title: Re-epithelialization of human oral keratinocytes in vitro.
abstract: Re-epithelialization involves interactions between keratinocytes and the extracellular matrix upon which these cells move. It is hypothesized that keratinocytes are activated when wounded, and the resultant phenotypic change directs re-epithelialization. We have adapted organotypic cultures, in which oral gingival keratinocytes are fully differentiated, to study re-epithelialization following wounding. To elucidate keratinocyte behavior and phenotype during re-epithelialization, we have investigated this process in the presence and absence of the growth factor TGF-beta 1 and have monitored expression of MMP-1 (Type I collagenase) mRNA by in situ hybridization. In addition, we have followed proliferation and migration of wound keratinocytes by genetically marking these cells with a retroviral vector and by measuring their proliferative index. We found that keratinocytes grown without TGF-beta 1 were hyperproliferative in response to wounding, and re-epithelialization was complete by 24 h. However, 2.5 ng/mL TGF-beta 1 induced a transient delay in re-epithelialization, a reduction in proliferation, and fewer clusters of genetically marked cells. Keratinocytes expressed MMP-1 mRNA only when they covered the wounded surface, suggesting that the cells acquire a collagenolytic phenotype during re-epithelialization and that contact with different ECM components may modulate keratinocyte expression of MMP-1. We conclude that the phenotype of oral keratinocytes is altered during re-epithelialization in vitro and that this process is modulated by TGF-beta 1. Re-epithelialization occurs as keratinocytes are activated to move over the wound bed. Understanding the phenotype of wounded keratinocytes may facilitate treatment of chronic oral wounds and periodontal disease.
authors.affiliation: Department of Oral Biology and Pathology, School of Dental Medicine, State University of New York at Stony Brook 11794-8702, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Garlick
authors.forename: W C
authors.initials: WC
authors.lastname: Parks
authors.forename: H G
authors.initials: HG
authors.lastname: Welgus
authors.forename: L B
authors.initials: LB
authors.lastname: Taichman
mesh_terms: D001973:Bromodeoxyuridine / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D017364:Collagenases / Q000187:drug effects / Q000378:metabolism; D003470:Culture Media; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology / Q000293:injuries; D005881:Gingiva / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000293:injuries; D006801:Humans; D017403:In Situ Hybridization; D015603:Keratinocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D020781:Matrix Metalloproteinase 1; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: D003470:Culture Media; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D017364:Collagenases; D020781:Matrix Metalloproteinase 1; D001973:Bromodeoxyuridine