We have made significant progresses in designing, developing, and optimizing the commercial level instrumentation of an automated microfluidic cell culture system, and have demonstrated an application of the system in direct converting human skin cells (fibroblasts) into neurons on the microfluidic chip.
A fundamental challenge for stem cell technology is finding the right cell culture conditions for growing cells and steering cells into the desired lineage. Cell fate is determined by timely coordination of many genes and environmental factors. With currently available tools, however, multifactor experiments are often labor intensive and difficult to carry out reproducibly. Using the core technology of Multilayer Soft Lithography at Fluidigm, we have developed a microfluidic chip and an automated instrument that can culture cells on the chip for extended period of time and automatically deliver multiple combinations of different factors to cells controlled by arrays of on-chip polymer microvalves. Cells can also be harvested from the chip for continued off-chip culturing, single-cell genomic analysis, and/or functional assays. We have updated several key components of the system (including hardware, firmware and software), and significantly improved the system performance and reliability. We have validated the thermal, pressure and fluidic performance of the system controller, and are planning to develop and optimize the other parts of the commercial instrumentation in the next period.
To demonstrate the biology application of the system, we have developed a novel method for long-term dosing of different micro RNAs and their permutations/combinations to human skin fibroblasts on chip and succeeded in direct conversion of the fibroblasts into neurons. Recently several laboratories have reported direct conversion of other type of cells into functional mouse and human neurons and specific neuronal subtypes without cells being reprogrammed to a stem cell stage first. Compared to differentiation from stem cells, direct conversion is much faster and efficient, and may reduce genetic/epigenetic aberrations associated with stem cell induction. Our new non-viral safe dosing approach generated neurons with high efficiency and cell viability. The results were in agreement with published reports, and were confirmed in large well-dish culture format.
The microfluidic cell culture system allows for precise control of microenvironment of cells, and is advantageous in screening multi-factorial conditions for cell maintenance, differentiation and reprogramming with minimal reagent consumption. We believe this system will be a valuable tool for the stem cell research community in both understanding of basic biological signaling mechanisms and developing of cell-based therapies.