Q&A: What can microfluidics do for stem-cell research?

Stem-cell biology and microfluidics have both been hotbeds of research activity for the past few years, yet neither field has been able to successfully commercialize a clinical 'killer application'. Stem-cell behavior is exquisitely sensitive to environmental cues, and the important cues are difficult to establish, manipulate and quantify in traditional cell culture. Because the microenvironment can be controlled in microfluidics platforms, micro-fluidics has a lot to offer stem-cell biology and there are many good reasons for the fields to join forces. What exactly is microfluidics? Microfluidics is the characterization and manipulation of fluids on the nanoliter or picoliter scale. The behavior and properties of fluids change as amounts decrease from the macroscale (volumes used for everyday applications) to the microscale. This means that microfluidic devices cannot be built by simply scaling down macroscale devices. For instance, at low microliter volumes, fluids act more like solids, and two fluids flowing alongside each other in a microchannel will not mix well (except by diffusion); therefore, a variety of techniques (pumps, valves, electrokinetics) are used in microfluidics platforms to actuate mixing and fluid flows. Most microfluidics applications in research labs concen trate on the 10 to 100 μm scale, basically the diameter of a single cell. Microfluidics lab-on-a-chip devices allow standard laboratory analyses, such as sample purification, labeling, detection and separation, to be carried out automatically as the sample is moved, via microchannels, to different regions of a chip. Various methods have been used to produce microfluidic devices, but inkjet printers offer an easily accessible way of printing channels and other features directly onto the device. This technique has been used to print precise patterns of proteins or protein gradients onto a surface on which cells can subsequently be cultured to investigate or control their behavior. A technically more advanced use of microfluidics is the integration of microchannels with nanoelectrospray emitters for preparing material for mass spectrometry in high-throughput proteomics analyses of biologic samples [1]. What background do you need for microfluidics? Physics (in particular fluid dynamics), mechanical engineer ing, or bioengineering backgrounds, the common feature of these being a strong mathematical foundation. On the one hand, scientists working on the development of pluripotent stem cells for clinical use are encountering a major challenge in scaling up cell cultures for master banks to be used as sources of cell therapies for large numbers of patients. Microfluidics is clearly not the answer to this …