the-mouse-stroke-unit-protocol-with-standardized-neurological-scoring

The Mouse Stroke Unit Protocol with Standardized Neurological Scoring for Translational Mouse Stroke Studies

The filament model of middle artery occlusion (fMCAo) is perhaps the most translational mouse stroke model, allowing for controlled ischemia with ...

national and kapodistrian university of athens

University of Munich Medical Center

Schoen Clinic Bad Aibling

National and Kapodistrian University of Athens

Tissue hypoxia occurs in various conditions such as myocardial or brain ischemia and infarction, sepsis, and trauma, and induces cellular damage and tissue remodeling with recapitulation of fetal-like reprogramming, which eventually results in organ failure. Analogies seem to exist between the damaged hypoxic and developing organs, indicating that a regulatory network which drives embryonic organ development may control aspects of heart (or tissue) repair. In this context, thyroid hormone (TH), which is a critical regulator of organ maturation, physiologic angiogenesis, and mitochondrial biogenesis during fetal development, may be of important physiological relevance upon stress (hypoxia)-induced fetal reprogramming. TH signaling has been implicated in hypoxic tissue remodeling after myocardial infarction and T3 prevents remodeling of the postinfarcted heart. Similarly, preliminary experimental evidence suggests that T3 can prevent early tissue hypoxia during sepsis with important physiological consequences. Thus, based on common pathways between different paradigms, we propose a possible role of TH in tissue hypoxia after sepsis with the potential to reduce secondary organ failure.

Effects of Thyroid Hormone on Tissue Hypoxia: Relevance to Sepsis Therapy.

Triiodothyronine prevents tissue hypoxia in experimental sepsis: potential therapeutic implications.

Why can we still not translate preclinical research to clinical treatments for acute strokes? Despite > 1000 successful preclinical studies, drugs, and concepts for acute stroke, only two have reached clinical translation. This is the translational block. Yet, we continue to routinely model strokes using almost the same concepts we have used for over 30 years. Methodological improvements and criteria from the last decade have shed some light but have not solved the problem. In this conceptual analysis, we review the current status and reappraise it by thinking "out-of-the-box" and over the edges. As such, we query why other scientific fields have also faced the same translational failures, to find common denominators. In parallel, we query how migraine, multiple sclerosis, and hypothermia in hypoxic encephalopathy have achieved significant translation successes. Should we view ischemic stroke as a "chronic, relapsing, vascular" disease, then secondary prevention strategies are also a successful translation. Finally, based on the lessons learned, we propose how stroke should be modeled, and how preclinical and clinical scientists, editors, grant reviewers, and industry should reconsider their routine way of conducting research. Translational success for stroke treatments may eventually require a bold change with solutions that are outside of the box.

Translational Block in Stroke: A Constructive and "Out-of-the-Box" Reappraisal.

An unbiased, automated and reliable method for analysis of brain lesions in tissue after ischemic stroke is missing. Manual infarct volumetry or by threshold-based semi-automated approaches is laborious, and biased to human error or biased by many false -positive and -negative data, respectively. Thereby, we developed a novel machine learning, atlas-based method for fully automated stroke analysis in mouse brain slices stained with 2% Triphenyltetrazolium-chloride (2% TTC), named "StrokeAnalyst", which runs on a user-friendly graphical interface. StrokeAnalyst registers subject images on a common spatial domain (a novel mouse TTC- brain atlas of 80 average mathematical images), calculates pixel-based, tissue-intensity statistics (z-scores), applies outlier-detection and machine learning (Random-Forest) models to increase accuracy of lesion detection, and produces volumetry data and detailed neuroanatomical information per lesion. We validated StrokeAnalyst in two separate experimental sets using the filament stroke model. StrokeAnalyst detects stroke lesions in a rater-independent and reproducible way, correctly detects hemispheric volumes even in presence of post-stroke edema and significantly minimizes false-positive errors compared to threshold-based approaches (false-positive rate 1.2-2.3%, p < 0.05). It can process scanner-acquired, and even smartphone-captured or pdf-retrieved images. Overall, StrokeAnalyst surpasses all previous TTC-volumetry approaches and increases quality, reproducibility and reliability of stroke detection in relevant preclinical models.

Machine learning based analysis of stroke lesions on mouse tissue sections.

The present study investigated the effects of triiodothyronine (T3) administration in  model of rat heart normothermic perfusion. T3 is cardioprotective and has the potential to repair the injured myocardium. Isolated hearts were subjected to normothermic perfusion (NP) with Krebs-Henseleit for 4 h with vehicle (NP) or 60 nM T3 in the perfusate (NP + T3). Left ventricular end diastolic pressure (LVEDP), left ventricular developed pressure (LVDP), perfusion pressure (PP) and percentage of change of these parameters from the baseline values were measured. Activation of stress induced kinase signaling was assessed in tissue samples. Baseline parameters were similar between groups. LVEDP was increased from the baseline by 13% (70) for NP + T3 vs. 139% (160) for NP group,  = 0.048. LVDP was reduced by 18.2% (5) for NP + T3 vs. 25.3% (19) for NP group,  = 0.01. PP was increased by 41% (19) for NP + T3 vs.91% (56) for NP group,  = 0.024. T3 increased activation of pro-survival Akt by 1.85 fold ( = 0.047) and AMPK by 2.25 fold ( = 0.01) and reduced activation of pro-apoptotic p38 MAPK by 3fold ( = 0.04) and p54 JNK by 4.0 fold ( = 0.04). Administration of T3 in normothermic perfusion had favorable effects on cardiac function and perfusion pressure and switched death to pro-survival kinase signaling.

Effects of T3 Administration on  Rat Hearts Subjected to Normothermic Perfusion: Therapeutic Implications in Donor Heart Preservation and Repair.

Heart transplantation remains the conventional treatment in end-stage heart failure, with static cold storage (SCS) being the standard technique used for donor preservation. Nevertheless, prolonged cold ischemic storage is associated with the increased risk of early graft dysfunction attributed to residual ischemia, reperfusion, and rewarming damage. In addition, the demand for the use of marginal grafts requires the development of new methods for organ preservation and repair. In this review, we focus on current knowledge and novel methods of donor preservation in heart transplantation. Hypothermic or normothermic machine perfusion may be a promising novel method of donor preservation based on the administration of cardioprotective agents. Machine perfusion seems to be comparable to cold cardioplegia regarding donor preservation and allows potential repair treatments to be employed and the assessment of graft function before implantation. It is also a promising platform for using marginal organs and increasing donor pool. New pharmacological cardiac repair treatments, as well as cardioprotective interventions have emerged and could allow for the optimization of this modality, making it more practical and cost-effective for the real world of transplantation. Recently, the use of triiodothyronine during normothermic perfusion has shown a favorable profile on cardiac function and microvascular dysfunction, likely by suppressing pro-apoptotic signaling and increasing the expression of cardioprotective molecules.

Article	Year
Effects of Thyroid Hormone on Tissue Hypoxia: Relevance to Sepsis Therapy. Journal of clinical medicine\| PubMed ID: 34945151	2021
Triiodothyronine prevents tissue hypoxia in experimental sepsis: potential therapeutic implications. Intensive care medicine experimental\| PubMed ID: 33834320	2021
Translational Block in Stroke: A Constructive and "Out-of-the-Box" Reappraisal. Frontiers in neuroscience\| PubMed ID: 34054413	2021
Machine learning based analysis of stroke lesions on mouse tissue sections. Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism\| PubMed ID: 35209753	2022
Effects of T3 Administration on Rat Hearts Subjected to Normothermic Perfusion: Therapeutic Implications in Donor Heart Preservation and Repair. Transplant international : official journal of the European Society for Organ Transplantation\| PubMed ID: 36824295	2023
Donor Heart Preservation: Current Knowledge and the New Era of Machine Perfusion. International journal of molecular sciences\| PubMed ID: 38069017	2023

Athanasios Lourbopoulos

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