Effects of Lipopolysaccharide on the Proliferation and Osteogenic Differentiation of Stem Cells from the Apical Papilla

Introduction

Stem cells from the apical papilla (SCAPs) were suggested as the stem cell source in regenerative endodontic procedures. However, bone and/or cementum-like structure were observed in root canals. Lipopolysaccharide (LPS) in infected root canals might alter SCAPs' osteogenic differentiation pattern. The objectives of this study were to investigate the effects of LPS on SCAPs' proliferation and osteogenic differentiation.

壳聚糖-磷酸三钙复合材料的动物相容性评价

目的:通过壳聚糖、磷酸三钙的复合制备一种具有较好生物相容性和生物可降解性的组织工程支架材料。方法:采用冷冻干燥法将2种材料复合成具有较高孔隙率的复合材料,对此材料进行动物实验以评价其生物安全性。结果:壳聚糖/磷酸三钙与肌肉组织可以形成紧密的结合,降解较快。结论:壳聚糖/磷酸三钙复合材料在生物学评价实验中符合评价标准,可用作组织工程支架的基质材料。     

Comparison of the remineralization potential of CPP-ACP and CPP-ACP with 900 ppm fluoride on eroded human enamel: An in situ study

Objective

The aim of this in situ study was to compare the remineralization potential of pastes containing CPP-ACP and CPP-ACP with 900 ppm fluoride on human enamel softened by a cola drink.

Design

Forty-five enamel specimens obtained from human third molar teeth were eroded in a cola drink for 8 min and then attached to intra-oral devices worn by five volunteers. The specimens were subjected to three different in situ remineralization protocols using: (1) CPP-ACP (Group I), (2) CPP-ACP with 900 ppm fluoride (Group II), and (3) saliva (Group III, control). Vickers microhardness measurements were obtained at baseline followed by demineralization and remineralization stages.

Results

The CPP-ACP, CPP-ACP with 900 ppm fluoride and saliva controls resulted in 46.24%, 64.25% and 2.98% increase in post-erosion microhardness values, respectively. One-way ANOVA revealed statistically significant differences in the mean microhardness values between pastes containing CPP-ACP and CPP-ACP with 900 ppm fluoride.

Conclusions

Both CPP-ACP and CPP-ACP with 900 ppm fluoride substantially remineralized the softened enamel, with the CPP-ACP and fluoride combination showing higher remineralization potential than CPP-ACP. This study confirmed the synergistic effect of fluoride with CPP-ACP on remineralization of eroded enamel.     

新型骨替代材料硫酸钙／磷酸钙的生物相容性研究

目的：通过两种不同比例骨替代材料硫酸钙，磷酸钙的生物相容性实验，为寻找一种更为合理的新型骨替代材料提供依据。方法：对两种不同比例复合的材料进行体外溶血实验、急性毒性实验和热原实验。结果：硫酸钙含量为20％和40％的复合材料硫酸钙，磷酸钙浸提液对健康兔血红细胞溶血率分别为2．66％和4．73％，均小于溶血标准的5％，可认为无溶血现象。两种材料浸提液注入小鼠未引起急性毒性反应及热原反应。结论：两种不同比例的硫酸钙，磷酸钙新型骨替代材料的生物相容性，均符合国际及国内相关规定的体内植入生物材料标准。     

双膦酸盐对大鼠颌面骨及外周骨不同来源骨髓间充质干细胞成骨分化的影响

目的 :研究临床常用第三代双膦酸盐——唑来膦酸,对大鼠颌面骨及外周骨两种来源的骨髓间充质干细胞(BMSCs)增殖及成骨分化的影响。方法:从新生SD大鼠中分离和培养颌骨或髂骨来源的BMSCs,观察不同浓度唑来膦酸对2种来源BMSCs的影响。观察较高浓度的唑来膦酸对这2种细胞碱性磷酸酶活性、骨钙素分泌的影响。结果:髂骨来源的BMSCs在唑来膦酸浓度≥2.0μg/m L时增殖受到抑制,浓度≤1.0μg/m L时增殖不受影响。而颌骨来源的BMSCs,当唑来膦酸浓度≥0.5μg/m L时细胞增殖就已受到明显的抑制。较高浓度的唑来膦酸(1.0μg/m L)可抑制颌骨BMSCs碱性磷酸酶的活性以及骨钙素形成;但此浓度,对于髂骨BMSCs碱性磷酸酶活性、骨钙素的形成并没有明显的影响。结论:双膦酸盐对不同来源的BMSCs增殖和成骨分化的影响有差异,可为探索双膦酸盐相关颌骨坏死的发病机制提供理论基础。     

Biocompatibility and Osteogenic Potential of New Generation Endodontic Materials Established by Using Primary Osteoblasts

Introduction

Generex A and Generex B (calcium silicate based), Capasio (calcium-phospho-alumino silicate based) along with Ceramicrete-D (magnesium phosphate based) are being introduced as a new generation of endodontic materials with the potential to facilitate bone healing. The aim of this study was to evaluate the biocompatibility and osteogenic potential of these new materials by using primary osteoblasts.

Methods

Primary osteoblasts were prepared from rat calvaria and exposed to mineral trioxide aggregate (MTA), Generex A, Generex B, Capasio, and Ceramicrete-D prepared to standardized size and shape (n = 5). Trypan blue staining was used to evaluate cell viability from 1-6 days. Mineralization potential was evaluated by scanning electron microscopy for the presence of mineralized nodules. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests.

Results

Only Generex A and MTA allowed cell growth and proliferation throughout the experiment. There were statistically significant differences between groups throughout the experiment beginning on day 1. The greatest amount of cell growth was consistently observed with Generex A and MTA. There was no difference in mineralized nodule formation between any test materials.

Conclusions

Generex A was the only new generation endodontic material that supported primary osteoblast growth; no material besides MTA facilitated nodule formation.     

Biocompatibility of New Calcium Aluminate Cement: Tissue Reaction and Expression of Inflammatory Mediators and Cytokines

Introduction

The aim of this study was to evaluate the biocompatibility of a new calcium aluminate cement (EndoBinder) in subcutaneous tissue of rats in comparison with mineral trioxide aggregate and calcium hydroxide hard-setting cement.

Methods

Polyethylene tubes (1.5 × 10 mm) containing the dental cements were implanted into dorsal subcutaneous tissue of 30 rats. After experimental periods of 7, 30, and 90 days, biopsies were performed for tissue response analysis under optical light microscope. The mRNA extraction was performed for molecular evaluation of the inflammatory process in the peri-implant tissue, which was submitted to quantitative real-time polymerase chain reaction analysis for inflammatory mediators and cytokines TNF-α, Ptges2, Il-1β, Il-4, and Il-10.

Results

On the basis of the score used to grade the tissue reaction (0–3), EndoBinder (0) presented no inflammatory reaction after the 90-day period, a similar result to mineral trioxide aggregate and calcium hydroxide. The thickness of inflammatory capsules (μm) also presented significant decrease during the course of periods (P < .05). As regards expression of inflammatory mediators, Ptges2 and Il-10 were detected only at 7 and 30 days, with no statistically significant difference among the experimental groups (P > .05).

Conclusions

EndoBinder induced limited inflammatory reaction. It was considered biocompatible when tested in subcutaneous tissue of rats.     

Antimicrobial Activity and Biocompatibility of Antibiotic-Loaded Chitosan Hydrogels as a Potential Scaffold in Regenerative Endodontic Treatment

IntroductionThe objective of this study was to determine the effectiveness of several antibiotic-loaded hydrogel scaffolds against Enterococcus faecalis, as well as their ability to stimulate proliferation and mineralization of dental pulp stem cells.MethodsFibrin (Fg) or chitosan-fibrin hydrogels (Ch) were prepared using 12.5 mg/mL fibrinogen and 0.4% (w/v) chitosan. Triple antibiotics, clindamycin-modified triple antibiotic paste, or double antibiotics were loaded in gels (1 mg/mL). Antibacterial effect against E. faecalis biofilm was determined by using colony-forming units (CFUs) and confocal laser scanning microscope (CLSM). Cell viability and morphology were determined by loading cells into different gels at 7 and 14 days using the water-soluble tetrazolium salt-1 cell viability assay and Live & Dead cell analysis. Mineralization was detected by using alkaline phosphatase and alizarin red staining activity.ResultsAntibiotic-loaded Fg gel and Ch gel alone without antibiotics resulted in a significant reduction in CFUs compared with the positive control (P < .05). When antibiotics were loaded in Ch gel, there were no CFUs detected in any groups (P < .05). CLSM images showed dense red areas with mostly dead bacteria on the dentin surface in antibiotic-loaded Ch groups, which showed significantly less live bacteria compared with the other groups (P < .05). Triple antibiotic-loaded Fg and Ch gels resulted in a dramatic decrease in the mineralized nodule formation compared with all other gel groups (P < .05). Ch hydrogels resulted in round cell morphology up to 7 days. Ch alone or with double antibiotic paste showed more cell spreading with spindle-shaped morphology at 14 days and higher alkaline phosphatase activity compared with other antibiotic-loaded Ch groups (P > .05).ConclusionsDouble antibiotic-loaded Ch gel appears to enhance the antibacterial properties while maintaining higher cell viability, cell spreading, and mineralization activity, compared with all the other scaffolds investigated.     

磷酸三钙与珊瑚羟磷灰石细胞相容性的实验研究

目的　探讨磷酸三钙 (TCP)、珊瑚羟磷灰石 (CHA)与骨髓基质细胞的生物相容性 ,为用组织工程方法修复牙周组织缺损提供依据。方法　将骨髓基质细胞分别与TCP、CHA复合体外培养 ,进行形态学观察、细胞增殖、矿化能力测定。结果　骨髓基质细胞能在TCP、CHA上贴附、生长 ,其增殖功能不受影响 ,矿化能力亦无明显变化。结论　TCP、CHA具有良好的生物相容性 ,可作为骨髓基质细胞的载体应用于牙周组织工程研究。     

新型多孔纳米双相磷酸钙陶瓷支架体外细胞相容性的实验研究

目的　评价新型多孔纳米双相磷酸钙陶瓷支架材料的体外细胞相容性。方法　SD大鼠骨髓基质细胞 (BMSCs)经矿化诱导培养、扩增并检测证实其已具成骨细胞表型后,分别与多孔纳米双相磷酸钙陶瓷支架(实验组)、普通多孔羟基磷灰石陶瓷支架(对照组)体外复合培养。扫描电镜观察BMSCs在材料上的生长及生理功能表达情况;测定细胞碱性磷酸酶活性及骨钙素的含量;流式细胞仪检测细胞的凋亡及周期、倍体,比较细胞的粘附能力、增殖活力及成骨活性。结果　BMSCs经体外诱导形成钙结节,Ⅰ型胶原和碱性磷酸酶免疫染色结果阳性。两组材料上皆有细胞附着生长,但实验组细胞的粘附能力、增殖活力及成骨活性均强于对照组。结论　SD大鼠BM- SCs与新型多孔纳米双相磷酸钙陶瓷支架材料有良好的细胞相容性。     

丝素蛋白-壳聚糖三维多孔支架材料生物相容性及促成骨性能研究

目的研究丝素蛋白-壳聚糖支架材料的生物相容性及成骨性能,为其在骨组织工程方面的应用提供理论挂础。方法采用冷冻干燥合并化学交联的方法制备出2组支架材料,实验组采用丝素蛋白-壳聚糖支架（质量比为2：3）,对照组采用壳聚糖支架。将MG-63成骨细胞接种于这2组支架上,通过Hoechst荧光染色观察其在支架材料上的生长,计算细胞粘附率和增殖率,最后通过矿化结节的形成以及MG-63成骨细胞分泌碱性磷酸酶能力来研究支架的成骨性能。以载玻片培养MG-63细胞为空白对照组。结果细胞培养1、3d时,对照组细胞粘附率分别为（26．63±0．57）％、（49．88±0．78）％,实验组细胞粘附率分别为（31．88±0．94）％、（62．13±0．36）％,实验组的细胞粘附率高于对照组,差异有统计学意义（P〈0．05）。细胞培养3d时,对照组和实验组细胞增确率检测的光镪度值分别为0．491±0．010、0．5964±0．008,实验组的细胞增殖率高于对照组,差异有统计学意义（P〈0．05）。实验组碱性磷酸酶活性和矿化结节的生长状况也均优于对照组。结论丝素蛋白-壳聚糖支架（质艟比为2：3）具有良好的生物相容性和优良的促成骨性能,对于骨组织工程研究有良好的应用前景。     

兔骨髓干细胞和脂肪干细胞体外成骨能力的比较

目的:评价两种不同来源的间充质干细胞,即骨髓干细胞(BMSC)和脂肪干细胞(ADSC)的体外成骨能力,为其将来应用于细胞治疗和组织工程研究提供一定的理论依据。方法:分别取同一只兔的髂骨骨髓和腹股沟脂肪作为BMSC和ADSC的来源,分离培养后比较成骨、成脂分化潜能,细胞表面抗原标记物;成骨诱导后检测碱性磷酸酶(ALP)活性,RT-PCR分析其成骨相关基因的表达情况。结果:BMSC和ADSC都具有向成骨、成脂分化的潜能;在成骨诱导分化后,BMSC有较高的ALP活性和较多的钙结节形成。RT-PCR结果显示:BMSC表达较高的BMP-2、OCN和OPN等成骨基因。结论:BMSC和ADSC都具有向成骨、成脂分化的潜能,ADSC有较好的成脂分化能力,BMSC有较好的成骨分化能力;两者都可以作为组织工程的种子细胞。     

Biocompatibility of dental materials used in contemporary endodontic therapy: a review. Part 1. Intracanal drugs and substances

Irrigation solutions and intracanal medicaments are used within the root canal to clean and aid in disinfecting the dentinal walls. Although these materials are intended to be contained within the root canal, they invariably contact the periapical tissues, either through inadvertent extrusion through the apex or leaching. This paper is a review on the methodology involved in biocompatibility testing followed by a discussion on biocompatibility of contemporary intracanal drugs and substances used in endodontics.