Analysis of fibroblast migration dynamics in idiopathic pulmonary fibrosis using image-based scaffolds of the lung extracellular matrix

Abstract

Idiopathic pulmonary fibrosis (IPF) is characterized by a profound remodeling of the collagen in the extracellular matrix (ECM), where the fibers become both denser and more highly aligned. However, it is unknown how this reconfiguration of the collagen matrix affects disease progression. Here, we investigate the role of specific alterations in collagen fiber organization on cell migration dynamics by using biomimetic image-based collagen scaffolds representing normal and fibrotic lung, where the designs are derived directly from high-resolution second harmonic generation microscopy images. The scaffolds are fabricated by multiphoton-excited (MPE) polymerization, where the process is akin to three-dimensional printing, except that it is performed at much greater resolution (∼0.5 microns) and with collagen and collagen analogs. These scaffolds were seeded with early passaged primary human normal and IPF fibroblasts to enable the decoupling of the effect of cell-intrinsic characteristics (normal vs. IPF) versus ECM structure (normal vs. IPF) on migration dynamics. We found that the highly aligned IPF collagen structure promoted enhanced cell elongation and F-actin alignment along with increased cell migration speed and straightness relative to the normal tissues. Collectively, the data are consistent with an enhanced contact guidance mechanism on the aligned IPF matrix. Although cell intrinsic effects were observed, the aligned collagen matrix morphology had a larger effect on these metrics. Importantly, these biomimetic models of the lung cannot be synthesized by conventional fabrication methods. We suggest that the MPE image-based fabrication method will enable additional hypothesis-based testing studies of cell-matrix interactions in the context of tissue fibrosis.

Role of Collagen Fiber Morphology on Ovarian Cancer Cell Migration Using Image-Based Models of the Extracellular Matrix

“…This treatment should result in further spreading and polarization as ROCK itself enhances contraction. To quantify the elongation, we measured the angle of the cells relative to the fiber axis, where lower angles correspond to increased alignment [ 61 ]. As we found the largest differences in motility, cell shape, and cytoskeleton expression/alignment for cells on the normal and high-grade models, we chose these scaffolds for this analysis.…”

Diaphragm muscle fibrosis involves changes in collagen organization with mechanical implications in Duchenne Muscular Dystrophy

“…78,79 The importance of mechanical and structural properties of the ECM is well documented in the literature, with ECM stiffness and alignment key regulators of cellular behaviors involved in fibrosis, such as fibroblast alignment, migration, and proliferation. 22,80 Our study reveals changes in both ECM structure and mechanics in fibrosis, highlighting the need to study the role of therapeutics on collagen organization. Further, we must account for differences in collagen organization between tissue systems, especially as we aim to alleviate the deleterious impacts of fibrosis in DMD in the diaphragm muscle.…”

“…[18][19][20][21] Beyond skeletal muscle, changes in collagen organization with fibrosis are implicated in additional tissue systems. Increased collagen fiber alignment is reported in pulmonary fibrosis 22 and increased collagen fiber straightness is reported in cancerous pancreatic tissue. 23 Changes in collagen organization, such as collagen fiber direction, alignment, and straightness, remain unknown in mdx diaphragm muscle, but are needed to understand how and why diaphragm muscle mechanics change during the progression of DMD.…”

Mechanosensitive Regulation of Fibrosis

“…The mechanisms of such cell positioning within fibrotic tissue were recently investigated by the Campagnola group. By tracking individual cells migrating on microfabricated three-dimensional collagen scaffolds, Tisler et al demonstrated that biomechanical features of collagen stroma affected by idiopathic pulmonary fibrosis greatly enhance cell polarity and facilitate directional cell movement along stiff and aligned collagen bundles [ 116 ]. It is tempting to speculate that contractile forces generated by myofibroblasts or other cell types in response to proinflammatory cytokines prestress and stiffen collagen fibers, and such mechanical gradients quickly propagate through tissue, attracting single cells and cell clusters to the fibrotic lesions [ 117 , 118 , 119 ].…”