UPDATE: This seminar will be virtual only via zoom – check email for zoom link or contact ksas@seas.upenn.edu.

Cell-induced matrix remodeling is a hallmark of tissue development, disease, and regeneration. My lab has been developing biomaterials and matrix characterization methods to study these dynamic cell-matrix interactions. In designing our biomaterials, we employ protein engineering methods to create biomimetic extracellular matrices with the direct ability to tune the matrix mechanics including stiffness and stress relaxation rate. We have identified matrix remodeling as a key property in the design of xeno-free matrices that support the growth of patient-derived primary tissue organoids. In a complementary project, we have developed a micro-rheology strategy that uses dynamic light scattering to characterize the mechanical properties of dynamic biomaterials over time. We have used this method to measure the changes in matrix stiffness in cultures of breast cancer cells. Interestingly, we discovered that the cells stiffen the matrix at short time-scales, while simultaneously fluidizing the matrix at long time-scales. This seemingly paradoxical stiffening and fluidization are a consequence of active cell forces that result in matrix remodeling. Our results suggest a mechanism whereby breast cancer cells reconcile the seemingly contradictory requirements for both tension and malleability in the matrix during invasion by differential alteration of matrix mechanics across different time-scales.