Dl-3-N-butylphthalide (NBP) is approved in China for the treatment of ischemic stroke. Previous studies have shown that NBP promotes recovery after stroke via multiple mechanisms. However, the effect ...of NBP on vascular function and thrombosis remains unclear. Here, we aim to study the effect of NBP on vascular function using a rat model of transient middle cerebral artery occlusion (MCAO) and a state-of-the-art high-resolution synchrotron radiation angiography. Eighty SD rats underwent MCAO surgery. NBP (90 mg/kg) was administrated daily by gavage. Synchrotron radiation angiography was used to evaluate the cerebral vascular perfusion, vasoconstriction, and vasodilation in real-time. Neurological scores, brain infarction and atrophy were evaluated. Real-time PCR was used to assess the expression levels of thrombosis and vasoconstriction-related genes. Results revealed that NBP attenuated thrombosis after MCAO and reduced brain infarct and atrophy volume. NBP administrated at 1 and 4 h after MCAO prevented the vasoconstriction of the artery and maintained its diameter at normal level. Administrated at one week after surgery, NBP functioned as a vasodilator in rats after MCAO while displayed no vasodilating effect in sham group. Our results suggested that NBP attenuates brain injury via increasing the regional blood flow by reducing thrombosis and vasoconstriction.
Single-cell RNA-seq (scRNA-seq) profiles gene expression with high resolution. Here, we develop a stepwise computational method-called SCAPTURE to identify, evaluate, and quantify cleavage and ...polyadenylation sites (PASs) from 3' tag-based scRNA-seq. SCAPTURE detects PASs de novo in single cells with high sensitivity and accuracy, enabling detection of previously unannotated PASs. Quantified alternative PAS transcripts refine cell identity analysis beyond gene expression, enriching information extracted from scRNA-seq data. Using SCAPTURE, we show changes of PAS usage in PBMCs from infected versus healthy individuals at single-cell resolution.
Microglia play a critical role in modulating cell death and neurobehavioral recovery in response to brain injury either by direct cell-cell interaction or indirect secretion of trophic factors. ...Exosomes secreted from cells are well documented to deliver bioactive molecules to recipient cells to modulate cell function. Here, we aimed to identify whether M2 microglia exert neuroprotection after ischemic attack through an exosome-mediated cell-cell interaction.
M2 microglia-derived exosomes were intravenously injected into the mouse brain immediately after middle cerebral artery occlusion. Infarct volume, neurological score, and neuronal apoptosis were examined 3 days after ischemic attack. Exosome RNA and target protein expression levels in neurons and brain tissue were determined for the mechanistic study.
Our results showed that the M2 microglia-derived exosomes were taken up by neurons
and
. M2 microglia-derived exosome treatment attenuated neuronal apoptosis after oxygen-glucose deprivation (p<0.05).
results showed that M2 microglia-derived exosome treatment significantly reduced infarct volume and attenuated behavioral deficits 3 days after transient brain ischemia (p<0.05), whereas injection of miR-124 knockdown (miR-124k/d) M2 microglia-derived exosomes partly reversed the neuroprotective effect. Our mechanistic study further demonstrated that ubiquitin-specific protease 14 (USP14) was the direct downstream target of miR-124. Injection of miR-124k/d M2 exosomes plus the USP14 inhibitor, IU1, achieved comparable neuroprotective effect as injection of M2 exosomes alone.
We demonstrated that M2 microglia-derived exosomes attenuated ischemic brain injury and promoted neuronal survival via exosomal miR-124 and its downstream target USP14. M2 microglia-derived exosomes represent a promising avenue for treating ischemic stroke.
A new hybrid lead(
ii
) halide perovskite, (TzH)
2
PbCl
4
, (TzH
+
= 1,2,4-triazolium), adopts a (001)-oriented layered perovskite structure, which can be considered as derived from the
n
= 1 ...Ruddlesden-Popper (RP) type. Variable temperature single crystal X-ray diffraction reveals a structural phase transition in the region 125 K <
T
< 173 K between a high temperature, high symmetry polymorph, space group
Cmcm
, and a low temperature, low symmetry chiral polymorph, space group
P
2
1
2
1
2
1
, which has a tripled unit cell volume. UV-Vis spectra suggest a band gap of 3.30 eV for (TzH)
2
PbCl
4
. A second polymorph of the bromide analogue, (TzH)
2
PbBr
4
-II, is also reported, and structural relationships between all three variants are discussed.
Three new layered hybrid perovskites are reported. (TzH)
2
PbCl
4
undergoes a unique structural phase transition, due to 'rippling' of perovskite-like layers.
Rationale: Cerebral ischemia upregulates aquaporin‐4 expression, increases blood‐brain barrier (BBB) permeability, and induces brain edema. Mesenchymal stem cells (MSCs) can repress inflammatory ...cytokines and show great potential for ischemic stroke therapy. However, the effect of MSCs regarding the protection of ischemia‐induced BBB break down is unknown. Objective: We test whether MSCs therapy protects BBB integrity and explore the molecular mechanisms of aquaporin‐4 on BBB integrity. Methods and Results: Two hundred and twenty‐eight adult CD1 male mice underwent 90 minutes transient middle cerebral artery occlusion and received 2 × 105 MSCs intracranial transplantation. The neurological severity score was improved and both ischemia‐induced brain edema and BBB leakage were reduced in MSC‐treated mice. MSCs therapy reduced astrocyte apoptosis and inhibited ischemia‐induced aquaporin‐4 upregulation. In addition, small‐interfering RNA knockdown of aquaporin‐4 after cerebral ischemia effectively reduced aquaporin‐4 expression, brain edema, BBB leakage, and astrocyte apoptosis. Conditional medium from lipopolysaccharide (LPS)‐activated microglia enhanced aquaporin‐4 expression, p38 and JNK phosphorylation, and apoptosis of cultured astrocytes. MSC treatment reduced the expression of inflammatory cytokines in LPS‐activated microglia, and subsequently reduced aquaporin‐4 expression and apoptosis of astrocytes. Knockdown of aquaporin‐4 in cultured astrocytes also reduced apoptosis. Treatment with p38 and JNK inhibitors showed that p38, but not the JNK signaling pathway, was responsible for the aquaporin‐4 upregulation. Conclusion: MSCs protected BBB integrity by reducing the apoptosis of astrocytes after ischemic attack, which was due to the attenuation of inflammatory response and downregulation of aquaporin‐4 expression via p38 signaling pathway. Stem Cells 2014;32:3150–3162
Nanostructured biomaterials have tremendous potential for tissue engineering. However, the performance and integration of the nanomaterials in vivo are not well understood. A challenge in vascular ...tissue engineering is to develop optimal scaffolds and establish expandable cell sources for the construction of tissue-engineered vascular grafts that are nonthrombogenic and have long-term patency. Here, we used tissue-engineered vascular grafts as a model to demonstrate the potential of combining nanofibrous scaffolds and bone marrow mesenchymal stem cells (MSCs) for vascular tissue engineering. Biodegradable nanofibrous scaffolds with aligned nanofibers were used to mimic native collagen fibrils to guide cell organization in vascular grafts. The results from artery bypass experiments showed that nanofibrous scaffolds allowed efficient infiltration of vascular cells and matrix remodeling. Acellular grafts (without MSCs) resulted in significant intimal thickening, whereas cellular grafts (with MSCs) had excellent long-term patency and exhibited well organized layers of endothelial cells (ECs) and smooth muscle cells (SMCs), as in native arteries. Short-term experiments showed that nanofibrous scaffolds alone induced platelet adhesion and thrombus formation, which was suppressed by MSC seeding. In addition, MSCs, as ECs, resisted platelet adhesion in vitro, which depended on cell-surface heparan sulfate proteoglycans. These data, together with the observation on the short-term engraftment of MSCs, suggest that the long-term patency of cellular grafts may be attributed to the antithrombogenic property of MSCs. These results demonstrate several favorable characteristics of nanofibrous scaffolds, the excellent patency of small-diameter nanofibrous vascular grafts, and the unique antithrombogenic property of MSCs.
Biocatalysis has emerged as a valuable and reliable tool for industrial and academic societies, particularly in fields related to bioredox reactions. The cost of cofactors, especially those needed to ...be replenished at stoichiometric amounts or more, is the chief economic concern for bioredox reactions. In this study, a readily accessible, inexpensive, and bench‐stable Hantzsch ester is verified as the viable and efficient NAD(P)H mimic by four enzymatic redox transformations, including two non‐heme diiron N‐oxygenases and two flavin‐dependent reductases. This finding provides the potential to significantly reduce the costs of NAD(P)H‐relying bioredox reactions.
Chemically stable Hantzsch ester is discovered to be an efficient and economical NAD(P)H mimic as sacrificial electron source in in vitro bioconversions.
Azoxy bond is an important chemical bond and plays a crucial role in high energy density materials. However, the biosynthetic mechanism of azoxy bond remains enigmatic. Here we report that the azoxy ...bond biosynthesis of azoxymycins is an enzymatic and non-enzymatic coupling cascade reaction. In the first step, nonheme diiron N-oxygenase AzoC catalyzes the oxidization of amine to its nitroso analogue. Redox coenzyme pairs then facilitate the mutual conversion between nitroso group and hydroxylamine via the radical transient intermediates, which efficiently dimerize to azoxy bond. The deficiency of nucleophilic reactivity in AzoC is proposed to account for the enzyme's non-canonical oxidization of amine to nitroso product. Free nitrogen radicals induced by coenzyme pairs are proposed to be responsible for the efficient non-enzymatic azoxy bond formation. This mechanism study will provide molecular basis for the biosynthesis of azoxy high energy density materials and other valuable azoxy chemicals.
BACKGROUND—Long noncoding RNAs (lncRNAs) have recently been implicated in many biological processes and diseases. Atherosclerosis is a major risk factor for cardiovascular disease. However, the ...functional role of lncRNAs in atherosclerosis is largely unknown.
METHODS AND RESULTS—We identified lincRNA-p21 as a key regulator of cell proliferation and apoptosis during atherosclerosis. The expression of lincRNA-p21 was dramatically downregulated in atherosclerotic plaques of ApoE mice, an animal model for atherosclerosis. Through loss- and gain-of-function approaches, we showed that lincRNA-p21 represses cell proliferation and induces apoptosis in vascular smooth muscle cells and mouse mononuclear macrophage cells in vitro. Moreover, we found that inhibition of lincRNA-p21 results in neointimal hyperplasia in vivo in a carotid artery injury model. Genome-wide analysis revealed that lincRNA-p21 inhibition dysregulated many p53 targets. Furthermore, lincRNA-p21, a transcriptional target of p53, feeds back to enhance p53 transcriptional activity, at least in part, via binding to mouse double minute 2 (MDM2), an E3 ubiquitin-protein ligase. The association of lincRNA-p21 and MDM2 releases MDM2 repression of p53, enabling p53 to interact with p300 and to bind to the promoters/enhancers of its target genes. Finally, we show that lincRNA-p21 expression is decreased in patients with coronary artery disease.
CONCLUSIONS—Our studies identify lincRNA-p21 as a novel regulator of cell proliferation and apoptosis and suggest that this lncRNA could serve as a therapeutic target to treat atherosclerosis and related cardiovascular disorders.
Blood-brain barrier (BBB) dysfunction is one of the hallmarks of ischemic stroke. USP14 has been reported to play a detrimental role in ischemic brain injury. However, the role of USP14 in BBB ...dysfunction after ischemic stroke is unclear.
In this study, we tested the role of USP14 in disrupting BBB integrity after ischemic stroke. The USP14-specific inhibitor IU1 was injected into middle cerebral artery occlusion (MCAO) mice once a day. The Evans blue (EB) assay and IgG staining were used to assess BBB leakage 3 days after MCAO. FITC-detran test was slected to examine the BBB leakage in vitro. Behavior tests were conducted to evaluate recovery from ischemic stroke.
Middle cerebral artery occlusion increased endothelial cell USP14 expression in the brain. Furthermore, the EB assay and IgG staining showed that USP14 inhibition through IU1 injection protected against BBB leakage after MCAO. Analysis of protein expression revealed a reduction in the inflammatory response and chemokine release after IU1 treatment. In addition, IU1 treatment was found to rescue neuronal loss resulting from ischemic stroke. Behavior tests showed a positive effect of IU1 in attenuating brain injury and improving motor function recovery. In vitro study showed that IU1 treatment could alleviate endothelial cell leakage induced by OGD in cultured bend.3 cells through modulating ZO-1 expression.
Our results demonstrate a role for USP14 in disrupting the integrity of the BBB and promoting neuroinflammation after MCAO.
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