An organotypic model of traumatic brain injury

在过去的十年里，人们在研究创伤性脑损伤的分子机制方面进行了激烈的科学活动，这是因为有压倒性的证据表明，通过药物抑制细胞凋亡来保护神经具有显著降低脑损伤影响的潜力。对神经保护剂进行系统研究的关键条件是 一种准确描述的、具有临床相关性的体外脑损伤模型。尽管有这种明显的需求，但在玻璃瓶中向标本提供这种明确的、现实的创伤的能力远远落后于用于测量反应的分子和生化分析的复杂性。在神经生物学家和生物工程师的共同努力下，我们因此开发出 一种体外脑损伤模型，使器官型脑培养受角加速度诱导的剪切损伤。在这个模型中，器官型脑培养真实地模拟了三维细胞基质中活体明显的异质细胞群体，而角加速度诱导的剪切应变提供了可扩展的、明确的和临床上的 相关的机械侮辱。 我们假设我们的器官型脑培养的加速模型可以真实地复制创伤性脑损伤，其中传递的剪切应变大小可以在细胞水平上量化。运用我们的模型，我们将能够确定细胞类型特定的损伤脆弱性，并确定caspase-8和caspase-9是否影响脑损伤后的细胞死亡。 我们建议完成我们新的脑损伤系统的正式实验表征，包括评估交付的角加速度大小和确定器官类型标本的组成属性(目标1)。由此产生的实验源数据将直接适用于制定现实的分析模型，该模型允许在主要机械损伤期间的任何时间点对整个大脑标本的剪切损伤进行计算模拟(目标2)。基于并伴随着这一严格的系统特征，我们将练习脑损伤模型以建立剂量/反应历史(目标3)，并且我们将描述继发于机械损伤的缺氧性脑损伤(目标4)的影响。最后，我们将使用我们的银型创伤模型来确定caspase-8和caspase-9(目标5)的神经保护潜力。 成功完成后，这种综合研究方法的结果将产生一个具有良好特征、可扩展、可重复性和临床相关的脑损伤模型。考虑到目前正在开发的旨在抑制主要是机械性脑损伤的继发性影响的级联治疗干预措施的广泛兴趣，我们的器质性创伤模型将直接满足对具有良好特征的实验性创伤的快速增长的需求。 系统提供临床上相关的创伤性侮辱-并可能被证明是发现基于caspase的神经保护机制的关键。

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.