Study Of Separation And Long-term Culture Of Circulating Tumor Cells Using Microfluidic Chips

According to the statistics of the Global Cancer Statistics Report 2018,there are more than 18 million new cancer patients worldwide.There are about 4.29 million new cancers in China,of which 2.87 million cancer patients have died.Early detection,diagnosis and treatment of cancer are important means to improve the cure rate and survival rate of cancer and reduce mortality.In recent years,filtering circulating tumor cells from the blood as a new method for cancer diagnosis has gradually attracted the attention of academic and medical circles.This technique is called liquid biopsy.Traditional cell sorting is carried out on a macro scale,such as centrifugal separation,chemical dissolution,and antibody labeling sorting based on fluorescence or magnetic beads.Although these methods are mature and reliable,they are cumbersome to operate,time-consuming,large in sample consumption,and serious loss of target cells,which are not conducive to future culture and research.To solve these problems,a microfluidic chip was designed,and the screening efficiency and cell culture of the chip were studied by numerical simulation and experimental methods.In order to isolate circulating tumor cells from blood containing a variety of cells,two microfluidic chips with four-level screening arrays were designed and manufactured.The microfluidic chip is designed based on the different physical properties of the main components of red blood cells(5～7 μm)and white blood cells(7.3～13.2 μm)and circulating tumor cells(12～25 μm)in the blood.At the same time,the valve design is conducive to cell culture and imaging;the high molecular polymer polydimethylsiloxane material is used in the production,which has good light transmission and good biocompatibility.The design scheme is simple and easy to operate.Under the condition of ensuring a certain separation efficiency,it solves the problem of cell separation and culture in one stop.According to the design results,The finite element model is established.The velocity field distribution in the microfluidic chip and the velocity of each capture site are simulated and analyzed under the condition of different inlet flow.Through quantitative analysis of the wall shear force,the interference factor that affects the cell viability of the separation experiment is eliminated;And use the two-phase flow model to study the pressure deformation behavior of a single cell when passing through the micro-column gap,so as to have an in-depth understanding of the physical process of cell deformation screening.The establishment of the finite element model has laid a foundation for guiding the design and optimization of the circulating tumor cell separation device.In the course of the experiment,the separation ability of the four-stage screening array was tested with a flow pump and a pressure pump;the best separation speed was obtained by comparing the separation efficiency of the chip with different fluid channel heights under different inlet flow rates;The chip was tested with mouse whole blood,and the screening rate was basically maintained above 80% under the injection of 6 μL/min;Through exploring long term culture method on microfluidic chip,proliferation amplification was carried out for 7 days,and delayed shoot platform could better understand cell proliferation process.Cell fusion was observed through anaphase treatment.Mapping single cell clone tree could better understand cell heterogeneity and provide a noninvasive and inexpensive method for tumor evaluation.To guide drug screening and individualized therapy.