title: Stem cell markers (cytokeratin 15, CD34 and nestin) in primary scarring and nonscarring alopecia.
abstract: BACKGROUND
  Although the pathogenesis of most primary scarring alopecias is poorly understood, recent studies implicate the bulge region as a possible target.
  
  
  OBJECTIVE
  To corroborate these results, we ascertained involvement of follicular bulge stem cells using a panel of antibodies that putatively targeted the same.
  
  
  METHODS
  Antibodies used included anticytokeratin (CK) 15, CD34 and nestin on vertical and horizontal tissue sections of 50 cases of scarring and 34 cases of nonscarring alopecia.
  
  
  RESULTS
  Comparing expression of these markers in scarring vs. nonscarring alopecia, CK15 was noted in the follicular bulge region in 23 of 43 (53%) vs. 27 of 27 (100%) cases and in the peripheral layer of the outer root sheath (ORS) (upper two-thirds of the follicle) in 50 of 50 (100%) vs. 34 of 34 (100%) cases; CD34 was noted in the peripheral layer of the ORS (below pilar muscle attachment) in 24 of 35 (69%) vs. 18 of 18 (100%) cases; and nestin was noted in the infundibular region in 18 of 46 (39%) vs. seven of 32 (22%) cases and in the inner aspect of the ORS (below pilar muscle attachment) in eight of 31 (26%) vs. 23 of 23 (100%) cases.
  
  
  CONCLUSIONS
  Our findings of differential follicular localization of stem cells underscore follicular progenitor cell heterogeneity and suggest the target in scarring alopecia is not merely follicular bulge stem cells but involves stem cells in the inner and outer aspect of the ORS. Enhanced expression of nestin in the infundibular region in scarring alopecia indicates availability of an accessible, in vivo niche of potential utility as an autologous source of stem cells for therapeutic application.
authors.affiliation: Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Hoang
authors.forename: M
authors.initials: M
authors.lastname: Keady
authors.forename: M
authors.initials: M
authors.lastname: Mahalingam
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000505:Alopecia / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D018952:Antigens, CD34 / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002648:Child; D002921:Cicatrix / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D018859:Hair Follicle / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007381:Intermediate Filament Proteins / Q000378:metabolism; D053569:Keratin-15 / Q000378:metabolism; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000378:metabolism; D064231:Nestin; D013234:Stem Cells / Q000378:metabolism / Q000473:pathology*; D055815:Young Adult
chemical_list: D018952:Antigens, CD34; D015415:Biomarkers; D007381:Intermediate Filament Proteins; D053569:Keratin-15; C577484:NES protein, human; D009419:Nerve Tissue Proteins; D064231:Nestin