Interrogation of single-cell communications on microfluidic platforms

Heterogeneous cell-cell communications are essential for organisms to regulate many biological processes, including development, dif-ferentiation, and immune regulation. They are also closely related to the occurrence and progression of a wide range of diseases. In vitro cell co-culture assay that cultivates different types of cells together is an effective approach to studying cell-cell communica-tions. However, conventional co-culture methods rely on popula-tions of cells, therefore only giving bulk-averaged results. In recent years, single-cell co-culture based on microfluidic platforms has emerged as a novel cultivation technique. It uses rationally designed microfluidic platforms to trap and cultivate different types of single cells together. Using this method, the heterogeneous interactions between different types of cells can be revealed at single-cell res-olution. This review summarizes the current advances in microflui-dics-based single-cell co-culture techniques, critically discusses their advantages and disadvantages, and summarizes the challenges and opportunities in this field.