BackgroundDental pulp tissue contains many undifferentiated mesenchymal cells, which retain the ability to differentiate into mature cells. Induced pluripotent stem cells have been developed from various cell sources, including dental pulp-derived stem cells, and evaluated for potential application to regenerative therapy. Dental pulp tissues overexpress CD44, a cell-adhesion factor involved in the induction of mineralization. In this study, we investigated the effects of hyaluronan—a known CD44 ligand—on dental pulp stem cells (DPSCs).MethodsDPSC CD44 expression was analyzed using immunofluorescence staining, flow cytometry, and western blotting. Cell proliferation was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Effects of hyaluronan on the cell cycle were analyzed by flow cytometry. Alkaline phosphatase activity was employed as marker of mineralization and measured by fluorometric quantification and western blotting. Bone morphogenetic protein (BMP)-2, BMP-4, dentin sialophosphoprotein (DSPP), and dentin matrix acidic phosphoprotein 1 (DMP-1) levels were measured using real-time polymerase chain reaction. Odontoblastic differentiation and the close cell signaling examination of DPSC differentiation were determined using western blotting.ResultsHyaluronan induced expression of the odontoblastic differentiation markers DMP-1 and DSPP. Moreover, the odontoblastic differentiation induced by hyaluronan was mediated by CD44—but not by Akt, Smad1 or MAPK signaling.ConclusionsOur results indicate that hyaluronan induces odontoblastic differentiation of DPSCs via CD44. This suggests that hyaluronan plays a crucial role in the induction of odontoblastic differentiation from DPSCs. Our findings may aid the development of new, inexpensive, and effective conservative treatments for dental pulp repair.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0399-8) contains supplementary material, which is available to authorized users.

Multipotent mesenchymal stem cell (MSC) therapies are being tested clinically for a variety of disorders. However, despite the remarkable clinical advancements in this field, most applications still use traditional culture media containing fetal bovine serum. Platelet-rich plasma (PRP) appears as a novel application for tissue engineering and its effect on bone healing is thought to be mainly dependent on the proliferation promoting function, with the molecular mechanisms largely unknown. In this study, mouse osteogenic progenitor mesenchymal stem cells (MSCs) were cultured in PRP or washed platelet (WPLT)-treated wells or in untreated wells, and analyzed on cycloxygenase 2 (COX2) expression (qRT-PCR), cell growth (MTT assay) and cell differentiation (alkaline phosphatase activity). The results showed that PRP and WPLT stimulated cell growth similarly in the first 6 days, together with the steady induction of COX2 and PGE2. 10 μmol/l celecoxib (an inhibitor of COX2) significantly inhibited the pro-proliferation effects. Interestingly, WPLT had stronger effects than PRP in proliferation at the later time points (6-9 days). ALP activity assay and collagen 1a expression revealed PRP had a mild but statistically significant pro-differentiation effect, while no obvious effects observed in WLPT group. In summary, PRP stimulates initial growth of MSCs in a COX2 partially dependent manner and the less obvious osteogenic differentiation promoting effects of WPLT strongly indicates WPLT rather than the PRP should be the optional choice for expanding MSCs in vitro for clinical use.

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Platelet-rich plasma (PRP), which contains growth factors for osteoblasts, is clinically used to promote regeneration of osseous tissue. However, we found that human plasma dose-dependently inhibits the growth of cultured MC3T3-E1 osteoblastic cells. In this study, the characteristics of osteoblast inhibiting factor in plasma were investigated. The inhibitory effect on MC3T3-E1 cells was inactivated by pre-heating the plasma. The molecular weight of this factor was estimated to be more than 100-kDaltons by the ultrafiltration method, and the macromolecular fraction strongly inhibited the spreading of MC3T3-E1 cells. Moreover, pre-treatment with a serine protease inhibitor abrogated the inhibitory effect of this factor, suggesting that serine proteases have an important role in inhibiting the growth of MC3T3-E1 cells. These results suggest that the improved preparation of platelets to exclude osteoblast-inhibiting factor from PRP is needed for the efficient regeneration of osseous tissue.

A local drug delivery system for treatment of periodontal pockets by antibiotic is often used on patient with periodontitis. However, a well-known side effect of the long-term use of antibiotics is the increase in Also, the latter drug was evaluated clinically for use in a mouth rinse. The results suggest that Chinese traditional drugs Folium and Radix Strobilanthis inhibited the growth of periodontopathic bacteria and cariogenic bacteria in vitro. Furthermore, Radix Strobilanthis inhibited the proliferation of oral bacteria when used in a mouth rinse.