Protocol to transfer epithelial acini between different extracellular matrices and orient fibril organization.

Extracellular matrix (ECM) provides fundamental support for epithelial tissues and controls cell function. The chemistry and mechanical properties of ECM components, including stiffness, elasticity, and fibrillar organization, influence epithelial tissue responses. Here we present a protocol describing the culture and transfer of epithelial acini from Matrigel to collagen gel and an approach to axially align the collagen fibrils by the external gel stretching. This protocol uses the acini of MCF10A cells and needs to be modified for different cell lines. For complete details on the use and execution of this protocol, please refer to Katsuno-Kambe et al. (2021).(1).