Growth factor therapy sequesters inflammation in affording neuroprotection in cerebrovascular diseases

An update on stem cell therapy for stroke patients: Where are we now?

With a foundation built upon initial work from the 1980s demonstrating graft viability in cerebral ischemia, stem cell transplantation has shown immense promise in promoting survival, enhancing neuroprotection and inducing neuroregeneration, while mitigating both histological and behavioral deficits that frequently accompany ischemic stroke. These findings have led to a number of clinical trials that have thoroughly supported a strong safety profile for stem cell therapy in patients but have generated variable efficacy. As preclinical evidence continues to expand through the investigation of new cell lines and optimization of stem cell delivery, it remains critical for translational models to adhere to the protocols established through basic scientific research. With the recent shift in approach towards utilization of stem cells as a conjunctive therapy alongside standard thrombolytic treatments, key issues including timing, route of administration, and stem cell type must each be appropriately translated from the laboratory in order to resolve the question of stem cell efficacy for cerebral ischemia that ultimately will enhance therapeutics for stroke patients towards improving quality of life.

Neuro-regeneration or Repair: Cell Therapy of Neurological Disorders as A Way Forward

The human central nervous system (CNS) has a limited capacity for regeneration and repair, as many other organs do. Partly as a result, neurological diseases are the leading cause of medical burden globally. Most neurological disorders cannot be cured, and primary treatments focus on managing their symptoms and slowing down their progression. Cell therapy for neurological disorders offers several therapeutic potentials and provides hope for many patients. Here we provide a general overview of cell therapy in neurological disorders such as Parkinson's disease (PD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Wilson's disease (WD), stroke and traumatic brain injury (TBI), involving many forms of stem cells, including embryonic stem cells and induced pluripotent stem cells. We also address the current concerns and perspectives for the future. Most studies for cell therapy in neurological diseases are in the pre-clinical stage, and there is still a great need for further research to translate neural replacement and regenerative therapies into clinical settings.

Induced Inflammatory and Oxidative Markers in Cerebral Microvasculature by Mentally Depressive Stress

Background

Cerebrovascular disease (CVD) is recognized as the leading cause of permanent disability worldwide. Depressive disorders are associated with increased incidence of CVD. The goal of this study was to establish a chronic restraint stress (CRS) model for mice and examine the effect of stress on cerebrovascular inflammation and oxidative stress responses.

Methods

A total of forty 6-week-old male C57BL/6J mice were randomly divided into the CRS and control groups. In the CRS group (n = 20), mice were placed in a well-ventilated Plexiglas tube for 6 hours per day for 28 consecutive days. On day 29, open field tests (OFT) and sucrose preference tests (SPT) were performed to assess depressive-like behaviors for the two groups (n = 10/group). Macrophage infiltration into the brain tissue upon stress was analyzed by measuring expression of macrophage marker (CD68) with immunofluorescence in both the CRS and control groups (n = 10/group). Cerebral microvasculature was isolated from the CRS and controls (n = 10/group). mRNA and protein expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), vascular cell adhesion molecule-1 (VCAM-1), and macrophage chemoattractant protein-1 (MCP-1) in the brain vessels were measured by real-time PCR and Western blot (n = 10/group). Reactive oxygen species (ROS), hydrogen peroxide (H₂O₂), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activities were quantified by ELISA to study the oxidative profile of the brain vessels (n = 10/group). Additionally, mRNA and protein expressions of NOX subunits (gp91^phox, p47^phox, p67^phox, and p22^phox) in the cerebrovascular endothelium were analyzed by real-time PCR and Western blot (n = 10/group).

Results

CRS decreased the total distances (p < 0.05) and the time spent in the center zone in OFT (p < 0.001) and sucrose preference test ratio in SPT (p < 0.01). Positive ratio of CD68⁺ was increased with CRS in the entire region of the brain (p < 0.001), reflecting increased macrophage infiltration. CRS increased the expression of inflammatory factors and oxidative stress in the cerebral microvasculature, including TNF-α (p < 0.001), IL-1β (p < 0.05), IL-6 (p < 0.05), VCAM-1 (p < 0.01), MCP-1 (p < 0.01), ROS (p < 0.001), and H₂O₂ (p < 0.001). NADPH oxidase (NOX) was activated by CRS (p < 0.01), and mRNA and protein expressions of NOX subunits (gp91^phox, p47^phox, p67^phox, and p22^phox) in brain microvasculature were found to be increased.

Conclusions

To our knowledge, this is the first study to demonstrate that CRS induces depressive stress and causes inflammatory and oxidative stress responses in the brain microvasculature.

Sufentanil alleviates cerebral ischemia-reperfusion injury by inhibiting inflammation and protecting the blood-brain barrier in rats

Stroke is a brain system disease with a high fatality rate and disability rate. About 80% of strokes are ischemic strokes. Cerebral ischemia-reperfusion injury (CIRI) caused by ischemic stroke seriously affects the prognosis of stroke patients. The purpose of this study is to investigate the effect of sufentanil (SUF) on CIRI model rats. We used middle cerebral artery occlusion (MCAO) to make the CIRI model in rats and monitored region cerebral blood flow (rCBF) to ensure that blood flow was blocked and recanalized. We used ELISA and RT-PCR to detect the expression of inflammatory factors in rat serum and brain tissue. In addition, we detected the expression of metalloproteinase (MMP) 2, MMP9 and collagen IV in brain tissues and performed Evans blue (EB) assay to determine the permeability of the blood-brain barrier (BBB). Finally, we clarified the apoptosis of brain tissue through the TUNEL staining and the detection of caspase3, Bcl2 and Bax. Various concentrations of SUF, especially 5, 10 and 25 μg/kg of SUF, all alleviated the infarct size, neurological function and brain edema of MCAO rats. SUF pretreatment also effectively reduced the expression of inflammatory cytokines in MCAO rats, including interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10 and tumor necrosis factor (TNF)-α. In addition, SUF also inhibited MMP2 and MMP9 and promoted the expression of collagen IV, indicating that SUF attenuated the destruction of the BBB. SUF also inhibited caspase3 and Bax rats and promoted Bcl2 in MCAO rats, thus inhibiting cell apoptosis. SUF pretreatment effectively improved the neurological function and cerebral infarction of MCAO rats, inhibited excessive inflammation in rats, protected the BBB, and inhibited cell apoptosis in brain tissue.

Amazon rainforest rodents (Proechimys) are resistant to post-stroke epilepsy

There are no clinical interventions to prevent post-injury epilepsy, a common and devastating outcome after brain insults. Epileptogenic events that run from brain injury to epilepsy are poorly understood. Previous studies in our laboratory suggested Proechimys, an exotic Amazonian rodent, as resistant to acquired epilepsy development in post-status epilepticus models. The present comparative study was conducted to assess (1) stroke-related brain responses 24-h and 30 days after cortical photothrombosis and (2) post-stroke epilepsy between Proechimys rodents and Wistar rats, a traditional animal used for laboratory research. Proechimys group showed smaller volume of ischemic infarction and lesser glial activation than Wistar group. In contrast to Wistar rats, post-stroke decreased levels of pro-inflammatory cytokines and increased levels of anti-inflammatory mediators and growth factors were found in Proechimys. Electrophysiological signaling changes assessed by cortical spreading depression, in vitro and in vivo, showed that Wistar's brain is most severely affected by stroke. Chronic electrocorticographic recordings showed that injury did not lead to epilepsy in Proechimys whereas 88% of the Wistar rats developed post-stroke epilepsy. Science gains insights from comparative studies on diverse species. Proechimys rodents proved to be a useful animal model to study antiepileptogenic mechanisms after brain insults and complement conventional animal models.

Therapeutic Potential of Cytokines in Demyelinating Lesions After Stroke

White matter damage is a component of most human stroke and usually accounts for at least half of the lesion volume. Subcortical white matter stroke (WMS) accounts for 25% of all strokes and causes severe motor and cognitive dysfunction. The adult brain has a very limited ability to repair white matter damage. Pathological analysis shows that demyelination or myelin loss is the main feature of white matter injury and plays an important role in long-term sensorimotor and cognitive dysfunction. This suggests that demyelination is a major therapeutic target for ischemic stroke injury. An acute inflammatory reaction is triggered by brain ischemia, which is accompanied by cytokine production. The production of cytokines is an important factor affecting demyelination and myelin regeneration. Different cytokines have different effects on myelin damage and myelin regeneration. Exploring the role of cytokines in demyelination and remyelination after stroke and the underlying molecular mechanisms of demyelination and myelin regeneration after ischemic injury is very important for the development of rehabilitation treatment strategies. This review focuses on recent findings on the effects of cytokines on myelin damage and remyelination as well as the progress of research on the role of cytokines in ischemic stroke prognosis to provide a new treatment approach for amelioration of white matter damage after stroke.

Cell therapy for central nervous system disorders: Current obstacles to progress

Cell therapy for disorders of the central nervous system has progressed to a new level of clinical application. Various clinical studies are underway for Parkinson's disease, stroke, traumatic brain injury, and various other neurological diseases. Recent biotechnological developments in cell therapy have taken advantage of the technology of induced pluripotent stem (iPS) cells. The advent of iPS cells has provided a robust stem cell donor source for neurorestoration via transplantation. Additionally, iPS cells have served as a platform for the discovery of therapeutics drugs, allowing breakthroughs in our understanding of the pathology and treatment of neurological diseases. Despite these recent advances in iPS, adult tissue‐derived mesenchymal stem cells remain the widely used donor for cell transplantation. Mesenchymal stem cells are easily isolated and amplified toward the cells' unique trophic factor‐secretion property. In this review article, the milestone achievements of cell therapy for central nervous system disorders, with equal consideration on the present translational obstacles for clinic application, are described.

The brain and eye: Treating cerebral and retinal ischemia through mitochondrial transfer

Stroke remains a devastating disease with limited treatment options, despite our growing understanding of its pathology. While ischemic stroke is traditionally characterized by a blockage of blood flow to the brain, this may coincide with reduced blood circulation to the eye, resulting in retinal ischemia, which may in turn lead to visual impairment. Although effective treatment options for retinal ischemia are similarly scarce, new evidence suggests that deleterious changes to mitochondrial structure and function play a major role in both cerebral and retinal ischemia pathologies. Prior studies establish that astrocytes transfer healthy mitochondria to ischemic neurons following stroke; however, this alone is not enough to significantly mitigate the damage caused by primary and secondary cell death. Thus, stem cell-based regenerative medicine targeting amelioration of ischemia-induced mitochondrial dysfunction via the transfer of functional mitochondria to injured neural cells represents a promising approach to improve stroke outcomes for both cerebral and retinal ischemia. In this review, we evaluate recent laboratory evidence supporting the remedial capabilities of mitochondrial transfer as an innovative stroke treatment. In particular, we examine exogenous stem cell transplants in their potential role as suppliers of healthy mitochondria to neurons, brain endothelial cells, and retinal cells.

Impact statement

Stroke constitutes a global health crisis, yet potent, applicable therapeutic options remain effectively inaccessible for many patients. To this end, stem cell transplants stand as a promising stroke treatment and as an emerging subject of research for cell-based regenerative medicine. This is the first review to synthesize the implications of stem cell-derived mitochondrial transfer in both the brain and the eye. As such, this report carries fresh insight into the commonalities between the two stroke-affected organs. We present the findings of this developing area of research inquiry with the hope that our evaluation may advance the use of stem cell transplants as viable therapeutic alternatives for ischemic stroke and related disorders characterized by mitochondrial dysfunction. Such lab-to-clinic translational advancement has the potential to save and improve the ever increasing millions of lives affected by stroke.

Hyperbaric oxygen therapy: A new look on treating stroke and traumatic brain injury

Although hyperbaric oxygen therapy (HBOT) is common as a treatment for injuries, this study aimed to research the ability of HBOT in preconditioning to diminish any potential damage. The hypothesis stated that HBOT preconditioning alleviated the death of cells in primary rat neuronal cells (PRNCs) by transferring mitochondria from astrocytes. In this experiment, PRNCs were given an HBOT treatment before a tumor necrosis factor-alpha or lipopolysaccharide injury which resembled cell death associated with stroke and traumatic brain injury (TBI). After being examined, the study found more cell viability in the PRNCs that had received HBOT precondition and a mitochondrial transfer. The mitochondrial transfer was visualized by a series of images showing the transfer after the HBOT treatment. This study demonstrated the ability of HBOT preconditioning as a treatment for inflammation in stroke and TBI, with the transfer of mitochondria from astrocytes to PRNCs reducing cell death. Along with discussion of the study, this review also focuses on different stroke treatments in comparison with HBOT.

Eye Opener in Stroke

Supplemental Digital Content is available in the text.

Retinal ischemia is a major cause of visual impairment in stroke patients, but our incomplete understanding of its pathology may contribute to a lack of effective treatment. Here, we investigated the role of mitochondrial dysfunction in retinal ischemia and probed the potential of mesenchymal stem cells (MSCs) in mitochondrial repair under such pathological condition.

Neuroinflammation caused by mental stress: the effect of chronic restraint stress and acute repeated social defeat stress in mice

Objectives: Cerebrovascular disease (CVD) is the leading cause of permanent disability worldwide. Inflammation has been reported to play an important role in the progression of CVD. Neuropsychiatric disorders such as depression are associated with increased incidence of CVD epidemiologically, although the mechanisms underlying this association are not clear. In this study, we assessed the effect of the acute repeated social defeat stress (RSDS) and chronic restraint stress (CRS) on neuroinflammation in mice. Methods: A total of 40 6-week-old male C57BL/6J mice were divided into RSDS, CRS, and corresponding control groups. In the RSDS group, male C57BL/6J mice were repeatedly subjected to bouts of social defeat by a larger CD-1 mouse for 10 min daily for 10 consecutive days. In the CRS group, the mice were exposed to restraint stress for 6 h per day for 28 consecutive days. Depressive behavior was evaluated by conducting sucrose preference test over 24 h. Peripheral blood serum and brain tissues were collected for measurement of corticosterone (CORT), epinephrine (EPI), and inflammatory factors (TNF-α and IL-6) using ELISA or real-time PCR 24 h after the sucrose preference test. Results: Both RSDS and CRS decreased the sucrose preference ratio. The acute stress increased serum CORT and EPI, while the chronic stress did not significantly influence them. Both stress models induced an inflammatory response in peripheral serum and the brain. Conclusions: RSDS and CRS are two effective models of depressive behavior, and both models cause neuroinflammation, which may be responsible for the increased risk of CVD seen in patients with depression.

Concise Review: Stem Cell Therapy for Stroke Patients: Are We There Yet?

Four decades of preclinical research demonstrating survival, functional integration, and behavioral effects of transplanted stem cells in experimental stroke models have provided ample scientific basis for initiating limited clinical trials of stem cell therapy in stroke patients. Although safety of the grafted cells has been overwhelmingly documented, efficacy has not been forthcoming. Two recently concluded stroke clinical trials on mesenchymal stem cells (MSCs) highlight the importance of strict adherence to the basic science findings of optimal transplant regimen of cell dose, timing, and route of delivery in enhancing the functional outcomes of cell therapy. Echoing the Stem Cell Therapeutics as an Emerging Paradigm for Stroke and Stroke Treatment Academic Industry Roundtable call for an NIH‐guided collaborative consortium of multiple laboratories in testing the safety and efficacy of stem cells and their derivatives, not just as stand‐alone but preferably in combination with approved thrombolytic or thrombectomy, may further increase the likelihood of successful fruition of translating stem cell therapy for stroke clinical application. The laboratory and clinical experience with MSC therapy for stroke may guide the future translational research on stem cell‐based regenerative medicine in neurological disorders. stem cells translational medicine2019;8:983&988

Prophylactic treatment of hyperbaric oxygen treatment mitigates inflammatory response via mitochondria transfer

Aims

Hyperbaric oxygen therapy (HBOT) has been widely used as postinjury treatment; however, we investigate its ability to mitigate potential damage as a preconditioning option. Here, we tested the hypothesis that HBOT preconditioning mitigates cell death in primary rat neuronal cells (PRNCs) through the transfer of mitochondria from astrocytes.

Methods

Primary rat neuronal cells were subjected to a 90‐minute HBOT treatment at 2.5 absolute atmospheres prior to either tumor necrosis factor‐alpha (TNF‐alpha) or lipopolysaccharide (LPS) injury to simulate the inflammation‐plagued secondary cell death associated with stroke and traumatic brain injury (TBI). After incubation with TNF‐alpha or LPS, the cell viability of each group was examined.

Results

There was a significant increase of cell viability accompanied by mitochondrial transfer in the injury groups that received HBOT preconditioning compared to the injury alone groups (44 ± 5.2 vs 68 ± 4.48, n = 20, P < 0.05). The transfer of mitochondria directly after HBOT treatment was visualized by capturing images in 5‐minute intervals, which revealed that the robust transfer of mitochondria begins soon after HBOT and persisted throughout the treatment.

Conclusion

This study shows that HBOT preconditioning stands as a robust prophylactic treatment for sequestration of inflammation inherent in stroke and TBI, possibly facilitating the transfer of resilient mitochondria from astrocytes to inflammation‐susceptible neuronal cells in mitigating cell death.

Inflammatory cytokines and cells are potential markers for patients with cerebral apoplexy in intensive care unit

Cerebral apoplexy is a disease caused by obstruction of the blood circulation in the brain. Evidence has indicated that inflammatory cytokines are implicated in ischaemic cerebral apoplexy and are regarded as a general cardiovascular risk factor, which may be a possible immediate trigger, a component of the response to tissue injury and a therapeutic target. The present study investigated changes of inflammatory cytokines and cells in patients with cerebral apoplexy at the intensive care unit (ICU). The plasma concentrations of inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-4, IL-6, IL-8, IL-10, IL-1β and IL-17A were evaluated using ELISA. Changes in the plasma concentrations of inflammatory cells were detected by using flow cytometry. The results indicated that serum levels of TNF-α, IL-4, IL-8, IL-1β and IL-17A were upregulated in patients with cerebral apoplexy compared with those in healthy individuals, while those of IL-6 and IL-10 were downregulated. Furthermore, it was demonstrated that the plasma concentration of lymphocytes, granulocytes and mononuclear cells was decreased in patients with cerebral apoplexy in the ICU compared with that in healthy individuals. Of note, humoral as well as cellular inflammatory cytokines were evidently increased in patients with cerebral apoplexy in ICU. In conclusion, the present study provided evidence that inflammatory cytokines and inflammatory cells are upregulated, while anti-inflammatory cytokines are downregulated in patients with cerebral apoplexy in an ICU setting. These results suggest that anti-inflammatory interventions may be beneficial either in the prevention or acute treatment of patients with cerebral apoplexy.