Microfluidic generation of monodisperse structurally homogeneous alginate microgels for cell encapsulation and 3D cell culture

摘要

Recent studies have shown that basic cellular behavior varies significantly between two- and three-dimensional culture systems. To identify the origins of these fundamental differences the design of reliable and precisely controlled environments is essential. While 2D cell culture is a well-established technique, the fabrication of defined three-dimensional culture models is still challenging. We present a new method for the microfluidic generation of a micron-sized three-dimensional cell culture system. We use a triggered ionic crosslink formation to generate highly monodisperse and structurally homogeneous alginate microbeads. Aqueous droplets containing a mixture of alginate and a water-soluble calcium-EDTA complex are formed by droplet-based microfluidics. In their complexed form, the calcium ions are homogenously distributed inside the droplet but not accessible for the crosslinking process. Acid addition is used to trigger the degradation of the complex, releasing calcium ions on demand that can physically crosslink the alginate chains. A homogeneous hydrogel network is thus generated which can be transferred into an aqueous environment without losing its structural integrity. Single cells can be encapsulated into these controlled microenvironments which provide structural support while allowing for continuous nutrient supply. We encapsulate individual mesenchymal stem cells (MSCs) into the microbeads which show the aspired cell growth and proliferation.