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Intravascularly transplanted bone marrow cells, including bone marrow mononuclear cells (BM-MNC) and mesenchymal stem cells, transfer water-soluble molecules to cerebral endothelial cells via gap junctions. After transplantation of BM-MNC, this fosters hippocampal neurogenesis and enhancement of neuronal function. Herein, we report the impact of transplanted BM-MNC on neural stem cells (NSC) in the brain. Surprisingly, direct transfer of water-soluble molecules from transplanted BM-MNC and peripheral mononuclear cells to NSC in the hippocampus was observed already 10 min after cell transplantation, and transfer from BM-MNC to GFAP-positive cortical astrocytes was also observed. In vitro investigations revealed that BM-MNC abolish the expression of hypoxia-inducible factor-1α in astrocytes. We suggest that the transient and direct transfer of water-soluble molecules between cells in circulation and NSC in the brain may be one of the biological mechanisms underlying the repair of brain function.
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Accumulation of lipotoxic lipids, such as free cholesterol, induces hepatocyte death and subsequent inflammation and fibrosis in the pathogenesis of nonalcoholic steatohepatitis (NASH). However, the underlying mechanisms remain unclear. We have previously reported that hepatocyte death locally induces phenotypic changes in the macrophages surrounding the corpse and remnant lipids, thereby promoting liver fibrosis in a murine model of NASH. Here, we demonstrated that lysosomal cholesterol overload triggers lysosomal dysfunction and profibrotic activation of macrophages during the development of NASH. ß-cyclodextrin polyrotaxane (ßCD-PRX), a unique supramolecule, is designed to elicit free cholesterol from lysosomes. Treatment with ßCD-PRX ameliorated cholesterol accumulation and profibrotic activation of macrophages surrounding dead hepatocytes with cholesterol crystals, thereby suppressing liver fibrosis in a NASH model, without affecting the hepatic cholesterol levels. In vitro experiments revealed that cholesterol-induced lysosomal stress triggered profibrotic activation in macrophages predisposed to the steatotic microenvironment. This study provides evidence that dysregulated cholesterol metabolism in macrophages would be a novel mechanism of NASH.
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Hepatopatia Gordurosa não Alcoólica , Animais , Camundongos , Modelos Animais de Doenças , Cirrose Hepática , Macrófagos , Colesterol , LisossomosRESUMO
X-ray microscopes adopting computed tomography enable nondestructive 3D visualization of biological specimens at micron-level resolution without conventional 2D serial sectioning that is a destructive/laborious method and is routinely used for analyzing renal biopsy in clinical diagnosis of kidney diseases. Here we applied a compact commercial system of laboratory-based X-ray microscope to observe a resin-embedded osmium-stained 1-mm strip of a mouse kidney piece as a model of renal biopsy, toward a more efficient diagnosis of kidney diseases. A reconstructed computed tomography image from several hours of data collection using CCD detector allowed us to unambiguously segment a single nephron connected to a renal corpuscle, which was consistent with previous reports using serial sectioning. Histogram analysis on the segmented nephron confirmed that the proximal and distal tubules were distinguishable on the basis of their X-ray opacities. A 3D rendering model of the segmented nephron visualized a convoluted structure of renal tubules neighboring the renal corpuscle and a branched structure of efferent arterioles. Furthermore, another data collection using scientific complementary metal-oxide semiconductor detector with a much shorter data acquisition time of 15 min provided similar results from the same samples. These results suggest a potential application of the compact laboratory-based X-ray microscope to analyze mouse renal biopsy.
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Nefropatias , Microscopia , Camundongos , Animais , Raios XRESUMO
Nerves in the renal parenchyma comprise sympathetic nerves that act on renal arteries and tubules to decrease blood flow and increase primary urine reabsorption, respectively. Synaptic vesicles release neurotransmitters that activate their effector tissues. However, the mechanisms by which neurotransmitters exert individual responses to renal effector cells remain unknown. Here, we investigated the spatial and molecular compositional associations of renal Schwann cells (SC) supporting the nerve terminals in male rats. The nerve terminals of vascular smooth muscle cells (SMCs) enclosed by renal SC processes were exposed through windows facing the effectors with presynaptic specializations. We found that the adrenergic receptors (ARs) α2A, α2C, and ß2 were localized in the SMC and the basal side of the tubules, where the nerve terminals were attached, whereas the other subtypes of ARs were distributed in the glomerular and luminal side, where the norepinephrine released from nerve endings may have indirect access to ARs. In addition, integrins α4 and ß1 were coexpressed in the nerve terminals. Thus, renal nerve terminals could contact their effectors via integrins and may have a structure, covered by SC processes, suitable for intensive and directional release of neurotransmitters into the blood, rather than specialized structures in the postsynaptic region.
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Terminações Nervosas , Sistema Nervoso Simpático , Animais , Integrinas , Masculino , Norepinefrina , Ratos , Receptores Adrenérgicos , Células de Schwann , Sistema Nervoso Simpático/fisiologiaRESUMO
Pathogenic variants in myosin heavy chain (Myh11) cause familial thoracic aortic aneurysms and dissections (FTAAD). However, the underlying pathological mechanisms remain unclear because of a lack of animal models. In this study, we established a mouse model with Myh11 K1256del, the pathogenic variant we found previously in two FTAAD families. The Myh11∆K/∆K aorta showed increased wall thickness and ultrastructural abnormalities, including weakened cell adhesion. Notably, the Myh11∆K/+ mice developed aortic dissections and intramural haematomas when stimulated with angiotensin II. Mechanistically, integrin subunit alpha2 (Itga2) was downregulated in the Myh11∆K/∆K aortas, and the smooth muscle cell lineage cells that differentiated from Myh11∆K/∆K induced pluripotent stem cells. The contractility of the Myh11∆K/∆K aortas in response to phenylephrine was also reduced. These results imply that the suboptimal cell adhesion indicated by Itga2 downregulation causes a defect in the contraction of the aorta. Consequently, the defective contraction may increase the haemodynamic stress underlying the aortic dissections.
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Aneurisma da Aorta Torácica , Dissecção Aórtica , Dissecção Aórtica/genética , Dissecção Aórtica/metabolismo , Animais , Aorta/patologia , Aneurisma da Aorta Torácica/patologia , Lisina/metabolismo , CamundongosRESUMO
Pericytes (PCs) are a mural support cell population elongated at intervals along the walls of capillaries. Recent studies reported that PCs are multipotent cells that are activated in response to tissue injury and contribute to the regenerative process. Using a C.B-17 mouse model of ischemic stroke, it has been proposed that normal brain pericytes (nPCs) are converted to ischemic pericytes (iPCs), some of which function as multipotent stem cells. Furthermore, oxygen-glucose deprivation (OGD) promoted mesenchymal-epithelial transition in nPCs; however, nestin was not induced under OGD conditions. Therefore, further studies are needed to elucidate the PC reprogramming phenomenon. We herein isolated nPCs from the cortex of C.B-17 mice, and compared the traits of iPCs and nPCs. The results obtained showed that nPCs and iPCs shared common pericytic markers. Furthermore, intercellular levels of reactive oxygen species and the nuclear accumulation of nuclear factor erythroid-2-related factor 2 (Nrf2), a key player in antioxidant defenses, were higher in iPCs than in nPCs. OGD/reoxygenation and a treatment with tBHQ, an Nrf2 inducer, increased nestin levels in nPCs. Moreover, epithelial marker levels, including nestin, Sox2, and CDH1 (E-cadherin) mRNAs, were elevated in Nrf2-overexpressing PCs, which formed neurosphere-like cell clusters that differentiated into Tuj1-positive neurons. The present results demonstrate that oxidative stress and Nrf2 are required for the generation of stem cells after stroke and will contribute to the development of novel therapeutic strategies for ischemic stroke.
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AVC Isquêmico , Fator 2 Relacionado a NF-E2 , Animais , Camundongos , Antioxidantes , Encéfalo/metabolismo , Glucose , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Oxigênio , Pericitos/metabolismo , Transdução de SinaisRESUMO
Circulating white blood cells (WBC) contribute toward maintenance of cerebral metabolism and brain function. Recently, we showed that during aging, transcription of metabolism related genes, including energy source transports, in the brain significantly decreased at the hippocampus resulting in impaired neurological functions. In this article, we investigated the changes in RNA transcription of metabolism related genes (glucose transporter 1 [Glut1], Glut3, monocarboxylate transporter 4 [MCT4], hypoxia inducible factor 1-α [Hif1-α], prolyl hydroxylase 3 [PHD3] and pyruvate dehydrogenase kinase 1 [PDK1]) in circulating WBC and correlated these with brain function in mice. Contrary to our expectations, most of these metabolism related genes in circulating WBC significantly increased in aged mice, and correlation between their increased RNA transcription and impaired neurological functions was observed. Bone marrow mononuclear transplantation into aged mice decreased metabolism related genes in WBC with accelerated neurogenesis in the hippocampus. In vitro analysis revealed that cell-cell interaction between WBC and endothelial cells via gap junction is impaired with aging, and blockade of the interaction increased their transcription in WBC. Our findings indicate that gross analysis of RNA transcription of metabolism related genes in circulating WBC has the potential to provide significant information relating to impaired cell-cell interaction between WBC and endothelial cells of aged mice. Additionally, this can serve as a tool to evaluate the change of the cell-cell interaction caused by various treatments or diseases.
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We developed an intranasal vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using the replication-incompetent human parainfluenza virus type 2 (hPIV2) vector BC-PIV, which can deliver ectopic gene as stable RNA and ectopic protein on the envelope. BC-PIV expressing the full-length prefusion-stabilized spike gene (K986P/V987P) of SARS-CoV-2, S-2PM, possessed a corona-like viral envelope. Intranasal vaccination of mice with BC-PIV/S-2PM induced high levels of neutralizing immunoglobulin G (IgG) and mucosal IgA antibodies against the spike protein. Although BC-PIV showed hemagglutinating activity, BC-PIV/S-2PM lacked such activity, in accordance with the presence of the massive spike protein on the viral surface. Furthermore, single-dose intranasal vaccination of hamsters with BC-PIV/S-2PM completely protected the lungs from SARS-CoV-2 at 11-week post-immunization, and boost vaccination two weeks before the challenge conferred virtually complete protection of the nasal turbinates against SARS-CoV-2. Thus, this chimeric hPIV2/spike intranasal vaccine is a promising vaccine candidate for SARS-CoV-2 to curtail virus transmission.
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NG2 immunoreactive cells (NG2 cells) are found in the brain and peripheral tissues including the skin, intestinal tracts, and bladder. In a previous study, we observed the presence of NG2 cells in the stomach using bioluminescence imaging techniques in NG2-firefly luciferase (fLuc) transgenic (Tg) rats. Here, we aimed to identify and characterize NG2 cells in the adult rat stomach. Immunohistochemical studies showed that NG2 cells were mainly present in the lamina propria and most of the cells were gastric telocytes, co-expressing CD34, and platelet-derived growth factor receptor alpha (PDGFRα), with a small oval-shaped cell body and extremely long and thin cellular prolongations. In the rat stomach, NG2-expressing telocytes comprised two subpopulations: NG2+/CD34+/PDGFRα+ and NG2+/CD34+/PDGFRα-. Furthermore, we showed that the expression of NG2 gene in the aged rat stomach decreased relative to that of the young rat stomach and the decline of NG2 expression in aged rats was mainly observed in NG2+/CD34+/PDGFRα+ telocytes. These findings suggested age-related alterations in NG2+/CD34+/PDGFRα+ telocytes of rat stomach.
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Antígenos/metabolismo , Mucosa Gástrica/metabolismo , Proteoglicanas/metabolismo , Estômago/fisiologia , Telócitos/metabolismo , Fatores Etários , Animais , Antígenos CD34/metabolismo , Mucosa/citologia , Mucosa/metabolismo , Ratos , Ratos Transgênicos , Ratos Wistar , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Estômago/citologia , Telócitos/citologiaRESUMO
Microglia are the principal phagocytes that clear cell debris in the central nervous system (CNS). This raises the question, which cells remove cell debris when microglial phagocytic activity is impaired. We addressed this question using Siglechdtr mice, which enable highly specific ablation of microglia. Non-microglial mononuclear phagocytes, such as CNS-associated macrophages and circulating inflammatory monocytes, did not clear microglial debris. Instead, astrocytes were activated, exhibited a pro-inflammatory gene expression profile, and extended their processes to engulf microglial debris. This astrocytic phagocytosis was also observed in Irf8-deficient mice, in which microglia were present but dysfunctional. RNA-seq demonstrated that even in a healthy CNS, astrocytes express TAM phagocytic receptors, which were the main astrocytic phagocytic receptors for cell debris in the above experiments, indicating that astrocytes stand by in case of microglial impairment. This compensatory mechanism may be important for the maintenance or prolongation of a healthy CNS.
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Astrócitos/fisiologia , Microglia/metabolismo , Fagocitose/fisiologia , Animais , Astrócitos/citologia , Encéfalo , Sistema Nervoso Central/fisiologia , Modelos Animais de Doenças , Feminino , Fatores Reguladores de Interferon/deficiência , Fatores Reguladores de Interferon/genética , Masculino , Camundongos , Camundongos Knockout , Microglia/ultraestrutura , Fagocitose/genéticaRESUMO
Background and Purpose- Bone marrow mononuclear cells (BM-MNCs) are a rich source of hematopoietic stem cells and have been widely used in experimental therapies for patients with ischemic diseases. Activation of angiogenesis is believed to be one of major BM-MNC mode of actions, but the essential mechanism by which BM-MNCs activate angiogenesis have hitherto been elusive. The objective of this study is to reveal the mechanism how BM-MNCs activate angiogenesis. Methods- We have evaluated the effect of direct cell-cell interaction between BM-MNC and endothelial cell on uptake of VEGF (vascular endothelial growth factor) into endothelial cells in vitro. Cerebral ischemia model was used to evaluate the effects of direct cell-cell interaction with transplanted BM-MNC on endothelial cell at ischemic tissue. Results- The uptake of VEGF into endothelial cells was increased by BM-MNC, while being inhibited by blockading the gap junction. Low-molecular-weight substance was transferred from BM-MNC into endothelial cells via gap junctions in vivo, followed by increased expression of hypoxia-inducible factor-1α and suppression of autophagy in endothelial cells. The concentration of glucose in BM-MNC cytoplasm was significantly higher than in endothelial cells, and transfer of glucose homologue from BM-MNC to endothelial cells was observed. Conclusions- Our findings demonstrated cell-cell interaction via gap junction is the prominent pathway for activation of angiogenesis at endothelial cells after ischemia and provided novel paradigm that energy source supply by stem cell to injured cell is one of the therapeutic mechanisms of cell-based therapy. Visual Overview- An online visual overview is available for this article.
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Transplante de Medula Óssea/métodos , Comunicação Celular/fisiologia , Junções Comunicantes/fisiologia , Neovascularização Fisiológica/fisiologia , Acidente Vascular Cerebral/terapia , Animais , Células da Medula Óssea/fisiologia , Células Endoteliais da Veia Umbilical Humana/transplante , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Acidente Vascular Cerebral/patologiaRESUMO
Mucopolysaccharidosis type II (MPS II) is a rare lysosomal storage disease (LSD) involving a genetic error in iduronic acid-2-sulfatase (IDS) metabolism that leads to accumulation of glycosaminoglycans within intracellular lysosomes. The primary treatment for MPS II, enzyme replacement therapy, is not effective for central nervous system (CNS) symptoms, such as intellectual disability, because the drugs do not cross the blood-brain barrier. Recently, autophagy has been associated with LSDs. In this study, we examined the morphologic relationship between neuronal damage and autophagy in IDS knockout mice using antibodies against subunit c of mitochondrial adenosine triphosphate (ATP) synthetase and p62. Immunohistological changes suggesting autophagy, such as vacuolation, were observed in neurons, microglia, and pericytes throughout the CNS, and the numbers increased over postnatal development. Oral administration of chloroquine, which inhibits autophagy, did not suppress damage to microglia and pericytes, but greatly reduced neuronal vacuolation and eliminated neuronal cells with abnormal inclusions. Thus, decreasing autophagy appears to prevent neuronal degeneration. These results suggest that an autophagy modulator could be used in addition to conventional enzyme replacement therapy to preserve the CNS in patients with MPS II.
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Autofagia , Mucopolissacaridose II/metabolismo , Neurônios/metabolismo , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Cloroquina/farmacologia , Iduronato Sulfatase/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/ultraestrutura , ATPases Mitocondriais Próton-Translocadoras/genética , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Mucopolissacaridose II/patologia , Neurônios/efeitos dos fármacos , Neurônios/ultraestrutura , Proteína Sequestossoma-1/genética , Proteína Sequestossoma-1/metabolismoRESUMO
Ectopic protein with proper steric structure was efficiently loaded onto the envelope of the F gene-defective BC-PIV vector derived from human parainfluenza virus type 2 (hPIV2) by a reverse genetics method of recombinant virus production. Further, ectopic antigenic peptide was successfully loaded either outside, inside, or at both sides of the envelope of the vector. The BC-PIV vector harboring the Ebola virus GP gene was able to elicit neutralizing antibodies in mice. In addition, BC-PIV with antigenic epitopes of both melanoma gp100 and WT1 tumor antigen induced a CD8+ T-cell-mediated response in tumor-transplanted syngeneic mice. Considering the low pathogenicity and recurrent infections of parental hPIV2, BC-PIV can be used as a versatile vector with high safety for recombinant vaccine development, addressing unmet medical needs.
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Vetores Genéticos/genética , Vírus da Parainfluenza 2 Humana/genética , Vacinas Sintéticas/genética , Vacinologia/métodos , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Chlorocebus aethiops , Epitopos/genética , Epitopos/imunologia , Ordem dos Genes , Engenharia Genética , Humanos , Camundongos , Testes de Neutralização , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Células VeroRESUMO
In the dorsal root ganglia (DRG), two types of glial cells (Schwann cells and satellite glial cells) have been identified based on cell morphology and expression of specific markers. In the present study, we observed unknown glial cells that were positive for p75 neurotrophin receptor (p75NTR), and therefore were immunohistochemically and ultrastructurally characterized for the first time. These cells exhibited stronger immunoreactivity against an anti-p75NTR antibody than the DRG neurons (hereafter referred to as p75NTR++ cells). Moreover, these cells covered the glial cells surrounding proximal process of the large-diameter DRG neurons. The proximal process is called "dendro-axon." The p75NTR++ cells were predominantly distributed where the first myelinating Schwann cells appear. The p75NTR++ cells were also positive for the pan-glial cell markers S100, nestin, and Sox10, but negative for fibroblast and macrophage markers. Moreover, they were negative for a satellite glial cell marker, inwardly rectifying potassium channel Kir4.1, as well as a nonmyelinating Schwann cell marker, glial fibrillary acidic protein. In addition, their morphological features were distinct from those of the myelinating Schwann cells. To investigate the three-dimensional ultrastructure of the p75NTR++ cells, we used array tomography combined with correlative light and electron microscopic observation. Three-dimensional ultrastructural observation revealed that the p75NTR++ cells loosely covered glial cells around the dendro-axons with highly ramified processes. Glial cells with these morphological features have not been reported before, indicating that the p75NTR++ glial cells are a new glial cell type in the DRG. Our results will give new insights into cell-cell relationships.
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Gânglios Espinais/citologia , Proteínas do Tecido Nervoso/metabolismo , Neuroglia/citologia , Receptores de Fatores de Crescimento/metabolismo , Animais , Gânglios Espinais/metabolismo , Masculino , Neuroglia/metabolismo , Ratos , Ratos WistarRESUMO
"Array tomography" is a method used to observe the fine structure of cells and tissues in a three-dimensional view. In this method, serial ultrathin sections in the ribbon state (ribbons) are mounted on a solid substrate and observed by scanning electron microscopy (SEM). The method may also be used in conjunction with post-embedding immunocytochemistry. However, it is difficult to mount many serial ribbons on a substrate manually. We developed an inexpensive laboratory-made device that mounts ribbons by pulling a nylon fishing line and lifting the substrate up from the water in a knife boat. Using this device, we succeeded in mounting several ribbons consisting a mean of 205.6 (SD: 37.7) serial ultrathin sections on 1.25 (SD: 0.06) × 1.25 (SD: 0.06)-cm silicon substrates. Furthermore, it was confirmed that our method is suitable for ribbons derived from water-soluble resin blocks. We were also able to stain the specimens by post-embedding immunocytochemistry. Thus, our method is useful in mounting numerus sections on a substrate for array tomography with SEM.
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Recent therapeutic advances have increased the likelihood of recanalizing the obstructed brain arteries in patients with stroke. Therefore, it is important to understand the fate of neural cells under transient ischemia/reperfusion injury. Accumulating evidence shows that neurogenesis occurs in perivascular regions following brain injury, although the precise mechanism and origin of these newborn neurons under transient ischemia/reperfusion injury remain unclear. Using a mouse model of transient brain ischemia/reperfusion injury, we found that neural stem cells (NSCs) develop within injured areas. This induction of NSCs following ischemia/reperfusion injury was observed even in response to nonlethal ischemia, although massive numbers of NSCs were induced by lethal ischemia. Immunohistochemical and immunoelectron microscopic studies indicated that platelet-derived growth factor receptor beta-positive (PDGFRß+) pericytes within injured areas following nonlethal ischemia began to express the NSC marker nestin as early as 3 days after transient ischemia/reperfusion. Some PDGFRß+ pericytes expressed the immature neuronal marker doublecortin at day 7. These findings indicate that brain pericytes are a potential source of the perivascular NSCs that generate neuronal cells under lethal and nonlethal ischemic conditions following transient ischemia/reperfusion. Thus, brain pericytes might be a target for neurogenesis mediation in patients with nonlethal and lethal ischemia following transient ischemia/reperfusion injury.
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Isquemia Encefálica/fisiopatologia , Células-Tronco Neurais/fisiologia , Neurogênese , Pericitos/fisiologia , Animais , Astrócitos/ultraestrutura , Encéfalo/fisiopatologia , Encéfalo/ultraestrutura , Morte Celular , Células Endoteliais/ultraestrutura , Masculino , Camundongos , Nestina/metabolismo , Células-Tronco Neurais/metabolismo , Neurônios/fisiologia , Pericitos/metabolismo , Pericitos/ultraestrutura , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Traumatismo por Reperfusão/fisiopatologiaRESUMO
Oligodendrocyte precursor cells (OPCs) in the adult brain contribute to white matter homeostasis. After white matter damage, OPCs compensate for oligodendrocyte loss by differentiating into mature oligodendrocytes. However, the underlying mechanisms remain to be fully defined. Here, we test the hypothesis that, during endogenous recovery from white matter ischemic injury, astrocytes support the maturation of OPCs by secreting brain-derived neurotrophic factor (BDNF). For in vitro experiments, cultured primary OPCs and astrocytes were prepared from postnatal day 2 rat cortex. When OPCs were subjected to chemical hypoxic stress by exposing them to sublethal CoCl2 for 7 d, in vitro OPC differentiation into oligodendrocytes was significantly suppressed. Conditioned medium from astrocytes (astro-medium) restored the process of OPC maturation even under the stressed conditions. When astro-medium was filtered with TrkB-Fc to remove BDNF, the BDNF-deficient astro-medium no longer supported OPC maturation. For in vivo experiments, we analyzed a transgenic mouse line (GFAP(cre)/BDNF(wt/fl)) in which BDNF expression is downregulated specifically in GFAP(+) astrocytes. Both wild-type (GFAP(wt)/BDNF(wt/fl) mice) and transgenic mice were subjected to prolonged cerebral hypoperfusion by bilateral common carotid artery stenosis. As expected, compared with wild-type mice, the transgenic mice exhibited a lower number of newly generated oligodendrocytes and larger white matter damage. Together, these findings demonstrate that, during endogenous recovery from white matter damage, astrocytes may promote oligodendrogenesis by secreting BDNF. SIGNIFICANCE STATEMENT: The repair of white matter after brain injury and neurodegeneration remains a tremendous hurdle for a wide spectrum of CNS disorders. One potentially important opportunity may reside in the response of residual oligodendrocyte precursor cells (OPCs). OPCs may serve as a back-up for generating mature oligodendrocytes in damaged white matter. However, the underlying mechanisms are still mostly unknown. Here, we use a combination of cell biology and an animal model to report a new pathway in which astrocyte-derived BDNF supports oligodendrogenesis and regeneration after white matter damage. These findings provide new mechanistic insight into white matter physiology and pathophysiology, which would be broadly and clinically applicable to CNS disease.
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Astrócitos/fisiologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Diferenciação Celular/fisiologia , Leucoencefalopatias/patologia , Animais , Antimutagênicos/farmacologia , Astrócitos/química , Astrócitos/metabolismo , Isquemia Encefálica/complicações , Fator Neurotrófico Derivado do Encéfalo/genética , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Células Cultivadas , Cromonas/farmacologia , Cobalto/farmacologia , Meios de Cultivo Condicionados/farmacologia , Modelos Animais de Doenças , Inibidores Enzimáticos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteína Glial Fibrilar Ácida/genética , Proteína Glial Fibrilar Ácida/metabolismo , Glutationa S-Transferase pi/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Leucoencefalopatias/etiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Morfolinas/farmacologia , Proteína Básica da Mielina/metabolismo , Bainha de Mielina/metabolismo , Bainha de Mielina/patologia , Fosfopiruvato Hidratase/metabolismo , Células-Tronco/fisiologiaRESUMO
Pericytes are embedded within basal lamina and play multiple roles in the perivascular niche in brain. Recently, oligodendrocyte precursor cells (OPCs) have also been reported to associate with cerebral endothelium. Is it possible that within this gliovascular locus, there may also exist potential spatial and functional interactions between pericytes and OPCs? Here, we demonstrated that in the perivascular region of cerebral white matter, pericytes and OPCs may attach and support each other. Immunostaining showed that pericytes and OPCs are localized in close contact with each other in mouse white matter at postnatal days 0, 60 and 240. Electron microscopic analysis confirmed that pericytes attached to OPCs via basal lamina in the perivascular region. The close proximity between these two cell types was also observed in postmortem human brains. Functional interaction between pericytes and OPCs was assessed by in vitro media transfer experiments. When OPC cultures were treated with pericyte-conditioned media, OPC number increased. Similarly, pericyte number increased when pericytes were maintained in OPC-conditioned media. Taken together, our data suggest a potential anatomical and functional interaction between pericytes and OPCs in cerebral white matter.
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Córtex Cerebral/citologia , Oligodendroglia/fisiologia , Pericitos/fisiologia , Células-Tronco/fisiologia , Substância Branca/citologia , Idoso , Animais , Comunicação Celular , Proliferação de Células , Células Cultivadas , Corpo Caloso/citologia , Feminino , Humanos , Masculino , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Oligodendroglia/citologia , Pericitos/citologia , Ratos Sprague-Dawley , Especificidade da Espécie , Células-Tronco/citologiaRESUMO
Trophic coupling between cerebral endothelium and their neighboring cells is required for the development and maintenance of blood-brain barrier (BBB) function. Here we report that oligodendrocyte precursor cells (OPCs) secrete soluble factor TGF-ß1 to support BBB integrity. Firstly, we prepared conditioned media from OPC cultures and added them to cerebral endothelial cultures. Our pharmacological experiments showed that OPC-conditioned media increased expressions of tight-junction proteins and decreased in vitro BBB permeability by activating TGB-ß-receptor-MEK/ERK signaling pathway. Secondly, our immuno-electron microscopic observation revealed that in neonatal mouse brains, OPCs attach to cerebral endothelial cells via basal lamina. And finally, we developed a novel transgenic mouse line that TGF-ß1 is knocked down specifically in OPCs. Neonates of these OPC-specific TGF-ß1 deficient mice (OPC-specific TGF-ß1 partial KO mice: PdgfraCre/Tgfb1flox/wt mice or OPC-specific TGF-ß1 total KO mice: PdgfraCre/Tgfb1flox/flox mice) exhibited cerebral hemorrhage and loss of BBB function. Taken together, our current study demonstrates that OPCs increase BBB tightness by upregulating tight junction proteins via TGF-ß signaling. Although astrocytes and pericytes are well-known regulators of BBB maturation and maintenance, these findings indicate that OPCs also play a pivotal role in promoting BBB integrity.