Ascorbic Acid, Inflammatory Cytokines (IL-1<i>β</i>/TNF-<i>α</i>/IFN-<i>γ</i>), or Their Combination’s Effect on Stemness, Proliferation, and Differentiation of Gingival Mesenchymal Stem/Progenitor Cells
Karim M. Fawzy El‐Sayed, Nguyen Thi Nhung, Christof E. Dörfer
Abstract
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-1 β /TNF- α /IFN- γ ), AA, or their combination on multipotency/pluripotency, proliferative, and differentiation characteristics of G-MSCs. Design . Human G-MSCs (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>5</mml:mn></mml:math>) were isolated and cultured in basic medium (control group), in basic medium with major inflammatory cytokines; 1 ng/ml IL-1 β , 10 ng/ml TNF- α , and 100 ng/ml IFN- γ (inflammatory group), in basic medium with 250 μ mol/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 β -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 . β -Catenin significantly decreased intracellularly in all experimental groups (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.002</mml:mn></mml:math>, Friedman). AA group exhibited significantly higher cellular counts on days 3, 6, 7, and 13 (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn>0.05</mml:mn></mml:math>) and the highest CFUs at 14 days [median-CFUs (Q25/Q75); 40 (15/50), <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mi>p</mml:mi><mml:mo>=</mml:mo><mml:mn>0.043</mml:mn></mml:math>]. Significantly higher Nanog expression was noted in AA group [median gene-copies/PGK1 (Q25/Q75); 0.0006 (0.0002/0.0007), <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mi>p</mml:mi><mml:mo><</mml:mo><mml:mn>0.01</mml:mn></mml:math>, 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/ β -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.