Amniotic membranes have been widely used in ophthalmology and skin injury repair because of their anti-inflammatory properties. In this study, we measured therapeutic efficacy and determined if amniotic membranes could be used for facial nerve repair. The facial nerves of eight rats were dissected and end-to-end anastomosis was performed. Amniotic membranes were covered on the anastomosis sites in four rats. Electromyography results showed that, at the end of the 3rd and 8th weeks after amniotic membrane covering, the latency values of the facial nerves covered by amniotic membranes were significantly shortened and the amplitude values were significantly increased. Compared with simple facial nerve anastomosis, after histopathological examination, facial nerve anastomosed with amniotic membrane showed better continuity, milder inflammatory reactions, and more satisfactory nerve conduction. These findings suggest that amniotic membrane covering has great potential in facial nerve repair.
(1) In the past, the placenta, the source of amniotic membranes, was discarded after parturition. Currently, besides ocular and dermal applications, amniotic membranes are also used in regenerative medicine.
(2) In this study, amniotic membrane was used to cover the anastomosed facial nerve to determine if this method facilitates facial nerve repair.
(3) Compared with simple facial nerve anastomosis, facial nerve anastomosed with amniotic membrane showed better continuity, milder inflammatory reaction, and more satisfactory nerve conduction. These findings suggest that amniotic membrane covering has great potential for use in facial nerve repair.
As chondroitinase ABC can improve the hostile microenvironment and cell transplantation is proven to be effective after spinal cord injury, we hypothesized that their combination would be a more effective treatment option. At 5 days after T8 spinal cord crush injury, rats were injected with bone marrow mesenchymal stem cell suspension or chondroitinase ABC 1 mm from the edge of spinal cord damage zone. Chondroitinase ABC was first injected, and bone marrow mesenchymal stem cell suspension was injected on the next day in the combination group. At 14 days, the mean Basso, Beattie and Bresnahan score of the rats in the combination group was higher than other groups. Hematoxylin-eosin staining showed that the necrotic area was significantly reduced in the combination group compared with other groups. Glial fibrillary acidic protein-chondroitin sulfate proteoglycan double staining showed that the damage zone of astrocytic scars was significantly reduced without the cavity in the combination group. Glial fibrillary acidic protein/growth associated protein-43 double immunostaining revealed that positive fibers traversed the damage zone in the combination group. These results suggest that the combination of chondroitinase ABC and bone marrow mesenchymal stem cell transplantation contributes to the repair of spinal cord injury.
(1) After spinal cord injury, a large number of inhibitory factors are generated in the microenvironment of the damage zone, such as chondroitin sulfate proteoglycan.
(2) To avoid the acute-stage complex pathological conditions, and to improve the effect of cell transplantation, chondroitinase ABC is used to overcome the damaging chemical barrier. This study paid attention to the improvement of microenvironment in the damage region, which is a novel idea for breaking conventional transplantation.
Following peripheral nerve compression, peripheral nerve microcirculation plays important roles in regulating the nerve microenvironment and neurotrophic substances, supplying blood and oxygen and maintaining neural conduction and axonal transport. This paper has retrospectively analyzed the articles published in the past 10 years that addressed the relationship between peripheral nerve compression and changes in intraneural microcirculation. In addition, we describe changes in different peripheral nerves, with the aim of providing help for further studies in peripheral nerve microcirculation and understanding its protective mechanism, and exploring new clinical methods for treating peripheral nerve compression from the perspective of neural microcirculation.
(1) This study summarized results of changes in nerve microcirculation following peripheral nerve compression.
(2) This study reviewed some characteristics of peripheral neural microcirculation including bidirectional blood supply. The blood supply of the distal segment is significantly larger than that of the proximal segment, and the number of anastomotic branches in the middle region is considerably less than that at both the proximal and distal ends. Changes in blood flow are not directly correlated with changes in vascular density or number during neural regeneration.
(3) This study provided a new idea for treatment of peripheral nerve lesions through improved nerve microcirculation.
Neurotrophin-3 (NT-3) can promote the repair of central nervous system and retinal damage. In previous reports, NT-3 has been expressed by viral vectors. However, plasmid vectors have a safer profile compared with viral vectors in clinical studies. This study recombined amplified human retinal NT-3 with a eukaryotic expression plasmid containing green fluorescent protein (GFP) to construct an NT-3 expression plasmid, pEGFP-N1-NT-3. The transfection efficiency 48 hours after pEGFP-N1-NT-3 transfection to 293T cells was 50.06 ± 2.78%. Abundant NT-3-GFP was expressed in 293T cells as observed by fluorescence microscopy, suggesting the construct pEGFP-N1-NT-3 effectively expressed and secreted NT-3-GFP. Secretory vesicles containing NT-3-GFP were observed in a constant location in cells by laser scan confocal microscopy, indicating the expression and secretion processes of NT-3 in eukaryotic cells were in accordance with the physical synthesis processes of secreted proteins. Western blot assay showed that pro-NT-3-GFP had a molecular weight of 56 kDa, further confirming NT-3-GFP expression. At 48 hours after transfection, the concentration of NT-3 in culture medium was 22.3 ng/mL, suggesting NT-3 produced by pEGFP-N1-NT-3 was efficiently secreted. This study constructed a human retinal-derived NT-3 eukaryotic expression plasmid that efficiently expressed and secreted NT-3.
(1) Neurotrophin-3 (NT-3) expression plasmid, pEGFP-N1-NT-3, was constructed from recombinant human retinal NT-3 in eukaryotic expression plasmid with green fluorescent protein marker.
(2) Forty-eight hours after pEGFP-N1-NT-3 transfection to 293T cells, transfection efficiency was 46.76% by fluorescence microscopy.
(3) After pEGFP-N1-NT-3 was transfected into 293T cells, NT-3 expression and secretion was similar to natural intracellular environments.
(4) pEGFP-N1-NT-3 expressed and secreted NT-3 efficiently.
(5) NT-3 delivered by encapsulated cell technology might have a controllable, sustained, long-term therapeutic effect in central nervous system and intraocular disease, such as retinitis pigmentosa.
Hemodynamic parameters play an important role in aneurysm formation and growth. However, it is difficult to directly observe a rapidly growing de novo aneurysm in a patient. To investigate possible associations between hemodynamic parameters and the formation and growth of intracranial aneurysms, the present study constructed a computational model of a case with an internal carotid artery aneurysm and an anterior communicating artery aneurysm, based on the CT angiography findings of a patient. To simulate the formation of the anterior communicating artery aneurysm and the growth of the internal carotid artery aneurysm, we then constructed a model that virtually removed the anterior communicating artery aneurysm, and a further two models that also progressively decreased the size of the internal carotid artery aneurysm. Computational simulations of the fluid dynamics of the four models were performed under pulsatile flow conditions, and wall shear stress was compared among the different models. In the three aneurysm growth models, increasing size of the aneurysm was associated with an increased area of low wall shear stress, a significant decrease in wall shear stress at the dome of the aneurysm, and a significant change in the wall shear stress of the parent artery. The wall shear stress of the anterior communicating artery remained low, and was significantly lower than the wall shear stress at the bifurcation of the internal carotid artery or the bifurcation of the middle cerebral artery. After formation of the anterior communicating artery aneurysm, the wall shear stress at the dome of the internal carotid artery aneurysm increased significantly, and the wall shear stress in the upstream arteries also changed significantly. These findings indicate that low wall shear stress may be associated with the initiation and growth of aneurysms, and that aneurysm formation and growth may influence hemodynamic parameters in the local and adjacent arteries.
(1) This study reconstructed aneurysm models prior to and after aneurysm formation and growth, to investigate possible associations between hemodynamic parameters and the initiation and growth of intracranial aneurysms.
(2) Low wall shear stress may be associated with the initiation and growth of aneurysms. With increasing size of the aneurysm, the area of low wall shear stress increased, and the wall shear stress at the dome of the aneurysm decreased significantly. Aneurysm formation and growth may influence the hemodynamic parameters in local and adjacent arteries.
Extracts from rabbit skin inflamed by the vaccinia virus can relieve pain and promote repair of nerve injury. The present study intraperitoneally injected extracts from rabbit skin inflamed by the vaccinia virus for 3 and 4 days prior to and following intrathecal injection of bupivacaine into pregnant rats. The pain threshold test after bupivacaine injection showed that the maximum possible effect of tail-flick latency peaked 1 day after intrathecal injection of bupivacaine in the extract-pretreatment group, and gradually decreased, while the maximum possible effect in the bupivacaine group continued to increase after intrathecal injection of bupivacaine. Histological observation showed that after 4 days of intrathecal injection of bupivacaine, the number of shrunken, vacuolated, apoptotic and caspase-9-positive cells in the dorsal root ganglion in the extract-pretreatment group was significantly reduced compared with the bupivacaine group. These findings indicate that extracts from rabbit skin inflamed by the vaccinia virus can attenuate neurotoxicity induced by intrathecal injection of bupivacaine in pregnant rats, possibly by inhibiting caspase-9 protein expression and suppressing nerve cell apoptosis.
This study aimed to elucidate the neuroprotective properties of extracts from rabbit skin inflamed by the vaccinia virus on nerve injury. Our results indicated that extracts could inhibit caspase-9 protein expression, reduce nerve cell apoptosis, and attenuate neurotoxicity induced by intrathecal injection of bupivacaine in pregnant rats.
Adolescence is a critical period for neurodevelopment. Evidence from animal studies suggests that isolated rearing can exert negative effects on behavioral and brain development. The present study aimed to investigate the effects of adolescent social isolation on latent inhibition and brain-derived neurotrophic factor levels in the forebrain of adult rats. Male Wistar rats were randomly divided into adolescent isolation (isolated housing, 38-51 days of age) and social groups. Latent inhibition was tested at adulthood. Brain-derived neurotrophic factor levels were measured in the medial prefrontal cortex and nucleus accumbens by an enzyme-linked immunosorbent assay. Adolescent social isolation impaired latent inhibition and increased brain-derived neurotrophic factor levels in the medial prefrontal cortex of young adult rats. These data suggest that adolescent social isolation has a profound effect on cognitive function and neurotrophin levels in adult rats and may be used as an animal model of neurodevelopmental disorders.
(1) This study investigated the effects of adolescent social isolation (postnatal days 38-51) on cognitive function in adult animals and the levels of brain-derived neurotrophic factor in the medial prefrontal cortex and nucleus accumbens.
(2) Adolescent social isolation impaired latent inhibition and increased brain-derived neurotrophic factor levels in the medial prefrontal cortex of adult rats.
(3) This study advances the use of isolation rearing as an animal model of psychiatric disease.
Diazoxide, an activator of mitochondrial ATP-sensitive potassium channels, can protect neurons and astrocytes against oxidative stress and apoptosis. In this study, we established a cellular model of epilepsy by culturing hippocampal neurons in magnesium-free medium, and used this to investigate effects of diazoxide preconditioning on the expression of inwardly rectifying potassium channel (Kir) subunits of the ATP-sensitive potassium. We found that neuronal viability was significantly reduced in the epileptic cells, whereas it was enhanced by diazoxide preconditioning. Double immunofluorescence and western blot showed a significant increase in the expression of Kir6.1 and Kir6.2 in epileptic cells, especially at 72 hours after seizures. Diazoxide pretreatment completely reversed this effect at 24 hours after seizures. In addition, Kir6.1 expression was significantly upregulated compared with Kir6.2 in hippocampal neurons after seizures. These findings indicate that diazoxide pretreatment may counteract epileptiform discharge-induced cytotoxicity by suppressing the expression of Kir subunits.
(1) We induced epilepsy in vitro by culturing hippocampal neurons in magnesium-free medium, and tested the influence of ATP-sensitive potassium channel activator diazoxide preconditioning on the expression of inwardly rectifying potassium channel (Kir) subunits of the ATP-sensitive potassium channel.
(2) Diazoxide improved the viability of hippocampal neurons exposed to magnesium-free medium and prevented seizure-induced increases in Kir6.1 and Kir6.2 expression.
(3) Kir6.1 expression was significantly upregulated compared with Kir6.2 after seizures.
(4) Diazoxide pretreatment may exert neuroprotective effects by inhibiting seizure-induced cytotoxicity, maintaining mitochondrial and cellular physiological functions, and ensuring normal metabolic balance and excitability.
Inhibitory control of movement in motor learning requires the ability to suppress an inappropriate action, a skill needed to stop a planned or ongoing motor response in response to changes in a variety of environments. This study used a stop-signal task to determine whether transcranial direct-current stimulation over the pre-supplementary motor area alters the reaction time in motor inhibition. Forty healthy subjects were recruited for this study and were randomly assigned to either the transcranial direct-current stimulation condition or a sham-transcranial direct-current stimulation condition. All subjects consecutively performed the stop-signal task before, during, and after the delivery of anodal transcranial direct-current stimulation over the pre-supplementary motor area (pre-transcranial direct-current stimulation phase, transcranial direct-current stimulation phase, and post-transcranial direct-current stimulation phase). Compared to the sham condition, there were significant reductions in the stop-signal processing times during and after transcranial direct-current stimulation, and change times were significantly greater in the transcranial direct-current stimulation condition. There was no significant change in go processing-times during or after transcranial direct-current stimulation in either condition. Anodal transcranial direct-current stimulation was feasibly coupled to an interactive improvement in inhibitory control. This coupling led to a decrease in the stop-signal process time required for the appropriate responses between motor execution and inhibition. However, there was no transcranial direct-current stimulation effect on the no-signal reaction time during the stop-signal task. Transcranial direct-current stimulation can adjust certain behaviors, and it could be a useful clinical intervention for patients who have difficulties with response inhibition.
(1) Anodal transcranial direct-current stimulation over the pre-supplementary motor area altered the motor-inhibition reaction time during the stop-signal task.
(2) Performance on the stop-signal task during and after anodal transcranial direct-current stimulation applied to the pre-supplementary motor area caused a significant reduction in the stop-signal reaction time required for the appropriate responses between motor execution and inhibition.
(3) Transcranial direct-current stimulation could be a useful clinical intervention for patients with difficulty in response inhibition.
The deposition of amyloid-beta is a pathological hallmark of Alzheimer's disease. Amyloid-beta is derived from amyloid precursor protein through sequential proteolytic cleavages by β-secretase (beta-site amyloid precursor protein-cleaving enzyme 1) and γ-secretase. To further elucidate the roles of beta-site amyloid precursor protein-cleaving enzyme 1 in the development of Alzheimer's disease, a yeast two-hybrid system was used to screen a human embryonic brain cDNA library for proteins directly interacting with the intracellular domain of beta-site amyloid precursor protein-cleaving enzyme 1. A potential beta-site amyloid precursor protein-cleaving enzyme 1-interacting protein identified from the positive clones was divalent cation tolerance protein. Immunoprecipitation studies in the neuroblastoma cell line N2a showed that exogenous divalent cation tolerance protein interacts with endogenous beta-site amyloid precursor protein-cleaving enzyme 1. The overexpression of divalent cation tolerance protein did not affect beta-site amyloid precursor protein-cleaving enzyme 1 protein levels, but led to increased amyloid precursor protein levels in N2a/APP695 cells, with a concomitant reduction in the processing product amyloid precursor protein C-terminal fragment, indicating that divalent cation tolerance protein inhibits the processing of amyloid precursor protein. Our experimental findings suggest that divalent cation tolerance protein negatively regulates the function of beta-site amyloid precursor protein-cleaving enzyme 1. Thus, divalent cation tolerance protein could play a protective role in Alzheimer's disease.
(1) Beta-site amyloid precursor protein-cleaving enzyme 1 is a critical enzyme in the processing of amyloid beta precursor protein and participates in the production of amyloid beta during the development of Alzheimer's disease. In this study, divalent cation tolerance protein was identified as a novel interaction partner for beta-site amyloid precursor protein-cleaving enzyme 1 using the yeast two-hybrid screening system.
(2) Divalent cation tolerance protein associates with endogenous beta-site amyloid precursor protein-cleaving enzyme 1 in the neuroblastoma cell line N2a. The overexpression of divalent cation tolerance protein did not affect the protein levels of beta-site amyloid precursor protein-cleaving enzyme 1; however, it led to increased levels of amyloid beta precursor protein with a concomitant decrease in the amyloid precursor protein cleavage product, amyloid precursor protein C-terminal fragment.
(3) Divalent cation tolerance protein negatively regulates the function of beta-site amyloid precursor protein-cleaving enzyme 1 and may play a protective role in the development of Alzheimer's disease.
In this study, PC12 cells were induced to differentiate into neuron-like cells using nerve growth factor, and were subjected to oxygen-glucose deprivation. Cells were treated with 0, 10, 20, 30, 50, 100 ng/mL exogenous Activin A. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide assay and Hoechst 33324 staining showed that the survival percentage of PC12 cells significantly decreased and the rate of apoptosis significantly increased after oxygen-glucose deprivation. Exogenous Activin A significantly increased the survival percentage of PC12 cells in a dose-dependent manner. Reverse transcription-PCR results revealed a significant increase in Activin receptor IIA, Smad3 and Smad4 mRNA levels, which are key sites in the Activin A/Smads signaling pathway, in neuron-like cells subjected to oxygen-glucose deprivation, while mRNA expression of the apoptosis-regulation gene caspase-3 decreased. Our experimental findings indicate that exogenous Activin A plays an anti-apoptotic role and protects neurons by means of activating the Activin A/Smads signaling pathway.
(1) Activin A-mediated signal transduction mainly relies on the Activin A/Smads pathway, which has multiple functional sites and related regulatory factors. However, little is known about the changes in pathway expression and target genes, and the mechanism of action after ischemic brain injury.
(2) To date, most studies on Activin A have focused on its neuroprotective effects in in vivo experiments. Here, we used in vitro conditions and aimed to explore the role of Activin A in the Activin A/Smads pathway. We found that exogenous Activin A had a neuroprotective effect following oxygen-glucose deprivation-induced neuronal injury.
(3) Exogenous Activin A plays a neuroprotective role by preventing apoptosis, and protecting neurons from injury through activation of the Activin A/Smads signal transduction pathway.