Establishing a Clinically Relevant Large Animal Model Platform for TBI Therapy Development: Using Cyclosporin A as a Case Study

Abstract

We have developed the first immature large animal translational treatment trial of a pharmacologic intervention for traumatic brain injury (TBI) in children. The preclinical trial design includes multiple doses of the intervention in two different injury types (focal and diffuse) to bracket the range seen in clinical injury and uses two post-TBI delays to drug administration. Cyclosporin A (CsA) was used as a case study in our first implementation of the platform because of its success in multiple preclinical adult rodent TBI models and its current use in children for other indications. Tier 1 of the therapy development platform assessed the short-term treatment efficacy after 24 h of agent administration. Positive responses to treatment were compared with injured controls using an objective effect threshold established prior to the study. Effective CsA doses were identified to study in Tier 2. In the Tier 2 paradigm, agent is administered in a porcine intensive care unit utilizing neurological monitoring and clinically relevant management strategies, and intervention efficacy is defined as improvement in longer term behavioral endpoints above untreated injured animals. In summary, this innovative large animal preclinical study design can be applied to future evaluations of other agents that promote recovery or repair after TBI. AbstractWe have developed the first immature large animal translational treatment trial of a pharmacologic intervention for traumatic brain injury (TBI) in children. The preclinical trial design includes multiple doses of the intervention in two different injury types (focal and diffuse) to bracket the range seen in clinical injury and uses two post-TBI delays to drug administration. Cyclosporin A (CsA) was used as a case study in our first implementation of the platform because of its success in multiple preclinical adult rodent TBI models and its current use in children for other indications. Tier 1 of the therapy development platform assessed the short-term treatment efficacy after 24 h of agent administration. Positive responses to treatment were compared with injured controls using an objective effect threshold established prior to the study. Effective CsA doses were identified to study in Tier 2. In the Tier 2 paradigm, agent is administered in a porcine intensive care unit utilizing neurological monitoring and clinically relevant management strategies, and intervention efficacy is defined as improvement in longer term behavioral endpoints above untreated injured animals. In summary, this innovative large animal preclinical study design can be applied to future evaluations of other agents that promote recovery or repair after TBI.

Alterations in Daytime and Nighttime Activity in Piglets after Focal and Diffuse Brain Injury

“…All details regarding anesthesia, injury methods, and immunohistochemistry quantification have been described previously. 17,24 The nighttime (NT, 7 pm to 7 am) and daytime (DT, 4 pm to 7 pm) patterns of active and inactive periods obtained 1 day pre-injury or anesthesia (day -1) and on day 4 post-TBI in focal and diffuse brain-injured piglets were compared to those of time-matched sham piglets experiencing only the anesthesia portion of the protocol. After a full set of data were collected for a piglet, the number of 0.1-g crossings on day -1 and day 4 were determined for every minute epoch, and any epoch with £3 crossings was designated as ''inactive,'' and epochs with more crossings were designated as ''active,'' with those active minutes with ‡100 crossings additionally defined as ''high activity.''…”

“…7), with a similar anatomic pattern, albeit with smaller lesion volume than we have published previously in this age group for the same head rotational velocity and direction within hours and 1 day post-TBI. 17,24 The focal brain injury included large regions of infarct, characterized by ischemic changes on H&E (hatched regions in Fig. 7), with persistent hemorrhagic regions (dark areas) and axonal injury documented on b-APP-positive regions in penumbral areas (circles, Fig.…”

“…Lesion volume at 8 days post-CCI was similar in size to our previously published values at 1 day post-CCI. 17 …”

“…[9][10][11][12][13][14] Although animal activity is typically captured from video analysis, there is an emerging science of acceleration-based actigraphy measurements for animal (rats, nonhuman primates, and marmots) 15 species, but none for pigs, a large animal used as a model for studying neurological diseases. 16,17 Given the value of large animal models in understanding the mechanisms and responses to TBI for the development of interventions and therapies, 17 and the similarity of the pig to humans, 16,18 we have adapted this technology and its analysis metrics for use in piglets with TBI.…”

Development of a Model of Hemispheric Hypodensity (“Big Black Brain”)

“…These photographs were printed and the area of brain damage (H&E stained sections) or pattern of APP or albumin staining was observed using the 5 · and 10 · objectives and drawn on the paper map of the slide using specific landmarks on the slide and slide photograph. [28][29][30] An area was determined to be ''damaged'' if the tissue had (1) ''red neurons,'' (2) acute tissue hemorrhage, or any of the following changes in combination with or adjacent to areas of red neurons: (3) vacuolization around blood vessels, or (4) vacuolization of neuropil, or (5) vacuolization around neurons. Operational criteria to classify neurons as red neurons were the presence of all three of the following features: (1) cell shrinkage with perineuronal vacuolization, (2) cytoplasmic hypereosinophilia, and (3) nuclear pyknosis.…”