Stroke: The past, present and future

Brain energy metabolism: A roadmap for future research

Although we have learned much about how the brain fuels its functions over the last decades, there remains much still to discover in an organ that is so complex. This article lays out major gaps in our knowledge of interrelationships between brain metabolism and brain function, including biochemical, cellular, and subcellular aspects of functional metabolism and its imaging in adult brain, as well as during development, aging, and disease. The focus is on unknowns in metabolism of major brain substrates and associated transporters, the roles of insulin and of lipid droplets, the emerging role of metabolism in microglia, mysteries about the major brain cofactor and signaling molecule NAD+, as well as unsolved problems underlying brain metabolism in pathologies such as traumatic brain injury, epilepsy, and metabolic downregulation during hibernation. It describes our current level of understanding of these facets of brain energy metabolism as well as a roadmap for future research.

Gender disparity versus equality in acute stroke: a Middle Eastern country hospital-based study

Background

Acute stroke management is well-established in developed countries with no gender difference. Yet, in developing countries there are reports on gender disparity in medical services including stroke services. Egypt, a developing low-middle-income country, heavily populated, in the Middle East is a good example to answer whether acute ischemic stroke service is provided equally to males and females or there is disparity in risk factors, onset to door (OTD), door to needle (DTN), and outcome. The current study was prospective observational analytical hospital-based study, on acute ischemic stroke cases admitted to Nasr city insurance hospital stroke unit between September 2020 and September 2022.

Results

350 cases were included, 257 males and 93 females. Hypertension was the commonest risk factor 66% males and 81% females P = 0.011, atrial fibrillation was predominant in females P < 0.001, smoking was predominant in males P < 0.001. Median OTD in hours was 8.0 among both genders with minimum zero and maximum 96 h in males compared to minimum 1 and maximum 120 h in females, DTN was around 30 min with no significant difference. Median NIHSS on which rtPA was administered was 12.5 (6-13) in females compared to 10 (6-12) in males. Males who did not receive rtPA had a better mRS on discharge and on 90 days P = 0.01, 0.009, respectively, while there was no significant difference on discharge and 90 days between both genders on receiving rtPA.

Conclusions

No gender disparity was found in DTN, discharge outcome, and 90 days among rtPA recipients. Females tended to have higher NIHSS and relatively delayed presentation to ER with less favorable outcome at discharge and 90 days in case of not receiving rtPA. Encouraging earlier arrival and conducting awareness campaigns for risk factors management is warranted.

International research priority setting exercises in stroke: A systematic review

BACKGROUND

Agreeing on priority topics for stroke research can help make best use of limited funding, people, and time. Formal priority-setting exercises collate stakeholders' opinions to reach consensus on the most important research questions. Several stroke research priority setting exercises have been published. Exploring commonalities and differences between these exercises could bring a better understanding of priority research topics.

AIM

We collated and compared published stroke research priority setting exercises across international healthcare systems.

SUMMARY OF REVIEW

Multidisciplinary, electronic literature databases were searched from 2000 to 2021, using a validated search syntax. Inclusion criteria were: full article; stroke focus (any subtype); prioritization method described; and lists priorities for research. Priorities were extracted, coded, and assigned to categories using thematic analysis. The Nine Common Themes of Good Practice and the Reporting guideline for priority setting of health research checklists were used to assess methodological and reporting quality respectively. From 623 titles assessed, 14 studies were eligible for inclusion, including 2410 participants and describing 165 priorities. The majority of priority setting exercises were conducted in high-income countries (86%, n = 12 articles), published between 2011 and 2021 (64%, n = 9), and included views of healthcare professionals (57%, n = 8), and stroke survivors (50%, n = 7). Caregivers (n = 3, 21%) were under-represented. The James Lind Alliance priority setting method was most commonly used (50%, n = 7). Priorities were grouped into 10 thematic categories. Rehabilitation and follow-up was the most common priority theme (15%, n = 25 priorities), followed by psychological recovery (14%, n = 23), pathology (14%, n = 23), and caregivers and support (14%, n = 23). Priorities differed by year and case-mix (stakeholder group and demographics) of respondents. No article was judged high quality for all aspects of method or reporting. Common limitations were around inclusiveness and evaluation of the exercise.

CONCLUSION

Stroke research priorities are dynamic and context-specific. However, there was a common theme of prioritizing research that considered life after stroke. Future priority settings should consider the inclusion of nonindustrialized countries and stroke survivors with a range of impairments.

Ischemic Stroke, Lessons from the Past towards Effective Preclinical Models

Ischemic stroke is a leading cause of death worldwide, mainly in western countries. So far, approved therapies rely on reperfusion of the affected brain area, by intravenous thrombolysis or mechanical thrombectomy. The last approach constitutes a breakthrough in the field, by extending the therapeutic window to 16-24 h after stroke onset and reducing stroke mortality. The combination of pharmacological brain-protective strategies with reperfusion is the future of stroke therapy, aiming to reduce brain cell death and decrease patients' disabilities. Recently, a brain-protective drug-nerinetide-reduced brain infarct and stroke mortality, and improved patients' functional outcomes in clinical trials. The success of new therapies relies on bringing preclinical studies and clinical practice close together, by including a functional outcome assessment similar to clinical reality. In this review, we focused on recent upgrades of in vitro and in vivo stroke models for more accurate and effective evaluation of therapeutic strategies: from spheroids to organoids, in vitro models that include all brain cell types and allow high throughput drug screening, to advancements in in vivo preclinical mouse stroke models to mimic the clinical reality in surgical procedures, postsurgical care, and functional assessment.

A Historical Review of Brain Drug Delivery

The history of brain drug delivery is reviewed beginning with the first demonstration, in 1914, that a drug for syphilis, salvarsan, did not enter the brain, due to the presence of a blood-brain barrier (BBB). Owing to restricted transport across the BBB, FDA-approved drugs for the CNS have been generally limited to lipid-soluble small molecules. Drugs that do not cross the BBB can be re-engineered for transport on endogenous BBB carrier-mediated transport and receptor-mediated transport systems, which were identified during the 1970s-1980s. By the 1990s, a multitude of brain drug delivery technologies emerged, including trans-cranial delivery, CSF delivery, BBB disruption, lipid carriers, prodrugs, stem cells, exosomes, nanoparticles, gene therapy, and biologics. The advantages and limitations of each of these brain drug delivery technologies are critically reviewed.

[Methods to restore fine motor skills in stroke patients]

The review article considers the problem of nonmedical post-stroke rehabilitation, in particular the restoration of fine motor skills in patients in the early period of the disease. A review and analysis of various randomized controlled trials concerning the use of various rehabilitation methods both in monotherapy and in their combined application is carried out, and modern technical devices, with the use of computer technology and biofeedback, are reviewed. Proceeding from the presented literature data and their analysis, there are certain grounds for introducing modern apparatus complexes and robotized devices for fine motor skills restoration in post-stroke patients, especially in the early period, into the multimodal rehabilitation system. However, further research in this direction is needed to achieve a sustained positive result.

Fecal Calprotectin Is Increased in Stroke

Background: While there have been major advances in unveiling the mechanisms comprising the ischemic cascade of CNS, stroke continues to be a significant burden. There is a need to extend the focus toward peripheral changes, and the brain–gut axis has recently gained much attention. Our study aimed to evaluate gut inflammation and its association with blood variables in stroke using fecal calprotectin (FC). Methods: Fecal samples were obtained from 27 stroke patients and 27 control subjects. FC was quantitatively measured using a commercial ELISA. Laboratory data on the fecal sample collection were also collected, including CBC, ESR, glucose, creatinine, total protein, albumin, transaminases, and CRP. Results: There was a significant increase in FC levels in stroke patients compared to the controls. Furthermore, FC in stroke patients was negatively correlated with the Glasgow Coma Scale. Moreover, FC in stroke patients was positively correlated with CRP and negatively correlated with lymphocyte count and albumin. Conclusions: Our findings show that increased FC is associated with consciousness and systemic response in stroke and warrants further studies to elucidate the usefulness of FC in the management of stroke.

Adjunctive cytoprotective therapies in acute ischemic stroke: a systematic review

With the introduction of endovascular thrombectomy (EVT), a new era for treatment of acute ischemic stroke (AIS) has arrived. However, despite the much larger recanalization rate as compared to thrombolysis alone, final outcome remains far from ideal. This raises the question if some of the previously tested neuroprotective drugs warrant re-evaluation, since these compounds were all tested in studies where large-vessel recanalization was rarely achieved in the acute phase. This review provides an overview of compounds tested in clinical AIS trials and gives insight into which of these drugs warrant a re-evaluation as an add-on therapy for AIS in the era of EVT. A literature search was performed using the search terms "ischemic stroke brain" in title/abstract, and additional filters. After exclusion of papers using pre-defined selection criteria, a total of 89 trials were eligible for review which reported on 56 unique compounds. Trial compounds were divided into 6 categories based on their perceived mode of action: systemic haemodynamics, excitotoxicity, neuro-inflammation, blood-brain barrier and vasogenic edema, oxidative and nitrosative stress, neurogenesis/-regeneration and -recovery. Main trial outcomes and safety issues are summarized and promising compounds for re-evaluation are highlighted. Looking at group effect, drugs intervening with oxidative and nitrosative stress and neurogenesis/-regeneration and -recovery appear to have a favourable safety profile and show the most promising results regarding efficacy. Finally, possible theories behind individual and group effects are discussed and recommendation for promising treatment strategies are described.

Discovery of First-in-Class Peptidomimetic Neurolysin Activators Possessing Enhanced Brain Penetration and Stability

Peptidase neurolysin (Nln) is an enzyme that functions to cleave various neuropeptides. Upregulation of Nln after stroke has identified the enzyme as a critical endogenous cerebroprotective mechanism and validated target for the treatment of ischemic stroke. Overexpression of Nln in a mouse model of stroke results in dramatic improvement of stroke outcomes, while pharmacological inhibition aggravates them. Activation of Nln has therefore emerged as an intriguing target for drug discovery efforts for ischemic stroke. Herein, we report the discovery and hit-to-lead optimization of first-in-class Nln activators based on histidine-containing dipeptide hits identified from a virtual screen. Adopting a peptidomimetic approach provided lead compounds that retain the pharmacophoric histidine moiety and possess single-digit micromolar potency over 40-fold greater than the hit scaffolds. These compounds exhibit 5-fold increased brain penetration, significant selectivity over highly homologous peptidases, greater than 65-fold increase in mouse brain stability, and 'drug-like' fraction unbound in the brain.

Privileged Quinolylnitrones for the Combined Therapy of Ischemic Stroke and Alzheimer's Disease

Cerebrovascular diseases such as ischemic stroke are known to exacerbate dementia caused by neurodegenerative pathologies such as Alzheimer’s disease (AD). Besides, the increasing number of patients surviving stroke makes it necessary to treat the co-occurrence of these two diseases with a single and combined therapy. For the development of new dual therapeutic agents, eight hybrid quinolylnitrones have been designed and synthesized by the juxtaposition of selected pharmacophores from our most advanced lead-compounds for ischemic stroke and AD treatment. Biological analyses looking for efficient neuroprotective effects in suitable phenotypic assays led us to identify MC903 as a new small quinolylnitrone for the potential dual therapy of stroke and AD, showing strong neuroprotection on (i) primary cortical neurons under oxygen–glucose deprivation/normoglycemic reoxygenation as an experimental ischemia model; (ii), neuronal line cells treated with rotenone/oligomycin A, okadaic acid or β-amyloid peptide Aβ_25–35, modeling toxic insults found among the effects of AD.

The Changing Characteristics of Arthroplasty Patients: A Retrospective Cohort Study

BACKGROUND

Total joint arthroplasty (TJA) is among the most common operations performed worldwide, with global volumes on the rise. It is important to understand if the characteristics of this patient population are changing over time for resource allocation and surgical planning. The purpose of this study is to examine how this patient population has changed between 2003 and 2017.

METHODS

A retrospective review of a prospective TJA database was conducted. Age, gender, body mass index, comorbidities, American Society of Anesthesiologists class, responsible diagnoses, and comorbidities were compared over 5-year intervals between 2003 and 2017. All patients undergoing primary, elective TJA were included.

RESULTS

Overall, 17,138 TJAs were included. Mean body mass index increased over the study period for total hip arthroplasty (THA; 29.4-30.4 kg/m², P < .0001) and total knee arthroplasty (TKA; 32.0-3.1 kg/m², P < .0001) patients. THA patients were significantly younger in more recent years (68.0-66.8 years old, P = .0026); this trend was not observed among TKA patients. Over the study period, a significantly higher proportion of patients were American Society of Anesthesiologists class III/IV for THA (50.5%-72.3%) and TKA (57.5%-80.7%) (P < .00001). Prevalence of common comorbidities did not change significantly.

CONCLUSION

The key findings of this retrospective analysis of a large prospective database are that patients undergoing TJA are becoming younger and more obese. It is unclear whether patients are becoming more medically complex. These trends paint a concerning picture of a population that is increasingly complex, and may require a greater allocation of resources in the future.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Biomonitoring and Digital Data Technology as an Opportunity for Enhancing Animal Study Translation

The failure of animal studies to translate to effective clinical therapeutics has driven efforts to identify underlying cause and develop solutions that improve the reproducibility and translatability of preclinical research. Common issues revolve around study design, analysis, and reporting as well as standardization between preclinical and clinical endpoints. To address these needs, recent advancements in digital technology, including biomonitoring of digital biomarkers, development of software systems and database technologies, as well as application of artificial intelligence to preclinical datasets can be used to increase the translational relevance of preclinical animal research. In this review, we will describe how a number of innovative digital technologies are being applied to overcome recurring challenges in study design, execution, and data sharing as well as improving scientific outcome measures. Examples of how these technologies are applied to specific therapeutic areas are provided. Digital technologies can enhance the quality of preclinical research and encourage scientific collaboration, thus accelerating the development of novel therapeutics.

Stroke Research Disparity in Southeast Asia: Socioeconomic Factors, Healthcare Delivery, and Stroke Disease Burden

BACKGROUND

Cerebrovascular disease is the second leading cause of death worldwide and provides a heavy burden of disease in Southeast Asia (SEA). Contribution to the collective knowledge of this disease is necessary to address practice and treatment disparities. There is limited data on research productivity in the region. This study aimed to determine research productivity on stroke and other cerebral and spinal vascular diseases among the SEA countries and determine its relationship with bibliometrics, socioeconomic parameters, healthcare delivery indices, and burden of disease.

METHODS

A comprehensive literature search was conducted using five major healthcare databases. We included studies published until June 2020 on cerebral and spinal vascular disease with at least one author from SEA. Country-specific socioeconomic parameters, the burden of disease, healthcare delivery indices, and the number of neurologists were collected from international databases and published data. Correlational analysis was done on bibliometric indices and collected data.

RESULTS

A total of 2577 articles were included. Singapore had the most publications (n=1095, 42.5%) and citations (PlumX n=16,592, 55.2%; Scopus n=22,351, 56.7%). Gross domestic product per capita, percent gross domestic product for research and development, universal health care effective coverage index overall and for stroke treatment, and the number of neurologists had a positive correlation to bibliometric indices.

CONCLUSIONS

There is a disparity in stroke research productivity among high-income and low-income countries in SEA. Priority must be given to scientific research output and its role in socioeconomic development and policy formulation.

Pathophysiology and Treatment of Stroke: Present Status and Future Perspectives

Stroke is the second leading cause of death and a major contributor to disability worldwide. The prevalence of stroke is highest in developing countries, with ischemic stroke being the most common type. Considerable progress has been made in our understanding of the pathophysiology of stroke and the underlying mechanisms leading to ischemic insult. Stroke therapy primarily focuses on restoring blood flow to the brain and treating stroke-induced neurological damage. Lack of success in recent clinical trials has led to significant refinement of animal models, focus-driven study design and use of new technologies in stroke research. Simultaneously, despite progress in stroke management, post-stroke care exerts a substantial impact on families, the healthcare system and the economy. Improvements in pre-clinical and clinical care are likely to underpin successful stroke treatment, recovery, rehabilitation and prevention. In this review, we focus on the pathophysiology of stroke, major advances in the identification of therapeutic targets and recent trends in stroke research.

Decellularized tissues as platforms for in vitro modeling of healthy and diseased tissues

Biomedical engineers are at the forefront of developing novel treatments to improve human health, however, many products fail to translate to clinical implementation. In vivo pre-clinical animal models, although the current best approximation of complex disease conditions, are limited by reproducibility, ethical concerns, and poor accurate prediction of human response. Hence, there is a need to develop physiologically relevant, low cost, scalable, and reproducible in vitro platforms to provide reliable means for testing drugs, biomaterials, and tissue engineered products for successful clinical translation. One emerging approach of developing physiologically relevant in vitro models utilizes decellularized tissues/organs as biomaterial platforms for 2D and 3D models of healthy and diseased tissue. Decellularization is a process that removes cellular content and produces tissue-specific extracellular matrix scaffolds that can more accurately recapitulate an organ/tissue's native microenvironment compared to other natural or synthetic materials. Decellularized tissues hold enormous potential for in vitro modeling of various disease phenotypes and tissue responses to drugs or external conditions such as aging, toxin exposure, or even implantation. In this review, we highlight the need for in vitro models, the advantages and limitations of implementing decellularized tissues, and considerations of the decellularization process. We discuss current research efforts towards applying decellularized tissues as platforms to generate in vitro models of healthy and diseased tissues, and where we foresee the field progressing. A variety of organs/tissues are discussed, including brain, heart, kidney, large intestine, liver, lung, skeletal muscle, skin, and tongue. STATEMENT OF SIGNIFICANCE: Many biomedical products fail to reach clinical translation due to animal model limitations. Development of physiologically relevant in vitro models can provide a more economic, scalable, and reproducible means of testing drugs/therapeutics for successful clinical translation. The use of decellularized tissues as platforms for in vitro models holds promise, as these scaffolds can effectively replicate native tissue complexity, but is not widely explored. This review discusses the need for in vitro models, the promise of decellularized tissues as biomaterial substrates, and the current research applying decellularized tissues towards the creation of in vitro models. Further, this review provides insights into the current limitations and future of such in vitro models.

Role of pericyte-derived SENP1 in neuronal injury after brain ischemia

Aims

SUMOylation is a posttranslational modification related to multiple human diseases. SUMOylation can be reversed by classes of proteases known as the sentrin/SUMO‐specific proteases (SENPs). In the present study, we investigate the potential role of SENP1 in pericytes in the brain ischemia.

Methods

Pericyte‐specific deletion of senp1 mice (Cspg4‐Cre; senp1^f/f) were used for brain function and neuronal damage evaluation following brain ischemia. The cerebral blood vessels of diameter, velocity, and flux were performed in living mice by two‐photon laser scanning microscopy (TPLSM). Biochemical analysis and immunohistochemistry methods were used to address the role and mechanism of pericyte‐specific SENP1 in the pathological process of brain ischemia. A coculture model of HBVPs and HBMECs mimicked the BBB in vitro and was used to evaluate BBB integrity after glucose deprivation.

Results

Our results showed that senp1‐specific deletion in pericytes did not affect the motor function and cognitive function of mice. However, the pericyte‐specific deletion of senp1 aggravated the infarct size and motor deficit following focal brain ischemia. Consistently, the TPLSM data demonstrated that SENP1 deletion in pericytes accelerated thrombosis formation in brain microvessels. We also found that pericyte‐specific deletion of senp1 exaggerated the neuronal damage significantly following brain ischemia in mice. Moreover, SENP1 knockdown in pericytes could activate the apoptosis signaling and disrupt the barrier integrity in vitro coculture model.

Conclusions

Our findings revealed that targeting SENP1 in pericytes may represent a novel therapeutic strategy for neurovascular protection in stroke.

Comparative Cerebroprotective Potential of d- and l-Carnosine Following Ischemic Stroke in Mice

l-carnosine is an attractive therapeutic agent for acute ischemic stroke based on its robust preclinical cerebroprotective properties and wide therapeutic time window. However, large doses are needed for efficacy because carnosine is rapidly degraded in serum by carnosinases. The need for large doses could be particularly problematic when translating to human studies, as humans have much higher levels of serum carnosinases. We hypothesized that d-carnosine, which is not a substrate for carnosinases, may have a better pharmacological profile and may be more efficacious at lower doses than l-carnosine. To test our hypothesis, we explored the comparative pharmacokinetics and neuroprotective properties of d- and L-carnosine in acute ischaemic stroke in mice. We initially investigated the pharmacokinetics of d- and L-carnosine in serum and brain after intravenous (IV) injection in mice. We then investigated the comparative efficacy of d- and l-carnosine in a mouse model of transient focal cerebral ischemia followed by in vitro testing against excitotoxicity and free radical generation using primary neuronal cultures. The pharmacokinetics of d- and l-carnosine were similar in serum and brain after IV injection in mice. Both d- and l-carnosine exhibited similar efficacy against mouse focal cerebral ischemia. In vitro studies in neurons showed protection against excitotoxicity and the accumulation of free radicals. d- and l-carnosine exhibit similar pharmacokinetics and have similar efficacy against experimental stroke in mice. Since humans have far higher levels of carnosinases, d-carnosine may have more favorable pharmacokinetics in future human studies.

Ischemia-related changes of fat-mass and obesity-associated protein expression in the gerbil hippocampus

Fat-mass and obesity-associated protein (Fto) plays important roles in energy metabolism. It also acts as a demethylase and is most abundantly found in the brain. In the present study, we examined the spatial and temporal changes of Fto immunoreactivity after five minutes of transient forebrain ischemia in the hippocampus. In the control group, Fto immunoreactivity was mainly observed in the nucleus of pyramidal cells in the CA1 and CA3 regions as well as the polymorphic layer, granule cell layer, and subgranular zone of the dentate gyrus. Fto immunoreactivity was transiently, but not significantly, increased in the hippocampal CA3 region and the dentate gyrus two days after ischemia compared to mice without ischemia in the sham-operated group. Four days after ischemia, low Fto immunoreactivity was observed in the stratum pyramidale of the CA1 region because of neuronal death, but Fto immunoreactive cells were abundantly detected in the stratum pyramidale of the CA3 region, which is relatively resistant to ischemic damage. Thereafter, Fto immunoreactivity progressively decreased in the hippocampal CA1 and CA3 regions and the dentate gyrus until ten days after ischemia. At this time-point, Fto immunoreactivity was significantly lower in the hippocampal CA1 and CA3 regions and the dentate gyrus compared to that in the sham-operated group. The reduction of Fto immunoreactive structures in the hippocampus may be associated with impairments in Fto-related hippocampal function.

Brain Functional Reserve in the Context of Neuroplasticity after Stroke

Stroke is the second cause of death and more importantly first cause of disability in people over 40 years of age. Current therapeutic management of ischemic stroke does not provide fully satisfactory outcomes. Stroke management has significantly changed since the time when there were opened modern stroke units with early motor and speech rehabilitation in hospitals. In recent decades, researchers searched for biomarkers of ischemic stroke and neuroplasticity in order to determine effective diagnostics, prognostic assessment, and therapy. Complex background of events following ischemic episode hinders successful design of effective therapeutic strategies. So far, studies have proven that regeneration after stroke and recovery of lost functions may be assigned to neuronal plasticity understood as ability of brain to reorganize and rebuild as an effect of changed environmental conditions. As many neuronal processes influencing neuroplasticity depend on expression of particular genes and genetic diversity possibly influencing its effectiveness, knowledge on their mechanisms is necessary to understand this process. Epigenetic mechanisms occurring after stroke was briefly discussed in this paper including several mechanisms such as synaptic plasticity; neuro-, glio-, and angiogenesis processes; and growth of axon.