Stem cells in the periodontal ligament

The ability to identify and manipulate stem cells has been a significant advancement in regenerative medicine and has contributed to the development of tissue engineering-based clinical therapies. Difficulties associated with achieving predictable periodontal regeneration, means that novel techniques such as tissue engineering need to be developed in order to regenerate the extensive soft and hard tissue destruction that results from periodontitis. One of the critical requirements for a tissue engineering approach is the delivery of ex vivo expanded progenitor populations or the mobilization of endogenous progenitor cells capable of proliferating and differentiating into the required tissues. By definition, stem cells fulfill these requirements and the recent identification of stem cells within the periodontal ligament represents a significant development in the progress toward predictable periodontal regeneration. In order to explore the importance of stem cells in periodontal wound healing and regeneration, this review will examine contemporary concepts in stem cell biology, the role of periodontal ligament progenitor cells in the regenerative process, recent developments in identifying periodontal stem cells and the clinical implications of these findings.     

Mesenchymal stem cells and their challenges for bone regeneration and osseointegration

Bone regeneration is an indispensable procedure for implant placement. Original techniques based on mesenchymal stromal cell (MSC) therapy are emerging with the goal of speeding up biology, thereby reducing the osseointegration period. Many products found their way in clinical application, yet their reliability remains uncertain because many in vitro culture-related challenges are facing these cells once they are out of their biologic environment. In this commentary, these limitations are discussed with the emphasis of their impact on the performance of MSCs. Clinicians should be aware of these issues before implementing this cell-based regenerative technique.     

Stem cells in craniofacial and dental tissue engineering

Mesenchymal stem cells (MSC) have been identified in a variety of adult tissues as a population of pluripotential self-renewing cells. Based on their adherence and colony forming properties, a small number of MSC can be isolated from most mesenchymal tissues as well as bone marrow. In the presence of one or more growth factors, these cells commit to lineages that lead to the formation of bone, cartilage, muscle, tendon and adipose tissue; recent studies indicate that stem cells for cementum, dentine and the periodontal ligament also exist. All of these cells can be expanded in vitro, and, embedded in a scaffold, inserted into defects to promote healing and tissue replacement. Increased understanding of the molecular mechanism directing lineage specification and morphogenesis is providing a rational approach for the regeneration of craniofacial tissues and oral structures.     

间充质干细胞调控破骨细胞分化及功能的研究进展

间充质干细胞(MSCs)对骨代谢的作用是多方面的。MSCs对破骨细胞和骨吸收的调控是其中一个很重要的方面。MSCs对破骨有双面的调节作用,可能促进或者抑制,取决于炎症环境的情况。在一些生理、病理环境下,MSCs通过分泌相关细胞因子对破骨细胞的形成及功能起正向调控作用。但在某些炎症状态下,MSCs可能也通过旁分泌作用实现对破骨细胞形成和分化的抑制作用,尤其是在体外共培养破骨细胞与MSCs,MSCs对破骨细胞的形成表现出抑制作用。了解MSCs对破骨细胞的调控作用,有助于了解炎症微环境下MSCs对骨丢失的治疗潜能。     

荧光活性染料(CM-Dil)对人骨髓间充质干细胞增殖能力的影响

目的:体外分离、培养人骨髓间充质干细胞(human bone marrow derived mesenchymal stem cells,hBMSCs),探讨应用不同浓度氯甲基苯甲酰氨荧光染料(CM-Dil)对hBMSCs增殖力的影响。方法:采用Ficoll梯密度离心法分离、培养hBMSCs,并促进其分别向成骨细胞、脂肪细胞分化;应用不同浓度CM-Dil分别标记第3代hBMSCs,观察不同浓度标记下细胞的荧光强度、标记效率、活性和增殖能力。结果:采用Ficoll梯密度离心法获得的hBMSCs,成骨、成脂分化染色阳性。不同浓度CM-Dil(5、10、20、30μmol/L)在30 min内均可成功标记hBMSCs,24 h后观察标记效率均达到98%以上(P>0.05)。直到20μmol/L的标记浓度对细胞的活力、增殖能力仍没有影响(P>0.05)。结论:CM-Dil是一种简便、安全的标记骨髓间充质干细胞的方法。     

Stem cells and periodontal regeneration

Periodontitis is an inflammatory disease which manifests clinically as loss of supporting periodontal tissues including periodontal ligament and alveolar bone. For decades periodontists have sought ways to repair the damage which occurs during periodontitis. This has included the use of a range of surgical procedures, the use of a variety of grafting materials and growth factors, and the use of barrier membranes. To date periodontal regeneration is considered to be biologically possible but clinically unpredictable. Recently, reports have begun to emerge demonstrating that populations of adult stem cells reside in the periodontal ligament of humans and other animals. This opens the way for new cell-based therapies for periodontal regeneration. For this to become a reality a thorough understanding of adult human stem cells is needed. This review provides an overview of adult human stem cells and their potential use in periodontal regeneration.     

Use of cultivated osteoprogenitor cells to increase bone formation in segmental mandibular defects: an experimental pilot study in sheep

The hypothesis of the present experimental pilot study was that autogeneous cultivated osteoprogenitor cells in porous calcium phosphate scaffolds can increase bone formation in segmental defects of the mandible. The autogenous osteoprogenitor cells of eight sheep were cultivated from bone biopsies from the iliac crest and seeded into cylindrical scaffolds of pyrolized bovine bone of an overall length of 35 mm and 13 mm in diameter. Segmental defects of 35 mm length were created unilaterally in the mandibles of the animals. Reconstruction was performed using cylinders with cultivated osteoprogenitor cells in four animals and empty scaffolds in the remaining four sheep, which served as controls. After 5 months, the mandibles were retrieved and the reconstructed areas were analyzed by qualitative and quantitative histology in serial undecalcified thick-section specimens. There was significantly more bone formation in the group that had received scaffolds with cultivated bone cells (P=0.028). Bone formation was present in 34.4% of the evaluated cross-sectional units in the seeded scaffolds, while it was found in 10.4% in the control group. Although the spatial distribution of bone formation was significantly different across the scaffold in both groups, osteoprogenitor cells appeared to have increased bone formation, particularly in the centre of the defect when compared to the control group. It is concluded that the repair of segmental defects of the mandible can be enhanced by the transplantation of autogenous osteoprogenitor cells in a porous calcium phosphate scaffold.     

颞下颌关节滑膜间充质干细胞成骨潜能的实验研究

目的　研究滑膜间充质干细胞的成骨潜能。方法　用2 g/L的Ⅰ型胶原酶消化获得滑膜细胞,待细胞汇 合后用有限稀释法进行单细胞克隆,筛选出滑膜间充质干细胞(SMSC)。取第3代SMSC进行成骨诱导培养,每天观 察细胞形态,并于培养7 d后检测ALP活性和骨桥蛋白的表达,RT-PCR检测核心结合因子al(cbfal)mRNA的转录; 培养30 d后作Von Kossa′s染色,检测成骨化程度。结果　SMSC在体外培养形成葵花样细胞集落,胞浆突起明显, 相互连接成网状;成骨化诱导剂可诱导SMSC定向分化为多形性成骨细胞,细胞ALP染色阳性,骨桥蛋白强阳性,电 泳显示有cbfal的特异性条带,矿化区经Von Kossa′s染色呈阳性反应。结论　经体外纯化的SMSC可定向诱导分化 为成骨细胞,符合成骨细胞的生物学特征。     

大鼠骨髓MSCs体外分离培养及多向分化的实验研究

目的：建立骨髓MSCs体外分离培养体系，并进行多向分化诱导，以证实其多向分化潜能，为MSCs进一步的临床应用研究提供实验依据。方法：用密度梯度离心法分离大鼠骨髓MSCs，并对其形态学特征进行观察。用诱导剂对MSCs向成骨细胞、神经元样细胞和成肌细胞进行诱导分化，并进行形态学观察和免疫细胞化学检测。结果：用密度梯度离心法成功分离获得了高纯度的骨髓MSCs，细胞增殖活性强。经骨向诱导后，ALP和矿化结节染色阳性；免疫细胞化学染色提示神经向诱导神经元特异性标志蛋白NSE和NF200，成肌细胞标志蛋白Deamin和Connexin-43阳性表达。结论：采用密度梯度离心法成功建立了大鼠骨髓MSCs体外分离和培养体系；并能够向成骨细胞、神经元样细胞和成肌细胞分化。     

兔骨髓间充质干细胞的体外分离培养、鉴定及向成骨细胞分化诱导

目的:探讨体外分离培养、鉴定兔骨髓间充质干细胞(BMSCs)的方法,并观察其向成骨细胞分化的潜能。方法:采用贴壁分离法分离培养兔BMSCs,通过细胞形态学观察和细胞表面抗原检测对细胞进行鉴定,并向成骨细胞分化诱导培养,通过钙钻法检测碱性磷酸酶表达,茜素红染色观察钙结节形成能力。结果:分离培养3d,可见贴壁细胞呈三角形、成纤维形或多角形外观,培养10～12d细胞长满瓶底,传代后细胞增殖明显加快;使用条件培养基传代培养2周,细胞呈集落生长后开始形成钙结节,茜素红染色阳性。结论:全骨髓贴壁法是一种简单实用的分离培养方法,可获得纯度较高的兔BMSCs,经过诱导后可向成骨细胞分化。     

Stem Cell Marker Expression in Persistent Apical Periodontitis

Introduction

This study evaluated the expression of CD90 (mesenchymal stem cell) and Sox2 (progenitor stem cell) markers in persistent apical periodontitis (PAP) (n = 16) and primary periapical lesions (PPLs) (n = 10).

人牙龈干细胞的分离鉴定及基质细胞衍生因子-1对其趋化效应的研究

目的 研究基质细胞衍生因子-1（SDF-1）受体CXCR4在人牙龈干细胞（GMSCs）上的表达及SDF-1对人GMSCs的趋化效应。方法 通过有限稀释法分离并培养人GMSCs,检测其表面干细胞标志物的表达情况,测试其克隆形成率及多向分化能力,利用免疫荧光染色法检测人GMSCs上SDF-1受体CXCR4的表达,用Transwell细胞培养室检测不同质量浓度SDF-1对人GMSCs的趋化反应,光镜下计数迁移至滤膜下侧面的不同视野的细胞数。结果 人GMSCs具有较高的自我更新能力,在体外呈克隆状生长,表达间充质干细胞表面标志物CD44、CD73、CD90、CD105和CD166,而造血干细胞表面标志物CD14、CD34和CD45的表达为阴性。体外诱导培养的人GMSCs能够向成骨细胞及成脂细胞分化,其克隆形成率为21.4%±2.8%。免疫荧光染色显示,人GMSCs表达SDF-1受体CXCR4。SDF-1的质量浓度为100、200 ng·mL^-1时,Transwell细胞培养室中迁移的细胞数目（每高倍视野分别为189.3±4.4和164.6±4.9）显著多于空白对照组（每高倍视野47.8±2.5）（P<0.01）;使用CXCR4中和抗体处理后,人GMSCs的迁移效应明显受到抑制（每高倍视野降低为29.0±2.4,P<0.01）。结论 人GMSCs表达趋化因子SDF-1受体CXCR4,SDF-1对人GMSCs有趋化效应,这种趋化效应可能是通过其特异性受体CXCR4介导的。     

小鼠颌骨间充质干细胞优化获取及鉴定

目的:摸索优化获取小鼠颌骨间充质干细胞(mesenchymal stem cells,MSCs)的方法。方法 :通过调整小鼠年龄、胶原酶浓度及酶消化时间等,采用骨片培养法从C57BL/6小鼠下颌骨中分离培养MSCs,并进行生物学鉴定。结果:采用3⁴周龄小鼠、0.3%胶原酶消化2 h的方法,分离培养出的细胞增殖能力最强,第3代MSCs即可高表达CD44、CD90及低表达CD34、CD45。各种条件所得MSCs均在成骨诱导后经茜素红染色、成软骨诱导后经甲苯胺蓝染色,结果呈阳性,其成骨、成软骨能力相同。结论:该改良后的骨片培养法可在较短时间内分离出较高纯度的小鼠颌骨间充质干细胞,适用于多种实验研究需要。     

皮肤真皮来源多能干细胞筛选与鉴定

目的:克隆培养SD大鼠皮肤真皮多能干细胞,并对其生物学特性进行检测,以期为组织工程再生牙齿探寻一种可靠的成体干细胞.方法:采用贴壁细胞培养法和有限稀释法培养出生1d的SD仔鼠掌趾部皮肤真皮成纤维细胞,分别检测其克隆形成能力、增殖能力和多向分化能力,并对其进行分子标志分析.结果:培养获得的SD大鼠皮肤真皮成纤维细胞,其中7株单克隆来源的细胞具有较强的克隆形成能力、较高的细胞群体倍增能力;同时,这部分细胞高表达细胞表面分子标志物CD44和CD90;成骨诱导后可形成矿化结节,成脂诱导后可见细胞内出现脂滴.结论:利用贴壁细胞培养法和有限稀释法培养皮肤真皮成纤维细胞,可获得具有类似间充质干细胞的生物学特性的真皮多能干细胞.本实验成功培养并获得了单克隆来源的真皮多能干细胞,为后续实验奠定了基础.