The immunomodulatory properties of periodontal ligament stem cells isolated from inflamed periodontal granulation.

Periodontitis is currently the main cause of tooth loss and as yet there is no appropriate method for establishing a functional and predictable periodontal regeneration. Tissue engineering involving seed cells provides a new prospect for periodontal regeneration. While periodontal ligament stem cells (PDLSCs) are a good choice for seed cells, it is not always possible to obtain the patients' own PDLSCs. We and others have found a type of stromal cells from inflamed periodontal granulation. These cells displayed similar differentiation properties to PDLSCs. Inflammation has a profound influence on the immunomodulatory properties of mesenchymal stem cells, which may affect therapeutic outcome. In this study, we assessed the immunomodulatory characteristics of these inflamed human (ih)PDLSCs. Along with the similarity in cell surface marker expressions, they also displayed immunomodulatory properties comparable to those in healthy human (hh)PDLSCs. Both hhPDLSCs and ihPDLSCs can suppress the proliferation and secretion of IFN-γ in peripheral blood mononuclear cells by indirect soluble mediators and direct cell-cell contact. Albeit with some quantitative variances, the gene expressions of inducible nitric oxide synthases, indoleamine 2,3 dioxygenase, cyclooxygenase-2, TNF-α-induced protein 6 and IL-10 in ihPDLSCs displayed similar patterns as those in hhPDLSCs. Taken together, our results suggest that ihPDLSCs can provide a promising alternative to hhPDLSCs in terms of evident similarities in immunomodulatory properties as well as their easier accessibility and availability.