Olfactory ensheathing cells promote differentiation of neural stem cells and robust neurite extension

IPSC-NSCs-derived exosomal let-7b-5p improves motor function after spinal cord Injury by modulating microglial/macrophage pyroptosis

BACKGROUND

Following spinal cord injury (SCI), the inflammatory storm initiated by microglia/macrophages poses a significant impediment to the recovery process. Exosomes play a crucial role in the transport of miRNAs, facilitating essential cellular communication through the transfer of genetic material. However, the miRNAs from iPSC-NSCs-Exos and their potential mechanisms leading to repair after SCI remain unclear. This study aims to explore the role of iPSC-NSCs-Exos in microglia/macrophage pyroptosis and reveal their potential mechanisms.

METHODS

iPSC-NSCs-Exos were characterized and identified using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and Western blot. A mouse SCI model and a series of in vivo and in vitro experiments were conducted to investigate the therapeutic effects of iPSC-NSCs-Exos. Subsequently, miRNA microarray analysis and rescue experiments were performed to confirm the role of miRNAs in iPSC-NSCs-Exos in SCI. Mechanistic studies were carried out using Western blot, luciferase activity assays, and RNA-ChIP.

RESULTS

Our findings revealed that iPSC-NSCs-derived exosomes inhibited microglia/macrophage pyroptosis at 7 days post-SCI, maintaining myelin integrity and promoting axonal growth, ultimately improving mice motor function. The miRNA microarray showed let-7b-5p to be highly enriched in iPSC-NSCs-Exos, and LRIG3 was identified as the target gene of let-7b-5p. Through a series of rescue experiments, we uncovered the connection between iPSC-NSCs and microglia/macrophages, revealing a novel target for treating SCI.

CONCLUSION

In conclusion, we discovered that iPSC-NSCs-derived exosomes can package and deliver let-7b-5p, regulating the expression of LRIG3 to ameliorate microglia/macrophage pyroptosis and enhance motor function in mice after SCI. This highlights the potential of combined therapy with iPSC-NSCs-Exos and let-7b-5p in promoting functional recovery and limiting inflammation following SCI.

Olfactory ensheathing cells as candidate cells for chronic pain treatment

Chronic pain is often accompanied by tissue damage and pain hypersensitivity. It easily relapses and is challenging to cure, which seriously affects the patients' quality of life and is an urgent problem to be solved. Current treatment methods primarily rely on morphine drugs, which do not address the underlying nerve injury and may cause adverse reactions. Therefore, in recent years, scientists have shifted their focus from chronic pain treatment to cell transplantation. This review describes the classification and mechanism of chronic pain through the introduction of the characteristics of olfactory ensheathing cells (OECs), an in-depth discussion of special glial cells through the phagocytosis of nerve debris, receptor-ligand interactions, providing nutrition, and other inhibition of neuroinflammation, and ultimately supporting axon regeneration and mitigation of chronic pain. This review summarizes the potential and limitations of OECs for treating chronic pain by objectively analyzing relevant clinical trials and methods to enhance efficacy and future development prospects.

Neural stem cell therapies for spinal cord injury repair: an update on recent preclinical and clinical advances

Traumatic spinal cord injury (SCI) is a leading cause of lifelong disabilities. Permanent sensory, motor and autonomic impairments after SCI are substantially attributed to degeneration of spinal cord neurons and axons, and disintegration of neural network. To date, minimal regenerative treatments are available for SCI with an unmet need for new therapies to reconstruct the damaged spinal cord neuron-glia network and restore connectivity with the supraspinal pathways. Multipotent neural precursor cells (NPCs) have a unique capacity to generate neurons, oligodendrocytes and astrocytes. Due to this capacity, NPCs have been an attractive cell source for cellular therapies for SCI. Transplantation of NPCs has been extensively tested in preclinical models of SCI in the past two decades. These studies have identified opportunities and challenges associated with NPC therapies. While NPCs have the potential to promote neuroregeneration through various mechanisms, their low long-term survival and integration within the host injured spinal cord limit the functional benefits of NPC-based therapies for SCI. To address this challenge, combinatorial strategies have been developed to optimize the outcomes of NPC therapies by enriching SCI microenvironment through biomaterials, genetic and pharmacological therapies. In this review, we will provide an in-depth discussion on recent advances in preclinical NPC-based therapies for SCI. We will discuss modes of actions and mechanism by which engrafted NPCs contribute to the repair process and functional recovery. We will also provide an update on current clinical trials and new technologies that have facilitated preparation of medical-grade human NPCs suitable for transplantation in clinical studies.

Raman spectroscopy to assess the differentiation of bone marrow mesenchymal stem cells into a glial phenotype

Background

Mesenchymal stem cells (MSCs) are multipotent precursor cells with the ability to self-renew and differentiate into multiple cell linage, including the Schwann-like fate that promotes regeneration after lesion. Raman spectroscopy provides a precise characterization of the osteogenic, adipogenic, hepatogenic and myogenic differentiation of MSCs. However, the differentiation of bone marrow mesenchymal stem cells (BMSCs) towards a glial phenotype (Schwann-like cells) has not been characterized before using Raman spectroscopy.

Method

We evaluated three conditions: 1) cell culture from rat bone marrow undifferentiated (uBMSCs), and two conditions of differentiation; 2) cells exposed to olfactory ensheathing cells-conditioned medium (dBMSCs) and 3) cells obtained from olfactory bulb (OECs). uBMSCs phenotyping was confirmed by morphology, immunocytochemistry and flow cytometry using antibodies of cell surface: CD90 and CD73. Glial phenotype of dBMSCs and OECs were verified by morphology and immunocytochemistry using markers of Schwann-like cells and OECs such as GFAP, p75 NTR and O4. Then, the Principal Component Analysis (PCA) of Raman spectroscopy was performed to discriminate components from the high wavenumber region between undifferentiated and glial-differentiated cells. Raman bands at the fingerprint region also were used to analyze the differentiation between conditions.

Results

Differences between Raman spectra from uBMSC and glial phenotype groups were noted at multiple Raman shift values. A significant decrease in the concentration of all major cellular components, including nucleic acids, proteins, and lipids were found in the glial phenotype groups. PCA analysis confirmed that the highest spectral variations between groups came from the high wavenumber region observed in undifferentiated cells and contributed with the discrimination between glial phenotype groups.

Conclusion

These findings support the use of Raman spectroscopy for the characterization of uBMSCs and its differentiation in the glial phenotype.

Bioprinted Schwann and Mesenchymal Stem Cell Co-Cultures for Enhanced Spatial Control of Neurite Outgrowth

Bioprinting nerve conduits supplemented with glial or stem cells is a promising approach to promote axonal regeneration in the injured nervous system. In this study, we examined the effects of different compositions of bioprinted fibrin hydrogels supplemented with Schwann cells and mesenchymal stem cells (MSCs) on cell viability, production of neurotrophic factors, and neurite outgrowth from adult sensory neurons. To reduce cell damage during bioprinting, we analyzed and optimized the shear stress magnitude and exposure time. The results demonstrated that fibrin hydrogel made from 9 mg/mL of fibrinogen and 50IE/mL of thrombin maintained the gel’s highest stability and cell viability. Gene transcription levels for neurotrophic factors were significantly higher in cultures containing Schwann cells. However, the amount of the secreted neurotrophic factors was similar in all co-cultures with the different ratios of Schwann cells and MSCs. By testing various co-culture combinations, we found that the number of Schwann cells can feasibly be reduced by half and still stimulate guided neurite outgrowth in a 3D-printed fibrin matrix. This study demonstrates that bioprinting can be used to develop nerve conduits with optimized cell compositions to guide axonal regeneration.

Neurotrophic and immunomodulatory effects of olfactory ensheathing cells as a strategy for neuroprotection and regeneration

Accumulating evidence sustains glial cells as critical players during central nervous system (CNS) development, homeostasis and disease. Olfactory ensheathing cells (OECs), a type of specialized glia cells sharing properties with both Schwann cells and astrocytes, are of critical importance in physiological condition during olfactory system development, supporting its regenerative potential throughout the adult life. These characteristics prompted research in the field of cell-based therapy to test OEC grafts in damaged CNS. Neuroprotective mechanisms exerted by OEC grafts are not limited to axonal regeneration and cell differentiation. Indeed, OEC immunomodulatory properties and their phagocytic potential encourage OEC-based approaches for tissue regeneration in case of CNS injury. Herein we reviewed recent advances on the immune role of OECs, their ability to modulate CNS microenvironment via bystander effects and the potential of OECs as a cell-based strategy for tissue regeneration.

A phosphoproteomics study reveals a defined genetic program for neural lineage commitment of neural stem cells induced by olfactory ensheathing cell-conditioned medium

Since both Olfactory ensheathing cells (OECs) and neural stem cells (NSCs) have shown certain efficacy in the cellular therapy of nerve injury and disease, there have been a series of investigations in recent years looking at the co-culture of NSCs and OECs. Protein phosphorylation forms the basis for identifying a variety of cellular signaling pathways responsible for regulating the self-renewal and differentiation of NSCs induced by OECs. To better understand the signaling cascades in the early phases of OEC-induced NSC differentiation, changes in the NSC proteome and phosphoproteome during the first 24 h were determined using dimethyl labeling and TiO₂ phosphorylation enrichment coupled with Liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 565 proteins and 2511 phosphorylation sites were identified. According to quantitative phosphoproteomics analyses of NSC differentiation induced by OECs during the first 12 and 24 h, it was speculated that there were at least two different signal waves: one peaking within 12 h after stimulation and the second upsurge after 24 h. In addition to understanding the dynamics of the proteome and phosphoproteome in the early stages of NSC differentiation, our analyses identified a key role of the TGF-β3 protein secreted by OECs, which may be an initiating factor that promotes differentiation of NSCs into neurons induced by OECs. These findings not only redemonstrated a OECs-based therapeutic strategy in cell therapy, but also added a node to the regulatory network for the neural lineage commitment of NSCs induced by OECs.

Olfactory ensheathing cells facilitate neurite sprouting and outgrowth by secreting high levels of hevin

Transplantation of olfactory ensheathing cells (OECs) has been shown to enhance synapse formation. However, the mechanisms underlying this effect are not completely understood. We performed profiling of the OEC and astrocyte secretomes via a proteomics approach, in case hevin secreted by astrocytes might be involved in the formation of synapses. Semi-quantitative proteomic analysis revealed that 25 proteins were highly expressed, and 22 were weakly expressed in OEC conditioned medium compared with astrocyte conditioned medium. These molecules are highly associated with neural differentiation and regeneration, enzyme regulatory activity, and growth factor binding. The quantification data of clusterin, fibronectin, hevin, insulin-like growth factor binding protein 2 and secreted protein acidic and rich in cysteine were further confirmed by western blotting. Moreover, the addition of hevin in the culture medium improved neurite sprouting and outgrowth of differentiated neural stem cells. The greater expression of hevin in OEC conditioned medium than in astrocyte conditioned medium was associated with a greater capacity of synaptic formation. Thus, our results indicate that soluble factors secreted by OECs provide a permissive environment for nerve repair, and hevin is one of the key molecules facilitating neurite sprouting and outgrowth.

Early wheel-running promotes functional recovery by improving mitochondria metabolism in olfactory ensheathing cells after ischemic stroke in rats

Olfactory ensheathing cells (OECs) has been widely studied in stroke. The present study was aimed at examining the role of wheel-running treatment (WR) on rat olfactory ensheathing cells (rOECs) functions. Thirty adult male Sprague Dawley rats were randomly divided into two groups: the middle cerebral artery occlusion (MCAO) group and WR + MCAO group. Motor behavior was assessed through the footfault test, and the results showed that WR training markedly improved the neurobehavioral outcome. The glucose metabolic status of the brain was assessed with the micro-PET. This training significantly enhanced the glucose uptake of olfactory bulb in the early stage of WR treatment. The function of rOECs mitochondrial was significantly enhanced after 10 days of treatment. Body weight of rats in both of the two groups decreased and then increased slowly following the days. But the growth trend of the WR + MCAO group was no significantly higher than that of the WR group. This training significantly enhanced the glucose uptake, improved the proliferation of rOECs and increased the expression level of cytochrome C (Cyt-c). The mechanism may be associated with the facilitation of mitochondrial function of rOECs cells. Including facilitation of mitochondrial fusion, fission, and accompanying increased quantities of mitochondria. Obtained results indicate that early WR treatment may exert enhanced function on rOECs in vivo and increased mitochondrial amounts, and improved the expression level of Cyt-c after ischemic stroke.

Bioprocessing strategies to enhance the challenging isolation of neuro-regenerative cells from olfactory mucosa

Olfactory ensheathing cells (OECs) are a promising potential cell therapy to aid regeneration. However, there are significant challenges in isolating and characterizing them. In the current study, we have explored methods to enhance the recovery of cells expressing OEC marker p75NTR from rat mucosa. With the addition of a 24-hour differential adhesion step, the expression of p75NTR was significantly increased to 73 ± 5% and 46 ± 18% on PDL and laminin matrices respectively. Additionally, the introduction of neurotrophic factor NT-3 and the decrease in serum concentration to 2% FBS resulted in enrichment of OECs, with p75NTR at nearly 100% (100 ± 0% and 98 ± 2% on PDL and laminin respectively), and candidate fibroblast marker Thy1.1 decreased to zero. Culturing OECs at physiologically relevant oxygen tension (2-8%) had a negative impact on p75NTR expression and overall cell survival. Regarding cell potency, co-culture of OECs with NG108-15 neurons resulted in more neuronal growth and potential migration at atmospheric oxygen. Moreover, OECs behaved similarly to a Schwann cell line positive control. In conclusion, this work identified key bioprocessing fundamentals that will underpin future development of OEC-based cell therapies for potential use in spinal cord injury repair. However, there is still much work to do to create optimized isolation methods.

Human Olfactory Ensheathing Cell Transplantation Improves Motor Function in a Mouse Model of Type 3 Spinocerebellar Ataxia

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 ensheathing cells (hOECs) in the ATXN3-84Q mouse model of SCA3. Motor function begins to decline in ATXN3-84Q transgenic mice at approximately 13 weeks of age. ATXN3-84Q mice that received intracranial hOEC transplantation into the dorsal raphe nucleus of the brain exhibited significant improvements in motor function, as measured by the rotarod performance test and footprint pattern analysis. In addition, intracranial hOEC transplantation alleviated cerebellar inflammation, prohibited Purkinje cells from dying, and enhanced the neuroplasticity of cerebellar Purkinje cells. The protein levels of tryptophan hydroxylase 2, the rate-limiting enzyme for serotonin synthesis in the cerebellum, and ryanodine receptor (RYR) increased in mice that received intracranial hOEC transplantation. Because both serotonin and RYR can enhance Purkinje cell maturation, these effects may account for the therapeutic benefits mediated by intracranial hOEC transplantation in SCA3 mice. These results indicate that intracranial hOEC transplantation has potential value as a novel strategy for treating SCA3.

Co-Transplantation of Adipose Tissue-Derived Stromal Cells and Olfactory Ensheathing Cells for Spinal Cord Injury Repair

Patients suffering from spinal cord injury (SCI) still have a dismal prognosis. Despite all the efforts developed in this area, currently there are no effective treatments. Therefore, cell therapies have been proposed as a viable alternative to the current treatments used. Adipose tissue-derived stromal cells (ASCs) and olfactory ensheathing cells (OECs) have been used with promising results in different models of SCI, namely due to the regenerative properties of the secretome of the first, and the guidance capability of the second. Using an in vitro model of axonal growth, the dorsal root ganglia explants, we demonstrated that OECs induce neurite outgrowth mainly through cell-cell interactions, while ASCs' effects are strongly mediated by the release of paracrine factors. A proteomic analysis of ASCs' secretome revealed the presence of proteins involved in VEGF, PI3K, and Cadherin signaling pathways, which may be responsible for the effects observed. Then, the cotransplantation of ASCs and OECs showed to improve motor deficits of SCI-rats. Particular parameters of movement such as stepping, coordination, and toe clearance were improved in rats that received the transplant of cells, in comparison to nontreated rats. A histological analysis of the spinal cord tissues revealed that transplantation of ASCs and OECs had a major effect on the reduction of inflammatory cells close the lesion site. A slight reduction of astrogliosis was also evident. Overall, the results obtained with the present work indicate that the cotransplantation of ASCs and OECs brings important functional benefits to the injured spinal cord. Stem Cells 2018;36:696-708.

Rostro-caudal maturation of glial cells in the accessory olfactory system during development: involvement in outgrowth of GnRH neurites

During mammalian embryonic development, GnRH neurones differentiate from the nasal placode and migrate through the nasal septum towards the forebrain. We previously showed that a category of glial cells, the olfactory ensheathing cells (OEC), forms the microenvironment of migrating GnRH neurones. Here, to characterize the quantitative and qualitative importance of this glial, we investigated the spatiotemporal maturation of glial cells in situ and the role of maturing glia in GnRH neurones development ex vivo. More than 90% of migrating GnRH neurones were found to be associated with glial cells. There was no change in the cellular microenvironment of GnRH neurones in the regions crossed during embryonic development as glial cells formed the main microenvironment of these neurones (53.4%). However, the phenotype of OEC associated with GnRH neurones changed across regions. The OEC progenitors immunoreactive to brain lipid binding protein formed the microenvironment of migrating GnRH neurones from the vomeronasal organ to the telencephalon and were also present in the diencephalon. However, during GnRH neurone migration, maturation of OEC to [GFAP+] state (glial fibrillary acid protein) was only observed in the nasal septum. Inducing depletion of OEC in maturation, using transgenic mice expressing herpes simplex virus thymidine kinase driven by the GFAP promoter, had no impact on neurogenesis or on triggering GnRH neurones migration in nasal explant culture. Nevertheless, depletion of [GFAP+] cells decreased GnRH neurites outgrowth by 57.4%. This study suggests that specific maturation of OEC in the nasal septum plays a role in morphological differentiation of GnRH neurones.

Phenotypic Modulation and Neuroprotective Effects of Olfactory Ensheathing Cells: a Promising Tool for Cell Therapy

Olfactory Ensheathing Cells (OECs), exhibiting phenotypic characteristics of both astrocytes and Schwann Cells, show peculiar plasticity. In vitro, OECs promote axonal growth, while in vivo they promote remyelination of damaged axons. We decided to further investigate OEC potential for regeneration and functional recovery of the damaged Central Nervous System (CNS). To study OEC antigen modulation, OECs prepared from postnatal mouse olfactory bulbs were grown in different culture conditions: standard or serum-free media with/without Growth Factors (GFs) and analyzed for different neural specific markers. OEC functional characterizations were also achieved. Resistance of OECs to the neurotoxin 6-hydroxydopamine (6-OHDA) was analyzed by evaluating apoptosis and death. OEC neuroprotective properties were investigated by in vitro co-cultures or by addition of OEC conditioned medium to the neuroblastoma SH-SY5Y cells exposed to 6-OHDA. We observed: 1) modification of OEC morphology, reduced cell survival and marker expression in serum-free medium; 2) GF addition to serum-free medium condition influenced positively survival and restored basal marker expression; 3) no OEC apoptosis after a prolonged exposition to 6-OHDA; 4) a clear OEC neuroprotective tendency, albeit non statistically significant, on 6-OHDA treated SH-SY5Y cells. These peculiar properties of OECs might render them potential clinical agents able to support injured CNS.

Natural compound-derived epigenetic regulators targeting epigenetic readers, writers and erasers

Post-translational modifications can affect gene expression in a long-term manner without changes in the primary nucleotide sequence of the DNA. These epigenetic alterations involve dynamic processes that occur in histones, chromatin-associated proteins and DNA. In response to environmental stimuli, abnormal epigenetic alterations cause disorders in the cell cycle, apoptosis and other cellular processes and thus contribute to the incidence of diverse diseases, including cancers. In this review, we will summarize recent studies focusing on certain epigenetic readers, writers, and erasers associated with cancer development and how newly discovered natural compounds and their derivatives could interact with these targets. These advances provide insights into epigenetic alterations in cancers and the potential utility of these alterations as therapeutic targets for the future development of chemopreventive and chemotherapeutic drugs.

Adult stem cells in neural repair: Current options, limitations and perspectives

Stem cells represent a promising step for the future of regenerative medicine. As they are able to differentiate into any cell type, tissue or organ, these cells are great candidates for treatments against the worst diseases that defy doctors and researchers around the world. Stem cells can be divided into three main groups: (1) embryonic stem cells; (2) fetal stem cells; and (3) adult stem cells. In terms of their capacity for proliferation, stem cells are also classified as totipotent, pluripotent or multipotent. Adult stem cells, also known as somatic cells, are found in various regions of the adult organism, such as bone marrow, skin, eyes, viscera and brain. They can differentiate into unipotent cells of the residing tissue, generally for the purpose of repair. These cells represent an excellent choice in regenerative medicine, every patient can be a donor of adult stem cells to provide a more customized and efficient therapy against various diseases, in other words, they allow the opportunity of autologous transplantation. But in order to start clinical trials and achieve great results, we need to understand how these cells interact with the host tissue, how they can manipulate or be manipulated by the microenvironment where they will be transplanted and for how long they can maintain their multipotent state to provide a full regeneration.