Cell Migrations: Causes and Functions

The last 20 years have seen the blooming ofmicrofluidics technologies applied to biologi-cal sciences. Microfluidics provides effectivetools for biological analysis, allowing theexperimentalists to extend their playgroundto single cells and single molecules, withhigh throughput and resolution which wereinconceivable few decades ago. In particular,microfluidic devices are profoundly changingthe conventional way of studying the cellmotility and cell migratory dynamics. In thischapter we will furnish a comprehensive viewof the advancements made in the research do-main of confinement-induced cell migration,thanks to the use of microfluidic devices. Thechapter is subdivided in three parts. Each sec-tion will be addressing one of the fundamentalquestions that the microfluidic technology iscontributing to unravel: (i) where cell migra-tion takes place, (ii) why cells migrate and,(iii) how the cells migrate. The first introduc-tory part is devoted to a thumbnail, and par-tially historical, description of microfluidicsand its impact in biological sciences. Stresswill be put on two aspects of the devices fab-rication process, which are crucial for biolog-ical applications: materials used and coatingmethods. The second paragraph concerns thecell migration induced by environmental cues:chemical, leading to chemotaxis, mechanical,at the basis of mechanotaxis, and electrical,which induces electrotaxis. Each of them willbe addressed separately, highlighting the fun-damental role of microfluidics in providingthe well-controlled experimental conditionswhere cell migration can be induced, inves-tigated and ultimately understood. The thirdpart of the chapter is entirely dedicated tohow the cells move in confined environments.Invadosomes (the joint name for podosomesand invadopodia) are cell protrusion that con-tribute actively to cell migration or invasion.The formation of invadosomes under confine-ment is a research topic that only recently hascaught the attention of the scientific commu-nity: microfluidic design is helping shapingthe future direction of this emerging field ofresearch.