RESUMEN
Müller glial cells (MGCs) are known to participate actively in retinal development and to contribute to homoeostasis through many intracellular mechanisms. As there are no homologous cells in other neuronal tissues, it is certain that retinal health depends on MGCs. These macroglial cells are located at the centre of the columnar subunit and have a great ability to interact with neurons, astrocytes, microglia and endothelial cells in order to modulate different events. Several investigations have focused their attention on the role of MGCs in diabetic retinopathy, a progressive pathology where several insults coexist. As expected, data suggest that MGCs display different responses according to the severity of the stimulus, and therefore trigger distinct events throughout the course of the disease. Here, we describe physiological functions of MGCs and their participation in inflammation, gliosis, synthesis and secretion of trophic and antioxidant factors in the diabetic retina. We invite the reader to consider the protective/deleterious role of MGCs in the early and late stages of the disease. In the light of the results, we open up the discussion around and ask the question: Is it possible that the modulation of a single cell type could improve or even re-establish retinal function after an injury?
Asunto(s)
Retinopatía Diabética , Células Ependimogliales/fisiología , Gliosis , Inflamación , Factores de Crecimiento Nervioso/fisiología , Estrés Oxidativo/fisiología , Animales , Retinopatía Diabética/inmunología , Retinopatía Diabética/metabolismo , Retinopatía Diabética/fisiopatología , Células Ependimogliales/inmunología , Células Ependimogliales/metabolismo , Gliosis/inmunología , Gliosis/metabolismo , Gliosis/fisiopatología , Humanos , Inflamación/inmunología , Inflamación/metabolismo , Inflamación/fisiopatología , Factores de Crecimiento Nervioso/inmunología , Factores de Crecimiento Nervioso/metabolismo , Estrés Oxidativo/inmunologíaRESUMEN
PURPOSE: Despite substantial advances in surgical care and rehabilitation, the consequences of spinal cord injury (SCI) continue to present major challenges. Here we investigate whether transplantation of mesenchymal stem cells (MSCs) in mice during the chronic stage of SCI has benefits in terms of morphological and functional outcomes. METHODS: Mice were subjected to laminectomy at the T9 level, followed by a 1 minute spinal cord compression with a vascular clip. Four weeks later, 8 × 105 MSCs obtained from GFP mice were injected into the injury site. After eight weeks the analyses were performed. RESULTS: The spinal cords of MSC-treated animals exhibited better white-matter preservation, greater numbers of fibers, higher levels of trophic factor expression, and better ultrastructural tissue organization. Furthermore, transplanted MSCs were not immunoreactive for neural markers, indicating that these cells mediate functional recovery through a paracrine effect, rather than by transforming into and replacing damaged glia in the spinal cord. MSC-treated mice also showed better functional improvement than control animals. CONCLUSION: We conclude that MSC-based cell therapy, even when applied during the chronic phase of SCI, leads to changes in a number of structural and functional parameters, all of which indicate improved recovery.
Asunto(s)
Trasplante de Células Madre Mesenquimatosas/métodos , Células Madre Mesenquimatosas/fisiología , Factores de Crecimiento Nervioso/inmunología , Traumatismos de la Médula Espinal/cirugía , Análisis de Varianza , Animales , Células Cultivadas , Modelos Animales de Enfermedad , Femenino , Proteína Ácida Fibrilar de la Glía/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Macrófagos , Células Madre Mesenquimatosas/ultraestructura , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Electrónica , Microscopía Electrónica de Transmisión , Factores de Crecimiento Nervioso/genética , Proteínas S100/metabolismo , Traumatismos de la Médula Espinal/patología , Resultado del Tratamiento , Sustancia Blanca/patología , Sustancia Blanca/ultraestructuraRESUMEN
S100, a calcium-binding protein, and basic fibroblast growth factor (bFGF, FGF-2) are found predominantly in astrocytes in the central nervous system. Those molecules show trophic properties to neurons and are upregulated after brain lesions. The present study investigated the changes in the S100beta and bFGF immunoreactivities after a partial lesion of the rat midbrain ascending dopamine pathways induced by intrastriatal injection of 6-hydroxydopamine (6-OHDA). Stereological method revealed increases in the estimated total number and density of bFGF immunoreactive astroglial profiles in the ipsilateral pars compacta of the substantia nigra (SNc) and ventral tegmental area (VTA). Increases in the counts of astroglial S100beta immunoreactive profiles were found in the striatum, SNc, and VTA mainly ipsilateral but also in the contralateral nuclei. These results open up the possibility that interactions between astroglial S100beta and bFGF may be relevant to paracrine events related to repair and maintenance of remaining dopamine neurons following striatal 6-OHDA induced partial lesion of ascending midbrain dopamine pathway.
Asunto(s)
Astrocitos/metabolismo , Cuerpo Estriado/patología , Dopamina/metabolismo , Factor 2 de Crecimiento de Fibroblastos/metabolismo , Factores de Crecimiento Nervioso/metabolismo , Proteínas S100/metabolismo , Sustancia Negra/patología , Animales , Anticuerpos , Astrocitos/patología , Recuento de Células/métodos , Cuerpo Estriado/metabolismo , Desnervación , Factor 2 de Crecimiento de Fibroblastos/inmunología , Inmunohistoquímica , Masculino , Factores de Crecimiento Nervioso/inmunología , Oxidopamina , Ratas , Ratas Wistar , Subunidad beta de la Proteína de Unión al Calcio S100 , Proteínas S100/inmunología , Sustancia Negra/metabolismo , Simpaticolíticos , Área Tegmental Ventral/metabolismo , Área Tegmental Ventral/patologíaRESUMEN
Thyroid hormones are important for neurogenesis and gliogenesis during brain development. We have previously demonstrated that triiodothyronine (T3) treatment induced proliferation in primary culture astrocytes derived from the cerebellum of neonatal rats. Conditioned medium obtained from those T3-treated astrocytes (T3CM) mimicked the effect of hormonal treatment on these cells. Because neuron-glia interaction plays an important role in brain development, we tested the ability of such T3-glial CM to influence neuronal physiology. With that aim, neurons from 19-day embryonic cerebella were cultivated for 24 h in the presence of CM obtained from T3-treated cerebellar astrocytes. Interestingly, the cerebellar neuronal population increased by 60-80% in T3CM. Addition of 5 microM forskolin enhanced the responsiveness of cerebellar neurons to astrocytes T3CM, but it did not interfere with neuronal survival in control medium. Conversely, inhibition of adenylate cyclase by its specific inhibitor, SQ22536, reversed the T3CM effect on neurons. These data strongly suggest that cAMP signal transduction pathways might be implicated in such an event. Analysis of bromodeoxyuridil incorporation revealed that the increase in neuron number in T3CM was partially due to neuron proliferation, because the proliferation index was three times higher in T3CM than in control medium. Neutralizing antibody assays demonstrated that T3CM effects on neurons are due, at least in part, to the presence of tumor necrosis factor-beta and epidermal growth factor. Thus, we report here a novel molecular mechanism of action of thyroid hormone on cerebellar neuronal cells: Thyroid hormone induces astrocytes to secrete growth factors that can interfere with neuronal proliferation via a paracrine pathway.
Asunto(s)
Astrocitos/efectos de los fármacos , Cerebelo/citología , Neuronas/fisiología , Triyodotironina/farmacología , Animales , Animales Recién Nacidos , Astrocitos/fisiología , Recuento de Células , División Celular/efectos de los fármacos , Células Cultivadas , Colforsina/farmacología , Medios de Cultivo Condicionados/farmacología , AMP Cíclico/fisiología , Inhibidores de Crecimiento/farmacología , Factores de Crecimiento Nervioso/inmunología , Factores de Crecimiento Nervioso/fisiología , Ratas , Ratas WistarAsunto(s)
Calcineurina/análisis , Proteínas de Unión al Calcio/análisis , Calmodulina/análisis , Factores de Crecimiento Nervioso/análisis , Proteínas S100 , Animales , Anticuerpos Monoclonales , Calcineurina/inmunología , Proteínas de Unión al Calcio/inmunología , Calmodulina/inmunología , Epítopos/análisis , Proteína Ácida Fibrilar de la Glía/análisis , Hipocampo/química , Inmunoensayo/métodos , Indicadores y Reactivos , Factores de Crecimiento Nervioso/inmunología , Ratas , Subunidad beta de la Proteína de Unión al Calcio S100 , Sensibilidad y EspecificidadRESUMEN
Cholinergic basal forebrain (CBF ) neurons have been shown to respond in vivo to exogenous administration of NGF. Although neurotrophins and their receptors are widely expressed in the CNS, little data exist for the physiological significance of endogenous neurotrophin signaling in CNS neurons. To test directly whether cortically derived NGF is functionally required for the cholinergic functions mediated by the cerebral cortex, repeated injections of anti-NGF mAbs were locally applied into the insular cortex (IC) of rats. The biochemical results, using an in vivo microdialysis technique, showed a dramatic lack of extracellular release of acetylcholine after high potassium stimulation compared with controls. Furthermore, by using small injections of the neurotracer fluorogold, we found a corresponding disruption in the connectivity between the IC and the CBF. Behavioral experiments showed that the NGF antibodies applied into the IC produced a significant disruption on the acquisition of conditioned taste aversion and inhibitory avoidance learning. However, the same animals were able to recall the taste aversion when the conditioning trial was established before injections of NGF antibodies. Given these results, it seems that cortical cholinergic functions are actively dependent on locally derived NGF in the adult normal brain, and that the cholinergic activity from the CBF is not necessary for recalling aversive stimuli, but is necessary for the acquisition of aversively motivated conditionings.
Asunto(s)
Reacción de Prevención/fisiología , Fibras Colinérgicas/fisiología , Factores de Crecimiento Nervioso/farmacología , Estilbamidinas , Factores de Edad , Animales , Anticuerpos Monoclonales/farmacología , Reacción de Prevención/efectos de los fármacos , Unión Competitiva/inmunología , Fibras Colinérgicas/efectos de los fármacos , Condicionamiento Psicológico/efectos de los fármacos , Condicionamiento Psicológico/fisiología , Desnervación , Colorantes Fluorescentes , Masculino , Memoria/fisiología , Microinyecciones , Factores de Crecimiento Nervioso/análisis , Factores de Crecimiento Nervioso/inmunología , Prosencéfalo/citología , Ratas , Ratas Wistar , Gusto/fisiología , Tálamo/química , Tálamo/citología , Tálamo/fisiologíaRESUMEN
Normal human (week 17-20) and rat (E16-17) amniotic fluids were used as culture media for primary cultures of rat fetal (E 16) cortical, mesencephalic and striatal cell dissociates, or astroglial subcultures from the same brain regions. Phase-bright and dark cells were identified under phase contrast microscopy and their cell processes were measured utilizing semi-automated procedures. Subcultured astroglia were immuno-reacted against glial fibrillary acidic protein and fibronectin. Rat and human amniotic fluid allowed survival and growth of neuronal and non-neuronal cells. Human amniotic fluid samples were trophic in variable degrees. Cerebral cortex subcultured astroglia usually expressed a radial-like morphotype. Although charcoal-adsorbed human amniotic fluid was trophic for primary cultures, its ability to sustain neuritic growth depended on its degree of trophism before treatment. Growth of cell processes in neuronal- and glial-like cells in primary cultures was inhibited to different degrees by the addition of antisera towards nerve or epidermal growth factors. It is concluded that amniotic fluid constitutes a trophic medium for astroglia and neurons. Both, nerve and epidermal growth factors appear to be necessary for growth of cell processes in neuronal and glial primary cultures in amniotic fluid. Trophic effect of amniotic fluid on subcultured astroglia did not seem to be diminished by nerve growth factor antiserum. The role of amniotic fluid during the early phases of brain organogenesis is discussed.