Spatial regulation of substrate adhesion directs fibroblast morphotype and phenotype

Abstract

Switching of fibroblast phenotype to myofibroblast is a hallmark of a wide variety of tissue pathologies. This phenotypical switch is known to be influenced by humoral factors such as TGF-β, but also by mechanical and physical cues in the cellular environment, and is accompanied by distinctive changes in cell morphology. However, the causative link between these cues, the concomitant morphological changes, and the resulting phenotypic switch remain elusive. Here we use protein micropatterning to spatially control dermal fibroblast adhesion without invoking exogenous mechanical changes and demonstrate that varying the spatial configuration of focal adhesions is sufficient to direct fibroblast phenotype. We further developed an automated morphometry analysis pipeline, which revealed focal adhesion eccentricity as the primary determinant of cell state positioning along the spectrum of fibroblast phenotype. Moreover, linear fibronectin patterns that constrain the focal adhesions were found to promote a further phenotype transition, characterized by dispersed expression of alpha-smooth muscle actin, pointing to an interesting possibility of controlling fibroblast phenotype beyond the canonical fibroblast–myofibroblast axis. Together, our study reveals that the spatial configuration of adhesion to the cellular microenvironment is a key factor governing fibroblast morphotype and phenotype, shedding new light on fibroblast phenotype regulation.