Effects of transforming growth factor-ß1 on plasminogen activation in stem cells from the apical papilla: role of activating receptor-like kinase 5/Smad2 and mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signalling.

AIM: To study the effects of TGF-ß1 on the plasminogen activation (PA) system of stem cells from the apical papilla (SCAP) and its signalling. METHODOLOGY: SCAP cells were isolated from the apical papilla of immature permanent teeth extracted for orthodontic reasons. They were exposed to various concentration of TGF-ß1 with/without pretreatment and coincubation by SB431542 (ALK/Smad2/3 inhibitor), or U0126 (MEK/ERK inhibitor). MTT assay, Western blotting and enzyme-linked immunosorbent assay (ELISA) were used to detect their effects on cell viability, and the protein expression of plasminogen activator inhibitor-1 (PAI-1), urokinase-type plasminogen activator (uPA), uPA receptor (uPAR) and their secretion. The paired Student's t-test was used for statistical analysis. RESULTS: TGF-ß1 significantly stimulated PAI-1 and soluble uPAR (suPAR) secretion of SCAP cells (P < 0.05), whereas uPA secretion was inhibited. Accordingly, TGF-ß1 induced both PAI-1 and uPAR protein expression of SCAP cells. SB431542 (an ALK5/Smad2/3 inhibitor) pretreatment and coincubation prevented the TGF-ß1-induced PAI-1 and uPAR of SCAP. U0126 attenuated the TGF-ß1-induced expression/secretion of uPAR, but not PAI-1 in SCAP. SB431542 reversed the TGF-ß1-induced decline of uPA. CONCLUSIONS: TGF-ß1 may affect the repair/regeneration activities of SCAP via differential increase or decrease of PAI-1, uPA and uPAR. These effects induced by TGF-ß1 are associated with ALK5/Smad2/3 and MEK/ERK activation. Elucidation the signalling pathways and effects of TGF-ß1 is useful for treatment of immature teeth with open apex by revascularization/revitalization procedures and tissue repair/regeneration.

Carboxylesterase expression in human dental pulp cells: role in regulation of BisGMA-induced prostanoid production and cytotoxicity.

Biocompatibility of dentin bonding agents (DBA) and composite resin may affect the treatment outcome (e.g., healthy pulp, pulpal inflammation, pulp necrosis) after operative restoration. Bisphenol-glycidyl methacrylate (BisGMA) is one of the major monomers present in DBA and resin. Prior studies focused on salivary esterase for metabolism and degradation of resin monomers clinically. This study found that human dental pulp cells expressed mainly carboxylesterase-2 (CES2) and smaller amounts of CES1A1 and CES3 isoforms. Exposure to BisGMA stimulated CES isoforms expression of pulp cells, and this event was inhibited by catalase. Exogenous addition of porcine esterase prevented BisGMA- and DBA-induced cytotoxicity. Interestingly, inhibition of CES by bis(p-nitrophenyl) phosphate (BNPP) and CES2 by loperamide enhanced the cytotoxicity of BisGMA and DBA. Addition of porcine esterase or N-acetyl-l-cysteine prevented BisGMA-induced prostaglandin E(2) (PGE(2)) and PGF(2α) production. In contrast, addition of BNPP and loperamide, but not mevastatin, enhanced BisGMA-induced PGE(2) and PGF(2α) production in dental pulp cells. These results suggest that BisGMA may induce the cytotoxicity and prostanoid production of pulp cells, leading to pulpal inflammation or necrosis via reactive oxygen species production. Expression of CES, especially CES2, in dental pulp cells can be an adaptive response to protect dental pulp against BisGMA-induced cytotoxicity and prostanoid release. Resin monomers are the main toxic components in DBA, and the ester group is crucial for monomer toxicity.