Effect of Ribes nigrum bud extract on human gingival mesenchymal stem cell cytokine release: a role on regenerative processes

The blackcurrant, Ribes nigrum, has been widely used in the traditional herbal medicine, and recently its anti-inflammatory, antioxidant and regenerative properties have been highlighted1. In the scenario of regenerative medicine, the gingival mesenchymal stem cells (GMSCs) have arisen as a promising tool to repair damaged tissues and promote the reepithelization processes. The GMSCs are a peculiar type of mesenchymal stem cell that besides the immunomodulatory and differentiation properties they behave as trophic mediators2; furthermore, they could be easily obtained from gingival lamina propria3. Herein, the GMSCs were isolated and characterized from healthy subjects, and a cell pool was used to investigate the regenerative effect of a R. nigrum bud extract. The R. nigrum bud extract was able to increase the GMSC proliferation and the gene expression of stemness markers (SOX2, Oct4) at least at high concentrations. Classic growth factors and cytokines, such as TGF-β, interleukins (IL-6, IL-10), and COX2 serve as paracrine control molecules secreted or packaged into extracellular vesicles by GMSCs, in response to an inflammatory stimuli (100 ng/ml TNF-α). The extract (50 µg/ml) was able to counteract the secretion of these inflammatory mediators. The presence of high TNF-α concentration affected the secretome of the GMSCs, inducing a decrease of the epithelial cells migration, so impairing the repairing processes. Interestingly, the negative effect of TNF-α was counteract by the R. nigrum bud extract that significantly restore the migration ability of the epithelial cells. Furthermore, the bud extract per se was able to significantly enhance the proliferation of the epithelial cells. Results from the HPLC-PDA/UV-ESI-MS/MS analyses revealed that R. nigrum bud preparation is rich in polyphenol constituents, according to data previously reported.4 In particular, phenolic acids derivatives and flavonol mono- and di-glycosides were identified. In conclusion, these results highlight the R. nigrum bud extract as a novel tool to enhance the reepithelialisation, through its direct effect on epithelial cells and through the modulation of cytokine release from GMSCs. Furthermore, the results could open the way to the development of the extract as topic agent in wound healing as well as in periodontal regeneration.