpretation of findings of ND modification seen upon treatment with this CSF1R inhibitor. [ABSTRACT FROM AUTHOR]

Human mesenchymal stem cells (hMSCs) secretome has been have been at the forefront of a new wave of possible therapeutic strategies for central nervous system neurodegenerative disorders, as Parkinson's disease (PD). While within its protein fraction, several promising proteins were already identified with therapeutic properties on PD, the potential of hMSCs-secretome vesicular fraction remains to be elucidated. Such highlighting is important, since hMSCs secretome-derived vesicles can act as biological nanoparticles with beneficial effects in different pathological contexts. Therefore, in this work, we have isolated hMSCs secretome vesicular fraction, and assessed their impact on neuronal survival, and differentiation on human neural progenitors' cells (hNPCs), and in a 6-hydroxydopamine (6-OHDA) rat model of PD when compared to hMSCs secretome (as a whole) and its protein derived fraction. From the results, we have found hMSCs vesicular fraction as polydispersity source of vesicles, which when applied in vitro was able to induce hNPCs differentiation at the same levels as the whole secretome, while the protein separated fraction was not able to induce such effect. In the context of PD, although distinct effects were observed, hMSCs secretome and its derived fractions displayed a positive impact on animals' motor and histological performance, thereby indicating that hMSCs secretome and its different fractions may impact different mechanisms and pathways. Overall, we concluded that the use of the secretome collected from hMSCs and its different fractions might be active modulators of different neuroregeneration mechanisms, which could open new therapeutical opportunities for their future use as a treatment for PD. • hMSCs secretome-derived vesicular fraction is a polydispersity source of vesicles. • Secretome vesicular fraction is a promoter of neuronal differentiation and survival. • The effects of hBM-MSCs secretome and its fractions decline over time. • Understand how the internal content of secretome interacts with neural differentiation or disease mechanisms is of great importance. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a prevalent movement disorder characterized by the progressive loss of dopaminergic neurons in substantia nigra pars compacta (SNpc). The 6-hydroxydopamine (6-OHDA) lesion is still one of the most widely used techniques for modeling Parkinson's disease (PD) in rodents. Despite commonly used in rats, it can be challenging to reproduce a similar lesion in mice. Moreover, there is a lack of characterization of the extent of behavioral deficits and of the neuronal loss/neurotransmitter system in unilateral lesion mouse models. In this study, we present an extensive behavioral and histological characterization of a unilateral intrastriatal 6-OHDA mouse model. Our results indicate significant alterations in balance and fine motor coordination, voluntary locomotion, and in the asymmetry's degree of forelimb use in 6-OHDA lesioned animals, accompanied by a decrease in self-care and motivational behavior, common features of depressive-like symptomatology. These results were accompanied by a decrease in tyrosine hydroxylase (TH)-labelling and dopamine levels within the nigrostriatal pathway. Additionally, we also identify a marked astrocytic reaction, as well as proliferative and reactive microglia in lesioned areas. These results confirm the use of unilateral intrastriatal 6-OHDA mice for the generation of a mild model of nigrostriatal degeneration and further evidences the recapitulation of key aspects of PD, thereby being suitable for future studies beholding new therapeutical interventions for this disease. [ABSTRACT FROM AUTHOR]

Parkinson's Disease (PD) is characterized by the massive loss of dopaminergic neurons, leading to the appearance of several motor impairments. Current pharmacological treatments, such as the use of levodopa, are yet unable to cure the disease. Therefore, there is a need for novel strategies, particularly those that can combine in an integrated manner neuroprotection and neuroregeneration properties. In vitro and in vivo models have recently revealed that the secretome of mesenchymal stem cells (MSCs) holds a promising potential for treating PD, given its effects on neural survival, proliferation, differentiation. In the present study, we aimed to access the impact of human bone marrow MSCs (hBM-MSCs) secretome in 6-hydroxydopamine (6-OHDA) PD model when compared to levodopa administration, by addressing animals' motor performance, and substantia nigra (SN), and striatum (STR) histological parameters by tyrosine hydroxylase (TH) expression. Results revealed that hBM-MSCs secretome per se appears to be a modulator of the dopaminergic system, enhancing TH-positive cells expression (e.g., dopaminergic neurons) and terminals both in the SN and STR when compared to the untreated group 6-OHDA. Such finding was positively correlated with a significant amelioration of the motor outcomes of 6-OHDA PD animals (assessed by the staircase test). Thus, the present findings support hBM-MSCs secretome administration as a potential therapeutic tool in treating PD, and although we suggest candidate molecules (Trx1, SEMA7A, UCHL1, PEDF, BDNF, Clusterin, SDF-1, CypA, CypB, Cys C, VEGF, DJ-1, Gal-1, GDNF, CDH2, IL-6, HSP27, PRDX1, UBE3A, MMP-2, and GDN) and possible mechanisms of hBM-MSCs secretome-mediated effects, further detailed studies are needed to carefully and clearly define which players may be responsible for its therapeutic actions. By doing so, it will be reasonable to presume that potential treatments that can, per se, or in combination modulate or slow PD may lead to a rational design of new therapeutic or adjuvant strategies for its functional modeling and repair. [ABSTRACT FROM AUTHOR]