An organotypic model of traumatic brain injury

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The past decade has witnessed intense scientific activity to investigate molecular mechanisms of traumatic brain injury, driven by overwhelming evidence that neuropotection by pharmacological inhibition of apoptosis has the potential to dramatically reduce the effects of brain trauma. Key requisite for the systematic investigation of neuroprotective agents is an accurately characterized, clinically relevant in vitro brain injury model. Despite this obvious need, the ability to deliver such defined, realistic trauma to specimens in vitrolags far behind the sophistication of molecular and biochemical assays used to measure the response. In a collaborative effort between neurobiologists and bioengineers, we therefore developed an in vitrobrain injury model which subjects organotypic brain cultures to angular acceleration-induced shear injury. In this model, organotypic brain cultures realistically model the in vivoapparent heterogeneous cell population in a three-dimensional cellular matrix, while angular acceleration-induced shear strain delivers a scalable, defined, and clinically relevant mechanical insult. We hypothesize that our acceleration model of organotypic brain cultures can realistically reproduce traumatic brain injury, where the delivered shear strain magnitude can be quantified on a cellular level. Exercising our model, we will be able to determine cell type specific injury vulnerability, and to determine if caspase-8 and caspase-9 affect cell death following brain trauma. We propose to complete a formal experimental characterization of our novel brain injury system, including assessment of the delivered angular acceleration magnitude and determination of the constitutive properties of the organotypic specimen (Aim 1). The resulting experimental source data will be directly applicable to formulate a realistic analytical model that allows computational simulation of the shear injury throughout the brain specimen for any point in time during the primary mechanical insult (Aim 2). Based on and concomitant to this rigorous system characterization, we will exercise the brain injury model to establish a dose/response history (Aim 3), and we will delineate the effects of hypoxic brain injury (Aim 4), secondary to the mechanical insult. Finally, we will employ our arganotypic trauma model to determine the neuroprotective potential of caspase-8 and caspase-9 (Aim 5). Upon successful completion, the results of this integrative research approach will yield a well-characterized, scalable, reproducible and clinically relevant brain injury model. Considering the vast interest in therapeutic interventions now under development aimed at inhibiting the cascade of secondary effects of primarily mechanical brain injuries, our organotypic trauma model will directly address the rapidly increasing demand for a well characterized, experimental system to deliver a clinically relevant traumatic insult - and may prove crucial for the discovery of caspase-based neuroprotective mechanisms.