3D co-culture of macrophages and fibroblasts in a sessile drop chip for unveiling the role of macrophages in skin wound-healing

Three-dimension (3D) cell co-cultural spheroids exhibit enhanced cellular functions and they can mirror in-vivo microenvironments. Herein, a sessile drop chip was developed to construct 3D spheroids for mirroring the wound healing microenvironment. The sessile drop chip holds the superhydrophobic surface of each microwell which can facilitate cell suspensions transfer to spheroids through the offset of surface tension and gravity, and each microwell has a cylinder hole that offers adequate oxygen to spheroids. It was demonstrated that the 3T3 fibroblast spheroid and the 3T3 fibroblast/M2-type macrophage co-culture spheroid can be formed and remained the physiological activity within nine days. 3D morphology of spheroids was reconstructed using the transparent processing technology and Z-stack function of confocal microscopy. Characteristics of proliferation and differentiation were analyzed by using nano antibody-based 3D immunostaining assay. Results revealed that M2-type macrophages can promote the proliferation and differentiation of the 3T3 fibroblast spheroid. This study presented a novel affordable platform for developing 3D spheroids and provides a 3D model for investigating the macrophages-associated wound healing microenvironment.