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      Dose–response, therapeutic time-window and tPA-combinatorial efficacy of compound 21: A randomized, blinded preclinical trial in a rat model of thromboembolic stroke

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          Abstract

          The aim of this translational, randomized, controlled, blinded preclinical trial was to determine the effect of compound 21 (C21) in embolic stroke. Rats were subjected to embolic-middle cerebral artery occlusion (eMCAO). They received C21 (0.01, 0.03 and 0.06 mg/kg/d) or saline (orally) for five days, with the first-dose given IV at 3 h post-eMCAO. For the time-window study, the optimal-dose of C21 was initiated at 3, 6 or 24 h post-eMCAO and continued for five days. For the combinatorial study, animals received IV-tissue plasminogen activator (tPA) at either 2 or 4 h, with IV-C21 (0.01 mg/kg) or saline at 3 h post-eMCAO and daily thereafter for five days. After performing the behavior tests, brains were collected for analyses. The dose–response study showed significant motor improvements with the lowest-dose (0.01 mg/kg) of C21. In the time-window study, this same dose resulted in improvements when given 6 h and 24 h post-eMCAO. Moreover, C21-treated animals performed better on the novel object recognition test. Neither the single treatment with C21 or tPA (4 h) nor the combination therapy was effective in reducing the hemorrhage or infarct size, although C21 alone lowered sensorimotor deficit scores post-eMCAO. Future studies should focus on the long-term cognitive benefits of C21, rather than acute neuroprotection.

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          Most cited references26

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          Tissue plasminogen activator (tPA) increases neuronal damage after focal cerebral ischemia in wild-type and tPA-deficient mice.

          Intravenous tissue plasminogen activator (tPA) is used to treat acute stroke because of its thrombolytic activity and its ability to restore circulation to the brain. However, this protease also promotes neurodegeneration after intracerebral injection of excitotoxins such as glutamate, and neuronal damage after a cerebral infarct is thought to be mediated by excitotoxins. To investigate the effects of tPA on cerebral viability during ischemia/reperfusion, we occluded the middle cerebral artery in wild-type and tPA-deficient mice with an intravascular filament. This procedure allowed us to examine the role of tPA in ischemia, independent of its effect as a thrombolytic agent. tPA-deficient mice exhibited approximately 50% smaller cerebral infarcts than wild-type mice. Intravenous injection of tPA into tPA-/- or wild-type mice produced larger infarcts, indicating that tPA can increase stroke-induced injury. Since tPA promotes desirable (thrombolytic) as well as undesirable (neurotoxic) outcomes during stroke, future therapies should be aimed at countering the excitotoxic damage of tPA to afford even better neuroprotection after an acute cerebral infarct.
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            Stem Cell Therapy as an Emerging Paradigm for Stroke (STEPS) II.

            Cell-based therapies represent a new therapeutic approach for stroke. In 2007, investigators from academia, industry leaders, and members of the National Institutes of Health crafted recommendations to facilitate the translational development of cellular therapies as a novel, emerging modality for stroke from animal studies to clinical trials. This meeting was called Stem Cell Therapies as an Emerging Paradigm in Stroke (STEPS) and was modeled on the format of the Stroke Therapy Academic Industry Roundtable (STAIR) meetings. Since publication of the original STEPS guidelines, there has been an explosive growth in the number of cellular products and in the number of new laboratory discoveries that impact the safety and potential efficacy of cell therapies for stroke. Any successful development of a cell product will need to take into consideration several factors, including the preclinical safety and efficacy profile, cell characterization, delivery route, in vivo biodistribution, and mechanism of action. In 2010, a second meeting called STEPS 2 was held to bring together clinical and basic science researchers with industry, regulatory, and National Institutes of Health representatives. At this meeting, participants identified critical gaps in knowledge and research areas that require further studies, updated prior guidelines, and drafted new recommendations to create a framework to guide future investigations in cell-based therapies for stroke.
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              Stroke Treatment Academic Industry Roundtable (STAIR) recommendations for maximizing the use of intravenous thrombolytics and expanding treatment options with intra-arterial and neuroprotective therapies.

              The goal of the Stroke Treatment Academic Industry Roundtable (STAIR) meetings is to advance the development of acute and restorative stroke therapies. Summary of Review- At the STAIR VII recommendations for strategies to maximize the use of intravenous thrombolytics through targeting public education, and the refinement of current treatment exclusion criteria were proposed. Increased utilization of mechanical devices for intra-arterial recanalization can be achieved by obtaining more definitive evidence of efficacy in randomized clinical trials, identification of patient characteristics associated with treatment efficacy, optimization of technical approaches, clarification of effective time windows, and development of approaches to limit complications. Neuroprotective strategies remain viable; recommendations for further study of these agents include an emphasis on rapid administration, consideration of the systemic effects of ischemic stroke, prevention of complications associated with early reperfusion, a focus on agents with multiple mechanisms of action, and consideration of possible interactions between neuroprotective and thrombolytic therapies. Extending intravenous thrombolysis to a broader patient population, clarifying the risk and benefits of intra-arterial reperfusion therapies, and further development of neuroprotective therapies were the key recommendations from STAIR VII.
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                Author and article information

                Journal
                Journal of Cerebral Blood Flow & Metabolism
                J Cereb Blood Flow Metab
                SAGE Publications
                0271-678X
                1559-7016
                March 14 2018
                March 14 2018
                : 0271678X1876477
                Affiliations
                [1 ]Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis TN, USA
                [2 ]Charlie Norwood VA Medical Center, and Program in Clinical and Experimental Therapeutics, College of Pharmacy, University of Georgia, Athens, GA, USA
                [3 ]Department of Biostatistics and Epidemiology, Augusta University, Augusta, GA, USA
                [4 ]Department of Physiology, Augusta University, Augusta, GA, USA
                [5 ]Department of Neurology, Augusta University, Augusta, GA, USA
                Article
                10.1177/0271678X18764773
                6681526
                29537907
                83ed8290-7b4b-4936-8d8c-387ebfc05a1d
                © 2018

                http://journals.sagepub.com/page/policies/text-and-data-mining-license


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