Exosomes derived from human dental pulp stem cells increase flap survival with ischemia-reperfusion injuries.

Aim: To investigate the effect of hDPSC-Exos in flap I/R injury, a condition in which tissue damage increases after blood flow is restored to the flap after ischemia. Materials & methods: HUVECs were used to investigate the influences and mechanisms of hDPSC-Exos on cell proliferation and migration. A rat model was established to verify the role of hDPSC-Exos in flap I/R injuries in vivo. Results: hDPSC-Exos promoted the proliferation, migration and tube formation of HUVECs in a dose-dependent way by activating PI3K/AKT signaling pathway, and improved the survival and microvessel density of the flap and suppressed epithelial cell apoptosis. Conclusion: hDPSC-Exos can enhance flap repair after I/R injury. This process may be mediated by the activation of PI3K/AKT signaling pathway.

Skin flap transplantation is one of the most important methods of repairing refractory wounds and organ reconstruction. I/R injury and insufficiency of neovascularization significantly affect the survival of flaps. Human dental pulp stem cells (hDPSCs) are a type of mesenchymal stem cells (MSCs) present in dental pulp tissue that have attracted increasing attention. They can play a repair role in a variety of ischemic injuries and neovascularization. Exosomes are important paracrine mediators between MSCs and target cells, containing a variety of proteins, mRNA and miRNA. Recent studies have shown that some exosomes derived from MSCs can improve I/R injury, promote angiogenesis and inhibit apoptosis. This study confirmed that hDPSC-Exos could promote the proliferation, migration and tubule formation of vein endothelial cells in a dose-dependent manner. Inhibition of PI3K/AKT signaling pathway can reduce the above promoting effects, suggesting that these processes may depend on the activation of PI3K/AKT signaling pathway. In the rat model, hDPSC-Exos can significantly improve the survival rate and microvessel density of flaps, and inhibit epithelial cell apoptosis.

Different concentrations of C5a affect human dental pulp mesenchymal stem cells differentiation.

BACKGROUND: During the process of deep decay, when decay approaches the pulp, an immune response is triggered inside the pulp, which activates the complement cascade. The effect of complement component 5a (C5a) on the differentiation of dental pulp mesenchymal stem cells (DPSCs) is related to dentin reparation. The aim of the present study was to stimulate DPSCs with different concentrations of C5a and evaluate the differentiation of odontoblasts using dentin sialoprotein (DSP). METHODS: DPSCs were divided into the following six groups: (i) Control; (ii) DPSCs treated with 50 ng/ml C5a; (iii) DPSCs treated with 100 ng/ml C5a; (iv) DPSCs treated with 200 ng/ml C5a; (v) DPSCs treated with 300 ng/ml C5a; and (vi) DPSCs treated with 400 ng/ml C5a. Flow cytometry and multilineage differentiation potential were used to identify DPSCs. Mineralization induction, Real-time PCR and Western blot were conducted to evaluate the differentiation of odontoblast in the 6 groups. RESULT: DPSCs can express mesenchymal stem cell markers, including CD105, CD90, CD73 and, a less common marker, mesenchymal stromal cell antigen-1. In addition, DPSCs can differentiate into adipocytes, neurocytes, chondrocytes and odontoblasts. All six groups formed mineralized nodules after 28 days of culture. Reverse transcription-quantitative PCR and western blotting indicated that the high concentration C5a groups expressed higher DSP levels and promoted DPSC differentiation, whereas the low concentration C5a groups displayed an inhibitory effect. CONCLUSION: In this study, the increasing concentration of C5a, which accompanies the immune process in the dental pulp, has demonstrated an enhancing effect on odontoblast differentiation at higher C5a concentrations in vitro.

The protective function of taurine on pesticide-induced permanent neurodevelopmental toxicity in juvenile rats.

Numerous studies have confirmed that prenatal or early postnatal exposure to pesticides can lead to functional deficits in the developing brain. This study aimed to investigate whether combined exposure to paraquat (PQ) and maneb (MB) during puberty could cause permanent toxic effects in the neural system of rats. In addition, the neuroprotective function of taurine (T) and its possible mechanism were investigated. Rats were administered PQ + MB intragastrically for 12 continuous weeks, while taurine dissolved in water was fed to the rats for 24 continuous weeks. In the behavioral tests, the rats' trajectories became complex, and the reaction latencies and mistake frequencies increased. Significant changes were found in the hippocampal neurons of the PQ + MB groups but not in the taurine treatment groups. PQ + MB stimulated cAMP to reduce the production of protein kinase A (PKA) and inhibited the activation of other elements, such as brain-derived neurotrophic factor (BDNF), cAMP response element binding protein (CREB), phospho-CREB (p-CREB), immediate-early genes (IEGs)Arc, and c-Fos. Importantly, taurine regulated the level of cAMP and the expression of the abovementioned proteins. Together, our findings implied that adolescent exposure to PQ + MB may impact the behavior and cognitive function of rats via the cAMP-PKA-CREB signaling pathway, while taurine may in turn exert neuroprotection by diminishing these impacts.

Loss of Fam20c causes defects in the acinar and duct structure of salivary glands in mice.

Family with sequence similarity 20­member C (FAM20C), a recently characterized Golgi kinase, performs numerous biological functions by phosphorylating more than 100 secreted proteins. However, the role of FAM20C in the salivary glands remains undefined. The present study demonstrated that FAM20C is mainly located in the cytoplasm of duct epithelial cells in the salivary glands. Fam20cf/f; Mmtv­Cre mice were created in which Fam20c was inactivated in the salivary gland cells and observed that the number of ducts and the ductal cross­sectional area increased significantly, while the number of acinar cells was reduced. The granular convoluted tubules (GCTs) exhibited an accumulation of aberrant secretory granules, along with a reduced expression and altered distribution patterns of ß nerve growth factor, α­amylase and bone morphogenetic protein (BMP) 4. This abnormality suggested that the GCT cells were immature and exhibited defects in developmental and secretory functions. In accordance with the morphological alterations and the reduced number of acinar cells, FAM20C deficiency in the salivary glands significantly decreased the salivary flow rate. The Na+, Cl- and K+ concentrations in the saliva were all significantly increased due to dysfunction of the ducts. Furthermore, Fam20c deficiency significantly increased BMP2 and BMP7 expression, decreased BMP4 expression, and attenuated the canonical and noncanonical BMP signaling pathways in the salivary glands. Collectively, the results of the present study demonstrate that FAM20C is a key regulator of acinar and duct structure and duct maturation and provide a novel avenue for investigating novel therapeutic targets for oral diseases including xerostomia.

Aspirin promotes osteogenic differentiation of human dental pulp stem cells.

Human dental pulp stem cells (hDPSCs) possess self­renewal and osteogenic differentiation properties, and have been used for orofacial bone regeneration and periodontal treatment. Aspirin has been demonstrated to enhance the regeneration of bone marrow mesenchymal stem cells (MSCs); however, the impact of aspirin on the osteogenic differentiation of hDPSCs remains unknown. In the present study, hDPSCs were characterized by flow cytometry, while their clonogenic potential and multipotency were assessed using alizarin red, Oil red O and alcian blue staining. The effect of aspirin on hDPSC viability was assessed using Cell Counting Kit­8 assay. Osteogenic capacity was examined by alkaline phosphatase activity, alizarin red staining, reverse transcription­polymerase chain reaction and western blotting. Furthermore, in vivo cranial defects were established in Sprague­Dawley rats to evaluate the effect of aspirin on hDPSC­based bone regeneration. Anorganic bovine bone was used as a bone replacement material and as the carrier for hDPSCs. New bone formation was observed through radiographic and histological analysis. The study demonstrated that hDPSCs expressed MSC markers and possessed multipotency in vitro. Aspirin was non­toxic to hDPSCs at a concentration of ≤100 µg/ml and enhanced the osteogenesis of hDPSCs in vitro. Aspirin significantly increased hDPSC­based bone formation in the rat cranial defect model at 8 or 12 weeks post­implantation (P<0.05). The data suggested that aspirin promotes the osteogenic potential of hDPSCs in vitro and in vivo. Overall, the present study indicated that aspirin improves the bone regeneration capacity of hDPSCs.

Endothelial cells and endothelin­1 promote the odontogenic differentiation of dental pulp stem cells.

It has been established that dental pulp stem cells (DPSCs) serve an important role in the restoration and regeneration of dental tissues. DPSCs are present in blood vessels and also exist in the vessel microenvironment in vivo and have a close association with endothelial cells (ECs). The present study aimed to evaluate the influence of ECs and their secretory product endothelin­1 (ET­1) on the differentiation of DPSCs. In the present study, cells were divided into four groups: i) a DPSC­only control group; ii) a DPSC with ET­1 administration group; iii) a DPSC and human umbilical vein endothelial cell (HUVEC) direct co­culture group; and iv) a DPSC and HUVEC indirect co­culture group using a Transwell system. Reverse transcription­quantitative polymerase chain reaction was used to detect the expression of the odontoblastic differentiation­associated genes, including dentin sialoprotein (DSP) and dentin matrix acidic phosphoprotein 1 (DMP­1) at days 4, 7, 14 and 21. Alizarin Red S staining, immunofluorescence and western blot analyses were also conducted to assess the differentiation of the DPSCs in each group. The highest expression levels of odontoblastic differentiation­associated genes were observed on day 7 and in the two co­culture groups were increased compared with the DPSC­only and DPSC + ET­1 culture groups at all four time points. However, expression levels in the DPSC + ET­1 group were not downregulated as notably as in the co­culture groups on days 14 and 21. The Transwell group exhibited the greatest ability for odontoblastic differentiation compared with the other groups according to staining with Alizarin Red S, immunofluorescence and western blot analysis results. According to the results of the present study, the culture solution with HUVECs affected the differentiation of DPSCs. In addition, ET­1 may promote the odontoblastic differentiation of DPSCs.

Aspirin-induced attenuation of adipogenic differentiation of bone marrow mesenchymal stem cells is accompanied by the disturbed epigenetic modification.

Aspirin has positive effects on bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation. However, researchers did not give much thought to its effect on BMSCs adipogenic differentiation. Here, we analyzed the effect of aspirin on the BMSCs adipogenic differentiation. To detect whether the effect of aspirin on the adipogenic differentiation of BMSCs is associated with the disturbed epigenetic modification, the expression of histone deacetylases (HDACs), activity of HDACs and HAT, global histone H3 acetylation and H3k9 acetylation alterations were investigated. Moreover, to further explore and understand the binding mode between aspirin and HDACs, an attempt was made to identify the interaction between aspirin and the HDACs with the aid of in silico docking study. The results showed that aspirin could induce inhibition of BMSCs adipogenesis. The level of HDAC activity, global histone H3 acetylation, and H3k9 acetylation were all down regulated during adipogenic differentiation, and aspirin can reverse these decreases. Furthermore, the HDAC isoforms have different expression patterns in those progresses. The expression of HDAC9 was increased in a does-dependent manner when aspirin was introduced during BMSCs adipogenic differentiation. Docking study showed that high affinity of HDAC9 to aspirin was existed, suggesting that HDAC9 may has an important role in the process of aspirin-induced suppression of adipogenesis. Further studies are needed to define the intricate mechanisms of the HDAC isoforms, and all of these enable us to understand aspirin and its efficacy of inhibition of adipogenic differentiation and pave the way to aspirin clinical using for the tissue regenerating.

Osteoblasts can induce dental pulp stem cells to undergo osteogenic differentiation.

Recent studies have shown that, in numerous species, systemically administered bone marrow-derived mesenchymal stem cells undergo site-specific differentiation. This suggests that osteoblasts, by means of cytokine secretion, may promote dental pulp stem cells (DPSCs) to undergo osteogenesis. The objective of this study was to assess the potential synergistic interaction effect of osteoblasts on DPSCs for promotion of osteogenesis. Stem cells, derived from dental pulp of healthy human donors, were co-cultured with calvaria osteoblasts using a culture insert system. The proliferation rate, calcium deposition, osteogenic-related gene expression of induced DPSCs, including Runx-2, bone sialoprotein, osteocalcin and collagen-1, were assayed using MTT, Alizarin Red S staining and reverse transcriptase polymerase chain reaction, respectively. Co-cultured DPSCs had the highest rate of proliferation compared with those cultured in absence of osteoblasts. The morphology and ultrastructure of DPSCs in the co-cultures showed improvement, with co-cultured DPSCs becoming more osteoblast-like as compared with DPSCs cultured alone, and the mineralization potential of co-cultured DPSCs was enhanced compared with DPSCs cultured alone. Furthermore, osteogenic-related genes were significantly over-expressed in co-cultured DPSCs after osteogenic induction. The results demonstrate that DPSCs successfully differentiate towards osteoblasts and that the paracrine interaction of osteoblasts is likely to contribute to DPSC differentiation. It is believed that this study demonstrates certain useful applications for DPSCs in bone tissue engineering.

Modulation of the differentiation of dental pulp stem cells by different concentrations of ß-glycerophosphate.

Dentinogenesis is a necessary prerequisite for dental tissue engineering. One of the steps for dentinogenesis is to obtain large quantities of highly purified odontoblasts. Therefore, we have undertaken an experiment applying different concentrations of ß-glycerophosphate (ß-GP) to induce the differentiation of dental pulp stem cells (DPSCs) in a long-term 28-day culture. In the meanwhile, we have studied the time- and maturation-dependent expression of matrix extracellular phosphoglycoprotein (MEPE) and that of the odontoblast-like marker-dentin sialoprotein (DSP), in order to investigate an optimized mineralized condition. Western blot results revealed that the expression of DSP became lower when accompanied by the increase of the ß-GP concentration, and there was also an influence on MEPE expression when different concentrations of ß-GP were applied. Meanwhile, the mineralized groups had an inhibitory function on the expression of MEPE as compared with the control group. Above all, all experimental groups successfully generated mineralized nodules by Alizarin Red S and the 5 mM ß-GP group formed more mineralized nodules quantitated using the CPC extraction method. In conclusion, there is a significant modulation of the ß-GP during the differentiation of the DPSCs. The degree of odontoblast differentiation is ß-glycerophosphate concentration dependent. A low concentration of ß-GP (5 mM) has been shown to be the optimal concentration for stimulating the maturation of the DPSCs. Moreover, MEPE accompanied with DSP clearly demonstrates the degree of the differentiation.