在体光镊诱导微血管堵塞技术及机制研究

Microcirculation is the circulation of the blood in the small blood vessels, present in the vasculature embedded within organ tissues. The main functions of the microcirculation are the delivery of oxygen and nutrients and the removal of carbon dioxide. The normal circulation of blood flow in the microvessel is important to realize the physiological functions of microcirculation. Due to the small shear stress in the microvessel, it is easy to induce Red Blood Cell aggregation, which will affect blood flow dynamics in the microvessel, even block the blood flow in the blood vessels. So studying the formation mechanism of red blood cells aggregation and microvessel blockage have important significance in microcirculation research and clinical applications. However, the studying in vitro may not reflect the formation mechanism and microvessel blockage process in vivo accurately and fully because of the complexity of the in vivo environment. Therefore, biological studies in vivo, especially in living animals, are important to verify our knowledge acquired from the in vitro studies.. This application is intended to optimize the current optical tweezers technology in vivo, and use it to study the functions of erythrocyte deformation and vascular wall injury in the process of microvessels blockage. Firstly, we measure the cell-cell interaction between erythrocytes in the microfluidic and microvessels. The results will be helpful to understand the microscopic mechanism of erythrocyte aggregation. Secondly, the optical tweezers are used to trap and manipulate the Red Blood Cells in mice and zebrafishs, which is used to study microvessels blockage process induced by erythrocytes aggregation in two animals respectively. This study aims to clear the function of erythrocyte deformation in the process of microvessels blockage. Finally, magnetic particles will be trapped and manipulated in living zebrafishs with the optical tweezers. The trapped magnetic particles will be used to thermally damage the microvessels wall. This study aims to clear the function of microvessel wall injury in the process of microvessels blockage in vivo..The results of this application will rich the experiment technology for microvessels blockage in vivo, and understand how erythrocytes aggregation and microvessel injury induce the microvessels blockage respectively.

微血管中血液正常流动是实现其生理功能的保障，在病理条件下它容易被红细胞聚集体堵塞，因此研究微血管堵塞机制具有临床应用价值。由于体内环境的复杂性，体外研究不能够全面准确的反映体内微血管堵塞过程，发展在体微血管堵塞技术开展相关机制是微血管堵塞研究的最终目标。本申请拟研究基于光镊的体内微血管堵塞技术，并结合微流道技术，研究微血管堵塞过程中的红细胞形变因素和血管壁损伤因素的作用。首先将光镊与微流道技术结合，测量体外微流道和体内微血管中形变红细胞的相互作用，理解红细胞聚集体形成的微观机制。其次应用光镊操控不同动物内的红细胞，分别研究其诱导微血管堵塞的过程，明确红细胞形变能力在微血管堵塞过程中的作用。最后使用光镊操控磁性颗粒，探索磁颗粒热损伤微血管壁技术，研究体内微血管堵塞过程中血管壁损伤因素的作用。将在体研究结果与微流道模拟研究进行验证，丰富体内微血管堵塞诱导技术，理解红细胞聚集体堵塞微血管机制。

由于动物体内环境的复杂性，体外对微血管堵塞机制的研究不能够全面准确的反映体内微血管堵塞过程，因此发展在体微血管堵塞技术并研究微血管堵塞机制很有必要。光镊是一种利用紧聚焦激光束对微纳米颗粒进行非接触操控的技术，广泛应用于物理、胶体化学、生物医学等领域的研究。近年来，研究人员利用光镊技术操控体内微血管中红细胞，对微血管进行堵塞。在本项目的资助下，课题组围绕光镊操控体内红细胞堵塞微血管，研究微血流中红细胞形变能力和细胞聚集的光学诱导方法，取得了如下阶段性的科研成果：（1）体内光镊系统优化设计。研究了非傍轴矢量光束的自聚焦传播特性、双高斯光镊在体内排列对红细胞的捕获效果，并探讨了捕获光束的高阶衍射条纹对微粒的操控能力。（2）微流场中被光镊捕获的红细胞形变规律研究。利用微流泵与光镊组合实现了微流场中被光镊捕获红细胞的形变规律测量，并将该特性应用实现了体内缺血微血管的重新灌注。（3）被捕获的红细胞堵塞微血管研究。研究了小鼠耳廓和斑马鱼中光镊诱导微血管堵塞的过程，结果表明光镊诱导微血管堵塞的主要因素是光阱力是否能够克服流体拖拽力，将多个红细胞形成聚集体，而红细胞与血管之间的粘附力并不是光镊诱导微血管堵塞的主导因素。（4）光镊操控吸热颗粒及其热效应用于微米颗粒的操控。研究报导了吸热颗粒三维振荡、热对流诱导颗粒和细胞聚集、利用激光加热微流道中的颗粒产生气泡并操控等现象和方法。通过本项目的实施，完善了用于体内微血管中红细胞的光流控技术，揭示了光镊诱导微血管堵塞的主导因素。另外，基于激光热效应研究发展了颗粒和细胞在微流道中的光热聚集方法。这些工作的完成为进一步开展光流控技术应用于体内更大血管、更快微血流中细胞操控和参数测量等提供了较为丰富的知识积累。