title: Thymosin beta4 increases hair growth by activation of hair follicle stem cells.
abstract: Thymosin beta4, a 43-amino acid polypeptide that is an important mediator of cell migration and differentiation, also promotes angiogenesis and wound healing. Here, we report that thymosin beta4 stimulates hair growth in normal rats and mice. A specific subset of hair follicular keratinocytes in mouse skin expresses thymosin beta4 in a highly coordinated manner during the hair growth cycle. These keratinocytes originate in the hair follicle bulge region, a niche for skin stem cells. Rat vibrissa follicle clonogenic keratinocytes, closely related, if not identical, to the bulge-residing stem cells, were isolated and their migration and differentiation increased in the presence of nanomolar concentrations of thymosin beta4. Expression and secretion of the extracellular matrix-degrading enzyme matrix metalloproteinase-2 were increased by thymosin beta4. Thus, thymosin beta4 accelerates hair growth, in part, due to its effect on critical events in the active phase of the hair follicle cycle, including promoting the migration of stem cells and their immediate progeny to the base of the follicle, differentiation, and extracellular matrix remodeling.
authors.affiliation: Cell Biology Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Philp
authors.forename: Mychi
authors.initials: M
authors.lastname: Nguyen
authors.forename: Brooke
authors.initials: B
authors.lastname: Scheremeta
authors.forename: Sharleen
authors.initials: S
authors.lastname: St-Surin
authors.forename: Ana M
authors.initials: AM
authors.lastname: Villa
authors.forename: Adam
authors.initials: A
authors.lastname: Orgel
authors.forename: Hynda K
authors.initials: HK
authors.lastname: Kleinman
authors.forename: Michael
authors.initials: M
authors.lastname: Elkin
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D010450:Endopeptidases / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006197:Hair / Q000187:drug effects* / Q000254:growth & development*; D018859:Hair Follicle / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D053569:Keratin-15; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D007633:Keratins / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013947:Thymosin / Q000378:metabolism / Q000494:pharmacology*; D000099201:Thymosin beta(4)
chemical_list: D010450:Endopeptidases; D053569:Keratin-15; D007633:Keratins; D020778:Matrix Metalloproteinase 2; D013947:Thymosin; D000099201:Thymosin beta(4); C492053:Krt15 protein, mouse