COMPARISON OF THE CHARACTERISTICS OF HUMAN GINGIVAL FIBROBLASTS AND PERIODONTAL-LIGAMENT CELLS

To ELUCIDATE THE CHARACTERISTICS Of human periodontal ligament cells, we compare these cells with gingival fibroblasts isolated from the per iodontal tissues of female human subjects. Human periodontal ligament (HPDL) cells had a sharper spindle shape and exhibited a higher growth rate than human gingival fibroblasts (HGF). HPDL cells had a high lev el of alkaline phosphatase (ALPase) activity, whereas HGF had a low le vel of such activity. Northern blot analysis demonstrated that HPDL ce lls produced ALPase mRNA. Decorin and biglycan mRNA were detected in b oth HPDL cells and HGF, whereas osteocalcin and bone sialoprotein mRNA was not detected in either cells. Both HPDL cells and HGF responded t o prostaglandin E(2) (PGE(2)) and isoproterenol, and produced cyclic A MP (cAMP), but did not respond to human 1-34 parathyroid hormone (PTH) . Intracellular Ca2+ ([Ca2+](i)) was measured in HPDL cells and HGF, u sing Fura 2-AM. Bradykinin (BK) and histamine (HIS), which are major c hemical mediators, caused a transient rise of [Ca2+](i), in the presen ce of extracellular Ca2+. In HGF, but not HPDL cells, HIS induced a bi phasic transient peak in [Ca2+](i). BK and HIS increased PGE(2) releas e in both HPDL cells and HGF However, HGF released a larger amount of PGE(2) than HPDL cells. These results demonstrate that HPDL cells have quite different characteristics from HGF HPDL cells proliferate at a higher rate than HGF show higher levels of cAMP production and greater ALPase activity, and respond in a different fashion to chemical media tors (BK and HIS) compared with HGF.