Fibroblasts and the ground they walk on

Abstract

Fibroblast migration is essential to normal wound healing and pathological matrix deposition in fibrosis. This review summarizes our understanding of how fibroblasts navigate 2D and 3D extracellular matrices, how this behavior is influenced by the architecture and mechanical properties of the matrix, and how migration is integrated with the other principle functions of fibroblasts, including matrix deposition, contraction, and degradation.

FIGURE 1.

Schematic representation of the steps in 2D cell migration, including extension of a lamellapodium, formation of a new adhesion, translocation of the cell body, and de-adhesion and retraction at the trailing edge Reproduced from Ref. with permission from IOP Publishing.

FIGURE 2.

Changes in fibroblast morphology, adhesion, cytoskeleton, and motility as a function of underlying substrate stiffness A: immunostaining of the focal adhesion protein vinculin in human lung fibroblasts cultured on collagen I-coated polyacrylamide gel surfaces of indicated shear modulus for 5 days showing gradual transition of focal adhesions from round (arrows) to elongated fibrillar shape (arrowheads). Bar = 10 μm. B: the cytoskeletal protein α-smooth muscle actin (α-SMA; green) is progressively incorporated into F-actin stress fibers (red), which themselves become increasingly distinct and organized as the underlying matrix stiffness increases (Liu F, Tschumperlin D, unpublished observations). Bar = 50 μm. C: fibroblast migration speed and persistence vary with underlying matrix stiffness, as measured with time-lapse video microscopy. Error bars indicate SD from 12 cells for each condition from two independent experiments. D: individual fibroblast migration tracks obtained from time-lapse video microscopy as in C. Digital images were taken every 2 min for a total of 5 h per experiment. Each wind rose plot shows centroid tracks from 7 to 10 representative cells from each indicated stiffness region, with the initial position of each track superimposed at a common origin. Bars = 50 μm. Reproduced from Ref. with permission from Rockerfeller University Press.

FIGURE 3.

Comparing adhesion structures in 2D culture with those in 3D cell-derived matrices 3T3 mouse embryonic fibroblasts expressing GFP-paxillin migrating on a 2D fibronectin-coated rigid surface (A) or through a 3D cell-derived matrix (B). Insets: magnifications of GFP-paxillin localization and adhesion formation in squared areas. Fibroblasts in 3D adopt a more elongated morphology adapted to the fibrillar structure of the cell-derived matrix. Adhesive structures are located all around the cell body and are aligned with the fibers (B). Reproduced from Ref. with permission from Elsevier.