Fractionation of growth plate chondrocytes: differential expression of IGF-I and growth hormone and IGF-I receptor mRNA in purified populations.
In vitro studies of growth plate cell kinetics have been hindered by the spatial arrangement and heterogeneity of cells within the plate. In this study, we describe a fractionation method that consistently generated five relatively pure populations of growth plate chondrocytes. Each fraction exhibited morphology, proliferative rates, and marker mRNA expression consistent with in vivo positional phenotypes. In characterizing the fractional response, fibroblast growth factor was most effective in stimulating resting cells to proliferate and least effective on cells actively dividing (fraction 3). Insulin-like growth factor-I (IGF-I) was most active on fraction 3 while epidermal growth factor's mitogenic induction was equivalent across all fractions. Growth hormone receptor (GHR) mRNA was most abundant in mature hypertrophic cells and undetectable in resting cells; IGF-I receptor (IGF-IR) mRNA was detectable in resting cells but two-fold higher in the fraction adjacent to cells possessing high GHR mRNA, while proliferating and resting chondrocytes had elevated IGF-I mRNA levels when compared to that for hypertrophic chondrocytes. The growth plate distribution of IGF-IR and GHR mRNA implies distinct roles for circulating IGF-I vs. paracrine produced IGF-I.
Oberbauer
A M
AM
Department of Animal Science, University of California, Davis, California 95616-8521, USA.
Peng
R
R
D000818:Animals; D015415:Biomarkers; D018929:Cell Culture Techniques / Q000379:methods; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002469:Cell Separation / Q000379:methods*; D048430:Cell Shape / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient / Q000379:methods; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics; D024121:Collagen Type X / Q000235:genetics; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000378:metabolism / Q000494:pharmacology; D006132:Growth Plate / Q000166:cytology / Q000378:metabolism*; D006984:Hypertrophy / Q000235:genetics / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000235:genetics* / Q000494:pharmacology; D008297:Male; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017526:Receptor, IGF Type 1 / Q000235:genetics*; D011986:Receptors, Somatotropin / Q000235:genetics*; D015854:Up-Regulation / Q000502:physiology
D015415:Biomarkers; D024043:Collagen Type II; D024121:Collagen Type X; D012333:RNA, Messenger; D011986:Receptors, Somatotropin; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1