Recombinant human bone morphogenetic protein-2 stimulates osteoblastic differentiation in cells isolated from human periodontal ligament

Periodontal Ligament cells may play an important role in the successful reg eneration of the periodontium. We investigated the effects of recombinant h uman bone morphogenetic protein-2 (rhBMP-2), one of the most potent growth factors that stimulates osteoblast differentiation and bone formation, on c ell growth and osteoblastic differentiation in human periodontal ligament c ells (HPLC) isolated from four adult patients. rhBMP-2 induced no significa nt changes in cell growth in any of the HPLCs. rhBMP-2 at concentrations ov er 50 ng/mL significantly stimulated alkaline phosphatase (ALPase) activity and parathyroid hormone (PTH)-dependent 3', 5'-cyclic adenosine monophosph ate accumulation, which are early markers of osteoblast differentiation, in the HPLCs. rhBMP-2 (500 ng/mL) also slightly enhanced the level of PTH/PTH -related peptide receptor mRNA expression in these cells. While interleukin -1 beta enhanced ALPase activity stimulated with rhBMP-2, tumor necrosis fa ctor-alpha inhibited the rhBMP-2-stimulated activity. Interleukin-6 induced no significant changes in ALPase activity stimulated with rhBMP-2. Althoug h HPLCs, whether treated with rhBMP-2 or not, could not produce measurable amounts of osteocalcin, which is a marker of more mature osteoblasts, 1,25- dihydroxyvitamin D-3[1,25(OH)(2)D-3] induced osteocalcin mRNA expression an d protein synthesis in these cells. rhBMP-2 inhibited 1,25(OH)(2)D-3-induce d osteocalcin synthesis in HPLCs at both the mRNA and protein levels. These results suggest that rhBMP-2 provides an anabolic effect on periodontal re generation by stimulation of osteoblastic differentiation in human periodon tal ligament cells, and that this stimulatory effect is differentially modu lated by inflammatory cytokines during the course of periodontal regenerati on.