Retinal blood barrier permeability using optical tracers

微血管内皮的一个关键功能是维持对液体和溶质运输的屏障。视网膜脉管系统的破坏是一些重要眼部疾病的一个决定性特征，包括糖尿病视网膜病变和年龄相关性黄斑变性。我们建议发展双示踪荧光血管造影作为评估视网膜血管通透性的一种新的定量工具。这项生物工程研究拨款提案的设计确定了这项新技术的具体特征，以供进一步开发和测试。这种双示踪剂荧光血管造影技术通过大小荧光示踪剂的不同运输来量化视网膜血管的通透性。我们使用示踪剂对荧光素钠（376D）和德州红葡聚糖（70kD）在大鼠中实施了这种视网膜成像技术，在少数动物中使用间苯二酚（235D）和FITC葡聚糖（2000kd）。我们通过5分钟的甘露醇输注获得了初步诱导。提出了进一步研究的三个目标。首先，我们计划确定最佳的囊内和血管内示踪剂，用于体内测量视网膜微循环的通透性。其次，我们建议开发光学仪器和图像分析技术，以同时测量视网膜血管中的两种荧光示踪剂。第三，我们计划建立数学模型，从视网膜循环入口和出口荧光示踪剂的动态来识别视网膜微循环渗透性特征。我们将使用简化的物理模型、数学模型，主要是在体内的大鼠研究来实现这些目标。我们的总体目标是发展这种方法作为测量视网膜通透性的工具，可以用于诊断和跟踪这种重要的临床视网膜病理的治疗效果，这是许多眼部疾病的特征。

A key function of the microvascular endothelium is maintenance of barrier against fluid and solute transport. Breakdown of the retinal vasculature is a defining feature of some significant ocular diseases including diabetic retinopathy and age related macular degeneration. We propose to develop dual tracer fluorescence angiography as a novel quantitative tool for assessing retinal vascular permeability. The design of this Bioengineering Research Grant proposal identify specific features of this new technique for further development and testing. This dual tracer fluorescence angiography technique quantifies the permeability of the retinal vasculature by differential transport of small and large fluorescent tracers. We have implemented this retinal imaging technique in rats using the tracer pairs sodium fluorescein (376D) & Texas Red dextran (70kD) and, in fewer animals, using resorufin (235D) & FITC dextran (2,000kD). We have obtained preliminary induced by 5 minutes of mannitol infusion. Three aims for further studies are proposed. First, we plan to identify the best intravesicular and transvascular tracers for in vivo measurement of the permeability of the retinal microcirculation. Secondly, we propose to develop optical instrumentation and image analysis techniques for the simultaneous measurement of two fluorescent tracers in retinal vessels. And thirdly, we plan to develop mathematical models for the identification of retinal microcirculatory permeability characteristics from the dynamics of fluorescent tracers at the inlet and outlet of the retinal circulation. We will use simplified physical models, mathematical models, and principally, in vivo rat studies to carry out these aims. Our overall goal is to develop this methodology as a tool to measure retinal permeability which can be applied to diagnose and track the efficacy of treatments of this significant clinical retinal pathology which is a characteristic feature of many ocular diseases.