The Role of Mast Cells in the Activation of Dermal Fibroblasts

• Author / Creator

  Campeau, Leah L

• Introduction: Hypertrophic scar (HTS) formation is a fibroproliferative disorder that commonly follows deep dermal burns with prolonged inflammation. It is characterized by excessive extracellular matrix such as collagen deposition mainly by dermal fibroblasts. Mast cells have been implicated in HTS as they degranulate in response to injury and release pro-inflammatory and profibrotic mediators that may contribute to scar formation via increased fibroblast activity. We hypothesize that mast cell mediators regulate deep dermal fibroblasts to become profibrotic, thus mediating HTS development. Methods: Mast cells were quantified in human HTS and scar tissue from dermal fibrotic mouse models including CXCR4-treated nude mice. In vitro, layered dermal fibroblasts were cultured with conditioned media from activated mast cells and examined for changes in fibroblast activity. The measures determined included MTT cell proliferation assays to assess cell viability and RT-PCR to assess fibrotic gene expression. Liquid chromatography/mass spectrometry analysis of 4-hydroxyproline was measured as an indicator of type I collagen production and flow cytometric analysis of -SMA expression as a measure of myofibroblast differentiation and contractile capacity in layered fibroblasts after exposure to conditioned media from mast cells. Results: In vivo, mast cell densities increased in scar tissues from all dermal fibrotic mouse models and decreased in scar tissues from CXCR4-treated nude mice. In the presence of conditioned media from activated mast cells, fibroblasts showed no significant change in proliferation or gene and protein expression of -SMA and type I collagen but showed general trends suggesting increase proliferation and decreased -SMA expression. Conclusion: In vivo, mast cells were found to be involved in hypertrophic scar formation. In our in vitro experiments, mast cells may have roles in HTS development but their effects on fibroblasts require further study and the mechanism of how mast cells could selectively influence the activity of superficial and deep fibroblasts warrants further investigation.

• Subjects / Keywords

  • Hypertrophic scarring
  • Fibroblasts
  • Mast cells

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3WW7749K

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.