SECRETION OF CSF-1 AND ITS INHIBITION IN RAT DENTAL FOLLICLE CELLS - IMPLICATIONS FOR TOOTH ERUPTION

Tooth eruption requires the presence of a dental follicle around the u nerupted tooth. Before the onset of eruption there is an influx of mon onuclear cells into the follicle which, in turn, form osteoclasts that erode the alveolar bone. Eruption can be accelerated by the injection of colony-stimulating factor-one (CSF-1), a molecule that is maximall y transcribed and translated in the dental follicle cells at the time of peak influx of mononuclear cells into the follicle of the rat first mandibular molar. To determine if the rat dental follicle cells secre te the CSF-1 needed for these cellular events, conditioned medium was collected from cultures of these cells. Using as a bioassay, a cell li ne (m-NFS 60) that is responsive to CSF-1 for growth, it was shown tha t conditioned medium from the follicle cells stimulated growth of the m-NFS 60 cells by almost 33% over the controls. Western blots confirme d that CSF-I was secreted into the medium. Treating the dental follicl e cells with an antisense oligodeoxynucleotide probe against CSF-1 red uced the amount of CSF-1 produced. These results demonstrate that CSF- 1 is secreted by the dental follicle cells and that the production of CSF-1 can be reduced with an antisense probe. This secretion by the de ntal follicle might recruit mononuclear cells into the follicle to ini tiate tooth eruption.