title: Stimulation of the side population fraction of ATDC5 chondroprogenitors by hypoxia.
abstract: The influence of oxygen tension on the side population (SP) fraction sorted from ATDC5 chondroprogenitor cells was investigated. ATDC5 cells cultured in normoxia (20%) or hypoxia (1% oxygen) were compared. The SP fraction was significantly higher in the cells cultured in hypoxia. The gene expression of 3 ABC transporters, abcb1a/b (mdr1a/b) and abcg2 (bcrp1) was quantified by RT-PCR. SP cells were characterized by the higher expression of abcb1a. The expression levels of abcb1b and abcg2 were higher than abcb1a. However, there was no significant difference between SP and non-SP fractions in the expression of abcb1b and abcg2. The telomeric repeat amplification protocol assay showed that SP cells tended to show lower telomerase activity than non-SP cells. Chondrogenic properties of ATDC5 cells derived from SP or non-SP were assessed by micromass culture. There were not significant differences between SP and non-SP derived cells in Alcian blue staining and sox9, Aggrecan, Col2a1 and SZP mRNA expression. The results demonstrate that the SP fraction was stimulated by hypoxia and chondrogenic properties of SP and non-SP fraction of ATDC5 cells were similar.
authors.affiliation: Center for Tissue Regeneration and Repair, Department of Orthopaedic Surgery, School of Medicine, University of California at Davis, Sacramento, CA 95817, USA. ahreddi@ucdavis.edu
authors.forename: Koshi N
authors.initials: KN
authors.lastname: Kishimoto
authors.forename: Carol L
authors.initials: CL
authors.lastname: Oxford
authors.forename: A Hari
authors.initials: AH
authors.lastname: Reddi
mesh_terms: D000818:Animals; D001562:Benzimidazoles; D002454:Cell Differentiation; D002458:Cell Fractionation; D015687:Cell Hypoxia / Q000502:physiology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019902:Chondrocytes / Q000378:metabolism / Q000473:pathology*; D005109:Extracellular Matrix / Q000378:metabolism; D005456:Fluorescent Dyes; D015870:Gene Expression; D051379:Mice; D010100:Oxygen / Q000502:physiology; D013234:Stem Cells / Q000378:metabolism / Q000473:pathology*; D019098:Telomerase / Q000378:metabolism*
chemical_list: D001562:Benzimidazoles; D005456:Fluorescent Dyes; D019098:Telomerase; C017807:bisbenzimide ethoxide trihydrochloride; D010100:Oxygen