Histological and ultrastructural comparison of cauterization and thrombosis stroke models in immune-deficient mice

Photothrombotic Middle Cerebral Artery Occlusion in Mice: A Novel Model of Ischemic Stroke

Stroke is one of the main causes of death and disability worldwide. Over the past decades, several animal models of focal cerebral ischemia have been developed allowing to investigate pathophysiological mechanisms underlying stroke progression. Despite intense preclinical research efforts, the need for noninvasive mouse models of vascular occlusion targeting the middle cerebral artery yet avoiding mechanical intervention is still pressing. Here, by applying the photothrombotic stroke model to the distal branch of the middle cerebral artery, we developed a novel strategy to induce a targeted occlusion of a large blood vessel in mice. This approach induces unilateral damage encompassing most of the dorsal cortex from the motor up to the visual regions 1 week after stroke. Pronounced limb dystonia one day after the damage is partially recovered after one week. Furthermore, we observe the insurgence of blood vessel leakage and edema formation in the peri-infarct area. Finally, this model elicits a notable inflammatory response revealed as a strong increase in astrocyte density and morphologic complexity in the perilesional region of the cortex compared with both other regions of the ipsilesional and contralesional hemispheres, and in sham-operated mice. To conclude, the stroke model we developed induces in mice the light-mediated occlusion of one of the main targets of human ischemic stroke, the middle cerebral artery, free from the limitations of commonly used preclinical models.

Integrated 16S rRNA gene sequencing and LC/MS-based metabolomics ascertained synergistic influences of the combination of acupuncture and NaoMaiTong on ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Acupuncture is an effective therapy for ischemic stroke, which has been widely used in China and gradually accepted in more countries and regions recently. In addition, Chinese medicine also plays an important role in stroke treatment, among which NaoMaiTong (NMT) is an example of an effective herbal formula for the treatment of stroke. A therapeutic strategy that combines acupuncture and medicine was widely used in stroke patients. However, the synergistic influences and mechanisms of combined acupuncture and medicine on ischemic stroke have not yet been entirely elucidated.

AIM OF THIS STUDY

The purpose of this study is to explore whether acupuncture and medicine combination treatments can produce synergism by using NMT, a clinically effective Chinese medicinal formula for the treatment of ischemic stroke for decades and has been demonstrated to be effective against ischemic brain injury, as a probe. Meanwhile, the potential mechanisms were investigated via cecal microbiome and plasma metabolomics to provide more strategies and basis for acupuncture-medicine combination for stroke.

MATERIALS AND METHODS

Adopted middle-cerebral artery occlusion/reperfusion (MCAO/R) rat models, the effect for the stroke of the combination treatment consisting of acupuncture and NMT was evaluated by detecting neurological issues, cerebral infarct dimensions, levels of inflammatory factors (IL-6, IL-1β, TNF-α) and oxidative stress factors (SOD, MDA) and brain-derived neurotrophic factor (BDNF). Subsequently,16S rRNA gene sequencing and LC/MS-based metabolomic analysis were utilized to explore the characteristics of cecal-contents microecology and plasma metabolic profile, respectively. Finally, the correlation between intestinal microecological characteristics and plasma metabolic characteristics was analyzed to explore the potential mechanism of the acupuncture-NMT combination.

RESULTS

The efficacy of acupuncture-NMT therapy was more effective than a single treatment on ischemic stroke, with more effectively reduced infarct sizes, improved neurobehavioral deficits, and alleviated oxidative stress and inflammatory responses. Besides, the combination therapy not only adjusted gut microbiota disturbances by enriching species diversity, reducing the abundance of pathogenic bacteria (such as Escherichia-Shaigella), as well as increasing the abundance of beneficial bacteria (such as Turicibacter, Bifidobacterium), but also improved metabolic disorders by reversing metabolite plasma levels to normality. The results of the correlation analysis demonstrated a significant association between intestinal microbiota and plasma metabolic profile, especially the strong correlation of Turicibacter and isoflavones phyto-estrogens metabolites.

CONCLUSION

The combination of acupuncture and NMT could produce synergism, suggesting acupuncture-medicine combination therapy might be more conducive to the recovery of ischemic stroke. And the potential mechanism was probably related to the mediation of intestinal microecology and plasma metabolism. Turicibacter and isoflavones phyto-estrogens metabolites might be the targets for acupuncture-NMT combination for stroke. Our current findings could provide a potential therapeutic strategy against ischemic stroke.

Aloe-emodin prevents nerve injury and neuroinflammation caused by ischemic stroke via the PI3K/AKT/mTOR and NF-κB pathway

Ischemic stroke (IS) caused by cerebral arterial occlusion is the leading cause of global morbidity and mortality. Cellular oxidative stress and inflammation play a vital role in the pathological process of neural damage in IS. It is necessary to develop functional food or drugs, which target neuroinflammation and oxidation mechanisms against IS. The molecule compound aloe-emodin (AE) is derived from aloe and rhubarb. However, the exact mechanism of the pharmacological action of AE on IS remains unclear. Here, for aiming to demonstrate the mechanism of AE, our study explored the middle cerebral occlusion reperfusion (MCAO/R) rats in vivo, oxygen and glucose deprivation reperfusion (OGD/R), and lipopolysaccharide (LPS)-stimulated cells in vitro. We found that AE significantly improved the infarct size and behavioral score of MCAO/R rats, decreased the expression of TNF-α, MDA, LDH, Caspase 3, and increased the expression of SOD, Bcl-2/Bax. Liquid chromatography-mass spectrometry (LC/MS) results showed that AE could penetrate the blood-brain barrier in the sham group and MCAO/R group. In vitro, AE significantly protected SH-SY5Y cells from the insult of OGD/R and reduced the production of inflammatory cytokines in BV2 cells stimulated by LPS. In vivo and in vitro, western blot analysis results showed that AE significantly increased the expression of PI3K, AKT and mTOR proteins. In addition, AE significantly decreased NF-κB protein expression in BV2 cells. The use of AKT-specific inhibitor MK-2206 2HCL to inhibit AKT expression can block the protective effect of AE on SH-SY5Y cells subjected to OGD/R insults. Overall, our study suggests that AE protected against cerebral ischemia-reperfusion injury probably via the PI3K/AKT/mTOR and NF-κB signaling pathways. Thus, these results indicated that AE could be a promising first-line therapy for preventing and treating ischemic stroke and can be used as functional food.

Neuroprotective Effects of Salidroside on Cerebral Ischemia/Reperfusion-Induced Behavioral Impairment Involves the Dopaminergic System

Salidroside, a phenylpropanoid glycoside, is the main bioactive component of Rhodiola rosea L. Salidroside has prominent anti-stroke effects in cerebral ischemia/reperfusion models. However, the underlying mechanisms of its actions are poorly understood. This study examined the anti-stroke effects of salidroside in middle cerebral artery occlusion (MCAO)-induced rat model of stroke and its potential mechanisms involving the dopaminergic system. Salidroside administration increased the levels of dopamine (DA), homovanillic acid (HVA), and 3,4-dihydroxyphenylacetic acid (DOPAC) in the ipsilateral striatum after induction of transient ischemia, which were assessed using microdialysis with high-performance liquid chromatography coupled with electrochemical detection (HPLC-ECD). Furthermore, treatment with salidroside ameliorated neurobehavioral impairment, assessed with the modified neurological severity scores (mNSS), the balance beam test, and the foot fault test. Moreover, enzyme-linked immunosorbent assay (ELISA) suggested that MCAO-induced reduction in monoamine oxidase (MAO) was inhibited by salidroside. Immunohistochemical and immunofluorescence analyses revealed high level of tyrosine hydroxylase (TH) in the ipsilateral striatal caudate putamen (CPu) after cerebral ischemia/reperfusion, which could be further elevated by salidroside. In addition, salidroside could reverse the decreased immunoreactivity of TH in the substantia nigra pars compacta (SNpc). These results suggest that the anti-stroke effects of salidroside in MCAO-induced cerebral ischemia/reperfusion may involve the modulation of monoamine metabolism in the striatum and SNpc, which may be related to the function of the dopaminergic system in the rat brain.

Motor deficit in the mouse ferric chloride-induced distal middle cerebral artery occlusion model of stroke

Ferric chloride-induced distal middle cerebral artery occlusion (MCAO) model of stroke was described in mice several years ago, however it lacked in-depth evaluation of the post-stroke functional outcomes in the animals. In this study, we reproduced the recently developed model and expanded its characterization by thorough evaluation of blood supply, cerebral infarction, and motor function in adult male and female mice up to 14 days after stroke. Our observations indicate near complete interruption of blood flow in the distal MCA shortly after application of 20 % ferric chloride over the artery through a cranial window, which remained occluded for at least 4 h. As expected, infarction of the brain tissue, documented by TTC and hematoxylin stains, was restricted to the cerebral cortex. We also systematically evaluated motor impairment of the animals in this model. For this, a series of studies were carried out in male and female mice up to 14 days after stroke, and motor function was assessed in cylinder and grid-walking tests in blinded manner. Contrary to our expectations, the results of both motor tests indicated minor, transient motor deficit in mice after stroke. Based on these observations, we conclude that the mouse ferric chloride-induced distal MCAO model is likely not suitable for proof-of-concept and preclinical studies where motor function is an important outcome measure.

Biohybrids of scaffolding hyaluronic acid biomaterials plus adipose stem cells home local neural stem and endothelial cells: Implications for reconstruction of brain lesions after stroke

Endogenous neurogenesis in stroke is insufficient to replace the lost brain tissue, largely due to the lack of a proper biological structure to let new cells dwell in the damaged area. We hypothesized that scaffolds made of hyaluronic acid (HA) biomaterials (BM) could provide a suitable environment to home not only new neurons, but also vessels, glia and neurofilaments. Further, the addition of exogenous cells, such as adipose stem cells (ASC) could increase this effect. Athymic mice were randomly assigned to a one of four group: stroke alone, stroke and implantation of BM, stroke and implantation of BM with ASC, and sham operated animals. Stroke model consisted of middle cerebral artery thrombosis with FeCl₃ . After 30 days, animals underwent magnetic resonance imaging (MRI) and were sacrificed. Proliferation and neurogenesis increased at the subventricular zone ipsilateral to the ventricle and neuroblasts, glial, and endothelial cells forming capillaries were seen inside the BM. Those effects increased when ASC were added, while there was less inflammatory reaction. Three-dimensional scaffolds made of HA are able to home newly formed neurons, glia, and endothelial cells permitting the growth neurofilaments inside them. The addition of ASC increase these effects and decrease the inflammatory reaction to the implant. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1598-1606, 2019.

Evaluation of the Safety and Efficacy of the Therapeutic Potential of Adipose-Derived Stem Cells Injected in the Cerebral Ischemic Penumbra

INTRODUCTION

Stroke represents an attractive target for cell therapy. Although different types of cells have been employed in animal models with variable results, the human adipose-derived stem cells (hASCs) have demonstrated favorable characteristics in the treatment of diseases with inflammatory substrate, but experience in their intracerebral administration is lacking. The purpose of this study is to evaluate the effect and safety of the intracerebral application of hASCs in a stroke model.

METHODS

A first group of Athymic Nude mice after stroke received a stereotactic injection of hASCs at a concentration of 4 × 10⁴/µL at the penumbra area, a second group without stroke received the same cell concentration, and a third group had only stroke and no cells. After 7, 15, and 30 days, the animals underwent fluorodeoxyglucose-positron emission tomography and magnetic resonance imaging; subsequently, they were sacrificed for histological evaluation (HuNu, GFAP, IBA-1, Ki67, DCX) of the penumbra area and ipsilateral subventricular zone (iSVZ).

RESULTS

The in vitro studies found no alterations in the molecular karyotype, clonogenic capacity, and expression of 62 kDa transcription factor and telomerase. Animals implanted with cells showed no adverse events. The implanted cells showed no evidence of proliferation or differentiation. However, there was an increase of capillaries, less astrocytes and microglia, and increased bromodeoxyuridine and doublecortin-positive cells in the iSVZ and in the vicinity of ischemic injury.

CONCLUSIONS

These results suggest that hASCs in the implanted dose modulate inflammation, promote endogenous neurogenesis, and do not proliferate or migrate in the brain. These data confirm the safety of cell therapy with hASCs.

Role of the chemokine receptors CCR2 and CX3CR1 in an experimental model of thrombotic stroke

Stroke is the second cause of mortality worldwide and occurs following the interruption of cerebral blood circulation by cerebral vessel burst or subsequent to a local thrombus formation. Ischemic lesion triggers an important inflammatory response, characterized by massive infiltration of leukocytes, activation of glial cells and neurovascular reorganization. Chemokines and their receptors, such as CCR2 and CX3CR1, play an important role in leukocyte recruitment in the damaged area. Mice genetically depleted for the two receptors CCR2 and CX3CR1 underwent focal cerebral ischemia, based on the topical application of ferric chloride to truncate the distal middle cerebral artery. The infarct, limited only to the cortical area, remained stable in WT mice, while it is reduced overtime in the transgenic mice. Moreover, we did not observe any significant changes in the level of the inflammatory response in the infarcted areas while immune cell infiltration and neurovascularization are modulated according to genotype. Our results show that the genetic deletion of both CCR2 and CX3CR1 receptors has neuroprotective effects in response to a cerebral permanent ischemia. This study underlines a key role of CCR2- and CX3CR1-expressing immune cells in the neuropathology associated with ischemic injuries.

Gualou Guizhi decoction promotes neurological functional recovery and neurogenesis following focal cerebral ischemia/reperfusion

Recovery following stroke involves neurogenesis and axonal remodeling within the ischemic brain. Gualou Guizhi decoction (GLGZD) is a Chinese traditional medicine used for the treatment of post-stroke limb spasm. GLGZD has been reported to have neuroprotective effects in cerebral ischemic injury. However, the effects of GLGZD on neurogenesis and axonal remodeling following cerebral ischemia remain unknown. In this study, a rat model of focal cerebral ischemia/reperfusion was established by middle cerebral artery occlusion. Neurological function was assessed immediately after reperfusion using Longa's 5-point scoring system. The rats were randomly divided into vehicle and GLGZD groups. Rats in the sham group were given sham operation. The rats in the GLGZD group were intragastrically administered GLGZD, once daily, for 14 consecutive days. The rats in the vehicle and sham groups were intragastrically administered distilled water. Modified neurological severity score test, balance beam test and foot fault test were used to assess motor functional changes. Nissl staining was performed to evaluate histopathological changes in the brain. Immunofluorescence staining was used to examine cell proliferation using the marker 5-bromo-2′-deoxyuridine (BrdU) as well as expression of the neural precursor marker doublecortin (DCX), the astrocyte marker glial fibrillary acidic protein (GFAP) and the axon regeneration marker growth associated protein-43 (GAP-43). GLGZD substantially mitigated pathological injury, increased the number of BrdU, DCX and GFAP-immunoreactive cells in the subventricular zone of the ischemic hemisphere, increased GAP-43 expression in the cortical peri-infarct region, and improved motor function. These findings suggest that GLGZD promotes neurological functional recovery by increasing cell proliferation, enhancing axonal regeneration, and increasing the numbers of neuronal precursors and astrocytes in the peri-infarct area.

PECAM-1-targeted micron-sized particles of iron oxide as MRI contrast agent for detection of vascular remodeling after cerebral ischemia

An increasing amount of studies have provided evidence for vascular remodeling, for example, angiogenesis, after cerebral ischemia, which may play a significant role in post-stroke brain plasticity and recovery. Molecular imaging can provide unique in vivo whole-brain information on alterations in the expression of specific endothelial markers. A possible target for molecular magnetic resonance imaging (MRI) of post-stroke (neo)vascularization is platelet endothelial cell adhesion molecule-1 (PECAM-1). Here we describe significantly increased PECAM-1 mRNA levels in ipsilesional brain tissue at 6 h, 24 h and 3 days after transient middle cerebral artery occlusion in mice, and elevated PECAM-1 staining throughout the lesion at 3, 7 and 21 days post-stroke. The potential of micron-sized particles of iron oxide (MPIO) conjugated with PECAM-1-targeted antibodies, that is, αPECAM-1-MPIO, to expose stroke-induced PECAM-1 upregulation with molecular MRI was assessed. In vitro studies demonstrated that PECAM-1-expressing brain endothelial cells could be effectively labeled with αPECAM-1-MPIO, giving rise to a fourfold increase in MRI relaxation rate R2. Injection of near-infrared fluorescent dye-labeled αPECAM-1 showed target specificity and dose efficiency of the antibody for detection of brain endothelial cells at 3 days post-stroke. However, in vivo molecular MRI at 3 and 7 days after stroke revealed no αPECAM-1-MPIO-based contrast enhancement, which was corroborated by the absence of αPECAM-1-MPIO in post mortem brain tissue. This indicates that this molecular MRI approach, which has been proven successful for in vivo detection of other types of cell adhesion molecules, is not invariably effective for MRI-based assessment of stroke-induced alterations in expression of cerebrovascular markers.

Therapeutic effects of hMAPC and hMSC transplantation after stroke in mice

Stroke represents an attractive target for stem cell therapy. Although different types of cells have been employed in animal models, a direct comparison between cell sources has not been performed. The aim of our study was to assess the effect of human multipotent adult progenitor cells (hMAPCs) and human mesenchymal stem cells (hMSCs) on endogenous neurogenesis, angiogenesis and inflammation following stroke. BALB/Ca-RAG 2(-/-) γC(-/-) mice subjected to FeCl(3) thrombosis mediated stroke were intracranially injected with 2 × 10(5) hMAPCs or hMSCs 2 days after stroke and followed for up to 28 days. We could not detect long-term engraftment of either cell population. However, in comparison with PBS-treated animals, hMSC and hMAPC grafted animals demonstrated significantly decreased loss of brain tissue. This was associated with increased angiogenesis, diminished inflammation and a glial-scar inhibitory effect. Moreover, enhanced proliferation of cells in the subventricular zone (SVZ) and survival of newly generated neuroblasts was observed. Interestingly, these neuroprotective effects were more pronounced in the group of animals treated with hMAPCs in comparison with hMSCs. Our results establish cell therapy with hMAPCs and hMSCs as a promising strategy for the treatment of stroke.