further these cells exhibit the potential to be useful

further numbers of PMNs and T-lymphocytes providing a source of immune competent
cells against potential pathogenic species (Schroeder & Listgarten, 1997). Furthermore,
fibroblasts exert function in periodontal regeneration processes (Somerman et al.,
1988). The ligament tissue includes at least three different cell populations, and thereby
represents a resource for fibroblasts, osteoblasts and cementoblasts (Melcher, 1985;
Saito et al., 1991).
The periodontal tissue provides stem cells which give rise to the different cell types
forming the hard and soft tissues. Isolation from the gingiva, dental pulp, apical papilla,
periodontal ligament, dental follicle and exfoliated deciduous teeth was previously
demonstrated (Gronthos et al., 2000; Miura et al., 2003; Seo et al., 2004; Jo et al., 2007;
Sonoyama et al., 2008; Zhang et al., 2009; Potdar & Jethmalani, 2015) as well as
characterization as mesenchymal stem cells (Baksh et al., 2007). These stem cells have
been demonstrated to differentiate into various cell types in vitro (Gronthos et al., 2000;
Seo et al., 2005; Chen et al., 2006; Sonoyama et al., 2008), express surface markers of
pluripotent stem cells, e.g., CD13, CD29, CD44, CD73, CD90 CD105, CD166, with
exclusion of hematopoietic marker expression, e.g., CD34, CD45, (Trubiani et al., 2005;
Lindroos et al., 2008; Song et al., 2010; Bakopoulou & About, 2016), and had an adherent
phenotype upon cultivation on plastic surfaces.
Stem cells from the dental follicle (hDFSCs) have the ability to differentiate into bone
and cementum cells, show high proliferation capacity and plasticity compared to other
dental stem cell resources (Lizier et al., 2013; Shoi et al., 2014; Lucaciu et al., 2015;
Potdar & Jethmalani, 2015). Thereby, these cells exhibit the potential to be useful in
periodontal regeneration strategies. Raffaghello et al. (2008) showed supportive
influence of stem cells on PMN survival in vitro depending on interleukin secretion.
These results underline the regenerative and immune modulating properties of stem
cells in the oral cavity.
The periodontal tissues are constantly but differentially exposed to the oral microbiome,
and epithelial cells have most of the interaction burden with microorganisms (Eberhard
et al., 2009). Nevertheless, tissue destruction due to periodontal inflammation might
allow interaction with other cells, e.g., dental stem cells. The analysis of stem cell –
bacteria interaction is highly relevant in the context of tissue regeneration or future
stem cell treatment of periodontitis.