Research On Tumor Metastasis Microdevices Simulating The Stiffness Of Extracellular Matrix

Cancer metastasis is a complex disease treatment matters faced by humankind.the metastasis and diffusion of cancerous cell is the main cause of high mortality rate of cancerous person.The composition,structure and mechanical properties of extracellular matrix can directly affect the biological behavior of cancerous cells.Such as the morphology,migration ability and proliferation of cancer cells.Among the mechanical properties of extracellular matrix,matrix stiffness is a very important factor affecting the diffusion and metastasis of cancer cells.At present,the traditional matrix stiffness-related models of tumor metastasis in vitro are mostly static cultures,which are different from the dynamic physical microenvironment in vivo.In this dissertation,we combine the fiber-gel hybrid scaffolds with biological microdevices to obtain a tumor metastasis microdevice imitating extracellular matrix stiffness,and explore the influence of matrix stiffness on tumor metastasis,which provides a dynamic microenvironment and scientific research platform for in vitro research such as cell culture,cancer metastasis and cancer-related drugs drug screening.(1)To design the structure of tumor metastasis microdevice mimicking the stiffness of extracellular matrix.Before all others,the overall structure of the microdevice was designed,which consisted of three channels,a cell culture pool and micro-columns.The cell culture pool is connecte by an intermediate channel and is loaded with a hybrid scaffold for inoculate,growing and propagating cancer cell,that channels at two sides are cell transfer channels,and the micro-column structures at two sides of the culture pool are used for limiting the position in the process of cell-collagen mixed solution perfusion.The modeling software and finite element simulation software were used to design and optimize the structure of the microdevice.Simulation results showed that the two unequal-gap circular micro-column structures had better effects of packaging collagen.A continuous and stable air-collagen interface was formed between the micro-columns during the process of cell-collagen solution perfusion,and it would not overflow to the two-side channels.After the chemokine solution was introduced,a good chemokine concentration gradient was presented in the chip,which was convenient for controlling the direction of cell transfer.The porous medium area in the culture pool can make the cells grow in a low-speed and stable three-dimensional environment.(2)Manufacture of mixed supports with different stiffness.The fiber scaffolds were obtained by adjusting the printing parameters of the electrostatic spinning machine.The hydrophilic modification of the fiber scaffolds were performed by using a plasma ashing instrument and tested by a liquid analyzer.The results showed that the wettability of hydrogel on fiber scaffold was improved after hydrophilic modification,and the wettability of hydrogel with two concentrations increased by 70.94% and 59.39% respectively.Manufacturing a mixed stent molding SU-8 mold,respectively introducing hydrogel solutions with different concentration ratios into the pores of the fiber stent in the mold,and performing ultraviolet polymerization to obtain two mixed stents.The stiffness(characterized by elastic modulus)of the above two hybrid scaffolds was tested by atomic force microscopy,and the results were19.73 k Pa and 1.13 k Pa,respectively.The fiber-hydrogel hybrid scaffold conformed to the extracellular matrix stiffness of cancerous tissue and normal tissue in vivo.(3)Fabrication of tumor metastasis microdevices and completion of fluid experiments and cell culture experiments.The PDMS structural plate was fabricated by the MEMS dry etching process and casting process.Then that hybrid scaffold was placed in the culture pool and bonded with the cover plate to obtain the complete microdevice.The collagen pre-polymerization solution perfusion experiment and the ink diffusion experiment were completed in the chip.The experimental results showed that the unequal-pitch micro-columns could effectively encapsulate the collagen solution and ensure no overflow.The stable concentration gradient was formed by ink diffusion in the micro-device.The microdevices were used for cell culture experiments.The microdevice is non-toxic and harmless in the process of cell culture.Experiments show that there are more false feet in the microdevice with cancerous stiffness matrix,showing stronger metastasis.