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Immunohistochemistry staining of human mitochondria on human olfactory ensheathing cell (hOEC)-transplanted group (A-C) and tumor necrosis factor α (TNF-α) on wild-type, vehicle, and hOEC-transplanted group (D-F) in mouse cerebellum. The human mitochondrial positive cells, as indicated by the arrow, were found in (A, B) Purkinje cell layer and (C) granular layer of mouse cerebellar. The TNF-α immunohistochemistry for the tissue samples in the (D) wild-type, (E) vehicle, and (F) hOEC group (Scale bar: 200 µm in D, E, and F).
Source publication
Spinocerebellar ataxia (SCA) is a progressive neurodegenerative disease that affects the cerebellum and spinal cord. Among the 40 types of SCA, SCA type 3 (SCA3), also referred to as Machado–Joseph disease, is the most common. In the present study, we investigated the therapeutic effects of intracranial transplantation of human olfactory ensheathin...
Citations
... In fact, the cell therapy applied for rescuing Purkinje cells from death in PCD mice by intravenous transplantation or bone-marrow replacement has had limited success up until now [4,5,48]. That is the reason we decided to inject IMCs directly into the cerebellum, which is what has been performed in the majority of the studies reporting cell therapy in mouse models of cerebellar degeneration [8,50,51,[59][60][61][62][63][64][65][66][67]. The major limitation of using this method is the mechanical injury that causes damage and inflammation to the surrounding tissue [68,69]. ...
Background
Myeloid-derived suppressor cells (MDSCs) constitute a recently discovered bone-marrow-derived cell type useful for dealing with neuroinflammatory disorders. However, these cells are only formed during inflammatory conditions from immature myeloid cells (IMCs) that acquire immunosuppressive activity, thus being commonly gathered from diseased animals. Then, to obtain a more clinically feasible source, we characterized IMCs directly derived from healthy bone marrow and proved their potential immunosuppressive activity under pathological conditions in vitro. We then explored their neuroprotective potential in a model of human cerebellar ataxia, the Purkinje Cell Degeneration (PCD) mouse, as it displays a well-defined neurodegenerative and neuroinflammatory process that can be also aggravated by invasive surgeries.
Methods
IMCs were obtained from healthy bone marrow and co-cultured with activated T cells. The proliferation and apoptotic rate of the later were analyzed with Tag-it Violet. For in vivo studies, IMCs were transplanted by stereotactic surgery into the cerebellum of PCD mice. We also used sham-operated animals as controls of the surgical effects, as well as their untreated counterparts. Motor behavior of mice was assessed by rotarod test. The Purkinje cell density was measured by immunohistochemistry and cell death assessed with the TUNEL technique. We also analyzed the microglial phenotype by immunofluorescence and the expression pattern of inflammation-related genes by qPCR. Parametric tests were applied depending on the specific experiment: one or two way ANOVA and Student’s T test.
Results
IMCs were proven to effectively acquire immunosuppressive activity under pathological conditions in vitro, thus acting as MDSCs. Concerning in vivo studios, sham-operated PCD mice suffered detrimental effects in motor coordination, Purkinje cell survival and microglial activation. After intracranial administration of IMCs into the cerebellum of PCD mice, no special benefits were detected in the transplanted animals when compared to untreated mice. Nonetheless, this transplant almost completely prevented the impairments caused by the surgery in PCD mice, probably by the modulation of the inflammatory patterns.
Conclusions
Our work comprise two main translational findings: (1) IMCs can be directly used as they behave as MDSCs under pathological conditions, thus avoiding their gathering from diseased subjects; (2) IMCs are promising adjuvants when performing neurosurgery.
... Regarding SCA3, one study reported that mouse cerebellar NPCs, when transplanted into the cerebellum of transgenic mice expressing human mutant ataxin-3 (ATXN3) bearing 69Q, could significantly overcome motor symptoms and neuropathology, with reduction of PC loss, cerebellar neuroinflammation and increased secretion of neurotrophic factors (Mendonca et al., 2015). Similar results were obtained in the SCA3-YAC-84Q transgenic mouse, which received an intracranial injection of human NPCs into the dorsal raphe nucleus after disease onset (Hsieh et al., 2017). Hsieh and colleagues also observed increased levels of tryptophan hydroxylase 2 enzyme, which is involved in serotonin synthesis, arguing for potentiation of the serotonin-dependent PC maturation after NPC transplantation in the SCA3 mouse cerebellum. ...
Spinocerebellar ataxias are heritable neurodegenerative diseases caused by a cytosine-adenine-guanine expansion, which encodes a long glutamine tract (polyglutamine) in the respective wild-type protein causing misfolding and protein aggregation. Clinical features of polyglutamine spinocerebellar ataxias include neuronal aggregation, mitochondrial dysfunction, decreased proteasomal activity, and autophagy impairment. Mutant polyglutamine protein aggregates accumulate within neurons and cause neural dysfunction and death in specific regions of the central nervous system. Spinocerebellar ataxias are mostly characterized by progressive ataxia, speech and swallowing problems, loss of coordination and gait deficits. Over the past decade, efforts have been made to ameliorate disease symptoms in patients, yet no cure is available. Previous studies have been proposing the use of stem cells as promising tools for central nervous system tissue regeneration. So far, pre-clinical trials have shown improvement in various models of neurodegenerative diseases following stem cell transplantation, including animal models of spinocerebellar ataxia types 1, 2, and 3. However, contrasting results can be found in the literature, depending on the animal model, cell type, and route of administration used. Nonetheless, clinical trials using cellular implants into degenerated brain regions have already been applied, with the expectation that these cells would be able to differentiate into the specific neuronal subtypes and re-populate these regions, reconstructing the affected neural network. Meanwhile, the question of how feasible it is to continue such treatments remains unanswered, with long-lasting effects being still unknown. To establish the value of these advanced therapeutic tools, it is important to predict the actions of the transplanted cells as well as to understand which cell type can induce the best outcomes for each disease. Further studies are needed to determine the best route of administration, without neglecting the possible risks of repetitive transplantation that these approaches so far appear to demand. Despite the challenges ahead of us, cell-transplantation therapies are reported to have transient but beneficial outcomes in spinocerebellar ataxias, which encourages efforts towards their improvement in the future.
... Spinocerebellar ataxia (SCA) is a term referring to an array of hereditary movement control difficulties, with the hallmarks of clinically altered gait, limb and facial movements (Masi et al. 2019). SCAs are a group of progressive NDDs, and type 2 and 3 (SCA2 and SCA3) are the most common cases (Hsieh et al. 2017). These two types of SCAs are caused by the persistent disappearing of Purkinje cells initiated by aggregated mutant proteins with neurotoxic properties (Bushart and Shakkottai 2019). ...
... These two types of SCAs are caused by the persistent disappearing of Purkinje cells initiated by aggregated mutant proteins with neurotoxic properties (Bushart and Shakkottai 2019). In neuronal development and natural aging, RyRs play a crucial role in the proliferation, differentiation and maturation of Purkinje cells (Ohashi et al. 2014;Hsieh et al. 2017;Abu-Omar et al. 2018). The upregulation of RyRs expression or RyRs action may prevent Purkinje cells from experiencing pathologic events of loss and demise (Vervliet 2018). ...
... The upregulation of RyRs expression or RyRs action may prevent Purkinje cells from experiencing pathologic events of loss and demise (Vervliet 2018). In a context of SCA3 mouse model, researchers found that upregulated RyRs and serotonin levels counteracted the disease-associated loss of Purkinje cells in the cerebellar region (Hsieh et al. 2017). Key discoveries in the field of SCA revealed that mutant ataxin-2 or ataxin-3 protein could cause intracellular Ca 2+ release via inositol 1,4,5-triphate receptor (IP 3 R), and this process was exaggerated by the RyRs through CICR (Liu et al. 2009;Chen et al. 2008). ...
Progressive neuronal demise is a key contributor to the key pathogenic event implicated in many different neurodegenerative disorders (NDDs). There are several therapeutic strategies available; however, none of them are particularly effective. Targeted neuroprotective therapy is one such therapy, which seems a compelling option, yet remains challenging due to the internal heterogeneity of the mechanisms underlying various NDDs. An alternative method to treat NDDs is to exploit common modalities involving molecularly distinct subtypes and thus develop specialized drugs with broad-spectrum characteristics. There is mounting evidence which supports for the theory that dysfunctional ryanodine receptors (RyRs) disrupt intracellular Ca2+ homeostasis, contributing to NDDs significantly. This review aims to provide direct and indirect evidence on the intersection of NDDs and RyRs malfunction, and to shed light on novel strategies to treat RyRs-mediated disease, modifying pharmacological therapies such as the potential therapeutic role of dantrolene, a RyRs antagonist.
... The timing of intravenous administration is important and may influence the efficacy of exosomes. Similar to other polyglutamate diseases, the pathological alterations occur before disease onset in MJD patients and animal models [26,28]. Therefore, pre-symptomatic treatment may be necessary. ...
... In the present study, YACMJD84.2 mice developed motor deficits as evidenced by the decline in rotarod performance at the age of 14 weeks, which was consistent with a previous study [28]. Intravenous administration of exosomes significantly prolonged normal motor function for 4 weeks and attenuated motor deficits for an additional 2 weeks, when compared with YACMJD84.2 ...
Background:
Machado-Joseph disease is the most common autosomal dominant hereditary ataxia worldwide without effective treatment. Mesenchymal stem cells (MSCs) could slow the disease progression, but side effects limited their clinical application. Besides, MSC-derived exosomes exerted similar efficacy and have many advantages over MSCs. The aim of this study was to examine the efficacy of MSC-derived exosomes in YACMJD84.2 mice.
Methods:
Rotarod performance was evaluated every 2 weeks after a presymptomatic administration of intravenous MSC-derived exosomes twice in YACMJD84.2 mice. Loss of Purkinje cells, relative expression level of Bcl-2/Bax, cerebellar myelin loss, and neuroinflammation were assessed 8 weeks following treatment.
Results:
MSC-derived exosomes were isolated and purified through anion exchange chromatography. Better coordination in rotarod performance was maintained for 6 weeks in YACMJD84.2 mice with exosomal treatment, compared with those without exosomal treatment. Neuropathological changes including loss of Purkinje cells, cerebellar myelin loss, and neuroinflammation were also attenuated 8 weeks after exosomal treatment. The higher relative ratio of Bcl-2/Bax was consistent with the attenuation of loss of Purkinje cells.
Conclusions:
MSC-derived exosomes could promote rotarod performance and attenuate neuropathology, including loss of Purkinje cells, cerebellar myelin loss, and neuroinflammation. Therefore, MSC-derived exosomes have a great potential in the treatment of Machado-Joseph disease.
... An alternative strategy for 5-HT modulation is cell therapy. Intracranial human olfactory ensheathing cell transplantation prevented PC loss and enhanced motor coordination through increased expression of TPH2 [118]. ...
Spinocerebellar ataxia type 3/Machado–Joseph disease (SCA3/MJD) is a progressive motor disease with no broadly effective treatment. However, most current therapies are based on symptoms rather than the underlying disease mechanisms. In this review, we describe potential therapeutic strategies based on known pathological biomarkers and related pathogenic processes. The three major conclusions from the current studies are summarized as follows: (i) for the drugs currently being tested in clinical trials; a weak connection was observed between drugs and SCA3/MJD biomarkers. The only two exceptions are the drugs suppressing glutamate-induced calcium influx and chemical chaperon. (ii) For most of the drugs that have been tested in animal studies, there is a direct association with pathological biomarkers. We further found that many drugs are associated with inducing autophagy, which is supported by the evidence of deficient autophagy biomarkers in SCA3/MJD, and that there may be more promising therapeutics. (iii) Some reported biomarkers lack relatively targeted drugs. Low glucose utilization, altered amino acid metabolism, and deficient insulin signaling are all implicated in SCA3/MJD, but there have been few studies on treatment strategies targeting these abnormalities. Therapeutic strategies targeting multiple pathological SCA3/MJD biomarkers may effectively block disease progression and preserve neurological function.
... Olfactory dysfunction is one of the main non-motor symptoms that was already described in patients with MJD [23,24]. In a previous study, transplantation of olfactory ensheathing cells, which are specialized glial cells of the primary olfactory system, were found to improve motor function in an MJD mice model, and were suggested as a novel potential strategy for MJD treatment [25]. Vesicle transport and synaptic pathways were also implicated in MJD, as well as in other neurodegenerative diseases [26,27]. ...
Machado-Joseph disease (MJD/SCA3) is the most common form of dominantly inherited ataxia worldwide. The disorder is caused by an expanded CAG repeat in the ATXN3 gene. Past studies have revealed that the length of the expansion partly explains the disease age at onset (AO) variability of MJD, which is confirmed in this study (Pearson's correlation coefficient R2 = 0.62). Using a total of 786 MJD patients from five different geographical origins, a genome-wide association study (GWAS) was conducted to identify additional AO modifying factors that could explain some of the residual AO variability. We identified nine suggestively associated loci (P < 1 × 10-5). These loci were enriched for genes involved in vesicle transport, olfactory signaling, and synaptic pathways. Furthermore, associations between AO and the TRIM29 and RAG genes suggests that DNA repair mechanisms might be implicated in MJD pathogenesis. Our study demonstrates the existence of several additional genetic factors, along with CAG expansion, that may lead to a better understanding of the genotype-phenotype correlation in MJD.
... In the NFL of the olfactory bulb, OECs are also intimately associated with olfactory axons and are thought crucial for axon defasciculation, sorting and refasciculation [17,18]. OECs secrete many neurotrophic factors, such as nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), various neuregulins and other neurotrophins (reviewed in [6,[19][20][21][22]). Furthermore, OECs are the primary phagocytes in the olfactory nerve, responsible for clearing axonal debris resulting from the turnover of olfactory neurons and after injury to the olfactory nerve [23][24][25][26][27]. OECs also have important innate immune functions preventing pathogens from invading the CNS via the olfactory nerve [23,[28][29][30][31]. Due to their ability to promote growth and survival of neurons, as well as their unique ability to migrate long distances, OECs have been investigated as viable candidates for cell therapies for spinal cord injuries [32][33][34][35][36][37][38][39][40][41][42][43], neurodegenerative diseases [44][45][46] and peripheral nerve repair [47][48][49][50] with promising but highly variable outcomes. ...
The glial cells of the primary olfactory nervous system, olfactory ensheathing cells (OECs), are unusual in that they rarely form tumors. Only 11 cases, all of which were benign, have been reported to date. In fact, the existence of OEC tumors has been debated as the tumors closely resemble schwannomas (Schwann cell tumors), and there is no definite method for distinguishing the two tumor types. OEC transplantation is a promising therapeutic approach for nervous system injuries, and the fact that OECs are not prone to tumorigenesis is therefore vital. However, why OECs are so resistant to neoplastic transformation remains unknown. The primary olfactory nervous system is a highly dynamic region which continuously undergoes regeneration and neurogenesis throughout life. OECs have key roles in this process, providing structural and neurotrophic support as well as phagocytosing the axonal debris resulting from turnover of neurons. The olfactory mucosa and underlying tissue is also frequently exposed to infectious agents, and OECs have key innate immune roles preventing microbes from invading the central nervous system. It is possible that the unique biological functions of OECs, as well as the dynamic nature of the primary olfactory nervous system, relate to the low incidence of OEC tumors. Here, we summarize the known case reports of OEC tumors, discuss the difficulties of correctly diagnosing them, and examine the possible reasons for their rare incidence. Understanding why OECs rarely form tumors may open avenues for new strategies to combat tumorigenesis in other regions of the nervous system.
... Increasing RyRs or RyR activity could potentially rescue the loss of Purkinje cells. This was explored in a SCA3 mouse model where increasing serotonin and RyR levels in the cerebellum rescued the loss of Purkinje cells associated with the disease (Hsieh et al., 2017). In a mouse model for SCA2 the mutant ataxin-2 protein was shown to trigger IP 3 R-mediated Ca 2+ release, which was amplified by RyR activity via CICR (Liu et al., 2009). ...
Intracellular Ca2+ signaling is important in the regulation of several cellular processes including autophagy. The endoplasmic reticulum (ER) is the main and largest intracellular Ca2+ store. At the ER two protein families of Ca2+ release channels, inositol 1,4,5-trisphosphate receptors (IP3Rs) and ryanodine receptors (RyRs), are expressed. Several studies have reported roles in the regulation of autophagy for the ubiquitously expressed IP3R. For instance, IP3R-mediated Ca2+ release supresses basal autophagic flux by promoting mitochondrial metabolism, while also promoting the rapid initial increase in autophagic flux in response to nutrient starvation. Insights into the contribution of RyRs in autophagy have been lagging significantly compared to the advances made for IP3Rs. This is rather surprising considering that RyRs are predominantly expressed in long-lived cells with specialized metabolic needs, such as neurons and muscle cells, in which autophagy plays important roles. In this review article, recent studies revealing roles for RyRs in the regulation of autophagy will be discussed. Several RyR-interacting proteins that have been established to modulate both RyR function and autophagy will also be highlighted. Finally, the involvement of RyRs in neurodegenerative diseases will be addressed. Inhibition of RyR channels has not only been shown to be beneficial for treating several of these diseases but also regulates autophagy.
Machado-Joseph disease (MJD) is a neurodegenerative disorder characterized by widespread neuronal death affecting the cerebellum. Cell therapy can trigger neuronal replacement and neuroprotection through bystander effects providing a therapeutic option for neurodegenerative diseases. Here, human control (CNT) and MJD iPSC-derived neuroepithelial stem cells (NESC) were established and tested for their therapeutic potential. Cells’ neuroectodermal phenotype was demonstrated. Brain organoids obtained from the Control NESC showed higher mRNA levels of genes related to stem cells' bystander effects, such as BDNF, NEUROD1, and NOTCH1, as compared with organoids produced from MJD NESC, suggesting that Control NESC have a higher therapeutic potential. Graft-derived glia and neurons, such as cells positive for markers of cerebellar neurons, were detected six months after NESC transplantation in mice cerebella. The graft-derived neurons established excitatory and inhibitory synapses in the host cerebella, although CNT neurons exhibited higher excitatory synapse numbers compared with MJD neurons. Cell grafts, mainly CNT NESC, sustained the bystander effects through modulation of inflammatory interleukins (IL1B and IL10), neurotrophic factors (NGF), and neurogenesis-related proteins (Msi1 and NeuroD1), for six months in the mice cerebella. Altogether this study demonstrates the long-lasting therapeutic potential of human iPSC-derived NESC in the cerebellum.
