IGFs, IGFBPs, IGF-binding sites and biochemical markers of bone metabolism during differentiation in human pulp fibroblasts.
OBJECTIVE
To investigate the role of the insulin-like growth factors (IGF) system during the differentiation of human pulp-derived fibroblasts (HPF).


METHODS
Primary HPF were cultured for 24 days in DMEM medium with IGF-I or IGF-II (50 ng/ml each). Cell growth and morphology, alkaline phosphatase (ALP) activity, the concentration of free deoxypyridinoline (DPD), IGF-I, -II, IGFBP-2 and -3 were studied. The number of (125)I-IGF-I binding sites was estimated by Scatchard analysis.


RESULTS
Light-microscopically visible nodules emerged during differentiation. Simultaneously, the ALP activity increased steadily between days 8 and 24, while the DPD concentration decreased by about 50%. The HPF produced high concentrations of IGF-II (2.00-1.30 microg/10(6) cells) but low IGF-I, IGFBP-2. IGFBP-2 was not changed, IGFBP-3 increased by 65% during differentiation. The number of IGF binding sites increased from 8,500 +/- 55 per cell (day 8) up to 22,000 +/- 570 (day 24).


CONCLUSIONS
The increasing number of IGF-binding sites accompanied by alterations in the biochemical bone markers during the differentiation of HPF suggests an autocrine/paracrine role for the IGFs in the formation of dentinal hard tissue.
Reichenmiller
Katharina M
KM
Department of Conservative Dentistry, School of Dental Medicine at the University of Tübingen, Germany. kathrin.reichenmiller@med.uni-tuebingen.de
Mattern
Christel
C
Ranke
Michael B
MB
Elmlinger
Martin W
MW
D000469:Alkaline Phosphatase / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D001665:Binding Sites; D015415:Biomarkers / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000096:biosynthesis; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism / Q000494:pharmacology*; D009994:Osmolar Concentration; D013997:Time Factors
D000596:Amino Acids; D015415:Biomarkers; D018972:Insulin-Like Growth Factor Binding Protein 3; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; C036020:deoxypyridinoline; D000469:Alkaline Phosphatase