Optimizing functional outcome endpoints for stroke recovery studies

Stereotactic aspiration versus conservative management for primary brainstem hemorrhage: A systematic review and meta-analysis

BACKGROUND

Primary brainstem hemorrhage (PBSH) is a fatal condition related to hypertension. PBSH definitive treatment remains controversial, mainly when surgical options are discussed.

OBJECTIVE

To aid decision-making in PBSH scenarios, we aimed to perform a meta-analysis and evaluate the literature on stereotactic aspiration (SA) for PBSH in comparison to conservative management (CM).

METHODS

The outcomes assessed were: 30-day mortality, mortality, 90-day good outcome (mRs ≤ 3), good outcome (mRs ≤ 3), good outcome (mRs ≤ 3 or GOS 4-5), 90-day poor outcome (mRs ≥ 4), poor outcome (mRs ≥ 4).

RESULTS

We included 1189 patients from 9 studies. 433 (36,41 %) patients were treated with SA. The risk of 30-Day Mortality (RR 0.57; 95 % CI 0.41-0.81; p=0.002; I²=58 %), Mortality (RR 0.56; 95 % CI 0.41-0.75; p<0.001; I²=54 %), 90-Day Poor Outcome (mRS ≥ 4) (RR 0.83; 95 % CI 0.73-0.93; p=0.001; I²=25 %), Poor Outcome (mRS ≥ 4) (RR 0.83; 95 % CI 0.75-0.93; p=0.001; I²=0 %) and Poor Outcome (mRS ≥ 4 or GOS ≤ 3) (RR 0.82; 95 % CI 0.74-0.91; p<0.001; I²=12 %) were significantly lower in patients receiving SA treatment. Also, the risk of 90-Day Good Outcome (mRS ≤ 3) (RR 1.60; 95 % CI 1.06-2.39; p=0.024; I²=21 %), Good Outcome (mRS ≤ 3) (RR 1.48; 95 % CI 1.13-1.94; p=0.005; I²=0) and Good Outcome (mRS ≤ 3 or GOS 4-5) (RR 1.72; 95 % CI 1.17-2.53; p=0.006; I²=25 %) were significant higher in the SA group.

CONCLUSION

SA demonstrated favorable outcomes, including reduced mortality rates and improved functional recovery. Further clinical trials are needed to validate these findings.

Stem cell therapy: a new hope for stroke and traumatic brain injury recovery and the challenge for rural minorities in South Carolina

Stroke and traumatic brain injury (TBI) are a significant cause of death and disability nationwide. Both are considered public health concerns in rural communities in the state of South Carolina (SC), particularly affecting the African American population resulting in considerable morbidity, mortality, and economic burden. Stem cell therapy (SCT) has emerged as a potential intervention for both diseases with increasing research trials showing promising results. In this perspective article, the authors aim to discuss the current research in the field of SCT, the results of early phase trials, and the utilization of outcome measures and biomarkers of recovery. We searched PubMed from inception to December 2023 for articles on stem cell therapy in stroke and traumatic brain injury and its impact on rural communities, particularly in SC. Early phase trials of SCT in Stroke and Traumatic Brain injury yield promising safety profile and efficacy results, but the findings have not yet been consistently replicated. Early trials using mesenchymal stem cells for stroke survivors showed safety, feasibility, and improved functional outcomes using broad and domain-specific outcome measures. Neuroimaging markers of recovery such as Functional Magnetic Resonance Imaging (fMRI) and electroencephalography (EEG) combined with neuromodulation, although not widely used in SCT research, could represent a breakthrough when evaluating brain injury and its functional consequences. This article highlights the role of SCT as a promising intervention while addressing the underlying social determinants of health that affect therapeutic outcomes in relation to rural communities such as SC. It also addresses the challenges ethical concerns of stem cell sourcing, the high cost of autologous cell therapies, and the technical difficulties in ensuring transplanted cell survival and strategies to overcome barriers to clinical trial enrollment such as the ethical concerns of stem cell sourcing, the high cost of autologous cell therapies, and the technical difficulties in ensuring transplanted cell survival and equitable healthcare.

The Simultaneous Application of Transcranial Magnetic Stimulation and Virtual Reality to Treat Cognitive Deficits Among Stroke Patients: A Randomized Controlled Trial

Background and objective Integrating virtual reality (VR) and transcranial magnetic stimulation (TMS) offers a promising strategy for stroke rehabilitation, as it specifically focuses on reorganizing neural connections and activating brain activity in the cortex. The main goal is to create equitable connections between the brain's two hemispheres to enhance the execution of voluntary movements by stimulating the central executive network (CEN) to strengthen both motor and cognitive abilities. This study aims to propose a therapeutic approach that can improve cognitive recovery and overall quality of life in patients after a stroke. Methods A total of 69 participants were enrolled in the study based on certain inclusion and exclusion criteria. The patients underwent pre-assessment and were randomly allocated into three groups: Group 1 received simultaneous repetitive TMS (rTMS) and virtual reality treatment (VRT), Group 2 received rTMS combined with sham VRT, and Group 3 received sham stimulation with VRT, in a 1:1:1 ratio using opaque, sealed, and stapled envelopes (SNOSE). Post-assessment was carried out using the same measures: the National Institutes of Health Stroke Scale (NIHSS), Addenbrooke's Cognitive Test (ACE III), and Montreal Cognitive Assessment (MOCA). Statistical analysis was conducted to determine the specific outcomes. Data analysis was carried out using IBM SPSS Statistics version 29 (IBM Corp., Armonk, NY), employing student's t-test for within-group comparisons and repeated measures ANOVA for between-group comparisons. The significance level was set at 5%. Results The results demonstrated statistical significance in NIHSS scores across all treatment groups (p<0.001). Regarding cognitive outcomes, improvements were observed in memory, language, and overall cognitive performance (ACE III) within all groups (p<0.05), with significant between-group outcomes (p = 0.009, p = 0.01, p = 0.004, respectively), suggesting variations in treatment effects across cognitive domains. However, no significant differences between groups were found in terms of fluency and visuospatial skills (p = 0.49, p = 0.13), indicating no treatment effects in these domains. Conclusions Based on our findings, the combined intervention involving rTMS and VRT, compared to sham treatments, demonstrates promising outcomes in alleviating stroke severity and improving specific cognitive functions such as memory, language, and overall cognitive performance. Additionally, the combined administration offers a more effective therapy than when they are administered separately.

Hi1a Improves Sensorimotor Deficit following Endothelin-1-Induced Stroke in Rats but Does Not Improve Functional Outcomes following Filament-Induced Stroke in Mice

Activation of acid-sensing ion channel 1a (ASIC1a) plays a major role in mediating acidosis-induced neuronal injury following a stroke. Therefore, the inhibition of ASIC1a is a potential therapeutic avenue for the treatment of stroke. Venom-peptide Hi1a, a selective and highly potent ASIC1a inhibitor, reduces the infarct size and functional deficits when injected into the brain after stroke in rodents. However, its efficacy when administered using a clinically relevant route of administration remains to be established. Therefore, the current investigation aims to examine the efficacy of systemically administered Hi1a, using two different models of stroke in different species. Mice were subjected to the filament model of middle cerebral artery occlusion (MCAO) and treated with Hi1a systemically using either a single- or multiple-dosing regimen. 24 h poststroke, mice underwent functional testing, and the brain infarct size was assessed. Rats were subjected to endothelin-1 (ET-1)-induced MCAO and treated with Hi1a intravenously 2 h poststroke. Rats underwent functional tests prior to and for 3 days poststroke, when infarct volume was assessed. Mice receiving Hi1a did not show any improvements in functional outcomes, despite a trend toward reduced infarct size. This trend for reduced infarct size in mice was consistent regardless of the dosing regimen. There was also a trend toward lower infarct size in rats treated with Hi1a. More specifically, Hi1a reduced the amount of damage occurring within the somatosensory cortex, which was associated with an improved sensorimotor function in Hi1a-treated rats. Thus, this study suggests that Hi1a or more brain-permeable ASIC1a inhibitors are a potential stroke treatment.

'Physical well-being is our top priority': Healthcare professionals' challenges in supporting psychosocial well-being in stroke services

BACKGROUND

Following stroke, a sense of well-being is critical for quality of life. However, people living with stroke, and health professionals, suggest that well-being is not sufficiently addressed within stroke services, contributing to persistent unmet needs. Knowing that systems and structures shape clinical practice, this study sought to understand how health professionals address well-being, and to examine how the practice context influences care practice.

METHODS

Underpinned by Interpretive Description methodology, we interviewed 28 health professionals across multiple disciplines working in stroke services (acute and rehabilitation) throughout New Zealand. Data were analysed using applied tension analysis.

RESULTS

Health professionals are managing multiple lines of work in stroke care: biomedical work of investigation, intervention and prevention; clinical work of assessment, monitoring and treatment; and moving people through service. While participants reported working to support well-being, this could be deprioritised amidst the time-oriented pressures of the other lines of work that were privileged within services, rendering it unsupported and invisible.

CONCLUSION

Stroke care is shaped by biomedical and organisational imperatives that privilege physical recovery and patient throughput. Health professionals are not provided with the knowledge, skills, time or culture of care that enable them to privilege well-being within their work. This has implications for the well-being of people with stroke, and the well-being of health professionals. In making these discourses and culture visible, and tracing how these impact on clinical practice, we hope to provide insight into why well-being work remains other to the 'core' work of stroke, and what needs to be considered if stroke services are to better support people's well-being.

PATIENT OR PUBLIC CONTRIBUTIONS

People with stroke, family members and people who provide support to people with stroke, and health professionals set priorities for this research. They advised on study conduct and have provided feedback on wider findings from the research.

Exploring the efficacy of virtual reality-based rehabilitation in stroke: a narrative review of current evidence

BACKGROUND

Stroke rehabilitation presents a complex challenge, necessitating innovative approaches to optimise functional recovery. Virtual Reality-Based Rehabilitation (VRBR) has emerged as a promising intervention that capitalises on immersive technology to engage stroke survivors in their recovery journey. This review aims to examine the efficacy of VRBR in stroke rehabilitation, focusing on its advantages and challenges.

METHODS

A comprehensive search of relevant literature was conducted to gather evidence on the efficacy of VRBR in stroke survivors. Studies that investigated the impact of VRBR on patient engagement, functional recovery, and overall rehabilitation outcomes were included. The review also assessed the ability of VRBR to simulate real-life scenarios and facilitate essential daily activities for stroke survivors.

RESULTS

The review highlights that VRBR offers a unique immersive experience that enhances patient engagement and motivation during rehabilitation. The immersive nature of VRBR fosters a sense of presence, which can positively impact treatment adherence and outcomes. Moreover, VRBR's capacity to replicate real-world scenarios provides stroke survivors with opportunities to practice vital daily activities, promoting functional independence. In contrast, conventional rehabilitation methods lack the same level of engagement and real-world simulation.

CONCLUSION

VRBR holds promise as an efficacious intervention in stroke rehabilitation. Its immersive nature enhances patient engagement and motivation, potentially leading to better treatment adherence and outcomes. The ability of VRBR to simulate real-life scenarios offers a unique platform. However, challenges such as cost, equipment, patient suitability, data privacy, and acceptance must be addressed for successful integration into stroke rehabilitation practice.

The relationship between Rating of Everyday Arm-use in the Community and Home (REACH) scale affected arm-use assessment, activity and participation after stroke

BACKGROUND AND OBJECTIVES

While arm function has been traditionally used as a primary goal for upper extremity rehabilitation post-stroke, we propose a simple measure of arm use, which may translate into better activities and participation. The aim was to determine the relationship between arm use and measures of activity and participation.

METHODS

This was a cross-sectional study with evaluative components involving community-dwelling individuals with chronic stroke. The Rating of Everyday Arm-Use in the Community and Home (REACH) Scale was used to assess affected arm use, Barthel Index and activity domain of the Stroke Impact Scale (SIS) for activities, and participation domain of the SIS for participation. The participants were also asked if they resumed driving after the stroke.

RESULTS

Forty-nine individuals (mean age = 70.3 ± 11.5 years, male sex = 51%) living with the effects of a stroke for at least 3 months participated in this study. There was a positive relationship between affected arm use and activities (Barthel Index score - rs  = 0.464; SIS activities - rs  = 0.686), participation (rs  = 0.479), and driving (rs  = 0.581). The Barthel Index scores were higher for individuals with dominant arm hemiparesis (p = 0.003) or left hemisphere lesions (p = 0.005). There was also greater arm use in left hemisphere lesions (p = 0.018).

CONCLUSIONS

Affected arm use in individuals with chronic stroke is related to activities and participation. Given the importance of arm use in activities and participation after stroke, rehabilitation therapists may consider utilizing the REACH Scale, a simple and quick outcome measure, as a means to assess arm use and implement effective interventions for improving arm use.

Study on the Cutoff Value of Backward Walking Speed to Distinguish the Mobility Deficits of Stroke Patients

BACKGROUND: Backward walking speed is an objective index to evaluate motor ability, but it is not clear whether it can screen stroke patients with mobility disorders. This study aims to test the diagnostic efficacy of backward maximum walking speed (BMWS) and backward comfortable walking speed (BCWS) on mobility defects in stroke patients and obtain the cutoff values of them. METHODS: We conducted a cross-sectional study of poststroke patients who were hospitalized from July 2021 to January 2022. 98 poststroke patients were selected for 6 functional tests and divided into the high–mobility function group and low–mobility function group by K-means cluster analysis. According to the test results of BMWS and BCWS, the receiver operating characteristic curve was drawn to determine the cutoff values and compare the diagnostic efficiency of the 2 indexes. RESULTS: The BMWS of stroke patients was 0.54 (0.29) m/s, and the BCWS was 0.37 (0.19) m/s. Receiver operating characteristic results showed that the cutoff value of BMWS for the diagnosis of mobility impairment in stroke patients was 0.3 m/s, the area under the curve was 0.95 (95% confidence interval, 0.89–0.98), the specificity was 0.86, and the sensitivity was 0.93. The cutoff value of BCWS was 0.27 m/s, the area under the curve was 0.91 (95% confidence interval, 0.84–0.96), the specificity was 0.91, and the sensitivity was 0.8. There was no significant difference between the 2 indexes in the diagnosis of mobility defects in stroke patients (P > .05). CONCLUSIONS: Backward walking speed is a useful indicator for discriminating stroke patients with mobility deficits. Considering the risks associated with backward walking, BCWS can be used in clinical assessments to guide nurses in the development and implementation of rehabilitation programs.

High-resolution micro-CT for 3D infarct characterization and segmentation in mice stroke models

Characterization of brain infarct lesions in rodent models of stroke is crucial to assess stroke pathophysiology and therapy outcome. Until recently, the analysis of brain lesions was performed using two techniques: (1) histological methods, such as TTC (Triphenyltetrazolium chloride), a time-consuming and inaccurate process; or (2) MRI imaging, a faster, 3D imaging method, that comes at a high cost. In the last decade, high-resolution micro-CT for 3D sample analysis turned into a simple, fast, and cheaper solution. Here, we successfully describe the application of brain contrasting agents (Osmium tetroxide and inorganic iodine) for high-resolution micro-CT imaging for fine location and quantification of ischemic lesion and edema in mouse preclinical stroke models. We used the intraluminal transient MCAO (Middle Cerebral Artery Occlusion) mouse stroke model to identify and quantify ischemic lesion and edema, and segment core and penumbra regions at different time points after ischemia, by manual and automatic methods. In the transient-ischemic-attack (TIA) mouse model, we can quantify striatal myelinated fibers degeneration. Of note, whole brain 3D reconstructions allow brain atlas co-registration, to identify the affected brain areas, and correlate them with functional impairment. This methodology proves to be a breakthrough in the field, by providing a precise and detailed assessment of stroke outcomes in preclinical animal studies.

Sam50 exerts neuroprotection by maintaining the mitochondrial structure during experimental cerebral ischemia/reperfusion injury in rats

AIM

To investigate the role of Sam50, a barrel protein on the surface of the mitochondrial outer membrane, in cerebral ischemia-reperfusion (I/R) injury and its underlying mechanisms.

METHODS

A middle cerebral artery occlusion/reperfusion (MCAO/R) model in adult male Sprague-Dawley rats was established in vivo, and cultured neurons were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate I/R injury in vitro. Lentiviral vector encoding Sam50 or Sam50 shRNA was constructed and administered to rats by intracerebroventricular injection to overexpress and knockdown Sam50, respectively.

RESULTS

First, after MCAO/R induction, the mitochondrial structure was damaged, and Sam50 protein levels were increased responsively both in vivo and in vitro. Then, it was found that Sam50 overexpression could reduce infarction size, inhibit neuronal cell death, improve neurobehavioral disability, protect mitochondrial structure integrity, and ameliorate mitochondrial dysfunction, which was induced by I/R injury both in vivo and in vitro. However, Sam50 downregulation showed the opposite results and aggravated I/R injury by inducing neuronal cell death, neurobehavioral disability, and mitochondrial dysfunction. Moreover, we found that the interaction between Sam50 and Mic19 was broken off after OGD/R, showing that the Sam50-Mic19-Mic60 axis was breakage in neurons, which would be a reason for mitochondrial structure and function abnormalities induced by I/R injury.

CONCLUSION

Sam50 played a vital role in the protection of neurons and mitochondria in cerebral I/R injury, which could be a novel target for mitochondrial protection and ameliorating I/R injury.

Bridging the Transient Intraluminal Stroke Preclinical Model to Clinical Practice: From Improved Surgical Procedures to a Workflow of Functional Tests

Acute ischemic stroke (AIS) remains a leading cause of mortality, despite significant advances in therapy (endovascular thrombectomy). Failure in developing novel effective therapies is associated with unsuccessful translation from preclinical studies to clinical practice, associated to inconsistent and highly variable infarct areas and lack of relevant post-stroke functional evaluation in preclinical research. To outreach these limitations, we optimized the intraluminal transient middle cerebral occlusion, a widely used mouse stroke model, in two key parameters, selection of appropriate occlusion filaments and time of occlusion, which show a significant variation in the literature. We demonstrate that commercially available filaments with short coating length (1–2 mm), together with 45-min occlusion, results in a consistent affected brain region, similar to what is observed in most patients with AIS. Importantly, a dedicated post-stroke care protocol, based on clinical practice applied to patients who had stroke, resulted in lower mortality and improved mice welfare. Finally, a battery of tests covering relevant fine motor skills, sensory functions, and learning/memory behaviors revealed a significant effect of tMCAO brain infarction, which is parallel to patient symptomatology as measured by relevant clinical scales (NIH Stroke Scale, NIHSS and modified Rankin Scale, mRS). Thus, in order to enhance translation to clinical practice, future preclinical stroke research must consider the methodology described in this study, which includes improved reproducible surgical procedure, postoperative care, and the battery of functional tests. This will be a major step s closing the gap from bench to bedside, rendering the development of novel effective therapeutic approaches.

Time-Varying Risk Factors Associated With the Progress of Functional Recovery and Psychological Distress in First-Ever Stroke Patients

ABSTRACT

BACKGROUND: Evaluation of stroke recovery outcome is crucial and a major goal of clinical practice. A recovery trajectory model serves as a prognostic tool that enables development of effective intervention and long-term management to improve poststroke recovery outcomes. This study explored time-varying risk factors associated with the progression of functional recovery and psychological distress poststroke. METHODS: Participants were patients with first-ever stroke who underwent assessment for activities of daily living, psychological distress, and social support at the onset (within 72 hours) and at 1, 3, and 6 months. A generalized estimation equation was used to account for the correlation between the repeated measurements. RESULTS: Of the 101 patients, 60.4% were men, and the mean (SD) age was 63.06 (13.12) years. Over time, the physical functions of patients after stroke significantly increased, and anxiety and depression significantly decreased. Approximately 50% of patients achieved full functional recovery after 6 months. The time-varying risk factors for National Institutes of Health Stroke Scale scores and depression levels affected the trajectory of functional recovery during follow-up. Factors associated with patient anxiety levels were National Institutes of Health Stroke Scale scores and depression levels. Factors associated with patient depression levels included education, anxiety, and social support levels. CONCLUSION: This study demonstrates the progression of time-varying risk factors for functional recovery and psychological distress in patients with first-ever stroke. We recommend that nurses work with patients and their families in the early poststroke stages to identify comprehensive goals based on individual needs and related factors at different stages and that they educate patients on what is required for them to regain independence.

Neurofunctional and neuroimaging readouts for designing a preclinical stem-cell therapy trial in experimental stroke

With the aim of designing a preclinical study evaluating an intracerebral cell-based therapy for stroke, an observational study was performed in the rat suture model of ischemic stroke. Objectives were threefold: (i) to characterize neurofunctional and imaging readouts in the first weeks following transient ischemic stroke, according to lesion subtype (hypothalamic, striatal, corticostriatal); (ii) to confirm that intracerebral administration does not negatively impact these readouts; and (iii) to calculate sample sizes for a future therapeutic trial using these readouts as endpoints. Our results suggested that the most relevant endpoints were side bias (staircase test) and axial diffusivity (AD) (diffusion tensor imaging). Hypothalamic-only lesions did not affect those parameters, which were close to normal. Side bias in striatal lesions reached near-normal levels within 2 weeks, while rats with corticostriatal lesions remained impaired until week 14. AD values were decreased at 4 days and increased at 5 weeks post-surgery, with a subtype gradient: hypothalamic < striatal < corticostriatal. Intracerebral administration did not impact these readouts. After sample size calculation (18-147 rats per group according to the endpoint considered), we conclude that a therapeutic trial based on both readouts would be feasible only in the framework of a multicenter trial.

The Emergence of Stereotyped Kinematic Synergies when Mice Reach to Grasp Following Stroke

Reaching tasks are commonly used in preclinical and clinical studies to assess the acquisition of fine motor skills and recovery of function following stroke. These tasks are often used to assess functional deficits in the absence of quantifying the quality of movement which requires kinematic analysis. To meet this need, this study uses a kinematic analysis in mice performing the Montoya staircase task at 5 and 14 days following a cortical photothrombosis-induced stroke. Following stroke, the mice had reaching impairments associated with sustained deficits including longer, unsmooth, and less individuated paw trajectories. Two weeks after stroke we also detected the emergence of abnormal elbow and shoulder angles, flexion/extensions, and stereotyped kinematic synergies. These data suggest that proximal and distal segments acting in concert is paramount during post-stroke reaching and encourage further analysis of synergies within the translational pipeline of preclinical to clinical studies.

Progress and challenges in preclinical stroke recovery research

Significant innovations in the management of acute ischemic stroke have led to an increased incidence in the long-term complications of stroke. Therefore, there is an urgent need for improvements in and refinement of rehabilitation interventions that can lead to functional and neuropsychological recovery. The goal of this review is to summarize the current progress and challenges involved with preclinical stroke recovery research. Moving forward, stroke recovery research should be placing an increased emphasis on the incorporation of comorbid diseases and biological variables in preclinical models in order to overcome translational roadblocks to establishing successful clinical rehabilitation interventions.

Change and predictive ability of circulating immunoregulatory lymphocytes in long-term outcomes of acute ischemic stroke

Lymphocytes play an important role in the immune response after stroke. However, our knowledge of the circulating lymphocytes in ischemic stroke is limited. Herein, we collected the blood samples of clinical ischemic stroke patients to detect the change of lymphocytes from admission to 3 months after ischemic stroke by flow cytometry. A total of 87 healthy controls and 210 patients were enrolled, and the percentages of circulating T cells, CD4⁺ T cells, CD8⁺ T cells, double negative T cells (DNTs), CD4⁺ regulatory T cells (Tregs), CD8⁺ Tregs, B cells and regulatory B cells (Bregs) were measured. Among patients, B cells, Bregs and CD8⁺ Tregs increased significantly, while CD4⁺ Tregs dropped and soon reversed after ischemic stroke. CD4⁺ Tregs, CD8⁺ Tregs, and DNTs also showed high correlations with the infarct volume and neurological scores of patients. Moreover, these lymphocytes enhanced the predictive ability of long-term prognosis of neurological scores when added to basic clinical information. The percentage of CD4⁺ Tregs within lymphocytes showed high correlations with both acute and long-term neurological outcomes, which exhibited a great independent predictive ability. These findings suggest that CD4⁺ Tregs can be a biomarker to predict stroke outcomes and improve existing therapeutic strategies of immunoregulatory lymphocytes.

Wiring and plumbing: Oligodendrocyte precursors and angiogenesis in the oligovascular niche

For efficient stroke recovery, the entire neurovascular unit must be repaired. A recent study underscores this concept by highlighting the importance of cellular crosstalk for white mater remodeling. In developing brains and in brains injured by hypoxia, interactions between oligodendrocyte precursors and endothelium play an essential role for physiological and compensatory angiogenesis. Further studies are warranted to build on these emerging findings in the oligovascular niche in order to identify novel therapeutic targets for stroke and other CNS diseases.

Translational Value of Skilled Reaching Assessment in Clinical and Preclinical Studies on Motor Recovery After Stroke

Background

Assessment of skilled reaching enables extensive analysis of upper limb function in clinical and preclinical studies on poststroke outcome. However, translational research if often limited by lack of correspondence between tests of human and rodent motor function.

Objectives

To determine (1) the translational value of skilled reaching performance for preclinical research by comparing the behavioral recovery profiles of skilled reaching characteristics between humans and rats recovering from stroke and (2) the relationship between skilled reaching performance and commonly used clinical outcome measures after stroke.

Methods

Twelve patients with ischemic or hemorrhagic stroke and 17 rats with photothrombotic stroke underwent an equivalent skilled reaching test at different time points, representing early to late subacute stages poststroke. Success scores and a movement element rating scale were used to measure the skilled reaching performance. The Fugl-Meyer Upper Extremity (FM-UE) assessment and the Action Research Arm Test (ARAT) were used as clinical outcome measures.

Results

Both species had muscle flaccidity at the early subacute stage after stroke and showed motor recovery following a proximal-distal principle toward the early subacute stage, albeit for rats within a shorter time course. Human skilled reaching scores and FM-UE and ARAT scores in the first 3 months poststroke were significantly correlated (P < .05).

Conclusions

Our study demonstrates that poststroke changes in skilled reaching performance are highly similar between rats and humans and correspond with standard clinical outcome measures. Skilled reaching testing therefore offers an effective and highly translational means for assessment of motor recovery in experimental and clinical stroke settings.

CD36 deficiency reduces chronic BBB dysfunction and scar formation and improves activity, hedonic and memory deficits in ischemic stroke

Ameliorating blood-brain barrier disruption and altering scar formation dynamics are potential strategies that may improve post-stroke recovery. CD36 is a class B scavenger receptor that plays a role in innate immunity, inflammation and vascular dysfunction and regulates post-stroke injury, neovascularization, reactive astrogliosis and scar formation. By subjecting WT and CD36KO mice to different MCAo occlusion durations to generate comparable acute lesion sizes, we addressed the role of CD36 in BBB dysfunction, scar formation and recovery. The majority of stroke recovery studies primarily focus on motor function. Here, we employed an extensive behavioral test arsenal to evaluate psychological and cognitive endpoints. While not evident during the acute phase, CD36 deficient mice displayed significantly attenuated BBB leakage and scar formation at three months after stroke compared to wild-type littermates. Assessment of motor (open field, rotarod), anxiety (plus maze, light-dark box), depression (forced swim, sucrose preference) and memory tests (water maze) revealed that CD36 deficiency ameliorated stroke-induced behavioral impairments in activity, hedonic responses and spatial learning and strategy switching. Our findings indicate that CD36 contributes to stroke-induced BBB dysfunction and scar formation in an injury-independent manner, as well as to the chronic motor and neurophysiological deficits in chronic stroke.

Principles and requirements for stroke recovery science

The disappointing results in bench-to-bedside translation of neuroprotective strategies caused a certain shift in stroke research towards enhancing the endogenous recovery potential of the brain. One reason for this focus on recovery is the much wider time window for therapeutic interventions which is open for at least several months. Since recently two large clinical studies using d-amphetamine or fluoxetine, respectively, to enhance post-stroke neurological outcome failed again it is a good time for a critical reflection on principles and requirements for stroke recovery science. In principal, stroke recovery science deals with all events from the molecular up to the functional and behavioral level occurring after brain ischemia eventually ending up with any measurable improvement of various clinical parameters. A detailed knowledge of the spontaneously occurring post-ischemic regeneration processes is the indispensable prerequisite for any therapeutic approaches aiming to modify these responses to enhance post-stroke recovery. This review will briefly illuminate the molecular mechanisms of post-ischemic regeneration and the principle possibilities to foster post-stroke recovery. In this context, recent translational approaches are analyzed. Finally, the principal and specific requirements and pitfalls in stroke recovery research as well as potential explanations for translational failures will be discussed.

Biphasic roles of pentraxin 3 in cerebrovascular function after white matter stroke

Recent clinical studies suggest that pentraxin 3 (PTX3), which is known as an acute-phase protein that is produced rapidly at local sites of inflammation, may be a new biomarker of disease risk for central nervous system disorders, including stroke. However, the effects of PTX3 on cerebrovascular function in the neurovascular unit (NVU) after stroke are mostly unknown, and the basic research regarding the roles of PTX3 in NVU function is still limited. In this reverse translational study, we prepared mouse models of white matter stroke by vasoconstrictor (ET-1 or L-Nio) injection into the corpus callosum region to examine the roles of PTX3 in the pathology of cerebral white matter stroke. PTX3 expression was upregulated in GFAP-positive astrocytes around the affected region in white matter for at least 21 days after vasoconstrictor injection. When PTX3 expression was reduced by PTX3 siRNA, blood-brain barrier (BBB) damage at day 3 after white matter stroke was exacerbated. In contrast, when PTX3 siRNA was administered at day 7 after white matter stroke, compensatory angiogenesis at day 21 was promoted. In vitro cell culture experiments confirmed the inhibitory effect of PTX3 in angiogenesis, that is, recombinant PTX3 suppressed the tube formation of cultured endothelial cells in a Matrigel-based in vitro angiogenesis assay. Taken together, our findings may support a novel concept that astrocyte-derived PTX3 plays biphasic roles in cerebrovascular function after white matter stroke; additionally, it may also provide a proof-of-concept that PTX3 could be a therapeutic target for white matter-related diseases, including stroke.

Can oligodendrocyte precursor cells be a therapeutic target for mitigating cognitive decline in cerebrovascular disease?

Oligodendrocyte precursor cells (OPCs) give rise to mature myelin-forming oligodendrocytes during white matter development. In adult brains, some populations of OPCs remain to renew oligodendrocyte pools and myelin. Two recent studies highlight the importance of OPCs in white matter homeostasis. Genetic tracing studies suggest that age-related decline in OPCs may contribute to diminished myelin renewal and memory deficits in mouse models. Single cell transcriptomics and imaging may now define specific subsets of OPCs involved in process elaboration, motility and myelination. These advances raise the possibility of pursuing OPCs as novel therapeutic targets for vascular cognitive impairment.

TMEM16F Aggravates Neuronal Loss by Mediating Microglial Phagocytosis of Neurons in a Rat Experimental Cerebral Ischemia and Reperfusion Model

Cerebral ischemia is a severe, acute condition, normally caused by cerebrovascular disease, and results in high rates of disability, and death. Phagoptosis is a newly recognized form of cell death caused by phagocytosis of viable cells, and has been reported to contribute to neuronal loss in brain tissue after ischemic stroke. Previous data indicated that exposure of phosphatidylserine to viable neurons could induce microglial phagocytosis of such neurons. Phosphatidylserine can be reversibly exposed to viable cells as a result of a calcium-activated phospholipid scramblase named TMEM16F. TMEM16F-mediated phospholipid scrambling on platelet membranes is critical for hemostasis and thrombosis, which plays an important role in Scott syndrome and has been confirmed by much research. However, few studies have investigated the association between TMEM16F and phagocytosis in ischemic stroke. In this study, a middle-cerebral-artery occlusion/reperfusion (MCAO/R) model was used in adult male Sprague-Dawley rats in vivo, and cultured neurons were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate cerebral ischemia-reperfusion (I/R) injury in vitro. We found that the protein level of TMEM16F was significantly increased at 12 h after I-R injury both in vivo and in vitro, and reversible phosphatidylserine exposure was confirmed in neurons undergoing I/R injury in vitro. Additionally, we constructed a LV-TMEM16F-RNAi transfection system to suppress the expression of TMEM16F during and after cerebral ischemia. As a result, TMEM16F knockdown alleviated motor function injury and decreased the microglial phagocytosis of viable neurons in the penumbra through inhibiting the “eat-me” signal phosphatidylserine. Our data indicate that reducing neuronal phosphatidylserine-exposure via deficiency of TMEM16F blocks phagocytosis of neurons and rescues stressed-but-still-viable neurons in the penumbra, which may contribute to reducing infarct volume and improving functional recovering.