BMP-2 and asporin expression regulate 5-aza-dC-mediated osteoblast/cementoblast differentiation of periodontal dental ligament mesenchymal progenitor cells.

Periodontal dental ligament (PDL) is composed of heterogeneous population of mesenchymal progenitor cells. The mechanisms that regulate the differentiation of these cells towards osteoblast/cementoblast phenotype are not fully understood. Some studies have demonstrated that is possible to change the pattern of cell differentiation via epigenetic mechanisms. The proposal of this study was to investigate whether 5-aza-2'-deoxycytidine (5-aza-dC) treatment would stimulate the osteoblast/cementoblast differentiation of periodontal ligament mesenchymal progenitor cells (PDL-CD105+ enriched cells), characterized as low osteoblast potential, through bone morphogenetic protein-2 (BMP-2) modulation. PDL-CD105+ cells from a single donor were cloned and characterized in two populations as high osteoblast/cementoblast potential (HOP) and low osteoblast/cementoblast potential (LOP) by mineralization in vitro and expression of osteogenic gene markers, such as runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteocalcin (OCN), bone morphogenetic protein 2 (BMP-2) and asporin (ASPN). Next, two LOP clones (L1 and L2) were pretreated with 5-aza-dC (10 µM) for 48 h, cultured under osteogenic condition and evaluated for mineralized matrix in vitro, transcription modulation of osteogenic gene markers, methylated and hydroxymethylated DNA levels of BMP-2 and ASPN and intracellular/extracellular expression of BMP-2 protein. LOP clones showed high expression of ASPN transcripts associated with low mRNA levels of BMP-2, RUNX2, ALP, and OCN. 5-aza-dC treatment raised hydroxymethylated DNA levels of BMP-2 and increased the expression of BMP-2 transcripts in both LOP clones. However, BMP-2 protein (intracellular and secreted forms) was detected only in L1 cell clones, in which it was observed an increased expression of osteoblast/cementoblast markers (RUNX2, ALP, OCN) associated with higher mineralization in vitro. In L2 cell clones, 5-aza-dC increased gene expression of ASPN, with no great change in for osteoblast/cementoblast differentiation potential. These data show that 5-aza-dC improves osteoblast/cementoblast differentiation of PDL-CD105+ cells via BMP-2 secretion, and this effect depends on low levels of ASPN expression.

Do smokers have a different gingival crevicular fluid cytokine/chemokine profile than nonsmokers in clinically healthy periodontal sites? A systematic review and meta-analysis.

OBJECTIVES: Assessing the evidence and comparing the levels of cytokines in gingival crevicular fluid (GCF) of periodontal healthy sites of smokers and nonsmokers. MATERIALS AND METHODS: Seven databases were surveyed for observational studies up to April 8, 2021. Studies comparing cytokine levels on GCF in periodontally healthy sites of smokers vs. nonsmokers were included in the study. The risk of bias was evaluated using NIH (2014) tool. For meta-analyses, levels in GCF were analyzed, followed by evidence certainty assessment using the GRADE approach. RESULTS: Eighteen studies were included for qualitative evaluation, and eight were included in meta-analysis. Qualitatively, despite high heterogeneity and risk of bias observed among the studies, most of them presented no significant difference in the gingival crevicular cytokine fluid levels between groups. Regarding meta-analyses, interleukin-8 (IL-8) and superoxide dismutase (SOD) levels in GCF were analyzed. The significant difference was observed only in SOD levels, where heavy smokers had lower levels compared to nonsmokers (MD - 30.06 [- 40.17, - 19.96], p = 0.07, 95%CI), as well as light smokers had lower levels compared to nonsmokers (MD - 15.22 [- 16.05, - 14.39], p < 0.00001, 95%CI). CONCLUSION: No distinct GCF cytokine profiles were detected for smokers and non-smokers. However, despite the limitations observed in the included studies, lower levels of SOD were identified in smokers. CLINICAL RELEVANCE: Indicating a distinct GCF profile of cytokines in periodontal healthy smokers may help to understand the mechanism whereby smoking may affect the host response.

Enhancing adhesion and alignment of human gingival fibroblasts on dental implants.

BACKGROUND: Promoting the directional attachment of gingiva to the dental implant leads to the formation of tight connective tissue which acts as a seal against the penetration of oral bacteria. Such a directional growth is mostly governed by the surface texture. MATERIAL AND METHODS: In this study, three different methods, mechanical structuring, chemical etching and laser treatment, have been explored for their applicability in promoting cellular attachment and alignment of human primary gingival fibroblasts (HGFIBs). RESULTS: The effectiveness of mechanical structuring was shown as a simple and a cost-effective method to create patterns to align HGIFIBs. CONCLUSION: Combining mechanical structuring with chemical etching enhanced both cellular attachment and the cellular alignment.