基于微流体装置的微血管网内红细胞流动和分布特性的研究

实体肿瘤血管具有扩张、扭曲、不规则分支以及分支间连接絮乱等特征. 为了考察这些特征对血液流动的影响，将肿瘤血管简化为垂直相互贯通的微血管网，借助微流体实验装置，以一定浓度的红细胞悬液作为流动介质，研究红细胞在微血管网中的流动和分布特性. 具体实验方案如下:首先，采用软刻蚀技术，在聚二甲基硅氧烷（polydimethylsiloxane, PDMS）上加工出微血管网；然后，采用微注射泵控制微血管网入口处的红细胞悬液流量，使用倒置显微镜和高速摄影系统观察并记录实验过程；最后，通过Matlab 软件包Piv-lab 及高速摄影配套软件对获得的视频图像进行处理，提取红细胞在微血管网中的流动和分布数据. 数据处理结果显示，红细胞在微血管网中的流动和分布特性受悬液内的红细胞压积（hematocit, Hct）的影响. 红细胞随悬液Hct 的不同呈现2 种运动轨迹:一种为仅沿着轴向微管道流动；另一种是从轴向微管道流入并穿过径向微管道，再进入另一侧的轴向微管道. 另外，入口流量相同时，红细胞在微血管网中的流动速度随Hct 变化呈现不同，Hct 为3% 和5% 的红细胞速度要明显高于Hct 为1% 的红细胞速度. 

THE OBSERVATIONS OF THE FLOW BEHAVIOR AND DISTRIBUTION OF RED BLOOD CELLS FLOWING THROUGH A MICRO-NETWORK CHANNEL

The structure of vascular network in solid tumor is extremely disordered and non-uniformed. These characteristics result in the complexity and diversity of the blood flow in tumor microcirculation which eventually make drug delivery and targeted therapy difficult in solid tumor. In order to investigate the influence of tumor microvascular network on the blood flow, a vertical interconnected micro-network channel was fabricated by soft lithographical method in this work, designed to simulate the expanding, multi-branched and multi-interconnected tumor vascular network. Employing the micro-flow-system, the red blood cell (RBC) suspension was injected into micro network channel at a certain speed. Inverted microscope was used to observe the migration of RBCs and the sequential images were recorded. PIV-lab package of Matlab and the tool box of the high-speed video camera were used to process the image data. The results show that, hemotocrit (Hct) level of RBC suspension is the main factor to affect the flow and distribution of RBCs in the micro-network. The trajectories of RBCs in the micro-network vary with different Hcts. When Hct level is as low as 1%, the RBCs in the micro-network flow only along the axial direction of the channels, while Hct level becomes higher, some RBCs will flow across the radial channel and the two types of RBC flow trajectories appeared. Furthermore, at the same inlet flow rate, the speeds of RBCs in the micro-network show difference with different Hct levels. The velocities of RBCs with 3% and 5% Hct levels are evidently higher than those of RBCs with 1% Hct level.