title: Differences between niche cells and limbal stromal cells in maintenance of corneal limbal stem cells.
abstract: OBJECTIVE
  To investigate the differing characteristics of limbal niche cells (LNCs) and limbal stromal cells (LSCs) in the maintenance of limbal epithelial stem/progenitor cells in the cornea.
  
  
  METHODS
  Limbal niche cells were obtained from direct dissection of the human corneal limbus, and LSCs were obtained from explant cultures of limbal stromal tissues under the same culture conditions. The resulting cultures were examined for their ability to support the growth of limbal stem/progenitor cells in colony-forming capacity, stratified epithelial cell sheet formation, maintenance of limbal epithelial stem/progenitor cell characteristics, and gene expression levels of factors that supported the limbal epithelial stem/progenitor cells.
  
  
  RESULTS
  The colony-forming efficiency of limbal epithelial stem/progenitor cells in the LNC group (6.57 ± 1.54%) was significantly higher than that in the LSC group (1.43 ± 0.47%). The epithelial cell sheets in the LNC group stratified into four or five layers compared with two or three stratified layers in the LSC group. Staining of both the colonies and the epithelial cell sheets in the LNC group showed a higher intensity of the limbal stem cell marker ΔNp63 than in the LSC group. Moreover, reverse transcription polymerase chain reaction analysis revealed that compared with the common expression of EGF and so on, the LNCs showed a higher expression level of E-cadherin and a lower expression level of neurotrophin-3 (NT3) than the LSCs.
  
  
  CONCLUSIONS
  LNCs have a different role compared to LSCs in their ability to support epithelial stem/progenitor cells and epithelial cellular sheet formation.
authors.affiliation: Department of Ophthalmology, Osaka University Medical School, Suita, Japan.
authors.forename: Yingli
authors.initials: Y
authors.lastname: Li
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Inoue
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Takamatsu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shiraishi
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maeda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Ohashi
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
mesh_terms: D002478:Cells, Cultured; D006801:Humans; D016850:Limbus Corneae / Q000166:cytology* / Q000378:metabolism; D055153:Stem Cell Niche / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D017154:Stromal Cells / Q000166:cytology* / Q000378:metabolism
keywords: colony forming efficiency; limbal stem cells; niche cells; stromal cells