Brain-derived Neurotrophic Factor Promotes the Migration of Olfactory Ensheathing Cells Through TRPC Channels

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.

Spinal cord injury: Olfactory ensheathing cell-based therapeutic strategies

Spinal cord injury (SCI) is a highly disabling neurological disorder that is difficult to treat due to its complex pathophysiology and nerve regeneration difficulties. Hence, effective SCI treatments are necessary. Olfactory ensheathing cells (OECs), glial cells derived from the olfactory bulb or mucosa, are ideal candidates for SCI treatment because of their neuroprotective and regenerative properties, ample supply, and convenience. In vitro, animal model, and human trial studies have reported discoveries on OEC transplantation; however, shortcomings have also been demonstrated. Recent studies have optimized various OEC transplantation strategies, including drug integration, biomaterials, and gene editing. This review aims to introduce OECs mechanisms in repairing SCI, summarize the research progress of OEC transplantation-optimized strategies, and provide novel research ideas for SCI treatment.

The growth status and functions of olfactory ensheathing cells cultured on randomly oriented and aligned type-I-collagen-based nanofibrous scaffolds

Aim. The potential of olfactory ensheathing cells (OECs) as a cell therapy for spinal cord reconstruction and regeneration after injury has drawn significant attention in recent years. This study attempted to investigate the influences of nano-fibrous scaffolds on the growth status and functional properties of OECs.Methods.The ultra-morphology of the scaffolds was visualized using scanning electron microscopy (SEM). To culture OECs, donated cells were subcultured and identified with p75. Cell proliferation, apoptosis, and survival rates were measured through MTT assay, Annexin-V/PI staining, and p75 cell counting, respectively. The adhesion of cells cultured on scaffolds was observed using SEM. Additionally, the functions of OECs cultured on scaffolds were assessed by testing gene expression levels through real time polymerase chain reaction.Results.The electrospun type I collagen-based nano-fibers exhibited a smooth surface and uniform distribution. It was indicated that the proliferation and survival rates of OECs cultured on both randomly oriented and aligned type I collagen-based nano-fibrous scaffolds were higher than those observed in the collagen-coated control. Conversely, apoptosis rates were lower in cells cultured on scaffolds. Furthermore, OEC adhesion was better on the scaffolds than on the control. The expression levels of target genes were significantly elevated in cells cultured on scaffolds versus the controls.Conclusion.As a whole, the utilization of aligned collagen nanofibers has demonstrated significant advantages in promoting cell growth and improving cell function. These findings have important implications for the field of regenerative medicine and suggest that the approach may hold promise for the future therapeutic applications.

Migratory Response of Cells in Neurogenic Niches to Neuronal Death: The Onset of Harmonic Repair?

Harmonic mechanisms orchestrate neurogenesis in the healthy brain within specific neurogenic niches, which generate neurons from neural stem cells as a homeostatic mechanism. These newly generated neurons integrate into existing neuronal circuits to participate in different brain tasks. Despite the mechanisms that protect the mammalian brain, this organ is susceptible to many different types of damage that result in the loss of neuronal tissue and therefore in alterations in the functionality of the affected regions. Nevertheless, the mammalian brain has developed mechanisms to respond to these injuries, potentiating its capacity to generate new neurons from neural stem cells and altering the homeostatic processes that occur in neurogenic niches. These alterations may lead to the generation of new neurons within the damaged brain regions. Notwithstanding, the activation of these repair mechanisms, regeneration of neuronal tissue within brain injuries does not naturally occur. In this review, we discuss how the different neurogenic niches respond to different types of brain injuries, focusing on the capacity of the progenitors generated in these niches to migrate to the injured regions and activate repair mechanisms. We conclude that the search for pharmacological drugs that stimulate the migration of newly generated neurons to brain injuries may result in the development of therapies to repair the damaged brain tissue.

Prospects for the use of olfactory mucosa cells in bioprinting for the treatment of spinal cord injuries

The review focuses on the most important areas of cell therapy for spinal cord injuries. Olfactory mucosa cells are promising for transplantation. Obtaining these cells is safe for patients. The use of olfactory mucosa cells is effective in restoring motor function due to the remyelination and regeneration of axons after spinal cord injuries. These cells express neurotrophic factors that play an important role in the functional recovery of nerve tissue after spinal cord injuries. In addition, it is possible to increase the content of neurotrophic factors, at the site of injury, exogenously by the direct injection of neurotrophic factors or their delivery using gene therapy. The advantages of olfactory mucosa cells, in combination with neurotrophic factors, open up wide possibilities for their application in three-dimensional and four-dimensional bioprinting technology treating spinal cord injuries.

Neuroblasts migration under control of reactive astrocyte-derived BDNF: a promising therapy in late neurogenesis after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a disease with high mortality and morbidity, which leads to severe neurological dysfunction. Neurogenesis has provided therapeutic options for treating TBI. Brain derived neurotrophic factor (BDNF) plays a key role in neuroblasts migration. We aimed to investigate to the key regulating principle of BDNF in endogenous neuroblasts migration in a mouse TBI model.

METHODS

In this study, controlled cortical impact (CCI) mice (C57BL/6J) model was established to mimic TBI. The sham mice served as control. Immunofluorescence staining and enzyme-linked immunosorbent assay were performed on the CCI groups (day 1, 3, 7, 14 and 21 after CCI) and the sham group. All the data were analyzed with Student's t-test or one-way or two-way analysis of variance followed by Tukey's post hoc test.

RESULTS

Our results revealed that neuroblasts migration initiated as early as day 1, peaking at day 7, and persisted till day 21. The spatiotemporal profile of BDNF expression was similar to that of neuroblasts migration, and BDNF level following CCI was consistently higher in injured cortex than in subventricular zone (SVZ). Reactive astrocytes account for the major resource of BDNF along the migrating path, localized with neuroblasts in proximity. Moreover, injection of exogenous CC chemokine ligand 2 (CCL2), also known as monocyte chemoattractant protein-1, at random sites promoted neuroblasts migration and astrocytic BDNF expression in both normal and CCI mice (day 28). These provoked neuroblasts can also differentiate into mature neurons. CC chemokine ligand receptor 2 antagonist can restrain the neuroblasts migration after TBI.

CONCLUSIONS

Neuroblasts migrated along the activated astrocytic tunnel, directed by BDNF gradient between SVZ and injured cortex after TBI. CCL2 might be a key regulator in the above endogenous neuroblasts migration. Moreover, delayed CCL2 administration may provide a promising therapeutic strategy for late neurogenesis post-trauma.

Wiring the senses: Factors that regulate peripheral axon pathfinding in sensory systems

Sensory neurons of the head are the ones that transmit the information about the external world to our brain for its processing. Axons from cranial sensory neurons sense different chemoattractant and chemorepulsive molecules during the journey and in the target tissue to establish the precise innervation with brain neurons and/or receptor cells. Here, we aim to unify and summarize the available information regarding molecular mechanisms guiding the different afferent sensory axons of the head. By putting the information together, we find the use of similar guidance cues in different sensory systems but in distinct combinations. In vertebrates, the number of genes in each family of guidance cues has suffered a great expansion in the genome, providing redundancy, and robustness. We also discuss recently published data involving the role of glia and mechanical forces in shaping the axon paths. Finally, we highlight the remaining questions to be addressed in the field.

Optimizing Olfactory Ensheathing Cell Transplantation for Spinal Cord Injury Repair

Cell transplantation constitutes an important avenue for development of new treatments for spinal cord injury (SCI). These therapies are aimed at supporting neural repair and/or replacing lost cells at the injury site. To date, various cell types have been trialed, with most studies focusing on different types of stem cells or glial cells. Here, we review commonly used cell transplantation approaches for spinal cord injury (SCI) repair, with focus on transplantation of olfactory ensheathing cells (OECs), the glial cells of the primary olfactory nervous system. OECs are promising candidates for promotion of neural repair given that they support continuous regeneration of the olfactory nerve that occurs throughout life. Further, OECs can be accessed from the nasal mucosa (olfactory neuroepithelium) at the roof of the nasal cavity and can be autologously transplanted. OEC transplantation has been trialed in many animal models of SCI, as well as in human clinical trials. While several studies have been promising, outcomes are variable and the method needs improvement to enhance aspects such as cell survival, integration, and migration. As a case study, we include the approaches used by our team (the Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia) to address the current problems with OEC transplantation and discuss how the therapeutic potential of OEC transplantation can be improved. Our approach includes discovery research to improve our knowledge of OEC biology, identifying natural and synthetic compounds to stimulate the neural repair properties of OECs, and designing three-dimensional cell constructs to create stable and transplantable cell structures.

Neuroprotective mechanisms of mangiferin in neurodegenerative diseases

The central nervous system (CNS) regulates and coordinates an extensive array of complex processes requiring harmonious regulation of specific genes. CNS disorders represent a large burden on society and cause enormous disability and economic losses. Traditional Chinese medicine (TCM) has been used for many years in the treatment of neurological illnesses, such as Alzheimer's disease, Parkinson's disease, stroke, and depression, as the combination of TCM and Western medicine has superior therapeutic efficacy and minimal toxic side effects. Mangiferin (MGF) is an active compound of the traditional Chinese herb rhizome anemarrhenae, which has antioxidant, anti-inflammation, anti-lipid peroxidation, immunomodulatory, and anti-apoptotic functions in the CNS. MGF has been demonstrated to have therapeutic effects in CNS diseases through a multitude of mechanisms. This review outlines the latest research on the neuroprotective ability of MGF and the diverse molecular mechanisms involved.

Olfactory Ensheathing Cells: A Trojan Horse for Glioma Gene Therapy

BACKGROUND

The olfactory ensheathing cells (OECs) migrate from the peripheral nervous system to the central nervous system (CNS), a critical process for the development of the olfactory system and axonal extension after injury in neural regeneration. Because of their ability to migrate to the injury site and anti-inflammatory properties, OECs were tested against different neurological pathologies, but were never studied in the context of cancer. Here, we evaluated OEC tropism to gliomas and their potential as a "Trojan horse" to deliver therapeutic transgenes through the nasal pathway, their natural route to CNS.

METHODS

OECs were purified from the mouse olfactory bulb and engineered to express a fusion protein between cytosine deaminase and uracil phosphoribosyltransferase (CU), which convert the prodrug 5-fluorocytosine (5-FC) into cytotoxic metabolite 5-fluorouracil, leading to a bystander killing of tumor cells. These cells were injected into the nasal cavity of mice bearing glioblastoma tumors and OEC-mediated gene therapy was monitored by bioluminescence imaging and confirmed with survival and ex vivo histological analysis. All statistical tests were two-sided.

RESULTS

OECs migrated from the nasal pathway to the primary glioma site, tracked infiltrative glioma stemlike cells, and delivered therapeutic transgene, leading to a slower tumor growth and increased mice survival. At day 28, bioluminescence imaging revealed that mice treated with a single injection of OEC-expressing CU and 5-FC had tumor-associated photons (mean [SD]) of 1.08E + 08 [9.7E + 07] vs 4.1E + 08 [2.3E + 08] for control group (P < .001), with a median survival of 41 days vs 34 days, respectively (ratio = 0.8293, 95% confidence interval = 0.4323 to 1.226, P <  .001) (n = 9 mice per group).

CONCLUSIONS

We show for the first time that autologous transplantation of OECs can target and deliver therapeutic transgenes to brain tumors upon intranasal delivery, the natural route of OECs to the CNS, which could be extended to other types of cancer.

Sphingosine 1-phosphate promotes the proliferation of olfactory ensheathing cells through YAP signaling and participates in the formation of olfactory nerve layer

Olfactory ensheathing cells (OECs) are unique glial cells with axonal growth-promoting properties in the olfactory epithelium and olfactory bulb, covering the entire length of the olfactory nerve. The proliferation of OECs is necessary for the formation of the presumptive olfactory nerve layer (ONL) during development and OECs transplantation. However, the molecular mechanism underlying the regulation of OEC proliferation in the ONL still remains unknown. In the present study, we examined the role of sphingosine 1-phosphate (S1P) and S1P receptors (S1PRs) on OEC proliferation. Initially, reverse transcription-PCR (RT-PCR), western blot and immunostaining revealed that S1PRs were highly expressed in the OECs in vitro and in vivo. Furthermore, we found that S1P treatment promoted the proliferation of primary cultured OECs mediated by S1PR1. Mechanistically, yes-associated protein (YAP) was required for S1P-induced OEC proliferation through RhoA signaling. Finally, conditional knockout of YAP in OECs reduced OEC proliferation in ONL, which impaired the axonal projection and growth of olfactory sensory neurons, and olfactory functions. Taken together, these results reveal a previously unrecognized function of S1P/RhoA/YAP pathway in the proliferation of OECs, contributing to the formation of ONL and the projection, growth, and function of olfactory sensory neurons during development.

Combination of olfactory ensheathing cells and human umbilical cord mesenchymal stem cell-derived exosomes promotes sciatic nerve regeneration

Olfactory ensheathing cells (OECs) are promising seed cells for nerve regeneration. However, their application is limited by the hypoxic environment usually present at the site of injury. Exosomes derived from human umbilical cord mesenchymal stem cells have the potential to regulate the pathological processes that occur in response to hypoxia. The ability of OECs to migrate is unknown, especially in hypoxic conditions, and the effect of OECs combined with exosomes on peripheral nerve repair is not clear. Better understanding of these issues will enable the potential of OECs for the treatment of nerve injury to be addressed. In this study, OECs were acquired from the olfactory bulb of Sprague Dawley rats. Human umbilical cord mesenchymal stem cell-derived exosomes (0–400 μg/mL) were cultured with OECs for 12–48 hours. After culture with 400 μg/mL exosomes for 24 hours, the viability and proliferation of OECs were significantly increased. We observed changes to OECs subjected to hypoxia for 24 hours and treatment with exosomes. Exosomes significantly promoted the survival and migration of OECs in hypoxic conditions, and effectively increased brain-derived neurotrophic factor gene expression, protein levels and secretion. Finally, using a 12 mm left sciatic nerve defect rat model, we confirmed that OECs and exosomes can synergistically promote motor and sensory function of the injured sciatic nerve. These findings show that application of OECs and exosomes can promote nerve regeneration and functional recovery. This study was approved by the Institutional Ethical Committee of the Air Force Medical University, China (approval No. IACUC-20181004) on October 7, 2018; and collection and use of human umbilical cord specimens was approved by the Ethics Committee of the Linyi People’s Hospital, China (approval No. 30054) on May 20, 2019.

A Milled Microdevice to Advance Glia-Mediated Therapies in the Adult Nervous System

Neurodegenerative disorders affect millions of adults worldwide. Neuroglia have become recent therapeutic targets due to their reparative abilities in the recycling of exogenous neurotoxins and production of endogenous growth factors for proper functioning of the adult nervous system (NS). Since neuroglia respond effectively to stimuli within in vivo environments on the micron scale, adult glial physiology has remarkable synergy with microscale systems. While clinical studies have begun to explore the reparative action of Müller glia (MG) of the visual system and Schwann Cells (ShC) of the peripheral NS after neural injury, few platforms enable the study of intrinsic neuroglia responses to changes in the local microenvironment. This project developed a low-cost, benchtop-friendly microfluidic system called the glia line system, or gLL, to advance the cellular study needed for emerging glial-based therapies. The gLL was fabricated using elastomeric kits coupled with a metal mold milled via conventional computer numerical controlled (CNC) machines. Experiments used the gLL to measure the viability, adhesion, proliferation, and migration of MG and ShC within scales similar to their respective in vivo microenvironments. Results illustrate differences in neuroglia adhesion patterns and chemotactic behavior significant to advances in regenerative medicine using implants and biomaterials, as well as cell transplantation techniques. Data showed highest survival and proliferation of MG and ShC upon laminin and illustrated a four-fold and two-fold increase of MG migration to dosage-dependent signaling from vascular endothelial growth factor (VEGF) and epidermal growth factor (EGF), respectively, as well as a 20-fold increase of ShC migration toward exogenous brain-derived neurotrophic factor (BDNF), compared to media control. The ability to quantify these biological parameters within the gLL offers an effective and reliable alternative to photolithography study neuroglia in a local environment ranging from the tens to hundreds of microns, using a low-cost and easily fabricated system.

The Bu Shen Yi Sui Formula Promotes Axonal Regeneration via Regulating the Neurotrophic Factor BDNF/TrkB and the Downstream PI3K/Akt Signaling Pathway

Axonal damage is recognized as an important pathological feature in the chronic progressive neurological disorder multiple sclerosis (MS). Promoting axonal regeneration is a critical strategy for the treatment of MS. Our clinical and experimental studies have shown that the Bu Shen Yi Sui formula (BSYS) promotes axonal regeneration in MS and experimental autoimmune encephalomyelitis (EAE), an animal model of MS, but the exact mechanism has not been thoroughly elucidated to date. In this study, we investigated the effects of BSYS and its two decomposed formulas-the Bu Shen formula (BS) and the Hua Tan Huo Xue formula (HTHX)-on brain-derived neurotrophic factor (BDNF)/TrkB and related signaling pathways to explore the mechanism by which axonal regeneration is promoted in vitro and in vivo. Damaged SH-SY5Y cells incubated with low serum were treated with BSYS-, BS-, and HTHX-containing serum, and EAE mice induced by the myelin oligodendrocyte glycoprotein (MOG)_35-55 peptide were treated with BSYS. The results showed that the BSYS-containing serum markedly increased cell viability and increased the levels of growth associated protein (GAP)-43, phosphorylated (p)-cAMP-response element binding protein (CREB), BDNF, TrkB, and p-PI3K. The BS and HTHX treatments also induced the protein expression of GAP-43 and p-extracellular signal-regulated kinase (ERK) in the cells. Furthermore, the effects of BSYS on cell viability, GAP-43, p-CREB, and neurite outgrowth were clearly inhibited by LY294002, a specific antagonist of the PI3K signaling pathways. The addition of U0126 and U73122, antagonists of the ERK and PLCγ pathway, respectively, significantly inhibited cell viability and GAP-43 protein expression. Moreover, BSYS treatment significantly increased the expression of the 68-, 160-, and 200-kDa neurofilaments (NFs) of proteins and the BDNF, TrkB, PI3K, and Akt mRNA and proteins in the brain or spinal cord of mice at different stages. These results indicated that BSYS promotes nerve regeneration, and its mechanism is mainly related to the upregulation of the BDNF/TrkB and PI3K/Akt signaling pathways. BS and HTHX also promoted nerve regeneration, and this effect involved the ERK pathway.

Semaphorin 3A as an inhibitive factor for migration of olfactory ensheathing cells through cofilin activation is involved in formation of olfactory nerve layer

Olfactory ensheathing cells (OECs) migrate from olfactory epithelium towards olfactory bulb (OB), contributing to formation of the presumptive olfactory nerve layer during development. However, it remains unclear that molecular mechanism of regulation of OEC migration in OB. In the present study, we found that OECs highly expressed the receptors of semaphorin 3A (Sema3A) in vitro and in vivo, whereas Sema3A displayed a gradient expression pattern with higher in inner layer of OB and lower in outer layer of OB. Furthermore, the collapse assays, Boyden chamber migration assays and single-cell migration assays showed that Sema3A induced the collapse of leading front of OECs and inhibited OEC migration. Thirdly, the leading front of OECs exhibited adaptation in a protein synthesis-independent manner, and endocytosis-dependent manner during Sema3A-induced OEC migration. Finally, Sema3A-induced collapse of leading front was required the decrease of focal adhesion and a retrograde F-actin flow in a cofilin activation-dependent manner. Taken together, these results demonstrate that Sema3A as an inhibitive migratory factor for OEC migration through cofilin activation is involved in the formation of olfactory nerve layer.

Ginsenoside Rg1 Promotes the Migration of Olfactory Ensheathing Cells via the PI3K/Akt Pathway to Repair Rat Spinal Cord Injury

The aim of this study was to determine the effects of ginsenoside Rg1 on the migration of olfactory ensheathing cells (OECs) in vitro, and its influence on the therapeutic efficacy of OECs transplanted in vivo for the treatment of spinal cord injury (SCI). Primary cultured and purified OECs (prepared from rats) were treated with ginsenoside Rg1. The wound healing test indicated that ginsenoside Rg1 promoted the migration of OECs. Real-time RT-PCR demonstrated that ginsenoside Rg1 upregulated the expression of migration-related factors of OECs, including matrix metalloproteinases-2 (MMP-2), MMP-9, and neural cell adhesion molecule 1 (NCAM1). Moreover, Western blot analysis indicated that ginsenoside Rg1 significantly promoted the migration of OECs via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. An SCI rat model was induced in vivo using a revised Allen's method. The Basso, Beattie, and Bresnahan (BBB) scores and histological analysis demonstrated that OECs, which were treated with ginsenoside Rg1, exhibited significant improvement in SCI compared with both the control group and the OEC group. Thus, ginsenoside Rg1 may represent a novel treatment target for SCI.

Neuroprotective effect of olfactory ensheathing cells co-transfected with Nurr1 and Ngn2 in both in vitro and in vivo models of Parkinson's disease

AIMS

The aim of the study is to evaluate the neuroprotective effects of olfactory ensheathing cells (OECs) with the overexpression of nuclear receptor-related factor 1 (Nurr1) and neurogenin 2 (Ngn2) in experimental models of Parkinson's disease (PD) and to elucidate the potential mechanism underlying the neuroprotective effects of OECs-Nurr1-Ngn2.

MATERIALS AND METHODS

In vitro study, OECs-Nurr1-Ngn2 conditioned medium (CM) was added to MPP⁺-treated PC12 cells for 24h, and then the viability of PC12 cells, oxidative stress and apoptosis were detected. In vivo study, 48 male Sprague-Dawley (SD) rats were randomly divided into four groups. OECs/VMCs and OECs-Nurr1-Ngn2/VMCs groups were transplanted with 2×10⁵ cells each of OECs or OECs-Nurr1-Ngn2 and VMCs into the right striatum one week after a unilateral 6-OHDA lesion. Control and PD groups were injected with 0.9% NaCl and 0.2% ascorbic acid into the same region. Rotational behavior was determined at 2, 4, 6 and 8weeks after injection or implantation in all groups. Neuronal differentiation markers, oxidative stress- and apoptosis-related indicators were detected at 8weeks post-grafting.

KEY FINDINGS

OECs-Nurr1-Ngn2 increased the viability of PC12 cells, inhibited oxidative stress and apoptosis, and these effects could be reversed by pre-treatment of k252a, a TrkB receptor inhibitor. The behavioral deficits of PD rat were ameliorated by the transplantation of OECs-Nurr1-Ngn2/VMCs.

SIGNIFICANCE

These results suggest that OECs-Nurr1-Ngn2 exhibits substantial neuroprotective, anti-oxidant, and anti-apoptotic effects against PD via the up-regulation of the neurotrophic factor-TrkB pathway.

Liquid Marble as Bioreactor for Engineering Three-Dimensional Toroid Tissues

Liquid marble is a liquid droplet coated with hydrophobic powder that can be used as a bioreactor. This paper reports the three-dimensional self-assembly and culture of a cell toroid in a slow-releasing, non-adhesive and evaporation-reducing bioreactor platform based on a liquid marble. The bioreactor is constructed by embedding a hydrogel sphere containing growth factor into a liquid marble filled with a suspension of dissociated cells. The hydrogel maintains the water content and concurrently acts as a slow-release carrier. The concentration gradient of growth factor induces cell migration and assembly into toroidal aggregates. An optimum cell concentration resulted in the toroidal (doughnut-like) tissue after 12 hours. The harvested cell toroids showed rapid closure of the inner opening when treated with the growth factor. We also present a geometric growth model to describe the shape of the toroidal tissue over time. In analogy to the classical two-dimensional scratch assay, we propose that the cell toroids reported here open up new possibilities to screen drugs affecting cell migration in three dimensions.

Polarized Distribution of Active Myosin II Regulates Directional Migration of Cultured Olfactory Ensheathing Cells

Migration of olfactory ensheathing cells (OECs) is critical for development of olfactory system and essential for neural regeneration after OEC transplantation into nerve injury site. However, the molecular mechanisms underlying the regulation of directional migration of OECs remain unclear. In this study, we found that in migrating OECs, phosphorylated myosin light chain (p-MLC, active myosin II) displayed a polarized distribution, with the leading front exhibiting higher than soma and trailing process. Over-expression of GFP-MLC significantly reduced OEC migration. Moreover, decreasing this front-to-rear difference of myosin II activity by the frontal application of a ML-7 (myosin II inhibitors) gradient induced the collapse of leading front and reversed soma translocation of OECs, whereas, increasing this front-to-rear difference of myosin II activity by the rear application of a ML-7 or BDM gradient or the frontal application of a Caly (myosin II activator) gradient accelerated the soma translocation of OECs. Finally, myosin II as a downstream signaling of repulsive factor Slit-2 mediated the reversal of soma translocation induced by Slit-2. Taken together, these results suggest that the polarized distribution of active myosin II regulates the directional migration of OECs during spontaneous migration or upon to extracellular stimulation such as Slit-2.

Antioxidant and Anti-Senescence Effect of Metformin on Mouse Olfactory Ensheathing Cells (mOECs) May Be Associated with Increased Brain-Derived Neurotrophic Factor Levels-An Ex Vivo Study

Metformin, the popular anti-diabetic drug was shown to exert multiple biological effects. The most recent metformin gained attention as an agent that mobilizes endogenous progenitor cells and enhances regenerative potential of organisms, for example by promoting neurogenesis. In the present study, we examined the role of metformin on mouse olfactory ensheathing cells (mOECs) derived from animals receiving metformin for eight weeks at a concentration equal to 2.8 mg/day. The mOECs expanded ex vivo were characterized in terms of their cellular phenotype, morphology, proliferative activity, viability and accumulation of oxidative stress factors. Moreover, we determined the mRNA and protein levels of brain-derived neurotrophic factor (BDNF), distinguishing the secretion of BDNF by mOECs in cultures and circulating serum levels of BDNF. The mOECs used in the experiment were glial fibrillary acidic protein (GFAP) and p75 neurotrophin receptor (p75^NTR) positive and exhibited both astrocyte-like and non-myelin Schwann cell-like morphologies. Our results revealed that the proliferation of OECs derived from mice treated with metformin was lowered, when compared to control group. Simultaneously, we noted increased cell viability, reduced expression of markers associated with cellular senescence and a decreased amount of reactive oxygen species. We observed increased mRNA expression of BDNF and its down-stream genes. Obtained results indicate that metformin may exert antioxidant, anti-apoptotic and senolytic action on OECs expanded ex vivo.