Effects of sex, injury, and docosahexaenoic acid in a preclinical porcine model of pediatric traumatic brain injury using novel serial collection of CSF, urine, and serum biomarkers

OBJECTIVE Traumatic brain injury (TBI) is a leading cause of acquired neurological disability in children of both sexes. Therapies that improve neurological disability in animal TBI models have universally failed in humans. Successful transition to clinical application should increase if experimental TBI models use animals that are more similar to humans and collect clinically relevant biomarkers. Porcine models of human disease are strong predictors of clinical efficacy. However, studies using immature swine of both sexes and serial collection of biological samples after TBI are lacking. In the authors’ rat model of pediatric TBI, docosahexaenoic acid (DHA) improved outcomes and decreased white matter injury, neuroinflammation, and oxidative stress. The authors conducted a proof-of-concept study to evaluate the feasibility of obtaining serial blood, cerebrospinal fluid (CSF), and urine samples from piglets of both sexes after TBI using fluid percussion injury (FPI), and to assess the utility of these samples for measuring clinically relevant biomarkers in a preclinical pediatric TBI model. METHODS After pilot testing of a CSF reservoir in cadaver piglets, the authors conducted FPI followed by reservoir placement in live 4-week-old male and female piglets. RESULTS The authors succeeded in obtaining all 3 types of samples and measuring biomarkers of white matter injury, neuroinflammation, and oxidative stress. When inserted to an optimal depth of 10 mm, CSF reservoir function was preserved for 3–7 days despite normal piglet activity. Surgery-related mortality (occurring within 1 hour) was 3/36 piglets. One piglet had a quickly resolved scalp infection. FPI increased serum neurofilament light (NfL), a marker of axonal injury, at postinjury day (PID) 1 and 7 in males, blunted by DHA, although the sample size was small. At PID 3, FPI increased CSF interleukin (IL)–4, -8, -12, and -18. DHA abrogated the FPI-induced increase in IL-8 in males. FPI increased IL-12 in DHA-treated females but not control (coconut oil–treated) females. Female sex was associated with increased levels of 10 of the 13 CSF cytokines even in the absence of FPI. At PID 1, the authors observed markedly decreased CSF total antioxidant capacity, a measure of oxidative stress, in all groups. CONCLUSIONS Modified piglet FPI allowed serial collection of CSF, urine, and blood samples during the 1st week after surgery. The authors anticipate that this model will be useful for preclinical pharmacokinetic and efficacy studies that require longer term survival and serial biofluid collection after TBI.