Supplementary Material for: Collagen I Derived Extracellular Matrix Motifs Alter Fibroblast Regenerative Response

Introduction
Damage-associated molecular patterns, or DAMPs, are molecules released in response to tissue or cellular damage to facilitate tissue regeneration. This inflammatory response can occur in sterile environments and is promoted by the release of damaged extracellular components such as the extracellular matrix. DAMPs have been implicated in various stages of wound healing but have yet to be explicitly utilized for regenerative medicine by leveraging selective modulation of the inflammatory response. With this in mind, we leverage inflammation to drive tissue regeneration by utilizing DAMPs collected from the native extracellular matrix, extracellular matrix motifs (mECM).
Methods
Here, mECMs were derived from UV-damaged rat tail collagen I. Fibroblast response to various concentrations and presentation of mECMs was investigated by evaluating changes in viability, proliferation, cell phenotype, and cytokine secretion.
Results
mEMCs had reduced intensity in collagen I associated bands, indicating successful fragmentation to lower molecular weights. Soluble free mECMs induced changes in fibroblast phenotype as indicated by a decrease in proliferation, decrease in nuclei area, and increase in percentage of elongated cells. In addition, free mECMs contributed to significant increases in cytokine secretion compared to insoluble bound mECMs. Across all experiments, bound mECMs exhibited effects on fibroblasts compared to the collagen control
Conclusion
Fibroblasts in vitro recognize mECMs, with significant differences observed based on the presentation of these proteins. This data indicates that cryptic regions that are recognized by fibroblasts may be exposed in the free version of the mECMs, which lead to a myofibroblast-like phenotype in fibroblasts. This work highlights the potential of DAMPs to serve as immunomodulatory therapeutics for tissue regeneration.