title: Adherent culture conditions enrich the side population obtained from the cochlear modiolus-derived stem/progenitor cells.
abstract: OBJECTIVE
  Previously, our group reported that sphere-forming cells derived from the organ of Corti represent the stem/progenitor cells (SPCs) of the cochlea due to their properties of self-renewal and multipotency. However, long-term propagation of sphere-forming cells under suspension culture conditions may fail to maintain the characteristic stemness of these cells. Therefore, this study investigated whether an adherent culture system would be beneficial in terms of preserving more stem-like cells for long-term manipulations in vitro.
  
  
  METHODS
  Isolated modiolus-derived SPCs were placed on poly-d-lysine-coated petri dishes to form the so-called "adherent" culture system.
  
  
  RESULTS
  Modiolus SPCs cultured under adherent conditions exhibited a significantly increased percentage of cells with the side population (SP) phenotype (18.6%) compared with cells cultured under conventional suspension culture conditions (0.8%). Even after repeated passages, modiolus SPCs cultured under adherent culture conditions preserved more SP phenotype cells. In comparison with the non-SP phenotype cells, the sorted SP cells exhibited more stem-like but less differentiated properties, with an upregulated expression of the ATP-binding cassette subfamily G member 2 (ABCG2), Nestin, Sox2, and Nanog proteins. Furthermore, Retinoic acid (RA) treatment confirmed the expression of the multipotent differentiation markers in the SP cells, including TUJ1, pancytokeratin, glial fibrillary acidic protein (GFAP), and p27(Kip1).
  
  
  CONCLUSIONS
  Employment of an adherent culture system, instead of a suspension culture system, resulted in the enrichment of the SP cells from SPCs while retaining their stemness and multipotency.
authors.affiliation: Medical Research Center, Cardinal Tien Hospital, Taipei, Taiwan, ROC.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Chao
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Wang
authors.forename: Hsin-Chien
authors.initials: HC
authors.lastname: Chen
authors.forename: Cheng-Ping
authors.initials: CP
authors.lastname: Shih
authors.forename: Huey-Kang
authors.initials: HK
authors.lastname: Sytwu
authors.forename: Kun-Lun
authors.initials: KL
authors.lastname: Huang
authors.forename: Shao-Yuan
authors.initials: SY
authors.lastname: Chen
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002453:Cell Cycle; D002454:Cell Differentiation; D002469:Cell Separation; D002470:Cell Survival; D002478:Cells, Cultured; D003051:Cochlea / Q000166:cytology*; D005434:Flow Cytometry; D015151:Immunoblotting; D007150:Immunohistochemistry; D051379:Mice; D013234:Stem Cells / Q000166:cytology*