Effect of leptin on differentiation of human dental stem cells

The potential bone regeneration effects of leptin- and osteolectin-coated 3D-printed PCL scaffolds: anin vivostudy

This study investigated the effectiveness of bone regeneration upon the application of leptin and osteolectin to a three-dimensional (3D) printed poly(ϵ-caprolactone) (PCL) scaffold. A fused deposition modeling 3D bioprinter was used to fabricate scaffolds with a diameter of 4.5 mm, a height of 0.5 mm, and a pore size of 420-520 nm using PCL (molecular weight: 43 000). After amination of the scaffold surface for leptin and osteolectin adhesion, the experimental groups were divided into the PCL scaffold (control), the aminated PCL (PCL/Amine) scaffold, the leptin-coated PCL (PCL/Leptin) scaffold, and the osteolectin-coated PCL (PCL/Osteo) scaffold. Next, the water-soluble tetrazolium salt-1 (WST-1) assay was used to assess cell viability. All groups exhibited cell viability rates of >100%. Female 7-week-old Sprague-Dawley rats were used forin vivoexperiments. Calvarial defects were introduced on the rats' skulls using a 5.5 mm trephine bur. The rats were divided into the PCL (control), PCL/Leptin, and PCL/Osteo scaffold groups. The scaffolds were then inserted into the calvarial defect areas, and the rats were sacrificed after 8-weeks to analyze the defect area. Micro-CT analysis indicated that the leptin- and osteolectin-coated scaffolds exhibited significantly higher bone regeneration. Histological analysis revealed new bone and blood vessels in the calvarial defect area. These findings indicate that the 3D-printed PCL scaffold allows for patient-customized fabrication as well as the easy application of proteins like leptin and osteolectin. Moreover, leptin and osteolectin did not show cytotoxicity and exhibited higher bone regeneration potential than the existing scaffold.

Association between Molecular Mechanisms and Tooth Eruption in Children with Obesity

Different works have reported earlier permanent teething in obese/overweight children compared to control ones. In contrast, others have reported a delayed permanent teething in undernutrition/underweight children compared to control one. It has been reported that becoming overweight or suffering from obesity can increase gingival pro-inflammatory drive and can affect orthodontic treatment (among other complications). In this sense, little is known about the molecular mechanisms affecting dental eruption timing. Leptin and adiponectin are adipocytokines signaling molecules released in overweight and underweight conditions, respectively. These adipocytokines can modulate osteocyte, odontoblast, and cementoblast activity, even regulating dental lamina initiation. The present review focuses on the molecular approach wherein leptin and adiponectin act as modulators of Runt-related transcription factor 2 (Runx 2) gene regulating dental eruption timing.

Leptin in Dental Pulp and Periapical Tissues: A Narrative Review

Leptin is a non-glycosylated 16 kDa protein synthesized mainly in adipose cells. The main function of leptin is to regulate energy homeostasis and weight control in a central manner. There is increasing evidence that leptin also has systemic effects, acting as a link between innate and acquired immune responses. The expression of leptin and its receptor in human dental pulp and periradicular tissues have already been described, as well as several stimulatory effects of leptin protein expression in dental and periodontal tissues. The aim of this paper was to review and to compile the reported scientific literature on the role and effects of leptin in the dental pulp and periapical tissues. Twelve articles accomplished the inclusion criteria, and a comprehensive narrative review was carried out. Review of the available scientific literature concluded that leptin has the following effects on pulpal and periapical physiology: 1) Stimulates odontogenic differentiation of dental pulp stem cells (DPSCs), 2) Increases the expression of dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1), odontoblastic proteins involved in odontoblastic differentiation and dentin mineralization, 3) Stimulates vascular endothelial growth factor (VEGF) expression in human dental pulp tissue and primary cultured cells of human dental pulp (hDPCs), 4) Stimulates angiogenesis in rat dental pulp cells, and 5) Induces the expression of interleucinas 6 and 8 in human periodontal ligament cells (hPDLCs). There is evidence which suggests that leptin is implicated in the dentin mineralization process and in pulpal and periapical inflammatory and reparative responses.

Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles

BACKGROUND

Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications.

HIGHLIGHTS

The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation.

CONCLUSION

Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.

Whitlockite-Enabled Hydrogel for Craniofacial Bone Regeneration

Growth-factor-free bone regeneration remains a challenge in craniofacial engineering. Here, we engineered an osteogenic niche composed of a commercially modified alginate hydrogel and whitlockite microparticles (WHMPs), which impart tunable physicochemical properties that can direct osteogenesis of human gingival mesenchymal stem cells (GMSCs). Our in vitro studies demonstrate that WHMPs induce osteogenesis of GMSCs more effectively than previously demonstrated hydroxyapatite microparticles (HApMPs). Alginate-WHMP hydrogels showed higher elasticity without any adverse effects on the viability of the encapsulated GMSCs. Moreover, the alginate-WHMP hydrogels upregulate the mitogen-activated protein kinase (MAPK) pathway, which in turn orchestrates several osteogenic markers, such as RUNX2 and OCN, in the encapsulated GMSCs. Concurrent coculture studies with human osteoclasts demonstrate that GMSCs encapsulated in alginate-WHMP hydrogels downregulate osteoclastic activity, potentially due to release of Mg2+ ions from the WHMPs along with secretion of osteoprotegerin from the GMSCs. In vivo studies demonstrated that the GMSCs encapsulated in our osteogenic niche were able to promote bone repair in calvarial defects in murine models. Altogether, our results confirmed the development of a promising treatment modality for craniofacial bone regeneration based on an injectable growth-factor-free hydrogel delivery system.

Leptin-Induced Angiogenesis of EA.Hy926 Endothelial Cells via the Akt and Wnt Signaling Pathways In Vitro and In Vivo

Angiogenesis involves the activation of endothelial cells followed by capillary formation. Leptin, the protein product of the ob gene, can induce the angiogenic potential of endothelial cells. However, the underlying cellular mechanism still remains to be elicited. We firstly evaluated the in vitro effects of leptin on proliferation and angiogenic differentiation of endothelial cell line EA.hy926. Leptin was found to potently induced cell proliferation, expression of angiogenic gene, migration and tube formation. Then we investigated the roles of the Akt and Wnt signaling pathways in the aforementioned processes. It showed that Akt and Wnt signaling pathways could be activated by leptin, while inhibition of the Akt and Wnt signaling pathways by siRNAs effectively blocked the leptin-induced angiogenesis. Finally, we used electrospinning to fabricated leptin-immobilized linear poly(L-lactide-co-caprolactone) (PLCL)-leptin. The in vivo vessel formation of PLCL-leptin was evaluated using subcutaneous implants in Sprague-Dawley rats. The histological and immunofluorescence revealed that cell infiltration with PLCL-leptin was much more significant than that with the control PLCL group. More importantly, the number of laminin⁺ vessels and CD31⁺ cells in PLCL-leptin grafts was significantly higher than in control grafts. The study demonstrated that it is via Akt and Wnt signaling pathways that leptin promotes the proliferation and angiogenic differentiation of endothelial cells and the capacity of endogenous tissue regeneration makes the novel leptin-conjugated PLCL promising materials for grafts.

Ferritin expression in the periodontal tissues of primates

Ferritin, an iron-binding protein, is composed of two subunits, ferritin heavy chain and ferritin light chain. It regulates many biological functions, such as proliferation, angiogenesis, and immunosuppression. The objective of this study was to determine the expression and distribution of ferritin in the periodontal tissues of primates. First, we assessed the expression of ferritin in primary cultured cells isolated from human periodontal tissues using the polymerase chain reaction and immunofluorescent staining in vitro. Second, we investigated the expression and distribution of ferritin in the periodontal tissues of Macaca fascicularis, human gingival tissues, and human gingival carcinoma tissues using immunohistochemistry in vivo. Both protein and mRNA of ferritin were constitutively present in human primary cultured cells, including those from the dental apical papilla, periodontal ligament, dental pulp, and gingival epithelium, as well as gingival fibroblasts. In M. fascicularis tissues, the immunohistochemical staining was particularly strong in blood vessel and mineralizing areas of the dental pulp and periodontal ligament. Ferritin heavy chain exhibited specific immunopositivity in the stratum basal of the epithelium in human gingival tissue, and strong immunostaining was found in peripheral regions of gingival carcinoma sites. Ferritin is constitutively present and widely distributed in the periodontal tissues of primates. Ferritin may play roles in epithelial proliferation, vascular angiogenesis, and mineralization in these tissues.

Do Third Molars Contribute to Systemic Inflammation? Results From a Population-Based Study From Northeast Germany

PURPOSE

Erupted and impacted third molars have been reported to contribute to systemic inflammation. This study investigated the systemic effect of third molars on serum levels of inflammatory parameters and on inflammatory messenger peptide hormones in a general population sample.

MATERIALS AND METHODS

Data of 2,151 participants from the Study of Health in Pomerania were included in this study. Erupted or impacted third molars were assessed with whole-body magnetic resonance imaging at 1.5 T and associated with biomarkers of inflammation, lipid metabolism, glucose metabolism, and peptide hormones by linear regression. Models were adjusted for age, gender, smoking status, education, and type 2 diabetes mellitus.

RESULTS

Neither erupted nor impacted third molars were associated with high-sensitivity C-reactive protein, white blood cell count, or fibrinogen as markers for systemic inflammation. Participants with erupted third molars had markedly lower serum levels of leptin (β coefficient, -2.47; 95% confidence interval [CI], -4.47 to -0.48), angiopoietin-2 (β coefficient, -135.1; 95% CI, 248.6 to -21.5), and ratio of angiopoietin-2 to tyrosine kinase with immunoglobulin-like loop epidermal growth factor homology domain 2 (β coefficient, -6.57; 95% CI, -13.06 to -00.7) than participants without third molars. No such associations were observed for impacted third molars.

CONCLUSION

The present results did not substantiate a relation between third molars and an increase in systemic inflammatory markers. Therefore, dental practitioners should be careful when considering this as the only indication for removal of third molars, especially in medically compromised patients. The results of this study showed that participants with erupted third molars had lower levels of messenger peptide hormones, such as leptin and angiopoetin-2.

An lncRNA‑miRNA‑mRNA ceRNA network for adipocyte differentiation from human adipose‑derived stem cells

Human adipose tissue‑derived stromal stem cells (HASCs) represent a promising regenerative resource for breast reconstruction and augmentation. However, the mechanisms involved in inducing its adipogenic differentiation remain to be fully elucidated. The present study aimed to comprehensively investigate the expression changes in mRNAs, microRNAs (miRNAs) and long non‑coding (lnc)RNAs during the adipogenic differentiation of HASCs, and screen crucial lncRNA‑miRNA‑mRNA interaction axes using microarray datasets GSE57593, GSE25715 and GSE61302 collected from the Gene Expression Omnibus database. Following pretreatment, differentially expressed genes (DEGs), miRNAs (DE‑miRNAs) or lncRNAs (DE‑lncRNAs) between undifferentiated and differentiated HASCs were identified using the Linear Models for Microarray data method. A protein‑protein interaction (PPI) network was constructed for the DEGs based on protein databases, followed by module analysis. The 'lncRNA‑miRNA‑mRNA' competing endogenous RNA (ceRNA) network was constructed based on the interactions between miRNAs and mRNAs, lncRNAs and miRNAs predicted by the miRWalk and lnCeDB databases. The underlying functions of mRNAs were predicted using the clusterProfiler package. In the present study, 905 DEGs, 36 DE‑miRNAs and 577 DE‑lncRNAs were screened between undifferentiated HASCs and differentiated adipocyte cells. PPI network analysis demonstrated that LEP may be a hub gene, which was also enriched in significant module 5. LEP was predicted to be involved in the Janus kinase‑signal transducer and activator of transcription signaling pathway, and the regulation of inflammatory response. The upregulation of LEP was regulated by downregulated hsa‑miRNA (miR)‑130b‑5p and hsa‑miR‑23a‑5p (or hsa‑miR‑302d‑3p). These miRNAs also respectively interacted with RP11‑552F3.9 (or RP11‑15A1.7), ultimately forming the ceRNA axes. In conclusion, the present study revealed that the RP11‑552F3.9 (RP11‑15A1.7)‑hsa‑miR‑130b‑5p/hsa‑miR‑23a‑5p (hsa‑miR‑302d‑3p)‑LEP interaction axes may be crucial for inducing the adipogenic differentiation of HASCs via involvement in inflammation.

Leptin stimulates DMP-1 and DSPP expression in human dental pulp via MAPK 1/3 and PI3K signaling pathways

INTRODUCTION

To investigate the physiological function of leptin in human dental pulp, and to determine the specific pathways implicated in its effect.

METHODS

Twenty-seven dental pulp samples were obtained from human third molars. Pulp samples were treated with or without human recombinant leptin. Leptin functional effect was analyzed in terms of regulation of the synthesis levels of DSPP and DMP-1, determined by immunoblot.

RESULTS

Leptin stimulated DMP-1 and DSPP synthesis in all human dental pulp specimens. The stimulatory effect of leptin on DMP-1 and DSPP synthesis was partially prevented by blocking mitogen-activated protein kinase (MAPK 1/3) and phosphatidylinositol 3 kinase (PI3K) pathways, respectively.

CONCLUSIONS

The present study demonstrates the functional effect of leptin in human dental pulp stimulating the expression of DMP-1 and DSPP, both proteins implicated in dentinogenesis. Leptin stimulates DSPP expression via PI3K pathway and DMP-1 synthesis via MAPK 1/3 pathway. These results support the role of leptin in pulpal reparative response, opening a new research line that could have translational application to the clinic in vital pulp therapy procedures.

Leptin Induces Odontogenic Differentiation and Angiogenesis in Human Dental Pulp Cells via Activation of the Mitogen-activated Protein Kinase Signaling Pathway

INTRODUCTION

Up-regulation of odontogenic differentiation, dentin formation, and angiogenesis in dental pulp are key factors in vital pulp therapy. The aim of this study was to investigate whether leptin could promote odontogenic differentiation and angiogenesis in human dental pulp cells (hDPCs). In addition, the involvement of the intracellular signaling pathway in these effects was determined.

METHODS

The viability of hDPCs treated with leptin was examined using the water soluble tetrazolium salt-1 assay. Real-time polymerase chain reaction was performed to determine messenger RNA (mRNA) expression levels of odontogenic and angiogenic markers. Western blot analysis was used to measure odontogenic and angiogenic protein expression levels and assess mitogen-activated protein kinase (MAPK) pathway involvement. Alkaline phosphatase (ALP) and alizarin red staining were used to evaluate expression levels of ALP and calcified nodule formation after treatment with leptin and/or the presence of MAPK inhibitors.

RESULTS

All concentrations of leptin used in this study did not significantly affect the viability of hDPCs. However, mRNA and protein levels of odontogenic and angiogenic markers, ALP activity, and calcified nodule formation were significantly increased in the leptin-treated group compared with those in the control group. Leptin enhanced phosphorylation of extracellular signal-related kinases, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinases within 5 minutes after treatment. However, leptin-induced dentin sialophosphoprotein and vascular endothelial growth factor protein expression and mineralization were appreciably blocked by the presence of MAPK inhibitors.

CONCLUSIONS

Leptin can induce angiogenesis, odontogenic differentiation, and mineralization in hDPCs via activating the MAPK signaling pathway.

Leptin Overexpression in Bone Marrow Stromal Cells Promotes Periodontal Regeneration in a Rat Model of Osteoporosis

BACKGROUND

Osteoporosis is associated with widespread periodontitis and impaired periodontal healing. However, there is a lack of information about the outcomes of regenerative approaches under the influence of osteoporosis. This study investigates the effect of leptin (LEP) overexpression on the regenerative potential of bone marrow stromal cells (BMSCs) in an osteoporotic rat periodontal fenestration defect model.

METHODS

Rat BMSCs were transfected with adenoviruses harboring the human (h)LEP gene. Cell proliferation and osteogenic differentiation were evaluated. A β-tricalcium phosphate scaffold seeded with transfected cells was implanted into nude mice to investigate ectopic osteogenesis and into an osteoporotic rat defect to study periodontal regeneration. Regenerated periodontal and bone-like tissues were analyzed by histologic methods.

RESULTS

hLEP overexpression induced osteogenic differentiation of BMSCs as evidenced by the upregulation of osteogenesis-related genes such as Runt-related transcription factor 2, alkaline phosphatase (ALP), and collagen Type I, as well as increased ALP activity and enhanced mineralization. Mice implanted with hLEP-BMSC-containing scaffolds showed more extensive formation of bone-like tissue than those in other groups. Periodontal defects were also filled to a greater degree when treated with hLEP-BMSCs and contained cementum and a well-organized periodontal ligament after 10 and 28 days.

CONCLUSION

hLEP overexpression in BMSCs can stimulate periodontal regeneration in osteoporotic conditions and might be a promising strategy for periodontal regeneration in patients with osteoporosis.

alproic Acid Modulates the Multipotency in Periodontal Ligament Stem Cells via p53-Mediated Cell Cycle

Human periodontal ligament stem cells (PDLSCs), a type of mesenchymal stem cell, are a promising source for dental regeneration and are identified in human periodontal ligaments from extracted third molars. Valproic acid (VPA) is a histone deacetylase inhibitor that has been used as a wide-spectrum antiepileptic drug and a medication for mood disorders. VPA has shown several effects on increasing the pluripotency of embryonic stem cells and controlling osteogenic differentiation, besides the prevention of seizures. However, its effect on proliferation and osteogenesis depends on the cell type and concentration. The aim of this study was to investigate the effects of cyclic and constant VPA treatment on PDLSCs. Proliferation and apoptosis of PDLSCs were determined with cyclic and constant VPA treatment. In cemento/osteogenic differentiation, osteogenic markers decreased significantly after cyclic treatment with 0.5 mM VPA. In contrast, VPA enhanced osteogenic differentiation after constant treatment. With cyclic VPA treatment, p53 levels related to apoptotic pathway decreased to induce proliferation. These findings indicated that VPA has different roles in proliferation and differentiation of PDLSCs in vitro and in vivo via p53-related pathway.

Role of leptin as a link between metabolism and the immune system

Leptin is an adipocyte-derived hormone not only with an important role in the central control of energy metabolism, but also with many pleiotropic effects in different physiological systems. One of these peripheral functions of leptin is a regulatory role in the interplay between energy metabolism and the immune system, being a cornerstone of the new field of immunometabolism. Leptin receptor is expressed throughout the immune system and the regulatory effects of leptin include cells from both the innate and adaptive immune system. Leptin is one of the adipokines responsible for the inflammatory state found in obesity that predisposes not only to type 2 diabetes, metabolic syndrome and cardiovascular disease, but also to autoimmune and allergic diseases. Leptin is an important mediator of the immunosuppressive state in undernutrition status. Placenta is the second source of leptin and it may play a role in the immunomodulation during pregnancy. Finally, recent work has pointed to the participation of leptin and leptin receptor in the pathophysiology of inflammation in oral biology. Therefore, leptin and leptin receptor should be considered for investigation as a marker of inflammation and immune activation in the frontier of innate-adaptive system, and as possible targets for intervention in the immunometabolic mediated pathophysiology.

Increased osteogenesis in osteoporotic bone marrow stromal cells by overexpression of leptin

Osteoporosis leads to increased bone fractures and net bone loss, in part because of the dysfunction of bone marrow stromal cells (BMSCs). Leptin is an adipokine that plays important roles in many biological processes, including the regulation of the actions of mesenchymal stem cells. Our aim is to investigate the osteogenic effects of leptin in osteoporotic BMSCs in vitro and in vivo. The leptin gene was transferred into BMSCs isolated from osteoporotic rats by using recombinant adenoviruses. Once the gene and protein expression of leptin had been confirmed, MTT assays were performed; leptin overexpression was confirmed not to affect the viability of osteoporotic BMSCs. However, alkaline phosphatase (ALP) activity measurements, Alizarin red staining and analyses by quantitative real-time reverse transcription with the polymerase chain reaction revealed that leptin upregulated ALP activity, mineral deposition and the mRNA levels of runt-related transcription factor 2, ALP and collagen type І. Lastly, the effects of leptin on osteogenic differentiation were assessed in vivo. Cells transfected with leptin exhibited increased osteogenic differentiation and enhanced formation of bone-like structures. This study thus reveals, for the first time, that the overexpression of leptin in osteoporotic BMSCs (1) enhances their capacity to differentiate into osteoblasts and to form bone-like tissue and (2) might be a useful skeletal regenerative therapy in osteoporotic patients.

Leptin promotes dentin sialophosphoprotein expression in human dental pulp

INTRODUCTION

Leptin, an inflammation-related adipokine, and its receptor (LEPR) are expressed in human dental pulp. Dentin sialophosphoprotein (DSPP) is involved in dentinogenesis and the dental pulp reparative response. The cell type expressing LEPR in dental human pulp and the resultant effect of the binding of leptin to LEPR remain unknown. This study describes the immmunohistochemical localization of LEPR and the effect of leptin on DSPP expression in human dental pulp.

METHODS

Twenty-five dental pulp specimens were obtained from freshly extracted caries-free and restoration-free human third molars. LEPR localization was examined by immunohistochemistry using the antihuman LEPR monoclonal antibody. The effect of leptin on DSPP expression was determined by immunoblot analysis and quantitative real-time polymerase chain reaction.

RESULTS

Immunoreactivity for LEPR concentrated in the odontoblast layer but was not evident in the central zone of the dental pulp. Leptin dose dependently stimulated DSPP expression. Western blot analysis revealed the presence of a protein with an apparent molecular weight of ∼00 kDa, the estimated molecular weight of DSPP. The expression of DSPP messenger RNA was confirmed by quantitative real-time polymerase chain reaction, and the size of the amplified fragments (298 bp) was confirmed by agarose gel electrophoresis.

CONCLUSIONS

The present study shows that human dental pulp is immunoreactive for LEPR, with the immunoreactivity concentrated in the odontoblast layer, and that leptin stimulates, in a dose-dependent manner, DSPP protein and messenger RNA (mRNA) expression in human dental pulp. These findings further support the functional role of leptin in the dentin mineralization process and/or in dental pulp reparative and immune responses.

Neurogenic differentiation of human dental stem cells in vitro

Objectives

The purpose of this study was to investigate the neurogenic differentiation of human dental pulp stem cells (DPSCs), periodontal ligament stem cells (PDLSCs), and stem cells from apical papilla (SCAP).

Materials and Methods

After induction of neurogenic differentiation using commercial differentiation medium, expression levels of neural markers, microtubule-associated protein 2 (MAP2), class III β-tubulin, and glial fibrillary acidic protein (GFAP) were identified using reverse transcriptase polymerase chain reaction (PCR), real-time PCR, and immunocytochemistry.

Results

The induced cells showed neuron-like morphologies, similar to axons, dendrites, and perikaryons, which are composed of neurons in DPSCs, PDLSCs, and SCAP. The mRNA levels of neuronal markers tended to increase in differentiated cells. The expression of MAP2 and β-tubulin III also increased at the protein level in differentiation groups, even though GFAP was not detected via immunocytochemistry.

Conclusion

Human dental stem cells including DPSCs, PDLSCs, and SCAP may have neurogenic differentiation capability in vitro. The presented data support the use of human dental stem cells as a possible alternative source of stem cells for therapeutic utility in the treatment of neurological diseases.

Temporal profiling of the growth and multi-lineage potentiality of adipose tissue-derived mesenchymal stem cells cell-sheets

Cell-sheet tissue engineering retains the benefits of an intact extracellular matrix (ECM) and can be used to produce scaffold-free constructs. Adipose tissue-derived stem cells (ASCs) are multipotent and more easily obtainable than the commonly used bone marrow-derived stem cells (BMSCs). Although BMSC cell sheets have been previously reported to display multipotentiality, a detailed study of the development and multilineage potential of ASC cell sheets (ASC-CSs) is non-existent in the literature. The aims of this study were to temporally profile: (a) the effect of hyperconfluent culture duration on ASC-CSs development; and (b) the multipotentiality of ASC-CSs by differentiation into the osteogenic, adipogenic and chondrogenic lineages. Rabbit ASCs were first isolated and cultured until confluence (day 0). The confluent cells were then cultured in ascorbic acid-supplemented medium for 3 weeks to study cell metabolic activity, cell sheet thickness and early differentiation gene expressions at weekly time points. ASC-CSs and ASCs were then differentiated into the three lineages, using established protocols, and assessed by RT-PCR and histology at multiple time points. ASC-CSs remained healthy up to 3 weeks of hyperconfluent culture. One week-old cell sheets displayed upregulation of early differentiation gene markers (Runx2 and Sox9); however, subsequent differentiation results indicated that they did not necessarily translate to an improved phenotype. ASCs within the preformed cell sheet groups did not differentiate as efficiently as the non-hyperconfluent ASCs, which were directly differentiated. Although ASCs within the cell sheets retained their differentiation capacity and remained viable under prolonged hyperconfluent conditions, future applications of ASC-CSs in tissue engineering should be considered with care. Copyright © 2016 John Wiley & Sons, Ltd.

Modulation of osteoblastic/odontoblastic differentiation of adult mesenchymal stem cells through gene introduction: a brief review

Bone tissue engineering is one of the important therapeutic approaches to the regeneration of bones in the entire field of regeneration medicine. Mesenchymal stem cells (MSCs) are actively discussed as material for bone tissue engineering due to their ability to differentiate into autologous bone. MSCs are able to differentiate into different lineages: osteo/odontogenic, adipogenic, and neurogenic. The tissue of origin for MSCs defines them as bone marrow-derived stem cells, adipose tissue-derived stem cells, and, among many others, dental stem cells. According to the tissue of origin, DSCs are further stratified into dental pulp stem cells, periodontal ligament stem cells, stem cells from apical papilla, stem cells from human exfoliated deciduous teeth, dental follicle precursor cells, and dental papilla cells. There are numerous in vitro/in vivo reports suggesting successful mineralization potential or osteo/odontogenic ability of MSCs. Still, there is further need for the optimization of MSCs-based tissue engineering methods, and the introduction of genes related to osteo/odontogenic differentiation into MSCs might aid in the process. In this review, articles that reported enhanced osteo/odontogenic differentiation with gene introduction into MSCs will be discussed to provide a background for successful bone tissue engineering using MSCs with artificially introduced genes.

Novel adipokines and bone metabolism

Osteoporosis is a serious social issue nowadays. Both the high morbidity and its common complication osteoporotic fracture load a heavy burden on the whole society. The adipose tissue is the biggest endocrinology organ that has a different function on the bone. The adipocytes are differentiated from the same cell lineage with osteoblast, and they can secrete multiple adipokines with various functions on bone remolding. Recently, several novel adipokines have been identified and investigated thoroughly. In this paper, we would like to highlight the complicated relation between the bone metabolism and the novel adipokines, and it may provide us with a new target for prediction and treatment of osteoporosis.