Proliferative Effect Of Hypochlorous Acid On Cells Of Oral Mucosa

Hypochlorous acid (HOCl) is a non-antibiotic antimicrobial solution naturally produced into the immune system during a cellular process known as respiratory burst in the elimination of antigens and has attracted interest as anti-plaque agent. Some studies have shown that HOCl can stimulate tissue regeneration in oral mucosa through oxidation/chlorination processes. 

Objective:

To assess the viability and proliferative effect of HOCl on cells of the oral mucosa. 

Method:

To evaluate the viability of the oral cells to HOCl exposure, the cellular line of human gingival fibroblast (HGF-1), ATCC® (CRL2014™) was used. Resazurin assay was selected to evaluate cell viability. Through a linear regression analysis the optimal cellular density required for the test (15.000/well in a 96-wells plate) was obtained. After adhesion, cells were exposed to chlorhexidine (CHX) at 0.2% and 0.12% as a standard and with stabilized HOCl at physiological balance at pH of 5.2 and 5.6 at concentrations from 0.065% to 0.0012% during 48 and 72 hrs. Cells treated with medium were used as control. Fulfilled the different contact times, absorbance for all tested concentrations were determined using an Elisa reader at 570-630nm. Measures were analyzed by triplicate and the results were transformed to percentage of survival. Using the statistical program GraphPad the percentages for lethal concentration 50 (LC₅₀) were calculated. 

Results:

HOCl at pH 5.2 has a range from 12-90% of cellular viability after 48hrs exposure with an LC₅₀ of 0.084%, while concentrations of HOCl at pH 5.6 shown a better behavior with a cell viability ranging 42-115% with an LC₅₀ of 0.0125%, well above the results obtained in the CHX treatment which did not exceeded 10% viability for all concentrations. 

Conclusion:

HOCl showed higher cell viability than CHX. At pH 5.6 the concentrations below of 0.0125% showed an important effect in cell proliferation.