Monolayer/spheroid co-culture of cells on PDMS well plate mediated by selective polydopamine coating
Here, we have selectively coated polydopamine (PDA) onto polydimethylsiloxane (PDMS) well plate to enable the cell co-culture of a monolayer and spheroids in a semi-segregated manner. During the coating process, the contact between PDA solution and PDMS well plate was limited to the outer flat surface because the strong hydrophobicity of PDMS prevented the access of PDA solution into the concave structures. This resulted in a spatially-defined coating of PDA. The success of PDA coating was evidenced by measuring the water contact angle, observing the liquid-air interface, and PDA-specific metallization. This platform provides a simultaneous cell culture both in monolayer and spheroids employing either the monotypic or heterotypic cells. For the monotypic culture, mesenchymal stem cells (MSC) were seeded over the well plate to concurrently generate the monolayer and spheroids. In the heterotypic culture, MSCs were first seeded into the wells to form spheroids. Then, human umbilical vein endothelial cells (HUVEC) were added over the flat surface of the well plate and were allowed to form a monolayer. The microscopic observation and fluorescence-based cell staining confirmed the clear segregation between the monolayer and spheroids in both monotypic and heterotypic cultures. This new model could pave the way for the construction of a platform closely mimicking the physiological environment used to investigate cell-cell interactions and communications applicable for drug screening.