Biomedical Engineering's Andre Levchenko and graduate students Raymond Cheong and Joanne Wang have created a new device that is set to change the way cancer is diagnosed and cellular signaling pathways are studied.
The new technology, in-chip immunostaining, or Imstain for short, is a microfluidic device that allows measuring of signal activity of kinases, transcription factors and target genes in a high-throughput, high-content manner.
Currently, one of the most commonly used methods for studying signaling proteins is live cell imaging, which uses fluorescent markers to tag a signaling protein of interest and visualizes them under microscopy. Though these experiments provide a tremendous amount of detail, they are also problematic.
The fluorescent tags can cause the proteins to behave differently than they normally would in the wild type and can cause proteins to be over-expressed, thus complicating and perturbing the system. In addition, the throughput of live imaging is low and no more than a few dozen cells can be analyzed at a time.
"We thought that maybe we could take advantage of microfluidics methodology, which basically is a new methodology that is part of the lab-on-a-chip effort." Levchenko said. "We want to create a chip where in one experiment we can expose the cell to different stimuli, for example, different drugs that would be used for chemotherapy or maybe check the status of different signaling pathways."
Microfluid devices are an example of microelectromechanical systems (MEMS), in which wells and fluid channels of micro or nanometer scale are created on silicon wafers using photolithography, a process in which patterns are etched on a wafer that is coated in light-sensitive chemicals.
Using MEMS methodology, Imstain was designed and fabricated to allow thousands of cells to be screened at once by first seeding them in the channels and filling the channels with medium or stimulus afterwards.
"Different channels can have cells exposed to different chemical for different periods of time, and we are able to look at different antibodies and the localization of different proteins," Levchenko said. "There is an amazing degree of flexibility on how [the device] can be used, and you can still screen thousands of cells per one experiment."
Imstain has already been used in several research projects, including one focused on the Nuclear Factor-kappa B (NF-kB) signaling pathway. NF-kB is a transcription factor crucial to the regulation of the immune system. Incorrect regulation of NF-kB has been linked to cancer, autoimmune diseases and viral infections.
"The NF-kB signaling pathway is interesting, since it is directly related to cancer, tumor necrosis and multiple sclerosis. The device that we designed was designed to help facilitate experiments looking at signaling pathways. We chose to study this signal pathway in particular, because we already have a relatively good understanding of the dynamics of the NF-kB pathways," Cheong, a graduate student who helped design and fabricate Imstain, said.
"In this particular pathway, the dynamics are important, because the timing of the NF-kB activity is very important to the control of the expression of certain genes."
The current goal of Levchenko's group is to bring Imstain to a clinical setting. The lab is focused on screening multiple cancer cell lines and has already screened a few thousand cell lines for useful information on cancer diagnostics and possible treatment options.
"This chip is scalable, so you can easily increase the number of cells that are passed, and the amount of tissue we need is almost invisible. So we will not necessarily interfere with some of the more conventional types of analysis yet we might end up with a lot more information using this device," Levchenko said.
"We are also using this device for regular research activities signaling pathways, and we see it as a research tool that can potentially truly change the way we perform diagnostic tests and research."
