As cell biology transitions into a quantitative science, it is critically important to develop experimental tools capable of precisely controlling the cellular microenvironment. In the emerging field of cellular systems biology, scientists hope to describe the complex behavior of living organisms by understanding the intricate relationships between molecular components. In order to confront this challenge, improved experimental technology needs to be developed. Specifically, a platform capable of precise, reliable, and standardized cell culture control in an array format is required. In this dissertation, the investigation of using microfluidic technology to address this concern is discussed.
Polydimethyl siloxane (PDMS) microfluidic structures were fabricated with multiple channel geometries (2-50 μm) to create fluidic resistances spanning over 5 orders of magnitude. This design principle was leveraged to create a 64 unit array of microscale cell culture units with uniform mass transport properties. This device was able to reproduce the standard operations of cell culture (cell growth, passage, optical microscopy, fluorescent assay) and support the growth of numerous cell lines, including cancer, neural, fibroblast, liver, and primary endothelial cells.
The microscale design of the cell culture system established a microenvironment that more closely replicates the in vivo mass transport condition. By defining fluidic resistances, cells were localized into a low shear “tissue unit” thatwas fed by nutrient diffusion from a continuous convective “blood” flow. The ability to use this system for cell experimentation was verified by observing cancer cell growth response at various concentrations of serum. In a 64 unit chip, eight serum concentrations were monitored with eight replicates of each condition. The overall trend and reproducibility matched well with expected results.
A number of related microfluidic devices were also developed for use in quantitative cell biology including: surface patterning inside an enclosed microfluidic compartment, manipulating two individual cells to study cell-cell communication, measuring forces exerted by single cells, and observation of signaling pathways in yeast cells. The integration of these various microfluidic tools with the cell culture array will produce a powerful platform for experimental quantitative biology.
May 31, 2006
Lee, P. J. (2006). Microfluidic Devices for Quantitative Cell Biology. (n.p.): University of California, Berkeley with the University of California, San Francisco.