Overexpression of miR-124 in astrocyte improves neurological deficits in rat with ischemic stroke via DLL4 modulation.

BACKGROUND: Astrocytes have been demonstrated to undergo conversion into functional neurons, presenting a promising approach for stroke treatment. However, the development of small molecules capable of effectively inducing this cellular reprogramming remains a critical challenge. METHODS: Initially, we introduced a glial cell marker gene, GFaABC1D, as the promoter within an adeno-associated virus vector overexpressing miR-124 into the motor cortex of an ischemia-reperfusion model in rats. Additionally, we administered NeuroD1 as a positive control. Lentiviral vectors overexpressing miR-124 were constructed and transfected into primary rat astrocytes. We assessed the cellular distribution of GFAP, DCX, and NeuN on days 7, 14, and 28, respectively. RESULTS: In rats with ischemic stroke, miR-124-transduced glial cells exhibited positive staining for the immature neuron marker doublecortin (DCX) and the mature neuron marker NeuN after 4 weeks. In contrast, NeuroD1-overexpressing model rats only expressed NeuN, and the positive percentage was higher in co-transfection with miR-124 and NeuroD1. Overexpression of miR-124 effectively ameliorated neurological deficits and motor functional impairment in the model rats. In primary rat astrocytes transduced with miR-124, DCX was not observed after 7 days of transfection, but it appeared at 14 days, with the percentage further increasing to 44.6% at 28 days. Simultaneously, 15.1% of miR-124-transduced cells exhibited NeuN positivity, which was not detected at 7 and 14 days. In vitro, double fluorescence assays revealed that miR-124 targeted Dll4, and in vivo experiments confirmed that miR-124 inhibited the expression of Notch1 and DLL4. CONCLUSIONS: The overexpression of miR-124 in astrocytes demonstrates significant potential for improving neurological deficits following ischemic stroke by inhibiting DLL4 expression, and it may facilitate astrocyte-to-neuronal transformation.

Effect of Electroacupuncture on Short-Chain Fatty Acids in Peripheral Blood after Middle Cerebral Artery Occlusion/Reperfusion in Rats Based on Gas Chromatography-Mass Spectrometry.

Previous fundamental and clinical research has shown that electroacupuncture (EA) at the acupoints of Quchi (LI11) and Zusanli (ST36) can successfully alleviate motor dysfunction following stroke. Additionally, it has been discovered that gut microbiota and their metabolites play an essential role in stroke. However, the relationship between the metabolites of gut microbiota and the efficacy of EA is still unclear. Therefore, the aim of this study was to evaluate the mechanism of EA at LI11 and ST36 in the treatment of motor dysfunction after middle cerebral artery occlusion/reperfusion (MCAO/R) in model rats by comparing the differences and correlation between different short-chain fatty acids (SCFAs) and the recovery of motor function. The results indicated that EA at LI11 and ST36 acupoints enhanced the neurological function, motor function, and infarct volume of MCAO/R rats. The levels of acetic acid, propionic acid, and total SCFAs were considerably lower in the MCAO/R group than in the sham group (P < 0.05). Acetic acid, propionic acid, and total SCFA concentrations were substantially higher in the MCAO/R + EA group than in the MCAO/R group (P < 0.05). Finally, Pearson correlation analysis revealed that the propionic acid concentration was substantially favorably connected with the duration on the rotarod (r = 0.633 and P < 0.05) and highly negatively correlated with the modified neurological severity score (mNSS) (r = -0.698 and P < 0.05) and the percentage of cerebral infarct volume (r = -0.729 and P < 0.05). Taken together, these findings indicate that the increase in propionic acid may be one of the mechanisms and targets of EA at LI11 and ST36 acupoints to improve poststroke motor dysfunction in MCAO/R rats.

In vitro evaluation of the ZX11 magnesium alloy as potential bone plate: Degradability and mechanical integrity.

Considering the excellent biocompatibility of magnesium (Mg) alloys and their better mechanical properties compared to polymer materials, a wrought MgZnCa alloy with low contents of Zn (0.7 wt%) and Ca (0.6 wt%) (ZX11) was developed by twin roll casting (TRC) technology as potential biodegradable bone plates. The degradability and cell response of the ZX11 alloy were evaluated in vitro, as well as the mechanical integrity according to tensile tests after immersion. The results revealed a slightly higher degradation rate for the rolled ZX11, in comparison to that of the annealed one. It was mainly caused by the deformation twins and residual strain stored in the rolled alloy, which also seemed to promote localized degradation, thereby leading to a relatively fast deterioration in mechanical properties, especially the fracture strain/elongation. In contrast, after the annealing treatment, the alloy showed relatively lower strength, yet a lower degradation rate and quite stable elongation during the initial weeks of immersion were observed. More importantly, the ZX11 alloy, regardless of the annealing treatment, showed good in vitro cytocomopatibility regarding human primary osteoblasts. The assessment indicates the rolled alloy as a good choice for implantation sites where relatively high mechanical strength is needed during the early implantation, while the annealed alloy is a potential candidate for the sites which demand stable mechanical integrity during service. STATEMENT OF SIGNIFICANCE: The development of magnesium alloys as bone implants demands low degradation rate to gain not only a slow hydrogen evolution, but also a stable mechanical integrity during service. The present study develops a micro-alloyed MgZnCa alloy via twin roll casting (TRC) technology. It exhibited limited cytotoxicity, fairly low degradation rate and comparable strength to the reported Mg-1Zn-5Ca alloy which has been used as bone screws in clinical trials, indicating the great potential application as biodegradable bone implants. Furthermore, it showed good mechanical integrity during immersion to support the defect healing. Our results can aid other researchers to evaluate the mechanical integrity of biodegradable materials and to pay more attention to the effect of degradation behaviour on mechanical integrity of materials.

Enhanced Wear Performance of Hybrid Epoxy-Ceramic Coatings on Magnesium Substrates.

Epoxy-based polymer was deposited as sealing agent on porous anodized coatings prepared by plasma electrolytic oxidation (PEO) to construct multilayered "soft-hard" coatings on Mg substrates. Different thicknesses and microstructures of the top epoxy layer were achieved by employing different dip-coating strategies. Atomic force microscopy, pull-off tests, and nanoindentation tests were conducted to study the surface roughness, the adhesion strength of the epoxy layer, and the mechanical properties of each component in the hybrid coating system. The micropores and other defects on the anodized layers were sealed by the epoxy polymer, which decreased the surface roughness. The dominant abrasive wear behavior of blank PEO coatings was significantly reduced by the epoxy layers, and the wear mechanism of the hybrid coatings was proposed considering both the microstructure of the hybrid coatings and the mechanical properties of the different components in the hybrid system.

Controllable degradation of medical magnesium by electrodeposited composite films of mussel adhesive protein (Mefp-1) and chitosan.

To control the degradation rate of medical magnesium in body fluid environment, biocompatible films composed of Mussel Adhesive Protein (Mefp-1) and chitosan were electrodeposited on magnesium surface in cathodic constant current mode. The compositions and structures of the films were characterized by atomic force microscope (AFM), scanning electron microscope (SEM) and infrared reflection absorption spectroscopy (IRAS). And the corrosion protection performance was investigated using electrochemical measurements and immersion tests in simulated body fluid (Hanks' solution). The results revealed that Mefp-1 and chitosan successfully adhered on the magnesium surface and formed a protective film. Compared with either single Mefp-1 or single chitosan film, the composite film of chitosan/Mefp-1/chitosan (CPC (chitosan/Mefp-1/chitosan)) exhibited lower corrosion current density, higher polarization resistance and more homogenous corrosion morphology and thus was able to effectively control the degradation rate of magnesium in simulated body environment. In addition, the active attachment and spreading of MC3T3-E1 cells on the CPC film coated magnesium indicated that the CPC film was significantly able to improve the biocompatibility of the medical magnesium.