Gingival fibroblasts prevent BMP‐mediated osteoblastic differentiation

Abstract

Objectives The inhibitory action of the superficial gingival connective tissues may limit the regenerative potential of alveolar bone in periodontal therapy or dental implant applications. The aims of this study were to investigate the hypothesis that gingival fibroblasts (GF) can inhibit bone morphogenetic protein (BMP)‐induced osteoblastic differentiation, to determine their expression of BMP inhibitors, and finally to determine whether reduction of these inhibitors can relieve suppression of osteoblastic differentiation. Methods Gingival fibroblasts were co‐cultured either directly or indirectly with calvarial osteoblasts to assess alkaline phosphatase inhibitory activity, a marker of osteoblastic differentiation. To test total BMP‐inhibitory activity of rat GF, conditioned media (GFCM) were collected from cultures. ROS 17/2.8 osteoblastic cells were stimulated with BMP2, together with GFCM. Inhibitor expression was tested using RT‐qPCR, Western blotting and in situ hybridization. Removal of inhibitors was carried out using immunoprecipitation beads. Results Co‐culture experiments showed GF‐secreted factors that inhibit BMP‐stimulated ALP activity. 10 ng/ml BMP2 increased alkaline phosphatase expression in ROS cells by 41%. GFCM blocked BMP activity which was equivalent to the activity of 100 ng/ml Noggin, a well‐described BMP inhibitor. Cultured gingival fibroblasts constitutively expressed BMP antagonist genes from the same subfamily, Grem1 , Grem2 and Nbl1 and the Wnt inhibitor Sfrp1 . Gremlin1 (6.7 × reference gene expression) had highest levels of basal expression. ISH analysis showed Gremlin1 expression was restricted to the inner half of the gingival lamina propria and the PDL. Removal of Gremlin1 protein from GFCM eliminated the inhibitory effect of GFCM on ALP activity in ROS cells. Subsequent addition of recombinant Gremlin1 restored the inhibitory activity. Conclusions Factors secreted by gingival fibroblasts inhibit BMP‐induced bone formation and a range of BMP inhibitors are constitutively expressed in gingival connective tissues. These inhibitors, particularly Gremlin1, may limit coronal alveolar bone regenerative potential during oral and periodontal surgery.

Exosomes derived from P2X7 receptor gene-modified cells rescue inflammation-compromised periodontal ligament stem cells from dysfunction

“…Inhibition or induction of GREM‐1 changed the osteogenic differentiation of PDLSCs under inflammatory conditions (Figure 7). Similar results have been reported by Ghuman, showing that GREM‐1 can also limit coronal alveolar bone regenerative potential during oral and periodontal surgery by inhibiting BMP‐induced bone formation 61 . Other studies have shown that GREM‐1 plays an important regularly role in organogenesis of the limbs and kidneys, 62 and mutations in GREM‐1 lead to abnormalities of the limbs, lungs, and kidneys in mice 63 …”

“…Similar results have been reported by Ghuman, showing that GREM-1 can also limit coronal alveolar bone regenerative potential during oral and periodontal surgery by inhibiting BMP-induced bone formation. 61 Other studies have shown that GREM-1 plays an important regularly role in organogenesis of the limbs and kidneys, 62 and mutations in GREM-1 lead to abnormalities of the limbs, lungs, and kidneys in mice. 63 Taken together, these results show that P2X7R has not been identified, and more in vivo experiments are needed to verify the positive influence of P2X7R on tissue regeneration.…”

The effects of Omarigliptin on promoting osteoblastic differentiation

“…We further measured the expression levels of important factors involved in the regulation of osteoblastic differentiation, such as BMP-2 [ 20 ], Ocn [ 21 ], and ALP [ 22 ]. We found that BMP-2, Ocn, and ALP ( Figure 3a-b ) were significantly upregulated in osteogenic medium-cultured MC3T3‑E1 cells at both the mRNA and protein levels, and pronouncedly further upregulated by 20 μM Omarigliptin, revealing the regulatory function of Omarigliptin on osteoblastic differentiation is associated with these factors.…”

Secreted Frizzled-Related Protein 1 Promotes Odontoblastic Differentiation and Reparative Dentin Formation in Dental Pulp Cells

“…Furthermore, SFRP1 expression was higher in hDPCs than in hPDLCs and hGFs. SFRP1 expression was confirmed in cultured rat gingival fibroblasts [ 25 ]. Other previous studies demonstrated that bone-lining osteoblast-like stromal cells and osteoclasts express SFRP1 [ 26 ] and that SFRP1 is expressed much more strongly in the periodontal ligament than in alveolar bone and cementum [ 27 ].…”

“…Various signals, such as growth factors, chemokines, and extracellular matrices, are involved in the regeneration and homeostasis of the dentin-pulp complex [ 25 , 26 , 27 , 28 , 29 , 30 ]. Additionally, the mesenchymal stem/progenitor cell population in pulp is considered to differentiate into odontoblast-like cells, which generate reparative dentin in response to injury [ 10 , 31 ].…”