title: A novel niche for skin derived precursors in non-follicular skin.
abstract: BACKGROUND
  Skin derived precursors (SKP) comprise a subset of specialized dermal cells that can be distinguished from fibroblast by their capacity for spheroidal growth. Recent investigations have shown that hair follicles constitute a niche for this cell type, but their localization and their definite function in non-follicular skin remains largely unknown.
  
  
  OBJECTIVE
  To identify the dermal niche of non-follicular SKPs and to analyze whether functional aspects correlate with this localization.
  
  
  METHODS
  SKPs were isolated from separate anatomical regions of human abdominal skin. Fluorescence activated cell sorting then was used to obtain a pure population of non-follicular SKPs. Functional characterization of these cells was performed applying differentiation and proliferation assays. Information on specific in vivo functions was derived from histological evaluation of quantity and localization patterns.
  
  
  RESULTS
  Sphere forming capacity and differentiation assays show that SKPs reside in the papillary part of the dermis. Further delineation revealed that the dermal capillaries represent a niche for these cells which subsequently could be isolated by FACS utilizing a perivascular marker. Whereas functional properties described for follicular SKPs could also be detected in the perivascular SKP population, histological analyses additionally point to a cross-talk with epidermal stem cells and a reduction during chronological aging.
  
  
  CONCLUSIONS
  Our data show that SKPs isolated from non-follicular skin originate from a perivascular niche. Compared to their follicular counterparts, no functional differences could be observed upon cultivation, but ex vivo analyses also point to unique functions and a contribution to the phenotype of aged skin.
authors.affiliation: Beiersdorf AG, R&D, Skin Research Center, Unnastrasse 48, Hamburg 20245, Germany. Martin.Ruetze@Beiersdorf.com
authors.forename: Martin
authors.initials: M
authors.lastname: Ruetze
authors.forename: Tanja
authors.initials: T
authors.lastname: Knauer
authors.forename: Stefan
authors.initials: S
authors.lastname: Gallinat
authors.forename: Horst
authors.initials: H
authors.lastname: Wenck
authors.forename: Volker
authors.initials: V
authors.lastname: Achterberg
authors.forename: Annette
authors.initials: A
authors.lastname: Maerz
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Deppert
authors.forename: Anja
authors.initials: A
authors.lastname: Knott
mesh_terms: D000005:Abdomen; D050156:Adipogenesis / Q000502:physiology; D000328:Adult; D053687:Adult Stem Cells / Q000166:cytology*; D051929:CD146 Antigen / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D020405:Dermis / Q000166:cytology*; D005347:Fibroblasts / Q000166:cytology*; D005434:Flow Cytometry; D018859:Hair Follicle / Q000166:cytology*; D006801:Humans; D010012:Osteogenesis / Q000502:physiology; D020286:Pericytes / Q000166:cytology* / Q000378:metabolism; D015595:Skin Aging / Q000502:physiology; D055153:Stem Cell Niche / Q000502:physiology*
chemical_list: D051929:CD146 Antigen; C497902:MCAM protein, human