CD24基因调控根尖牙乳头干细胞的成骨分化功能

目的 研究干细胞表面标记CD24基因对根尖牙乳头干细胞成骨分化能力的影响。方法 利用CD24 shRNA基因敲除CD24进行丧失性功能研究;实时定量RT-PCR检测CD24的基因敲除效果;通过ALP活性检测、茜素红染色及钙离子定量分析明确根尖牙乳头干细胞体外成骨分化能力的变化;实时荧光定量RT-PCR检测成骨分化相关基因-I型胶原蛋白1A、I型胶原蛋白1B、骨涎蛋白、骨桥蛋白和成骨相关转录因子RUNX2的表达分析研究根尖牙乳头干细胞基因表达改变。结果 实时定量RT-PCR结果显示CD24可以在根尖牙乳头干细胞有效的被敲除;碱性磷酸酶活性结果显示敲除CD24抑制根尖牙乳头干细胞碱性磷酸酶活性;茜素红染色及钙离子定量分析结果显示敲除CD24明显抑制根尖牙乳头干细胞体外矿化能力;实时定量RT-PCR结果显示敲除CD24明显抑制I型胶原蛋白A、型胶原蛋白B、骨涎蛋白、骨桥蛋白和RUNX2的表达。结论 基因沉默CD24可以通过抑制转录因子RUNX2及成骨分化基因的表达,从而抑制根尖牙乳头干细胞体外成骨分化功能。     

HOXC6同型蛋白2对根尖牙乳头干细胞成骨/成牙分化功能的影响

目的 探讨同源盒基因C6同型蛋白2对牙源性间充质细胞成骨/成牙分化的影响.方法 成骨诱导培养基诱导人根尖牙乳头干细胞体外成骨/成牙分化;逆转录病毒转染构建过表达HOXC6-ISO2稳定转染牙乳头干细胞进行HOXC6-ISO2获得性功能研究;碱性磷酸酶活性实验检测成骨/成牙早期分化指标-碱性磷酸酶活性;茜素红染色及钙离子定量分析检测干细胞体外矿化能力;实时荧光定量反转录PCR检测成骨/成牙分化相关基因-Sp7转录因子、Runt相关转录因子2和骨钙素及同源盒基因C6下游基因胰岛素结合蛋白5的表达.结果 结果显示过表达同源盒基因C6同型蛋白2明显抑制牙乳头干细胞的碱性磷酸酶活性;茜素红染色及钙离子定量分析结果显示过表达同源盒基因C6同型蛋白2明显抑制牙乳头干细胞体外矿化能力;实时荧光定量反转录PCR显示过表达同源盒基因C6同型蛋白明显抑制骨钙素的表达,并且抑制下游基因胰岛素结合蛋白5的表达.结论 同源盒基因C6同型蛋白2通过抑制下游基因胰岛素结合蛋白5抑制牙乳头干细胞体外成骨/成牙分化的功能.     

BMP4对牙源性干细胞精氨酸组蛋白甲基化酶表达影响的研究

目的 探索人重组骨形成蛋白4(BMP4)对牙源性干细胞精氨酸组蛋白甲基化酶表达的影响.方法 利用BMP4对根尖牙乳头干细胞和牙周膜干细胞进行诱导,Real-time PCR检测精氨酸组蛋白甲基化酶基因家族的主要相关基因PMRT1～9的表达变化.结果 Real-time PCR结果显示50 ng/ml BMP4促进根尖牙乳头干细胞精氨酸组蛋白甲基化酶基因家族中的PRMT2、PRMT4、PRMT5、PRMT6、PRMT7和PRMT9的表达,而在牙周膜干细胞50 ng/ml BMP4只促进PRMT6的表达.结论 BMP4促进根尖牙乳头干细胞和牙周膜干细胞部分精氨酸组蛋白甲基化酶的表达,可能在牙源性干细胞成骨分化中起一定的作用.     

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.

组蛋白去甲基化酶KDM4B促进根尖牙乳头干细胞中成骨和成牙本质分化

目的 研究组蛋白去甲基化酶KDM4B对根尖牙乳头干细胞定向分化能力的影响.方法 人重组骨形成蛋白4(BMP4)刺激根尖牙乳头干细胞后检测KDM4B的表达;利用慢病毒转染过表达或者基因敲除KDM4B进行获得性或丧失性功能研究.通过检测碱性磷酸酶(ALP)活性、茜素红染色、钙离子定量分析研究根尖牙乳头干细胞体外成骨和成牙本质分化能力.结果 BMP4促进根尖牙乳头干细胞KDM4B的表达.基因敲除KDM4B抑制根尖牙乳头干细胞ALP活性及体外矿化能力、促进转录因子PPAR-gamma的表达.过表达KDM4B增强根尖牙乳头干细胞ALP活性和体外矿化能力.结论 组蛋白去甲基化酶KDM4B具有促进根尖牙乳头干细胞成骨和成牙本质分化的潜能.     

The Clinical Potential of Senolytic Drugs

Senolytic drugs are agents that selectively induce apoptosis of senescent cells. These cells accumulate in many tissues with aging and at sites of pathology in multiple chronic diseases. In studies in animals, targeting senescent cells using genetic or pharmacological approaches delays, prevents, or alleviates multiple age‐related phenotypes, chronic diseases, geriatric syndromes, and loss of physiological resilience. Among the chronic conditions successfully treated by depleting senescent cells in preclinical studies are frailty, cardiac dysfunction, vascular hyporeactivity and calcification, diabetes mellitus, liver steatosis, osteoporosis, vertebral disk degeneration, pulmonary fibrosis, and radiation‐induced damage. Senolytic agents are being tested in proof‐of‐concept clinical trials. To do so, new clinical trial paradigms for testing senolytics and other agents that target fundamental aging mechanisms are being developed, because use of long‐term endpoints such as lifespan or healthspan is not feasible. These strategies include testing effects on multimorbidity, accelerated aging‐like conditions, diseases with localized accumulation of senescent cells, potentially fatal diseases associated with senescent cell accumulation, age‐related loss of physiological resilience, and frailty. If senolytics or other interventions that target fundamental aging processes prove to be effective and safe in clinical trials, they could transform geriatric medicine by enabling prevention or treatment of multiple diseases and functional deficits in parallel, instead of one at a time.     

Exposure to a continuous low dose of tetrachlorodibenzo-p-dioxin impairs the development of the tooth root in lactational rats and alters the function of apical papilla-derived stem cells

Objectives

Ubiquitous environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) cause abnormalities in reproduction and development. TCDD inhibits the development of teeth, and its effects depend on its dose and the developmental stage of the tooth. Our aim here was to investigate the effect of lower doses of TCDD on the development of the tooth root in vivo and in vitro.

Design

We observed tooth root development in lactational rats exposed to continuous low doses of TCDD starting on postnatal day 6 using Mico-CT analyses and histopathological examinations. And then the characteristics of stem cells derived from the apical papilla (SCAPs) were evaluated and compared with SCAPs induced by lower doses of TCDD both in vitro and in vivo.

Results

The results of experiments showed that rat pups exposed to low dose TCDD at prenatal stage developed, dentine hypoplasia, and hypomineralization. Further, TCDD impaired the functions of SCAPs in vivo by inhibiting cell proliferation and osteogenic and odontogenic differentiation. The impairment of SCAPs after TCDD exposure was accompanied by increased expression of AHR, down-regulation of the expression of Runx2, and alkaline phosphatase, suggesting that the AHR pathway mediated the effects of TCDD.

Conclusion

These results provide the first insights into the toxicity of TCDD, which adversely affects the development of the tooth root through indirectly altering the function of SCAPs.