血管靶向光动力中激光光热效应规律的实验及数学模型研究

Vascular diseases involve in millions of patients. Vascular targeting photodynamic therapy (V-PDT）is a new selected treatment for these diseases. Its efficiency and safety are based on the accurate laser dose. A big spot, medium energy and long time irradiation is the mode of laser in V-PDT. The insufficient study in photo-thermal effect result that the selection of laser dose in clinic is difficult. This project is designed to study the photo-thermal effect of V-PDT in vitro, in vivo and in mathematical model basing on port wine stains. The apoptosis and necrosis of cells is tested by flow cytometry, the blood coagulation factor and heat shock protein is tested by ELISA. The photo-thermal damage on animal tissue is tested by special dyeing and immunohistochemical, the temperature is detected by infrared thermal imaging, and the blood perfusion is detected by laser speckle.A systemical mathematic model including the laser distribution, heat distribution and heat damage model is established, and the damage function and blood perfusion function which come from in vivo experiment should be used in the mathematic model. The study results would expose the photo-thermal law of V-PDT, offer the threshold of photo-thermal damage, get the software and key data for clinic detection of laser dose, and offer theoretical basic for efficiency and safety in clinical V-PDT.

血管性疾病涉及近千万患者，血管靶向光动力疗法（V-PDT）是精确破坏病变血管的一种新型疗法，其有效性和安全性有赖于激光剂量的准确选择。V-PDT使用大光斑中等能量连续照射的激光治疗模式，其光热效应缺乏系统研究，造成临床光剂量选择的困难。本项目拟以鲜红斑痣为疾病模型，从细胞、动物和数学模型三个层次系统研究V-PDT的光热效应。用流式细胞仪检测热作用后细胞的凋亡和坏死、ELISA检测凝血因子和热休克蛋白；用特染、免疫组化检测动物组织的光热损伤、红外热像仪检测照光过程中温度的变化、激光散斑血流仪检测血流灌注量的变化；构建包含光分布、温度分布、热损伤分布的综合数学模型，并将细胞和动物实验中获得的损伤函数和血流变化函数应用于数学模型中。研究结果将揭示V-PDT光热效应的机制和规律，提供光热损伤阈值，获得可用于临床光剂量监测的软件和关键数据，为临床V-PDT治疗的有效性和安全性提供理论基础。

本项目对皮肤的三种主要构成细胞（血管内皮细胞、角质形成细胞、成纤维细胞）在不同的温度和作用时间下，其热损伤规律、热休克蛋白（HSP27、HSP60、HSP70、HSP90）的表达规律进行了研究，其中，血管内皮细胞显示对热的作用更为敏感，为利用热作用选择性治疗血管性疾病提供一个依据。利用兔耳观察血管及周围组织的热升温曲线，发现血管周围的组织温度升高最显著，血管中的温度为最低。激光共聚焦显示随着激光照射功率的增加，血流速度增加，由此而产生的血流带走热的作用增强。课题组提出了联合离散-连续热传导模型（CCD），对于流速较大的血管，对其传热进行单独考察，以刻画血液强对流化热作用；对于毛细血管的传热效应，则视为均匀结构。同时，用3D表达组织热效应，而大血管则采用1D计算，计算效率大大提高。课题组用CCD方法，仿真了肝组织中热源作用时温升的不均衡情况，以及冷冻治疗时分支血管对冷核形状的影响，证明CCD方法仿真结果对组织的温度变化有更精确的反应。