In vivo imaging of extracellular matrix remodeling by tumor-associated fibroblasts.

Here we integrated multiphoton laser scanning microscopy and the registration of second harmonic generation images of collagen fibers to overcome difficulties in tracking stromal cell-matrix interactions for several days in live mice. We show that the matrix-modifying hormone relaxin increased tumor-associated fibroblast (TAF) interaction with collagen fibers by stimulating beta1-integrin activity, which is necessary for fiber remodeling by matrix metalloproteinases.