Materials Interface Modulates Cell Behaviors

Extracellular matrix(ECM)plays crucial role in regulation of cell behaviors.They are subjected to interaction between intercellular network and material surface.In this process,cell senses surrounding microenvironment signals such as surface morphology,topologic structure,and stiffness by cytoskeletal proteins.These physical or mechanical cues significantly affect cell signal pathway and protein expression by remolding cytoskeleton,as a result to induce cell traction force and behavior changes.The mechanism study about cell behaviors on material surface is significant for biomaterial preparation and clinical research.By nanofabrication of three types of surfaces from low degree to high degree,isotropy and homogeneity,we study cancer cell behavior changes on biointerface and discuss the relevant mechanism form molecular level.Firstly,we fabricated nanofiber-based material by mimicking the tissue fibrous matrix to investigate the dynamics of epithelial breast cancer cell migration.Then,we fabricated arranged nanoarray structure to study mechanical induced cytoskeleton rearrangement and the mechanotransduction-related signal pathways of epithelial pancreatic cancer cell.Finally,we made homogeneous hydrogel surface by mimicking tissue stiffness to understand the PDX primary tumor cell cluster behaviors and dynamic process during tumorigenesis.The main results are described as follows:1.By mimicking low degree of tissue fibrous matrix,we fabricated polycaprolactone(PCL)nanofibers with various disorders using electrospinning methods to study cell migration behaviors.By in-suit observation,we found that MDA-MB-231 cell motion trajectories and cytoskeleton arrangement templated the fiber orientation.Vimentin and the upstream ?-catenin obviously affected cell motion on nanofiber surface.The si RNA knockdown of vimentin and ?-catenin enhanced migration velocity but decreased the direction ratio as responses.While the si RNA knockdown of filopodia related protein RAC1 and CDC42 enhanced migration velocity but make no influence on direction ratio.2.By metal-assisted chemical etching method,arranged silicon nanoarray with controllable size(diameters 380 nm and 100 nm and heights from 0.7 ?m to 8.2 ?m)were fabricated for cell behaviors study.Mostly,PANC-1 cancer cells exhibited spherical morphology on nanopillars array,and pillars at cell perihelial were bent by cell contract force.The cytoskeleton structure on arrays were disrupted,causing proliferation rate and migration ability decreased,which was much lower than that on flat silicon.3.Arranged silicon nanoarrays were sued for study of cell cytoskeleton rearrangement.By super-resolution confocal images and filaments analysis,we found cytoskeleton filaments of cell on nanopillar array was rearranged.The actin filaments orientation was 60° between each other,which templated the array arrangement.Tubulin and actin accumulated at cell peripheral to maintain cell morphology,which induced decrease of cell migration ability.Instead of polarizing,vimentin intermediated filaments surrounded the cell nucleus with high polymerization degree,which inhibited cell migration and proliferation.4.Arranged silicon nanoarrays were sued for study of cellular mechanical responses.The nominal spring constant of SNP300 and SNP100 are calculated 4.5 n N/nm and 0.24 n N/nm,respectively.Average deflection of nanopillars at cell periphery were measured 102 nm and 671 nm,and average contract force were 462 n N and 161 n N.We found cytoskeleton stress fiber on arrays were disrupted,and cell nucleus was heavily deformed with wizened nuclear envelope,compared to that on flat silicon.Cell height and nucleus height were obviously increased on nanopillar array,and cell volume maintain unchanged,while nucleus volume increased slightly.Mechanotransduction-related signal factors activating transcription factor ATF3 was highly expressed and endowed more than 40% nuclear location.5.Surface homogeneous polyacrylamide hydrogel was fabricated to study cell behaviors as response to matrix stiffness.We found that time point to reached exponential phase was delayed for PDX primary tumor cells on soft hydrogel(0.487 k Pa)compared to hard hydrogel(21 k Pa).Single cell induced surface indentation on soft hydrogel for lacking of mechanical support from substrate,while indentation was smaller for cell cluster,because of mechanical support from cell interaction.On soft hydrogel,the cells in cell cluster were compressed and deformed,which was similar to a tumor tissue.The cytoskeleton of cells at center of cell cluster was uniformly distributed,while showed polarity at cluster peripheral.