Conditioned medium of periodontal ligament mesenchymal stem cells exert anti-inflammatory effects in lipopolysaccharide-activated mouse motoneurons

MyD88/ERK/NFkB pathways and pro-inflammatory cytokines release in periodontal ligament stem cells stimulated by Porphyromonas gingivalis

The present study was aimed at investigating whether human Periodontal Ligament Stem Cells (hPDLSCs) were capable of sensing and reacting to lipopolysaccharide from Porphyromonas gingivalis (LPS-G) which is widely recognized as a major pathogen in the development and progression of periodontitis. At this purpose hPDLCs were stimulated with 5 μg/mL LPS-G at various times and the expression of toll-like receptor 4 (TLR4) was evaluated. Toll-like receptors (TLRs) play an essential role in innate immune signaling in response to microbial infections, and in particular TLR4, type-I transmembrane proteins, has been shown recognizing LPS-G. Our results put in evidence, in treated samples, an overexpression of TLR4 indicating that, hPDLSCs express a functional TLR4 receptor. In addition, LPS-G challenge induces a significant cell growth decrease starting from 24 h until 72 h of treatment. LPS-G leads the activation of the TLR4/MyD88 complex, triggering the secretion of proinflammatory cytokines cascade as: IL-1α, IL-8, TNF-α and β and EOTAXIN. Moreover, the upregulation of pERK/ERK signaling pathways and NFkB nuclear translocation was evident. On the basis of these observations, we conclude that hPDLSCs could represent an appropriate stem cells niche modeling leading to understand and evaluate the biological mechanisms of periodontal stem cells in response to LPS-G, mimicking in vitro an inflammatory process occurring in vivo in periodontal disease.

Conditioned medium from relapsing-remitting multiple sclerosis patients reduces the expression and release of inflammatory cytokines induced by LPS-gingivalis in THP-1 and MO3.13 cell lines

The present research was aimed at evaluating the effect of the conditioned medium (CM) from human periodontal ligament stem cells (hPDLSCs) obtained from healthy donors (hPDLSCs-CM) and from Relapsing-Remitting Multiple Sclerosis patients (RR-MS-CM) on inflammatory response induced by Porphyromonas gingivalis lipopolysaccharide (LPS-G) in a monocytoid human cell line (THP-1) and human oligodendrocyte cell line (MO3.13). Human periodontal ligament biopsies were carried out from control donor patients and selected RR-MS donors. Sample tissues were obtained from premolar teeth during root scaling and subsequently cultured. The effect of hPDLSCs-CM and RR-MS-CM on cell viability in PMA differentiated THP-1 (as a model of microglia) was measured using a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay. The same experiments were performed in undifferentiated and differentiated MO3.13 cells used as models of progenitor cells and oligodendrocytes, respectively. The expression of tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1β and IL-6 was evaluated by Real-Time Polymerase Chain Reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA). The expression level of the Toll-like receptor 4 (TLR-4), for which LPS-G is a ligand, was evaluated by Western blot analysis. The results were analyzed by ANOVA using Graph Pad Prism software. LPS-G significantly increased TNFα, IL-1β and IL-6 mRNA expression and protein levels in the differentiated THP-1 cells and oligodendrocyte MO3.13 progenitor cells. Treatment with hPDLSCs-CM or with RR-MS-CM significantly attenuated the LPS-induced expression and production of these pro-inflammatory cytokines. The CM from both healthy donors and RR-MS patients also reduced the LPS-G stimulated protein levels of TLR-4 in differentiated THP-1 cells. On the whole our data add new evidence on the anti-inflammatory effects of these peculiar stem cells even when derived from RR-MS patients and open novel perspectives in the therapeutic use of autologous periodontal stem cells in neuroinflammatory/neurodegenerative diseases including MS.

Stemness Maintenance Properties in Human Oral Stem Cells after Long-Term Passage

Background. Neural crest-derived mesenchymal stem cells (MSCs) from human oral tissues possess immunomodulatory and regenerative properties and are emerging as a potential therapeutic tool to treat diverse diseases, such as multiple sclerosis, myocardial infarction, and connective tissue damages. In addition to cell-surface antigens, dental MSCs express embryonic stem cell markers as neural crest cells originate from the ectoderm layer. In vitro passages may eventually modify these embryonic marker expressions and other stemness properties, including proliferation. In the present study, we have investigated the expression of proteins involved in cell proliferation/senescence and embryonic stem cell markers during early (passage 2) and late passages (passage 15) in MSCs obtained from human gingiva, periodontal, and dental pulp tissues. Methods. Cell proliferation assay, beta galactosidase staining, immunocytochemistry, and real-time PCR techniques were applied. Results. Cell proliferation assay showed no difference between early and late passages while senescence markers p16 and p21 were considerably increased in late passage. Embryonic stem cell markers including SKIL, MEIS1, and JARID2 were differentially modulated between P2 and P15 cells. Discussion. Our results suggest that the presence of embryonic and proliferation markers even in late passage may potentially endorse the application of dental-derived MSCs in stem cell therapy-based clinical trials.