AN IN-VITRO INVESTIGATION OF THE ROLE OF HIGH-MOLECULAR-WEIGHT HUMAN SALIVARY SULFATED GLYCOPROTEIN IN PERIODONTAL WOUND-HEALING

HIGH MOLECULAR WEIGHT HUMAN salivary sulphated glycoprotein (SGP) inhi bits attachment of fibroblasts to cementum in vitro and thus may enhan ce periodontal wound healing by repair with long junctional epithelium . However, competitive inhibition by serum constituents might prevent adequate binding of SGP for this effect to occur in vivo. The primary aim of this study was to investigate the co-adsorption in vitro, of SG P, fibronectin (FN), and albumin (ALE) to synthetic hydroxyapatite (HA ) from solutions of SGP/FN (62.5/2 mu g/mL respectively), or SGP/FN/AL B (62.5/2/4 mu g/mL), or from individual solutions of the agents as co ntrols. Desorption of SGP and FN was studied by preabsorbing HA with S GP or FN and subsequently exposing it to the other agent, or to buffer only as control. Adsorbates were assayed after incubation periods of up to 26 hours using specific ELISAs. SGP displaced previously adsorbe d FN after 3 hours and significantly inhibited adsorption of FN and AL E compared with controls, Neither FN or ALE had a significant effect o n SGP adsorption. These results are consistent with the possibility th at salivary adsorption to cementum during surgery might interfere with repopulation of the root by connective tissue cells and thus contribu te to wound healing by repair rather than regeneration. Separate studi es taken to validate the ELISA used for SGP determination showed that HA-bound SGP contained all constituents of native SGP as revealed by S DS-PAGE and that ion exchange chromatography of SGP gave 6 fractions ( I through VI), of which only the most ionic (VI) was able to inhibit c ell attachment in vitro.