Abstract Body: Background: The Stroke Preclinical Assessment Network (SPAN), a multi-center network consisting of a coordinating center and testing laboratories, was created to enhance the rigor of preclinical research, including testing of potential therapies in animals of different species, sex, age, and co-morbidities, with blinding and randomization. SPAN evaluated six potential therapies with the goal of identifying one or more efficacious agents to advance toward a clinical trial. Remote ischemic post-conditioning (RIC) was selected as a candidate therapy for testing.
Methods: In Stage I, young, healthy mixed-sex mice were randomized into treatment groups by the coordinating center. In Stage II, aged mice, mice with high-fat diet-induced obesity, and spontaneously hypertensive rats were utilized. Each stage included 25% of the study population and efficacy/futility was determined after each stage. RIC was bilaterally administered as the first session occurred immediately after reperfusion, and the second session occurred as close as possible to 12 ± 2 hours at post-MCAo, using an automated blood pressure cuff that delivered 200-mmHg to the hindlimbs for 4 cycles x 5 minutes/cycle and then once per day x 5 days under anesthesia. Sham-conditioned animals were treated with a cuff that did not inflate. The primary outcome measure was a modified corner test on days 7 and 30 post-stroke. MRI was performed at 48 hours and 30 days. Probabilistic index models, which adjusted for covariates of interest, were fit to estimate the probability of a lower corner test index (better outcome) between sham and RIC.
Results: A total of 266 mice (132 sham, 134 RIC) were enrolled in the study, with 50 sham and 51 RIC-treated mice dying within 5 days of stroke. Analysis of all data revealed no significant differences in day 30 alternative corner test index between sham and RIC-treated mice after stroke in young, healthy mice (p=0.449), aged mice (p=0.079), mice with diet-induced obesity (p=0.135), or in spontaneously hypertensive rats (p=0.807). The secondary analysis found that RIC improved day 30 tissue infarction volume by MRI in young, healthy mice (p=0.024 vs. sham) but not in other co-morbid conditions.
Conclusions: After advancing through Stages I and II, RIC was deemed futile at the end of Stage II, as determined by the modified corner test on day 30. The requirement for repeated daily general anesthesia during RIC administration may have been a complicated factor.