title: Epidermis promotes dermal fibrosis: role in the pathogenesis of hypertrophic scars.
abstract: Hypertrophic scarring is a pathological process characterized by fibroblastic hyperproliferation and by excessive deposition of extracellular matrix components. It has been hypothesized that abnormalities in epidermal-dermal crosstalk explain this pathology. To test this hypothesis, a tissue-engineered model of self-assembled reconstructed skin was used in this study to mimic interactions between dermal and epidermal cells in normal or pathological skin. These skin equivalents were constructed using three dermal cell types: normal wound (Wmyo) or hypertrophic wound (Hmyo) myofibroblasts and normal skin fibroblasts (Fb). Epidermis was reconstructed with normal skin keratinocytes (NK) or hypertrophic scar keratinocytes (HK). In the absence of keratinocytes, Hmyo formed a thicker dermis than Wmyo. When seeded with NK, the dermal thickness of Hmyo (121.2 +/- 31.4 microm vs 196.2 +/- 27.8 microm) and Fb (43.7 +/- 7.1 microm vs 83.6 +/- 16.3 microm) dermis was significantly (p < 0.05) reduced, while that of Wmyo (201.5 +/- 15.7 microm vs 160.7 +/- 21.1 microm) was increased. However, the presence of HK always induced significantly thicker dermis formation than observed with NK (Wmyo: 238.8 +/- 25.9 microm; Hmyo: 145.5 +/- 22.4 microm; Fb: 74.2 +/- 11.2 microm). These results correlated with collagen and MMP-1 secretion and with cell proliferation, which were increased when keratinocytes were added, except for the collagen secretion of Hmyo and Fb in the presence of NK. The level of dermal apoptosis was not different when epidermis was added to the dermis (<1% in each category). These observations strongly suggest that hypertrophic scar keratinocytes play a role in the development of pathological fibrosis by influencing the behaviour of dermal cells.
authors.affiliation: Laboratoires des grands brûlés/LOEX, Hôpital du Saint-Sacrement du Centre Hospitalier Affilié Université de Québec, Québec, Canada.
authors.forename: Judith
authors.initials: J
authors.lastname: Bellemare
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Roberge
authors.forename: Danielle
authors.initials: D
authors.lastname: Bergeron
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Lopez-Vallé
authors.forename: Michel
authors.initials: M
authors.lastname: Roy
authors.forename: Véronique J
authors.initials: VJ
authors.lastname: Moulin
mesh_terms: D017209:Apoptosis; D016022:Case-Control Studies; D002450:Cell Communication; D002454:Cell Differentiation; D017439:Cicatrix, Hypertrophic / Q000201:enzymology / Q000473:pathology*; D020405:Dermis / Q000201:enzymology / Q000473:pathology; D004817:Epidermis / Q000201:enzymology / Q000473:pathology; D005347:Fibroblasts / Q000473:pathology; D005355:Fibrosis; D006801:Humans; D015603:Keratinocytes / Q000473:pathology; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D008954:Models, Biological; D012867:Skin / Q000201:enzymology / Q000473:pathology*; D023822:Tissue Engineering / Q000379:methods; D014945:Wound Healing
chemical_list: D020781:Matrix Metalloproteinase 1