Targeted microcarrier design and optimization

描述（由申请人提供）：改善许多疾病治疗的一种战略方法是将药物包装成载体颗粒，然后靶向药物载体将血液直接输送到病变组织。这种方法的好处包括可能增加到达病变组织的药物剂量（增强治疗效果）和同时减少到达正常组织的药物剂量（降低毒性）。这种方法的成功部分依赖于将功能化的靶向药物载体注射到靠近疾病组织的血流中的技术和临床方法的发展。成功直接依赖于载体颗粒的设计和制造，这些载体颗粒具有特定的特征，如颗粒大小和与所治疗疾病特有的结合分子的表面覆盖，从而导致所需的和必要的初始事件：载体颗粒与病变组织内血管中的内皮细胞结合。靶向纳米载体在流动中的运动、控制特异性结合的生物分子受体-配体相互作用以及细胞膜上受体的热/运输动力学之间的复杂相互作用，本质上是一个多尺度问题。结合的物理环境最终决定了纳米载体在靶细胞上的阻滞效果。纳米载体的结合和阻滞受到以下因素的影响：血流、细胞表面特定目标决定因子的表达水平、它们在膜上的横向扩散、糖萼的存在与否以及膜的流动性。我们假设可以优化实验和设计参数，如纳米载体上的受体密度、载体尺寸和对流动特性（如剪切应力水平）的结合响应，以增强纳米载体对特定（应力）细胞的靶向性。为了验证这一假设，我们提出了四个具体目标：1)建立一个空间分辨的随机多尺度模型，用于预测靶向球形纳米载体与内皮细胞结合的能量和动力学；2)实验量化了不同尺寸配体功能化纳米载体在静态和剪切条件下与固定细胞的结合动力学；3)实验量化在静态和剪切条件下，配体功能化的不同大小的纳米载体与活细胞的结合动力学；4)将Aim 1中的模型扩展到a)包括膜迁移、受体的横向扩散和活细胞中糖萼构成的机械/水动力屏障对结合的额外影响；b)包括红细胞-纳米载体相互作用和非牛顿流变性的影响。我们将开发一个协同建模和实验平台，以获取和连接与靶向纳米载体血管递送相关的多个长度和时间尺度。我们的目标是定量表征和预测球形纳米载体在剪切流下与固定和活内皮细胞结合的瞬态纳米级结合力学和动力学，作为各种实验可调参数的函数，将导致许多疾病治疗方法的改进。改善许多疾病治疗的一种战略方法是将药物包装成载体颗粒，然后靶向药物载体将血液直接输送到患病组织。我们将开发一个协同实验和计算平台，解决靶向纳米载体的血流输送问题。这项定量表征和计算预测纳米载体与内皮细胞结合的结合力学和动力学的工作将导致许多疾病治疗方法的改进。

DESCRIPTION (provided by applicant): A strategic approach to improve the treatment of many diseases is to package a drug into carrier particles and then target that drug carrier for bloodstream delivery directly to the diseased tissue. Benefits of this approach include the possibility of an increase in the dose of the drug reaching diseased tissue (enhanced therapeutic efficacy) and a concomitant decrease in the dose of drug reaching normal tissue (reduced toxicity). Success of this approach relies in part on the development of technologies and clinical methods for injecting functionalized, targeted drug carriers into the blood stream close to the disease tissue. Success is directly dependent on the design and manufacture of carrier particles that have specific features such as particle size and surface coverage with binding molecules specific to the diseases being treated that lead to the desired, and necessary, initial event: binding of the carrier particle to endothelial cells in blood vessels within the diseased tissue. The complex interplay between targeted nanocarrier motion in flow, biomolecular receptor- ligand interactions governing specific binding, and thermal/transport dynamics of receptors on the cell membrane, is inherently a multiscale problem. The physical environment for binding ultimately defines the efficacy of nanocarrier arrest on the target cell. The nanocarrier binding and arrest are influenced by hydrodynamic forces resulting from blood flow, expression-levels of specific target determinants on the cell surface, their lateral diffusion on the membrane, the presence or absence of a glycocalyx, and membrane mobility. We hypothesize that experimental and design parameters such as receptor density on nanocarriers, carrier size, and binding response to flow characteristics such as shear stress levels can be optimized for enhancing the targeting the nanocarriers to specific (stressed) cells. To test this hypothesis, we propose four specific aims: 1) develop a spatially resolved stochastic multiscale model for predicting the energetic and kinetics of targeted spherical nanocarriers binding to endothelial cells; 2) experimentally quantify the kinetics of binding for ligand functionalized nanocarriers of varying size to fixed cells under static and shear conditions; 3) experimentally quantify the kinetics of binding for ligand functionalized nanocarriers of varying size to live cells under static and shear conditions and 4) extend the model in Aim 1 to a) include additional effects on binding due to membrane mobility, lateral diffusion of receptors and the mechano/hydrodynamic barrier posed by the glycocalyx in live cells; b) include effects of RBC-nanocarrier interactions and non-Newtonian rheology. We will develop a synergistic modeling and experimental platform for accessing and bridging the multiple length and time scales relevant for vascular delivery of targeted nanocarriers. Our objectives of quantitatively characterizing and predicting the transient nanoscale binding mechanics and dynamics for spherical nanocarrier binding to fixed and live endothelial cells under shear flow as a function of the various experimentally tunable parameters will lead to improvements in therapeutics for many diseases. A strategic approach to improve the treatment of many diseases is to package a drug into carrier particles and then target that drug carrier for bloodstream delivery directly to the diseased tissue. We will develop a synergistic experimental and computational platform addressing bloodstream delivery of targeted nanocarriers. This work to characterize quantitatively and predict computationally the binding mechanics and dynamics for nanocarrier binding to endothelial cells will lead to improvements in therapeutics for many diseases.