Microfluidic-Based Cell-Embedded Microgels Using Nonfluorinated Oil as a Model for the Gastrointestinal Niche.

Microfluidic-based cell encapsulation has promising potential in therapeutic applications. It also provides a unique approach for studying cellular dynamics and interactions, though this concept has not yet been fully explored. No in vitro model currently exists that allows us to study the interaction between crypt cells and Peyer's patch immune cells because of the difficulty in recreating, with sufficient control, the two different microenvironments in the intestine in which these cell types belong. However, we demonstrate that a microfluidic technique is able to provide such precise control and that these cells can proliferate inside microgels. Current microfluidic-based cell microencapsulation techniques primarily use fluorinated oils. Herein, we study the feasibility and biocompatibility of different nonfluorinated oils for application in gastrointestinal cell encapsulation and further introduce a model for studying intercellular chemical interactions with this approach. Our results demonstrate that cell viability is more affected by the solidification and purification processes that occur after droplet formation rather than the oil type used for the carrier phase. Specifically, a shorter polymer cross-linking time and consequently lower cell exposure to the harsh environment (e.g., acidic pH) results in a high cell viability of over 90% within the protected microgels. Using nonfluorinated oils, we propose a model system demonstrating the interplay between crypt and Peyer's patch cells using this microfluidic approach to separately encapsulate the cells inside distinct alginate/gelatin microgels, which allow for intercellular chemical communication. We observed that the coculture of crypt cells alongside Peyer's patch immune cells improves the growth of healthy organoids inside these microgels, which contain both differentiated and undifferentiated cells over 21 days of coculture. These results indicate the possibility of using droplet-based microfluidics for culturing organoids to expand their applicability in clinical research.