| As one of most effective methods for reparing of misssing teeth, dental implant has been accepted by more and more patients in recent years. The key factor influencing the sucess of dental implants is the osseointegration of the implant with enough and healthy bone which may give the support of implant against chewing forces. One of systemic diseases the elder people common face is osteoporosis and skeleton of the whole body including jaw bone undergos degeneration under it. Jaw bone suffering osteoporosis can not provide enough and healthy bone tissue for implants, and therefore osteoporosis is considered to be one of the most dangerous factors for dental implant. Bisphosphonates are the most potent anti-bone resorption drugs and have strong affinity with bone mineral components. These drugs can interfere with the attachment of osteoclast on the bone surface, change the ultrastructure of cellular plasm, and even lead to cell death or called apoptosis.C-fos is a very important gene in regulating differentiation of osteoclast and expressed in nucleus of many cells including macrophage cell, neurocyte, odontoblast and as well as osteoclast. Although alendronate is commonly uesed in clinic to decrease osteoclast-mediated bone resorption, the mechanism of its effection on osteoclast is still unfully understood. Can alendronate affect gene expression of c-fos? And how does the variation of concentration of alendronate affect c-fos expression and osteoclast differentiation? All these questions remain unclear and further studies should be taken to eluicidate them.Objective Osteoclast was cultured in vitro by using and induction of murine bone marrow cells. Alendronate was added into the culture system to explore its effect on c-fos gene expression during osteoclast differentiation.MethodsRANKL and M-CSF were used for stimulating differentiation of osteoclast from bone marrow hematopoietic stem cells. TRAP staining and SEM scanning was performed to verify the formation of multinuclear osteoclasts and its bone resorption function, respectively. Cells were divided into 6 groups according to concentration of alendronate and they are the control, 10-4M, 10-6M, 10-8M, 10-10M and 10-12M group. Real-Time fluorescent quantitative PCR and Western blot were used to detect gene expression of c-fos.Results:1) Induction with M-CSF and RANKL led to osteoclast differentiation of bone marrow cells and the control cells remained intact. Under the induction, the cells were mainly single-nuclear cells within the first 3 days and they became to gather, merge to form multinuclear cells later. On the 6th day, many multinuclear (more than three) osteoclasts can be found.2) TRAP positive multinuclear osteoclasts were formed at day 6th and the number of osteoclasts increased with the time and reched the top number on day 8th. Then osteoclasts became decreased and the reduction was obvious on day 10 th to 12 th.3) Under the SEM onservation, absorbing lacunae were formed in the dentin and the border of the lacunae was clear. The alcunae was rough and collagen fibers of dentin were exposed.4)C-fos gene expression was detected during osteoclast differentiation under the stimulation of different concentrations of alendronate. The results indicated that the inhibition of gene expression of c-fos was strengthened with the decrease of concentration of alendronate within 10-4M~10-8M; however, the inhibition was decreased with the alendronate concentration within 10-8M~10-12M. The strongest inhibition of alendronate to c-fos expression was fond at 10-8M.ConclusionWithin the in vitro osteoclast culture system, alendronate can inhibit gene expression of c-fos during differentiation stage of osteoclast and the inhibition was closely related to the concentration of alendronate. Alendronate exhibited strongest inhibition effect on c-fos expression at concentration of 10-8M. |
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