Pneumatic Microfluid1c For Three Dimensional Micro Vasculature Construction And Cell Micropatterning

Cells are the base of life. They reside in a milieu composed of soluble factors, cell-matrixinteractions, and cell-cell contacts, and do so while living within an environment with specificphysicochemical properties. These elements give the environment a distinct physiologicalcharacter, and provide a set of extracellular cues that work in concert to regulate cell structure,function, and behavior, and ultimately influence the growth, development, and repair ofneighboring tissue. The combination of these biochemical, physical, and physicochemicalfactors constitutes the cell microenvironment. Therefore, ability of controlling cells and thesurrounding microenvironment will be important to understanding the physiopathology.Microfluidic is supposed to be a promising platform with the ability of manipulating cells andreconstructing the surrounding microenvironment, due to its excellent performance in thespatiotemporal control of microfluidic perfusion and biological samples (e.g., cells and ECM),in simulation of tissue-relevant context, as well as in the feasible sequential manipulation. Inthis study, we developed two types of pneumatic microfluidic devices for three-dimensionalmicrovasculature construction and protein and cell micropatterning, respectively. Our resultsshowed that the pneumatic microfluidic will provide a new method for on-chip manipulationof cells and reconstruction of physiologically relevant microenvironment. The results obtainedin the present work are as follows:1. A pneumatic microfluidic device with good mechanical properties and structuralintegrity, which was utilized for the construction of three-dimensional microvasculature, wasfabricated through adjusting the optimal conditions during the fabrication process. Themicrofluidic device was composed of four layers: the fluidic layer, the control layer (i.e., thepneumatic microchannel network layer), the supporting layer, and a glass slide. It wasdemonstrated that the whole pneumatic microchannel network (PμCN) in the microfluidicdevice presented a uniformly spatial appearance through systematically evaluating thedimensional dynamics of the PμCN with varied pneumatic pressure.2. A pneumatic microchannel network (PμCN) fabrication method for producing athree-dimensional microvascular system in an integrated microfluidic device is described. A microvessel network-embedded hydrogel scaffold is constructed using in situ pneumaticactuation of the PμCN and collagen polymerization. The endothelium-containingmicrovasculature, which has high cell viability and typical vascular functions and features,was formed by seeding and cultivating human umbilical vein endothelial cells.3. A quantitative investigation of the adhesive interactions between breast cancer cellsand endothelial cells was performed with vascular tissue-mimicry in the hydrogel-supportedendothelial network using human breast cancer cells and endothelial cells. The results showedthat very low proportion of breast cancer cells were located on the endothelial surfaces whenthe endothelium was not treated with breast cancer cell conditioning medium. However, thebreast cancer cells conditioning medium treatment significantly enhanced cancer cellattachment to the endothelium throughout the microvasculature, and the cancer cellspresented a region-preferred adhesion behavior.4. In this study, we described a simple and in situ micropatterning method using anintegrated microfluidic device with pneumatic microstructures (PμSs) for highly controllableimmobilization of both proteins and cells in a high throughput, geometry-dynamic, andmulti-patterning way. The precise Pluronic F-127passivation of microchamber surface exceptthe PμSs-blocking regions was performed and characterized, and spatial dynamics andconsistency of both the PμSs and protein/cell micropatterning were optically evaluated andquantitatively demonstrated. A systematical investigation of PμSs-assisted micropatterning inmicrofluidics was carried out. In addition, the feature of high throughput and spatial control ofmicropatterning can be simply realized by using the well-designated PμS arrays.5. Co-micropatterning of different proteins (bovine serum albumin and chicken eggalbumin) and cells (human umbilical vein endothelial cells and human hepatocellularcarcinoma cells) in microfluidic device was successfully accomplished with the orderly serialmanipulation of PμS groups.