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OBJECTIVE: Ascorbic acid (AA) and controlled inflammatory stimuli are postulated to possess the ability to independently exert positive effects on a variety of proliferative, pluripotency, and differentiation attributes of gingival mesenchymal stem/progenitor cells (G-MSCs). The current study's objective was to explore and compare for the first time the impact of the major inflammatory cytokines (IL-1ß/TNF-α/IFN-γ), AA, or their combination on multipotency/pluripotency, proliferative, and differentiation characteristics of G-MSCs. DESIGN: Human G-MSCs (n = 5) were isolated and cultured in basic medium (control group), in basic medium with major inflammatory cytokines; 1 ng/ml IL-1ß, 10 ng/ml TNF-α, and 100 ng/ml IFN-γ (inflammatory group), in basic medium with 250 µmol/l AA (AA group) and in inflammatory medium supplemented by AA (inflammatory/AA group). All media were renewed three times per week. In stimulated G-MSCs intracellular ß-catenin at 1 hour, pluripotency gene expression at 1, 3, and 5 days, as well as colony-forming units (CFUs) ability and cellular proliferation over 14 days were examined. Following a five-days stimulation in the designated groups, multilineage differentiation was assessed via qualitative and quantitative histochemistry as well as mRNA expression. RESULTS: ß-Catenin significantly decreased intracellularly in all experimental groups (p = 0.002, Friedman). AA group exhibited significantly higher cellular counts on days 3, 6, 7, and 13 (p < 0.05) and the highest CFUs at 14 days [median-CFUs (Q25/Q75); 40 (15/50), p = 0.043]. Significantly higher Nanog expression was noted in AA group [median gene-copies/PGK1 (Q25/Q75); 0.0006 (0.0002/0.0007), p < 0.01, Wilcoxon-signed-rank]. Significant multilineage differentiation abilities, especially into osteogenic and chondrogenic directions, were further evident in the AA group. CONCLUSIONS: AA stimulation enhances G-MSCs' stemness, proliferation, and differentiation properties, effects which are associated with a Wnt/ß-catenin signaling pathway activation. Apart from initially boosting cellular metabolism as well as Sox2 and Oct4A pluripotency marker expression, inflammation appeared to attenuate these AA-induced positive effects. Current results reveal that for AA to exert its beneficial effects on G-MSCs' cellular attributes, it requires to act in an inflammation-free microenvironment.
RESUMO
OBJECTIVES: This randomized controlled trial compares for the first time effects of Alvogyl versus absorbable gelatin sponge as palatal wound dressings on postoperative pain, amount of analgesic consumption, post-surgical bleeding, and wound re-epithelization. MATERIALS AND METHODS: Following sample size calculation, 36 systemically healthy patients requiring palatal mucosal graft harvesting were randomized to receive Alvogyl (intervention group, 18 patients) or absorbable gelatin sponge (control group, 18 patients) palatal dressings. Patient-reported VAS pain scores over 2 weeks were defined as primary outcome. Post-surgical bleeding, number of analgesics consumed, and complete re-epithelialization of the palatal wound for up to 5 weeks were defined as secondary outcomes. RESULTS: Although significantly higher VAS pain scores were reported in the control as compared with the intervention group up to 12 days post-surgically (from (median [range]) 8.5 [2-10] to 1 [0-2] and from 6 [0-10] to 0 [0-2] respectively), with higher analgesics consumption (from 2 [1-3] to 1 [0-3] and from 1 [0-3] to 0 [0-2] tablets respectively), a multivariate regression analysis considering age, gender, graft width/length, tissue thickness, analgesics intake, and dressing type demonstrated no statistically significant effect of any factor, including dressing type on VAS pain scores. At 4 weeks, 22.2% of patients in the intervention group versus 11.1% in the control group demonstrated complete re-epithelization of their palatal engraftment site, before complete re-epithelization in both groups at 5 weeks. No post-surgical bleeding was reported with both dressings. CONCLUSIONS: Within the study's limitations, results suggest Alvogyl as a practical palatal surgical dressing, comparable with absorbable gelatin sponge in cost, pain reduction, hemostasis, and re-epithelization properties. TRIAL REGISTRATION: www.ClinicalTrials.gov Identifier: NCT03402321 CLINICAL RELEVANCE: Alvogyl could present a novel palatal wound dressing material, comparable with gelatin sponge.