Objective Rho-associated kinase (ROCK) is a key regulator of numerous processes in multiple cell types relevant in stroke pathophysiology. ROCK inhibitors have improved outcome in experimental models of acute ischemic or hemorrhagic stroke. However, the relevant ROCK isoform (ROCK1 or ROCK2) in acute stroke is not known. Methods We characterized the pharmacodynamic and pharmacokinetic profile, and tested the efficacy and safety of a novel selective ROCK2 inhibitor KD025 (formerly SLx-2119) in focal cerebral ischemia models in mice. Results KD025 dose-dependently reduced infarct volume after transient middle cerebral artery occlusion. The therapeutic window was at least 3 hours from stroke onset, and the efficacy was sustained for at least 4 weeks. KD025 was at least as efficacious in aged, diabetic or female mice, as in normal adult males. Concurrent treatment with atorvastatin was safe, but not additive or synergistic. KD025 was also safe in a permanent ischemia model, albeit with diminished efficacy. As one mechanism of protection, KD025 improved cortical perfusion in a distal middle cerebral artery occlusion model, implicating enhanced collateral flow. Unlike isoform-nonselective ROCK inhibitors, KD025 did not cause significant hypotension, a dose-limiting side effect in acute ischemic stroke. Interpretation Altogether, these data show that KD025 is efficacious and safe in acute focal cerebral ischemia in mice, implicating ROCK2 as the relevant isoform in acute ischemic stroke. Data suggest that selective ROCK2 inhibition has a favorable safety profile to facilitate clinical translation.

Spontaneous spreading depolarizations are frequent after various forms of human brain injury such as ischemic or hemorrhagic stroke and trauma, and worsen the outcome. We have recently shown that supply-demand mismatch transients trigger spreading depolarizations in ischemic stroke. Here, we examined the mechanisms triggering recurrent spreading depolarization events for many days after subarachnoid hemorrhage. Despite large volumes of subarachnoid hemorrhage induced by cisternal injection of fresh arterial blood in rodents, electrophysiological recordings did not detect a single spreading depolarization for up to 72 h after subarachnoid hemorrhage. Cortical susceptibility to spreading depolarization, measured by direct electrical stimulation or topical KCl application, was suppressed after subarachnoid hemorrhage. Focal cerebral ischemia experimentally induced after subarachnoid hemorrhage revealed a biphasic change in the propensity to develop peri-infarct spreading depolarizations. Frequency of peri-infarct spreading depolarizations decreased at 12 h, increased at 72 h and normalized at 7 days after subarachnoid hemorrhage compared with sham controls. However, ischemic tissue and neurological outcomes were significantly worse after subarachnoid hemorrhage even when peri-infarct spreading depolarization frequency was reduced. Laser speckle flowmetry implicated cerebrovascular hemodynamic mechanisms worsening the outcome. Altogether, our data suggest that cerebral ischemia is required for spreading depolarizations to be triggered after subarachnoid hemorrhage, which then creates a vicious cycle leading to the delayed cerebral ischemia syndrome.

Objective:To test the hypothesis that the prevalence of cervical artery dissection remains constant across age groups, we evaluated the relationship between age and cervical artery dissection in patients with stroke using a Nationally Representative Sample from the United States.Methods:We used inpatient claims data included in the 2012-2015 releases of the National Inpatient Sample (NIS). We used validated ICD-9-CM codes to identify adults hospitalized with ischemic stroke and a concomitant diagnosis of carotid- or vertebral-artery dissection. Survey weights provided by the NIS and population estimates from the U.S. census were used to calculate nationally representative estimates. The chi-square test for trend was used to compare the prevalence of concomitant dissection among stroke hospitalizations across patient subgroups defined by age. Poisson regression and the Wald test for trend were used to evaluate whether the prevalence of hospitalizations for stroke and concomitant dissection per million person-years varied by age groups.Results:There were 17,320 (95% confidence interval [CI], 15,614-19,026) hospitalizations involving ischemic stroke and a concomitant dissection. The prevalence of dissection among stroke hospitalizations decreased across 10-year age groups from 7.2% (95% CI, 6.2%-8.1%) among persons younger than age 30 years to 0.2% (95% CI, 0.1%-0.2%) among persons older than age 80 years (P value for trend <0.001). However, the prevalence of hospitalizations for stroke and concomitant dissection increased from 5.4 (95% CI, 4.6-6.2) hospitalizations per million person-years among adults younger than age 30 to 24.4 (95% CI, 21.0-27.9) hospitalizations per million person-years among adults older than age 80 (P value for trend <0.01).Conclusions:In a nationally representative sample, the prevalence of hospitalizations for dissection-related stroke increased with age.