It has long been known that cells in tissues produce stabilizing network of fibers known as the extracellular matrix (ECM). The stiffness of those tissues influences cell behavior. If the ECM stiffness is disrupted, diseases such as cancer may result. However, scientists have only been studying this interaction using 2D elastic, flat, gel surfaces where cells were found to proliferate more with stiffness. This model, however, incompletely simulates the natural setting. Bioengineer Brendon Baker and polymer chemist Britta Trappmann, who are members of a team led by Prof. Christopher Chen of Boston University, have developed 3D matrices of fibers. The team embedded adult stem cells and studied their response to varying stiffness.
The cells were found to behave differently in either model. The cells only modestly stretched the surface in the 2D model. On the other hand, they dramatically and permanently changed the arrangements of the 3D model. As the stiffness was adjusted, the cells were found to proliferate more in the softer environment, in contrast to what can be found using the 2D model. The cells apply forces to the fiber network, and with a softer network, the cells can pull in more fibers, bringing more of the matrix within reach. These findings highlight a gap in our understanding on how cells interact with the ECM. The new 3D material can hopefully allow better understanding on the complex relationship between cells and their environment.