A 2 × 2 factorial design for the combination therapy of minocycline and remote ischemic perconditioning: efficacy in a preclinical trial in murine thromboembolic stroke model.

Md Nasrul Hoda,David C Hess,Phillip Wang,Mohammad B Khan,Jennifer L Waller,Aizaz Chaudhary,Kumar Vaibhav,Krishnan M Dhandapani,Susan C Fagan

doi:10.1186/2040-7378-6-10

Abstract

BackgroundAfter the failure of so many drugs and therapies for acute ischemic stroke, innovative approaches are needed to develop new treatments. One promising strategy is to test combinations of agents in the pre-hospital setting prior to the administration of intravenous tissue plasminogen activator (IV-tPA) and/ or the use of mechanical reperfusion devices in the hospital.MethodsWe performed a 2 × 2 factorial design preclinical trial where we tested minocycline (MINO), remote ischemic perconditioning (RIPerC) and their combination treatment in a thromboembolic clot model of stroke in mice, without IV-tPA or later treated with IV-tPA at 4 hours post-stroke. Cerebral blood flow (CBF) was measured by laser speckle contrast imaging (LSCI), behavioral outcomes as neurological deficit score (NDS) and adhesive tape removal test, and infarct size measurement were performed at 48 hours post-stroke. Mice within the experimental sets were randomized for the different treatments, and all outcome measures were blinded.ResultsRIPerC significantly improved CBF as measured by LSCI in both with and without tPA treated mice (P < 0.001). MINO and RIPerC treatment were effective alone at reducing infarct size (p < 0.0001) and improving short-term functional outcomes (p < 0.001) in the tPA and non-tPA treated animals. The combination treatment of MINO and RIPerC significantly reduced the infarct size greater than either intervention alone (p < 0.05). There were trends in favor of improving functional outcomes after combination treatment of MINO and RIPerC; however combination treatment group was not significantly different than the individual treatments of MINO and RIPerC. There was no “statistical” interaction between minocycline and RIPerC treatments indicating that the effects of RIPerC and MINO were additive and not synergistic on the outcome measures.ConclusionIn the future, combining these two safe and low cost interventions in the ambulance has the potential to “freeze” the penumbra and improve outcomes in stroke patients. This pre-clinical 2 × 2 design can be easily translated into a pre-hospital clinical trial.

Highlights

Bold and innovative strategies are needed to break the logjam of failed acute stroke clinical trials
Minocycline or vehicle was infused at 1 hr poststroke while remote limb ischemic perconditioning (RIPerC) or its sham procedure was performed at 2 hrs post-stroke, as needed in the relevant groups and explained in the table
MINO did not improve the Cerebral blood flow (CBF) significantly with intravenous tissue plasminogen activator (IV-tPA) (MINO main effect F(1,24) = 2.76, p = 0.1095) but did without IV-tPA (F(1,27) = 10.01, p = 0.0038), there was a trend towards increased perfusion at 48 hrs post-stroke possibly due to vascular as well as neuroprotective effects of MINO

Summary

Introduction

Bold and innovative strategies are needed to break the logjam of failed acute stroke clinical trials. Even after 4-cycles of RLIC, the prothrombin time (PT), and international normalized ratio (INR) remain in the normal range without any hemorrhagic complications [10] Both MINO and RIPerC work well alone and in combination with intravenous tissue plasminogen activator (IV-tPA) and are ideal adjuvant therapies during reperfusion [11,12,13]. They both are interventions that “freeze” the penumbra [2]. One promising strategy is to test combinations of agents in the pre-hospital setting prior to the administration of intravenous tissue plasminogen activator (IV-tPA) and/ or the use of mechanical reperfusion devices in the hospital

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Discussion

Conclusion