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Melatonin's effect on hepatic differentiation of stem cells remains unclear. The aim of this study was to investigate the action of melatonin on hepatic differentiation as well as its related signaling pathways of human dental pulp stem cells (hDPSCs) and to examine the therapeutic effects of a combination of melatonin and hDPSC transplantation on carbon tetrachloride (CCl4 )-induced liver fibrosis in mice. In vitro hepatic differentiation was assessed by periodic acid-Schiff (PAS) staining and mRNA expression for hepatocyte markers. Liver fibrosis model was established by injecting 0.5 mL/kg CCl4 followed by treatment with melatonin (5 mg/kg, twice a week) and hDPSCs. In vivo therapeutic effects were evaluated by histopathology and by means of liver function tests including measurement of alanine transaminase (ALT), aspartate transaminase (AST), and ammonia levels. Melatonin promoted hepatic differentiation based on mRNA expression of differentiation markers and PAS-stained glycogen-laden cells. In addition, melatonin increased bone morphogenic protein (BMP)-2 expression and Smad1/5/8 phosphorylation, which was blocked by the BMP antagonist noggin. Furthermore, melatonin activated p38, extracellular signal-regulated kinase (ERK), and nuclear factor-κB (NF-κB) in hDPSCs. Melatonin-induced hepatic differentiation was attenuated by inhibitors of BMP, p38, ERK, and NF-κB. Compared to treatment of CCl4 -injured mice with either melatonin or hDPSC transplantation alone, the combination of melatonin and hDPSC significantly suppressed liver fibrosis and restored ALT, AST, and ammonia levels. For the first time, this study demonstrates that melatonin promotes hepatic differentiation of hDPSCs by modulating the BMP, p38, ERK, and NF-κB pathway. Combined treatment of grafted hDPSCs and melatonin could be a viable approach for the treatment of liver cirrhosis.

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The aim of the present study was to investigate the effects of a composite nanofibrous matrix made of biopolymer blend polycaprolactone-gelatin (BP) and mesoporous bioactive glass nanoparticles (BGNs) on the odontogenic differentiation of human dental pulp cells (HDPCs). BGN-BP nanomatrices, with BGN content of up to 20 wt%, were produced via electrospinning. The differentiation of the HDPCs was evaluated by using an ALP activity assay, calcified nodule formation, and mRNA expression for markers. Integrin and its underlying signal pathways were assessed via reverse transcriptase-polymerase chain reaction and Western blot analysis. Although cell growth and attachment on the BGN-BP nanomatrix was similar to that on BP, ALP activity, mineralized nodule formation, and mRNA, expressions involving ALP, osteocalcin, osteopontin, dentin sialophosphoprotein, and dentin matrix protein-1 were greater on BGN-BP. BGN-BP upregulated the key adhesion receptors (integrin components α1, α2, α5, and β1) and activated integrin downstream pathways, such as phosphorylated-focal adhesion kinase (p-FAK), and p-paxillin. In addition, BGN-BP activated BMP receptors, BMP-2 mRNA, and p-Smad 1/5/8, and such activation was blocked by the BMP antagonist, noggin. Furthermore, BGN-BP induced phosphorylation of extracellular signal-regulated kinase, protein kinase 38, and c-Jun-N-terminal kinase mitogen-activated protein kinases and activated expression of the transcription factors Runx2 and Osterix in HDPCs. Collectively, the results indicated for the first time that a BGN-BP composite nanomatrix promoted odontogenic differentiation of HDPCs through the integrin, BMP, and mitogen-activated protein kinases signaling pathway. Moreover, the nanomatrix is considered to be promising scaffolds for the culture of HDPCs and dental tissue engineering.

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The aim of this study is to determine the effects of the combination of recombinant human BMP-2 (rh-BMP-2) and dentin sialoprotein (rh-DSP) on growth and differentiation in human cementoblasts and determine the underlying signal transduction mechanism. Compared to treatment of cementoblasts with either rh-BMP-2 or rh-DSP alone, the combination of rh-BMP-2 and rh-DSP synergistically increased cell growth, ALP activity, nodule formation and expression of differentiation markers. The differentiation-promoting effect was also observed in periodontal ligament cells and an osteoblastic cell line. Likewise, combination of rh-DSP and rh-BMP-2 increased BMP-2 mRNA expression and Smad1/5/8 phosphorylation, which was blocked by the BMP antagonist noggin. The expression levels of α2β1 integrin and RhoA, as well as the phosphorylation status of FAK and Akt, were increased by the combination of rh-BMP-2 and rh-DSP in a time-dependent manner. In addition, rh-BMP-2 and rh-DSP enhanced expression of Wnt ligands, β-catenin activation and GSK-3β phosphorylation, all of which were inhibited by the Wnt receptor antagonist DKK1. Furthermore, treatment with rh-DSP plus rh-BMP-2 resulted in phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 and also induced the nuclear translocation of the NF-κB p65 subunit, which was blocked by noggin. This study demonstrates for the first time that rh-DSP and rh-BMP-2 act synergistically, enhancing each other's ability to stimulate cementoblastic cell growth and differentiation in vitro via autocrine BMP, integrin, Wnt/β-catenin, MAP kinase and NF-κB pathways. These results support the therapeutic potential of a combination strategy for aiding periodontal regeneration.