Induced pluripotent stem cells (iPSCs) generated from patient-derived somatic cells provides the opportunity for model development in order to study patient-specific disease states with the potential for drug discovery. However, use of lentivirus and exposure of iPSCs to animal-derived products limit their therapeutic utility and affect lineage differentiation and subsequent downstream functionality of iPSC derivatives. Within the context of this study, we describe a simple and practical protocol enabling the efficient reprogramming of terminally differentiated adult fibroblasts into integration-free human iPSCs (hiPSCs) using a combination of episomal plasmids with small molecules (SMs). Using this approach, there was a 10-fold increase in reprogramming efficiency over single plasmid vector-based methods. We obtained approximately 100 iPSCs colonies from 1 × 105 human adult dermal fibroblasts (HADFs) and achieved approximately 0.1 % reprogramming efficiencies. Concurrently, we developed a highly conducive culture system using xeno-free media and human vitronectin. The resulting hiPSCs were free of DNA integration and had completely lost episomal vectors, maintained long-term self-renewal, featured a normal karyotype, expressed pluripotent stem cell markers, and possessed the capability of differentiating into components of all three germ layers in vivo. Finally, we demonstrate that the integration-free hiPSCs could be differentiated into motor neurons under xeno-free culture conditions. This induction method will promote the derivation of patient-specific integration-free and xeno-free iPSCs and improve the strategy for motor neuron derivation. Our approach provides a useful tool for human disease models, drug screen, and clinical applications.

The original article [1] contains a major error carried across the captions of Tables 1, 2, and 3. In each table caption, the data were expressed as "mean ± standard deviation (SD)"; unfortunately, the authors had mistakenly expressed the data as "mean ± standard error (SE)" instead. As such, all mentions of "mean ± standard error" in those table captions should of course state "mean ± standard deviation". The authors are deeply sorry for these errors.

Stem cells have received a great deal of interest from the research community as potential therapeutic “tools” for a variety of chronic debilitating diseases that lack clinically effective therapies. Stem cells are also of interest for the regeneration of tooth-supporting tissues that have been lost to periodontal disease. Indeed, substantial data have demonstrated that the exogenous administration of stem cells or their derivatives in preclinical animal models of periodontal defects can restore damaged tissues to their original form and function. As we discuss here, however, considerable hurdles must be overcome before these findings can be responsibly translated to novel clinical therapies. Generally, the application of stem cells for periodontal therapy in clinics will not be realized until the best cell(s) to use, the optimal dose, and an effective mode of administration are identified. In particular, we need to better understand the mechanisms of action of stem cells after transplantation in the periodontium and to learn how to preciously control stem cell fates in the pathological environment around a tooth. From a translational perspective, we outline the challenges that may vary across preclinical models for the evaluation of stem cell therapy in situations that require periodontal reconstruction and the safety issues that are related to clinical applications of human stem cells. Although clinical trials that use autologous periodontal ligament stem cells have been approved and have already been initiated, proper consideration of the technical, safety, and regulatory concerns may facilitate, rather than inhibit, the clinical translation of new therapies.

In situ tissue engineering has been proposed as a promising method to address the need for the clinical regeneration of a wide variety of damaged tissues. This approach comprises the use of a cell-free instructive scaffold that incorporates and releases topical chemotactic factors to recruit host endogenous stem/progenitor cells for tissue regrowth at the locus of implantation. However, the clinical translation of this concept is hampered when repeated doses of medication must be administrated over an extended period of time. In this study, we designed a delivery platform characterized by microcapsules containing thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm) gates on their outer pore surfaces for the controlled release of stromal cell-derived factor (SDF)-1α, an important chemokine for stem cell recruitment/homing. Double-phase emulsified condensation polymerization was used to prepare interconnected porous glycidyl methacrylated dextran (Dex-GMA)/gelatin microcapsules, and plasma-graft pore-filling polymerization was used to graft PNIPAAm into the surface pores of the microcapsules. The in vitro results showed that the PNIPAAm-grafted microcapsules featured thermo-responsive drug release properties due to the swollen-shrunken property of PNIPAAm gates in response to temperature changes. After subcutaneous implantation, the thermally responsive microcapsules resulted in a more sustained and long-term SDF-1α release compared with those without PNIPAAm-grafting. In the future, this delivery system may have great potential for use in cell recruiting biomaterials for various tissue engineering and regenerative medicine applications.

Cell sheet engineering is a scaffold-free delivery concept that has been shown to improve mesenchymal stem cell-mediated regeneration of injured or pathologically damaged periodontal tissues in preclinical studies and several clinical trials. However, the best strategy for cell sheet production remains to be identified. The aim of this study was to investigate the biological effects of osthole, a coumarin-like derivative extracted from Chinese herbs, on the cell sheet formation and osteogenic properties of human periodontal ligament stem cells (PDLSCs) and jaw bone marrow mesenchymal stem cells (JBMMSCs). Patient-matched PDLSCs and JBMMSCs were isolated, and an appropriate concentration of osthole for cell culture was screened for both cell types in terms of cell proliferation and alkaline phosphatase (ALP) activity. Next, the best mode of osthole stimulation for inducing the formation of sheets by each cell type was selected by evaluating the amount of their extracellular matrix (ECM) protein production as well as osteogenic-related gene expression. Furthermore, both PDLSC and JBMMSC sheets obtained from each optimized technique were transplanted subcutaneously into nude mice to evaluate their capacity for ectopic bone regeneration. The results revealed that 10(-5) m/L osthole significantly enhanced the proliferation of both PDLSCs and JBMMSCs (P < 0.05), although for JBMMSCs, there was no concentration-related change among the four established osthole groups (P > 0.05). In addition, 10(-5) m/L osthole was the best concentration to promote the ALP activities of both cells (P < 0.01). Based on both the production of ECM proteins (collagen type I, integrin β1, and fibronectin) and the expression of osteogenic genes (ALP, Runt-related transcription factor 2 (RUNX2), and osteocalcin (OCN)), the provision of 10(-5) m/L osthole throughout the entire culture stage (10 days) for PDLSCs or at the early stage (first 3 days) for JBMMSCs was the most effective osthole administration mode for cell sheet formation (P < 0.05). The results of in vivo transplantation showed that osthole-mediated PDLSC and JBMMSC sheets formed more new bone than those obtained without osthole intervention (P < 0.001). Our data suggest that a suitable concentration and mode of osthole stimulation may enhance ECM production and positively affect cell behavior in cell sheet engineering.

Background and Objective In recent years, various laser systems have been introduced into the field of laser-assisted endodontic therapy. The aim of this study was to evaluate the bactericidal effect of Nd:YAG, Er:YAG, Er,Cr:YSGG laser radiation, and antimicrobial photodynamic therapy (aPDT) in experimentally infected root canals compared with standard endodontic treatment of 5.25% sodium hypochlorite (NaClO) irrigation. Materials and Methods Two hundred and twenty infected root canals from extracted human teeth (contaminated with Enterococcus faecalis ATCC 4083 for 4 weeks) were randomly divided into five experimental groups (Nd:YAG, Er:YAG?+?5.25% NaClO?+?0.9% normal saline?+?distilled water (Er:YAG/NaClO/NS/DW), Er:YAG?+?0.9% normal saline?+?distilled water (Er:YAG/NS/DW), Er,Cr:YSGG, and aPDT) and two control groups (5.25% NaClO as positive control and 0.9% normal saline (NS) as negative control). The numbers of bacteria on the surface of root canal walls and at different depths inside dentinal tubules before and after treatment were analyzed by means of one-way analysis of variance (one-way ANOVA). The morphology of bacterial cells before and after treatment was examined by scanning electron microscopy (SEM). Results After treatment, the bacterial reductions in the experimental groups and the positive control group were significantly greater than that of the negative control group (P?<?0.001). However, only Er:YAG/NaClO/NS/DW group showed no bacterial growth (the bacterial reduction reached up to 100%) on the surface of root canal walls or at 100/200?mu m inside the dentinal tubules. Conclusions All the laser radiation protocols tested, especially Er:YAG/NaClO/NS/DW, have effective bactericidal effect in experimentally infected root canals. Er:YAG/NaClO/NS/DW seems to be an ideal protocol for root canal disinfection during endodontic therapy. Lasers Surg. Med. 44: 824831, 2012. (c) 2012 Wiley Periodicals, Inc.

INTRODUCTION:The aim of the study was to test retentive forces of different adhesive systems after cementation of glass-fiber posts with or without prior silanization of the post by using a pullout test and scanning electron microscope (SEM) observation to detect the mode of failure.METHODS:Fifty-six roots were randomly divided into 6 experimental and 2 control groups: ParaCore (PAR), Paracore + silane (PAR-SIL), RelyX Unicem (RXU), RelyX Unicem + silane (RXU-SIL), RelyX ARC (RXA), RelyX ARC + silane (RXA-SIL), negative control (NEG-CON), and positive control (POS-CON). ParaCore posts were placed in the experimental groups (each n = 8) by using an adhesive resin with or without prior silanization. NEG-CON received uncemented posts (n = 4); POS-CON received an active screw post with an adhesive (n = 4). All samples were subjected to a pullout test in a universal mechanical testing machine for pullout tests and SEM to assess the fiber posts and the roots after the tests.RESULTS:Mean failure load values for each ground were PAR 247.4 ± 59.3 N, PAR-SIL 240.5 ± 68.8 N, RXU 102.3 ± 22.8 N, RXU-SIL 106.4 ± 19.8 N, RXA 119.8 ± 27.3 N, RXA-SIL 125.8 ± 28.3 N, NEG-CON 0 ± 0 N, and POS-CON 412.9 ± 27.4 N. There was a statistically significant difference between the 3 experimental adhesive systems (P < .001) and between each experimental group and NEG-CON and POS-CON (P < .05). PAR was significantly different from RXU and RXA (P < .05). No statistically significant differences existed between RXU and RXA and between the use of silanization or not. Representative samples for SEM showed cohesive failure as the principal fracture mode for PAR and mainly adhesive failure for RXU and RXA.CONCLUSIONS:The results indicated that silanization of fiber posts does not make a difference to prevent dislocation of a post. Full-etching systems demonstrated significantly higher retentive forces than self-etching systems.

Periodontitis, an inflammatory disease, is the most common cause of tooth loss in adults. Attempts to regenerate the complex system of tooth-supporting apparatus (i.e., the periodontal ligament, alveolar bone and root cementum) after loss/damage due to periodontitis have made some progress recently and provide a useful experimental model for the evaluation of future regenerative therapies. Concentrated efforts have now moved from the use of guided tissue/bone regeneration technology, a variety of growth factors and various bone grafts/substitutes toward the design and practice of endogenous regenerative technology by recruitment of host cells (cell homing) or stem cell-based therapeutics by transplantation of outside cells to enhance periodontal tissue regeneration and its biomechanical integration. This shift is driven by the general inability of conventional therapies to deliver satisfactory outcomes, particularly in cases where the disease has caused large tissue defects in the periodontium. Cell homing and cell transplantation are both scientifically meritorious approaches that show promise to completely and reliably reconstitute all tissue and connections damaged through periodontal disease, and hence research into both directions should continue. In view of periodontal regeneration by paradigms that unlock the body's innate regenerative potential has been reviewed elsewhere, this paper specifically explores and analyses the stem cell types and cell delivery strategies that have been or have the potential to be used as therapeutics in periodontal regenerative medicine, with particular emphasis placed on the efficacy and safety concerns of current stem cell-based periodontal therapies that may eventually enter into the clinic.

AIM: To study the prevalence of Enterococcus faecalis in the root canals after failure of root canal therapy and the characteristics of the clinical isolated strains.METHODS: Fifty-four clinical samples were collected.Enterococcus faecalis were selectively cultured by SF medium and Enterococcus faecalis agar.The isolated Enterococcus faecalis strains were confirmed by the 16SrRNA sequencing.And the characteristics(such as the growth character,the abilities of biofilm formation and drug resistance) of the isolated strains were tested and compared.The standard strain of the Enterococcus faecalis,E.f 29212,was used as positive control.RESULTS: Fifty-four clinical samples were collected and 18 strains were selected and confirmed as Enterococcus faecalis.The prevalence of Enterococcus faecalis in the root canals after failure of root canal therapy was 33.33%.No significant prevalence difference was found between gender,age,diameter of the lesion around the root apex and the interval after pretreatment.However,the prevalence of Enterococcus faecalis was significantly higher when the root filling was shorter than the working length(P=0.013).But there was no statistical difference among the limited-filled groups.The clinically isolated strain showed no statistical difference with the control strain in growth,biofilm formation and drug resistance.CONCLUSION: The prevalence of Enterococcus faecalis in the root canals after root canal therapy failure was 33.33% and there was corelation between the prevalence and the root filling condition of the pretreatment.It was higher when the root filling was shorter than the working length.There was no statistical difference in growth,biofilm formation and drug resistance between the isolated strains and the control strain.

AIM: To explore the possibility of using Bio-Gide membrane as cell vehicle for periodontal tissue engineering,we evaluated the biological properties of Bio-Gide membrane using human periodontal stem cells(PDLSCs).METHODS: Human PDLSCs were cultured and characterized,and co-cultured with the lixiviated solution of Bio-Gide membrane.Cytotoxicity of the lixiviated solution of Bio-Gide membrane was evaluated by tetrazolium salt-diphenyltetrazolium bromide] assay.Cell attachment and proliferation of human PDLSCs were observed using SEM and fluorescence nuclear staining.RESULTS:No cytotoxicity was found with the lixiviated solution of Bio-Gide membrane,and the rate of cell proliferation of PDLSCs on membrane was 122.66%.The multiplicate growth of PDLSCs on the Bio-Gide membrane was detemined by SEM observations,and a multiple cell sheet on Bio-Gide membrane was formed.The adherence rate of the PDLSCs on the Bio-Gide membrane was 86.7%.CONCLUSION: Bio-Gide membrane shows good cell biological performance and cell compatibility.It has no cytotoxicity on seeding PDLSCs,and supports PDLSCs to form cell membrance,suggesting a potential application of Bio-Gide membrance for cell delivery.

Since calcium phosphates (CaPs) were first proposed, a wide variety of formulations have been developed and continuously optimized, some of which (e.g. calcium phosphate cements, CPCs) have been successfully commercialized for clinical applications. These CaP-based biomaterials have been shown to be very attractive bone substitutes and efficient drug delivery vehicles across diverse biomedical applications. In this article, CaP biomaterials, principally CPCs, are addressed as alternatives/complements to autogenous bone for grafting in implant dentistry and as coating materials for enhancing the osteoinductivity of titanium implants, highlighting their performance benefits simultaneously as carriers for growth factors and as scaffolds for cell proliferation, differentiation and penetration. Different strategies for employing CaP biomaterials in dental implantology aim to ultimately reach the same goal, namely to enhance the osseointegration process for dental implants in the context of immediate loading and to augment the formation of surrounding bone to guarantee long-term success.

目的:对自行研制的医用可吸收粘连材料膨化聚乙烯复合膜的体外生物相容性进行评价。方法:实验于2003-03/2003-08在第二军医大学肝胆外科实验室完成。采用细胞毒性试验、溶血试验和急性全身中毒试验3种方法。结果:①培养的L-929小鼠成纤维细胞经膨化聚乙烯复合膜浸提液处理后形态良好,增值旺盛,膨化聚乙烯复合膜组培养2,4,7dA值分别为0.552±0.044,0.783±0.040,1.198±0.052;阳性对照组分别为0.347±0.025,0.446±0.018,0.565±0.025,二者比较,差异有非常显著性意义（t=26.47～31.12,P＜0.01）。细胞相对增殖率≥100%,材料毒性评级为0级。②溶血率为2.21%（＜5%）,符合溶血试验标准要求。③无急性全身中毒反应。全身急性毒性试验24,48,72h膨化聚乙烯复合膜组动物体质量增加分别为（1.77±0.42）,（2.57±0.39）,（3.30±0.43）g,阳性对照组分别为-2.79±0.23),（-3.83±0.35）,(（-3.89±0.34）g,二者比较,差异有非常显著性意义（t=58.34～87.12,P＜0.01）。结论:膨化聚乙烯复合膜具有良好的生物相容性。

OBJECTIVE To observe the effects of cells and scaffolds tissue engineering on the periodontal regeneration, and to evaluate the feasibility of nano-Hap-collagen (nHAC) as the scaffold material for periodontal tissue engineering. METHODS Dog autogenous periodontal ligament cells (PDLCs) cultured in vitro were collected and seeded on the three-dimensional framework of nHAC. The cell growth in the scaffolds was observed by scanning electron microscope. And then the PDLCs-nHAC composites were transplanted into man-made periodontal defects, and the groups filled with nothing or filled only with nHAC were the controls. The dogs were sacrificed after 8 weeks and the periodontal regeneration was observed histologically. RESULTS Scanning electron microscope showed the porous structure of nHAC and the eugonic growth of cells in the nHAC scaffolds. The histological observation showed that the PDLCs-nHAC groups exhibited more new bone, new periodontal ligament and new cementum occupying the majority of the defects than the control groups, and the epitheliums were not observed. CONCLUSIONS Periodontal regeneration could be enhanced by the cells and scaffolds tissue engineering, and the PDLCs and nHAC could be used as the seed cell and the scaffold material for periodontal tissue engineering.

Objective Three-dimensional cultured model o f human periodontal ligament cells was established to evaluate the feasibility of the two materials as the scaffolds of periodontal tissue engineering.Methods Human periodontal ligament cells cu ltured in vitro were col-lected and seede d on three-dimensio nal framework of cancellous bone matrix(CBM)and nano-HAp /collagen(nHAC)composite.The cell growth in the scaffolds was observed by c ell counting and scanning electr onic microscope.Results Cells adhered and prol iferated on th e three-dimensional scaffolds,and s canning electronic microsco pe show ed the porous structure of the two materials and the eugonic growth of c ells in the scaffolds.Conclusion It is feasible to establish three-di mensiona l cultured model of human periodontal ligament cells by seeding the cells on the scaffolds of CBM or nH AC.And CBM and nHAC are valued to further study as the scaffolds of periodontal tissue engineering.