Neurofilament light chain for assessment of brain injury in four porcine cardiac arrest models

Background Anoxic brain injury is the leading cause of death following successful resuscitation after out-of-hospital cardiac arrest. No experimental neuroprotective therapy has translated into clinical benefit. Collaborative efforts to harmonize methods may be essential for translational success. Neurofilament light chain (NfL) is a biomarker of neuroaxonal injury with emerging use in clinical practice, but data on its robustness and association with outcomes in porcine models is limited. Our aim was to use NfL as a quantitative marker to compare brain injury severity in different porcine cardiac arrest models. Methods Forty-four pigs ( Sus scrofa domestica ) were resuscitated after cardiac arrest in different experimental models in four laboratories. Plasma samples were collected prior to the arrest and at 4 and 24 hours after return of spontaneous circulation. NfL concentration was measured using a Single molecule array (Simoa) immunoassay. Results NfL levels changed significantly over time (p <0.001), with similar temporal patterns observed across all laboratories. Inter-laboratory comparisons indicated essentially consistent NfL levels, with modest differences at 24 hours. NfL levels at 24 hours showed an association with no-flow duration (n = 43) in both correlation and univariate regression analyses (p = 0.034, p = 0.041), while no significant associations were found with functional outcomes (n = 26) (p = 0.32, p = 0.20). Conclusion NfL increased consistently across four porcine cardiac arrest models, and higher 24-hour NfL levels were associated with longer no-flow duration, supporting its robustness as a biomarker of neuroaxonal injury. Larger studies are needed to clarify its relationship with functional outcome, as the exploratory analyses were underpowered.