Acidic fibroblast growth factor attenuates the cytotoxic effects of peroxynitrite in primary human osteoblast precursors.
BACKGROUND
Skeletal injury and associated ischemia and inflammation induce the generation of pro-oxidants such as peroxynitrite (ONOO-), which has been demonstrated to induce apoptosis in several cell lines. Fibroblast growth factor (FGF-1) is important for coordinating osteogenesis and angiogenesis of osseous repair. In vitro studies were performed examining the effect of FGF-1 on human osteoblast progenitor stromal stem (HSS) cell proliferation, differentiation, and response to ONOO-.


METHODS
HSS cells were isolated and growth kinetics determined in the presence and absence of FGF-1. The effect of FGF-1 on HSS cell expression of osteoblast-specific osteopontin and osteocalcin mRNA and protein was examined by reverse transcriptase polymerase chain reaction and Western blot techniques. To determine the sensitivity of HSS cells to ONOO- in the absence and presence of FGF-1 pretreatment, cells were exposed to varying concentrations of the oxidant and examined for cell death using quantitative fluorescence staining with fluorescein diacetate and propidium diacetate.


RESULTS
Treatment of HSS cells with FGF-1 significantly enhanced cellular growth rates by 5 days (4.6 x 105 cells/mL vs. 3.1 x 105 cells/mL) and induced expression of both osteopontin and osteocalcin mRNA and protein. Exposure of HSS cells to ONOO- resulted in a dose- and time-dependent delayed cell death that was more characteristic of apoptosis than necrosis. Pretreatment of HSS cells with FGF-1 prevented ONOO- mediated apoptosis.


CONCLUSIONS
In vitro, treatment of HSS cells with FGF-1 stimulates cell growth and induces expression of differentiation markers specific to osteoblasts. FGF-1 treatment renders osteoblast precursors resistant to the cytotoxic effects of ONOO-. These results suggest that FGF-1 promotes the progression of bone repair mechanisms by increasing the population of osteoblasts and imparting protection to the cell line from the hostile inflammatory environment.
Center for Injury Sciences, Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, USA. Donald.Reiff@ccc.uab.edu
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Reiff
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Kelpke
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Thompson
D017209:Apoptosis / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000502:physiology*; D004353:Drug Evaluation, Preclinical; D016220:Fibroblast Growth Factor 1 / Q000502:physiology* / Q000627:therapeutic use*; D017102:Fracture Healing / Q000187:drug effects* / Q000276:immunology*; D050723:Fractures, Bone / Q000188:drug therapy* / Q000276:immunology*; D006801:Humans; D007249:Inflammation; D018919:Neovascularization, Physiologic / Q000502:physiology*; D009566:Nitrates / Q000502:physiology*; D015675:Osteocalcin; D010012:Osteogenesis / Q000502:physiology*; D053495:Osteopontin; D016877:Oxidants / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000502:physiology*; D012795:Sialoglycoproteins; D013234:Stem Cells / Q000502:physiology*; D017154:Stromal Cells / Q000502:physiology*
D009566:Nitrates; D016877:Oxidants; D017382:Reactive Oxygen Species; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D016220:Fibroblast Growth Factor 1; D015675:Osteocalcin; D053495:Osteopontin; C039642:peroxynitric acid