Fibroblast alignment and matrix remodeling induced by a stiffness gradient in a skin-derived extracellular matrix hydrogel

Fenghua Zhao; Meng Zhang; Mehmet Nizamoglu; Hans J Kaper; Linda A Brouwer; Theo Borghuis; Janette K Burgess; Martin C Harmsen; Prashant K Sharma

doi:10.1016/j.actbio.2024.05.018

Fibroblast alignment and matrix remodeling induced by a stiffness gradient in a skin-derived extracellular matrix hydrogel

Acta Biomater. 2024 May 13:S1742-7061(24)00257-5. doi: 10.1016/j.actbio.2024.05.018. Online ahead of print.

Authors

Fenghua Zhao¹, Meng Zhang², Mehmet Nizamoglu³, Hans J Kaper⁴, Linda A Brouwer⁵, Theo Borghuis⁵, Janette K Burgess⁶, Martin C Harmsen⁶, Prashant K Sharma⁷

Affiliations

¹ University of Groningen, University Medical Centre Groningen, W.J. Kolff Institute for Biomedical Engineering and Materials Science-FB41, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Department of Biomaterials and Biomedical Technology-FB40, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Department of Pathology and Medical Biology, Hanzeplein 1 (EA11), 9713 GZ Groningen, the Netherlands.
² University of Groningen, University Medical Centre Groningen, W.J. Kolff Institute for Biomedical Engineering and Materials Science-FB41, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Department of Pathology and Medical Biology, Hanzeplein 1 (EA11), 9713 GZ Groningen, the Netherlands.
³ University of Groningen, University Medical Centre Groningen, Department of Pathology and Medical Biology, Hanzeplein 1 (EA11), 9713 GZ Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Groningen Research Institute for Asthma and COPD (GRIAC), Hanzeplein 1 (EA11), 9713 AV Groningen, the Netherlands.
⁴ University of Groningen, University Medical Centre Groningen, W.J. Kolff Institute for Biomedical Engineering and Materials Science-FB41, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Department of Biomaterials and Biomedical Technology-FB40, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands.
⁵ University of Groningen, University Medical Centre Groningen, Department of Pathology and Medical Biology, Hanzeplein 1 (EA11), 9713 GZ Groningen, the Netherlands.
⁶ University of Groningen, University Medical Centre Groningen, W.J. Kolff Institute for Biomedical Engineering and Materials Science-FB41, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Department of Pathology and Medical Biology, Hanzeplein 1 (EA11), 9713 GZ Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Groningen Research Institute for Asthma and COPD (GRIAC), Hanzeplein 1 (EA11), 9713 AV Groningen, the Netherlands.
⁷ University of Groningen, University Medical Centre Groningen, W.J. Kolff Institute for Biomedical Engineering and Materials Science-FB41, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands; University of Groningen, University Medical Centre Groningen, Department of Biomaterials and Biomedical Technology-FB40, A. Deusinglaan 1, 9713 AV Groningen, the Netherlands. Electronic address: p.k.sharma@umcg.nl.

PMID: 38750915
DOI: 10.1016/j.actbio.2024.05.018

Abstract

Large skin injuries heal as scars. Stiffness gradually increases from normal skin to scar tissue (20x higher), due to excessive deposition and crosslinking of extracellular matrix (ECM) mostly produced by (myo)fibroblasts. Using a custom mold, skin-derived ECM hydrogels (dECM) were UV crosslinked after diffusion of ruthenium (Ru) to produce a Ru-dECM gradient hydrogel. The Ru diffusion gradient equates to a stiffness gradient and models physiology of the scarred skin. Crosslinking in Ru-dECM hydrogels results in a 23-fold increase in stiffness from a stiffness similar to that of normal skin. Collagen fiber density increases in a stiffness-dependent fashion while stress relaxation also alters, with one additional Maxwell element necessary for characterizing Ru-dECM. Alignment of fibroblasts encapsulated in hydrogels suggests that the stiffness gradient directs fibroblasts to orientate at ∼45 ° in regions below 120 kPa. In areas above 120 kPa, fibroblasts decrease the stiffness prior to adjusting their orientation. Furthermore, fibroblasts remodel their surrounding ECM in a gradient-dependent fashion, with rearrangement of cell-surrounding ECM in high-stiffness areas, and formation of interlaced collagen bundles in low-stiffness areas. Overall, this study shows that fibroblasts remodel their local environment to generate an optimal ECM mechanical and topographical environment. STATEMENT OF SIGNIFICANCE: This study developed a versatile in vitro model with a gradient stiffness using skin-derived ECM hydrogel with unchanged biochemical environment. Using Ruthenium crosslinking, a 20-fold stiffness increase was achieved as observed in fibrotic skin. The interaction between fibroblasts and matrix depends on changes in the matrix stiffness. The stiffness gradient directed the alignment of fibroblasts with ∼45° in regions with≤ 120 kPa. The cells in regions with the higher stiffness decreased stiffness first and then oriented themselves. Furthermore, fibroblasts remodeled surrounding ECM and regulated its mechanics in a gradient-dependent fashion to reach an optimal condition. Our study highlights the dynamic interplay between cells and surrounding matrix, shedding light on potential mechanisms and strategies to target scar formation and remodeling.

Keywords: Collagen; Extracellular matrix hydrogel; Fibroblasts; Gradient stiffness; Scarring.