Microfluidic platform to generate dynamic and diverse profiles of chemical for long time to study biology at single cell

Abstract

Significant advances in micro technology has been made to study cellular behavior, but there is still absence of robust profile generating device for mammalian cells. Unlike the unicellular organism, mammalian cell needs longer period of stimulation at least 6 hours more. Moreover, previous research revealed the limitation of petri-dish based conventional experiment. Since the cells are exposed to dynamic environment rather than static, conventional method cant represent our real world. There has been lots of studies to generate versatile gradient for long-time, but the stimulation time is too short to employ to mammalian cells. In addition to this point, we could only generate one type of profile such as pulsing, gradient. Here we propose the microfluidic device that can generate all kinds of user defined profiles sequentially through computer controlled system. With this versatile device, we could generate pulsatile, ramping up/down, various gradient switching for long time. Moreover, recent study discovered heterogeneous behavior of single cells, which has never stood out before with average-based analysis. Based on the result, the single cells exhibit heterogeneity in ERK activation under the EGF or NGF stimulation. In this thesis, when the cells exposed to EGF gradient, some of the cells showed sustained activation. In contrast, the others behaved like the stimulation without any growth factors. It implies the cells might be switched on when they reached their threshold. Moreover, we observed that decay of activation was also delayed. Further studies are needed to determine what exactly affect this phenomena and rewire the signaling molecules. However, this work is still meaningful in the aspect of building long term multi-functional microfluidic platform. We expect this novel device to be used to study dynamic stimulation and their related cellular response in diverse filed of biology.