Growth hormone regulates osteogenic marker mRNA expression in human periodontal fibroblasts and alveolar bone-derived cells.
BACKGROUND
Growth hormone (GH) is a potent regulator of bone formation. The proposed mechanism of GH action is through the stimulation of osteogenic precursor cell proliferation and, following clonal expansion of these cells, promotion of differentiation along the osteogenic lineage.


OBJECTIVE
We tested this hypothesis by studying the effects of GH on primary cell populations of human periodontal ligament cells (PLC) and alveolar bone cells (ABC), which contain a spectrum of osteogenic precursors.


METHODS
The cell populations were assessed for mineralization potential after long-term culture in media containing beta-glycerophosphate and ascorbic acid, by the demonstration of mineral deposition by Von Kossa staining. The proliferative response of the cells to GH was determined over a 48-h period using a crystal violet dye-binding assay. The profile of the cells in terms of osteogenic marker expression was established using quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for alkaline phosphatase (ALP), osteopontin, osteocalcin, bone sialoprotein (BSP), as well as the bone morphogenetic proteins BMP-2, BMP-4 and BMP-7.


RESULTS
As expected, a variety of responses were observed ranging from no mineralization in the PLC populations to dense mineralized deposition observed in one GH-treated ABC population. Over a 48-h period GH was found to be non-mitogenic for all cell populations. Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) BSP mRNA expression correlated well with mineralizing potential of the cells. The change in the mRNA expression of the osteogenic markers was determined following GH treatment of the cells over a 48-h period. GH caused an increase in ALP in most cell populations, and also in BMP expression in some cell populations. However a decrease in BSP, osteocalcin and osteopontin expression in the more highly differentiated cell populations was observed in response to GH.


CONCLUSIONS
The response of the cells indicates that while long-term treatment with GH may promote mineralization, short-term treatment does not promote proliferation of osteoblast precursors nor induce expression of late osteogenic markers.
Haase
H R
HR
Department of Dentistry, Department of Physiology and Pharmacology, University of Queensland, Brisbane, Queensland, Australia.
Ivanovski
S
S
Waters
M J
MJ
Bartold
P M
PM
D000469:Alkaline Phosphatase / Q000187:drug effects; D000539:Alveolar Process / Q000166:cytology / Q000187:drug effects*; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000187:drug effects; D002113:Calcification, Physiologic / Q000187:drug effects; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D058574:Integrin-Binding Sialoprotein; D015675:Osteocalcin / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects*; D053495:Osteopontin; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects*; D012333:RNA, Messenger / Q000187:drug effects*; D012795:Sialoglycoproteins / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000187:drug effects
C525718:BMP2 protein, human; C525809:BMP4 protein, human; C525819:BMP7 protein, human; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; C546871:IBSP protein, human; D058574:Integrin-Binding Sialoprotein; D012333:RNA, Messenger; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D053495:Osteopontin; D019382:Human Growth Hormone; D000469:Alkaline Phosphatase