19 Aug Microfluidic Platform for Monitoring Microglial Dynamics in Neuroinflammatory Conditions
Understanding how microglia, the brain’s immune cells, respond to inflammation is pivotal for grasping the complexities of neurological diseases. Traditional methods, though useful, often fall short in replicating the dynamic environments of living tissues. The development of a novel microfluidic platform, marks a significant leap in our ability to simulate and study these processes more accurately. In a recent article published in Microsystems and Nanoengineering, a research team discusses the development of a programmable microfluidic chip called CAM-μTAS, which enables monitoring of calcium dynamics in microglia cells during neuroinflammation, aiming to improve the understanding of cellular behaviors under cytokine gradients. This microfluidic device platform integrates advanced microfluidics technology with a system that can generate and control cytokine gradients, which are crucial for mimicking the natural inflammatory responses observed in neurological conditions.
“Leveraging programmable pneumatically actuated lifting gate microvalve arrays and a Quake valve, CAM-μTAS delivers cytokine gradients to microglia, mimicking neuroinflammation. Our device automates sample handling and cell culture, enabling rapid media changes in just 1.5 s, thus streamlining the experimental workflow “, the authors explained.
“a A fabricated CAM-μTAS, including the lifting gate valve and a scan electron microscopy image of the Quake valve. b CAD design of the CAM-μTAS, including lifting gate valves, microfluidic rectifiers, and a quake valve. c A feature illustration of the CAM-μTAS. The device combines a series of lifting gate valves into a micropump to automatically and precisely meter cell culture media changes, load calbryte 520-Am, and eliminate backflow. The CAM-μTAS leverages the flow-blocking capability of the Quake valve to generate a concentration gradient, which enables a biomimetic delivery of inflammatory signals to the cells” Reproduced from Shebindu, A., Kaveti, D., Umutoni, L. et al. A programmable microfluidic platform to monitor calcium dynamics in microglia during inflammation. Microsyst Nanoeng 10, 106 (2024). under a CC BY 4.0 Attribution 4.0 International license
The researchers aimed to develop a microfluidic device that could more accurately mimic in vivo conditions by creating cytokine gradients. The microfluidic device leverages a combination of pneumatically actuated microvalve arrays and Quake valves to deliver cytokine gradients to the microglial cells. The Quake valves typically consist of a flexible membrane that can obstruct a microchannel when actuated. The membrane is part of the control layer of the device, which is separate from the flow layer containing the channels through which fluids movThe system automates sample handling and allows for rapid changes in the media, which are key for simulating the dynamic environment of neuroinflammation. The CAM-μTAS was microfabricated using photolithography and soft lithography techniques, utilizing materials like polydimethylsiloxane (PDMS) and various photoresists to create the microfluidic channels and valve structures necessary for the device’s functionality.
The device operation relies heavily on pneumatic actuation to control the microvalves. By applying air pressure through the control lines, the valves can either be opened or closed, regulating the flow of fluids through the device’s channels. This setup allows for the automated and precise delivery of cytokines and other reagents to the cell culture chambers. The flow rates and pressure settings were meticulously adjusted to ensure optimal conditions for microglia culture and treatment. The device was capable of rapid media changes, taking only 1.5 seconds, thanks to the efficient design of the valve system.
“a The process of actuating the lifting gate valves in series to create a micropump following a continuous flow regime in order to load calbryte 520-AM/normal bath/cell medium to the microglia cell culture chamber and cytokines+ATP to the cytokine chamber. b Microglia cells before and after calbryte 520-AM incubation. Miniaturization accelerated the incubation process allowing calbryte 520-AM to penetrate the cells in 30 min. (20X magnification)” Reproduced from Shebindu, A., Kaveti, D., Umutoni, L. et al. A programmable microfluidic platform to monitor calcium dynamics in microglia during inflammation. Microsyst Nanoeng 10, 106 (2024). under a CC BY 4.0 Attribution 4.0 International license
Microglia cells were cultured directly within the microfluidic device. Once adhered and stable, the device facilitated the application of a cytokine gradient, mimicking inflammatory conditions. This was done by opening the Quake valve at controlled intervals, allowing cytokines to flow toward the microglia cells at gradient concentrations. Experimental results showed that the CAM-μTAS could effectively create cytokine gradients and stimulate microglia in a way that mirrors natural activation during brain inflammation. The system enabled observations of location-dependent microglial activation patterns, which differ significantly from the results obtained using traditional non-gradient-based methods. The CAM-μTAS also integrated automated calcium imaging. This involved incubating the cells with a calcium-sensitive dye and then observing the changes in fluorescence as the cells responded to the cytokine treatment. The setup allowed for continuous monitoring of cellular responses under various experimental conditions.
The fabrication and operation of the CAM-μTAS highlight the sophisticated integration of microengineering and biological techniques to create a versatile platform for studying neuroinflammation. By automating many of the processes, from cell culture to treatment application and imaging, the device opens new avenues for precise and replicable experiments in neurobiology research.
“In conclusion, the addition of automation to microsystems promises a new era of precision, speed, and consistency in understanding and manipulating human cellular behavior, opening the doors for advancements in personalized medicine, disease modeling, and drug discovery. “, the authors concluded.
Figures are reproduced from Shebindu, A., Kaveti, D., Umutoni, L. et al. A programmable microfluidic platform to monitor calcium dynamics in microglia during inflammation. Microsyst Nanoeng 10, 106 (2024). https://doi.org/10.1038/s41378-024-00733-1 under a CC BY 4.0 Attribution 4.0 International license.
Read the original article: A programmable microfluidic platform to monitor calcium dynamics in microglia during inflammation
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