釉基质蛋白衍生物对人牙周膜干细胞分化、增殖的影响

背景：釉基质衍生物已经在临床上用于治疗严重的牙周炎,发现其可促进牙周组织修复、再生,但其中的机制还未阐明。 目的：探讨釉基质衍生物对牙周膜干细胞分化和增殖的作用。 方法：分离培养人牙周膜干细胞,检测其克隆形成率、表面抗原表达情况,鉴定其多向分化潜能。将不同质量浓度的釉基质衍生物(20,50或100 mg/L)作用于牙周膜干细胞培养2,4周,用Trichrome和Von Kosa’s染色法检测牙周膜干细胞胶原合成及矿化结节形成情况,Real time RT-PCR方法检测成骨分化相关基因Ⅰ型胶原、骨钙素、RUX2的表达,MTT法和生长率法检测牙周膜干细胞的增殖情况。 结果与结论：牙周膜干细胞呈梭形,其克隆形成率较牙周膜细胞高,表面抗原CD105,CD29,CD45,CD44的表达率分别为99.8%,99.7%,1.26%,98.8%,具备多向分化潜能。釉基质衍生物呈现一定的时间剂量效应关系促进牙周膜干细胞胶原合成及矿化结节形成,促进成骨分化相关基因Ⅰ型胶原、骨钙素、RUX2的表达,促进牙周膜干细胞的增殖,可能在牙周组织修复、再生中发挥作用。 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

釉基质蛋白及其在牙周组织工程中的运用

釉基质蛋白(Enamel matrix proteins,EMP)是牙胚发育过程中由上皮根鞘分泌的一组蛋白质,具有促进牙周组织再生、生物矿化和骨诱导等生物特性。本文主要将釉基质蛋白对牙周组织工程中的种子细胞的不同作用及其应用前景做一综述。     

干细胞分化来源血管内皮细胞研究进展

种子细胞是细胞治疗和组织工程化组织构建的基础,在缺血性疾病细胞治疗和组织工程血管构建中,内皮细胞的来源一直是亟待解决的问题之一.自体血管壁分离获得的内皮细胞由于数量少、体外培养困难、增殖能力有限.应用受到限制.随着干细胞研究的兴起,干细胞逐渐成为内皮细胞来源的研究焦点.就具有向成熟血管内皮细胞分化潜能的干细胞(内皮祖细胞,造血干细胞,骨髓基质干细胞,脂肪来源基质干细胞,胚胎干细胞)来源、分布、特点、诱导分化、动物实验或临床应用及近期相关研究予以综述,并比较各自的优缺点.为内皮细胞来源的选择提供参考.     

蛋白诱导诱导多能干细胞技术的研究进展

诱导多能干细胞（inducedplufipotentsterncells,iPSC）自2006年出现后被认为是干细胞研究领域的一个突破性进展。首次成功制备iPSC的日本学者将4种重编程蛋白基因Oct3／4、Sox2、Klfd、C—Myc通过反转录病毒载体导入成纤维细胞并在其中表达,进而激活内源性重编程体系,最终导致细胞性质发生改变,成为具有类似胚胎干细胞（embryonicstemcells,ESC）的一种多能干细胞,即iPSCEI。由于其可来源于自体细胞,无需破坏胚胎组织,因而不涉及伦理争议。     

诱导多能干细胞的研究进展

人类组织工程的最终目的 是细胞在体外生长、分化为功能组织和器官以替代、修复、维持或者增强受损组织和器官功能.胚胎干细胞由于具有体外无限扩增的能力以及分化为机体各种类型细胞的潜能而成为组织工程中首选的细胞来源.主要就应用不同转录因子Oct3/4、Sox2、c-myc、Klf4、Nanog和LIN28经逆病毒导入未经遗传修改的成纤维细胞,从而使该类细胞去分化与重编程成具有分化为其它各种类型细胞的多能干细胞的研究进展作一综述.     

骨髓间充质干细胞向雪旺细胞诱导分化方法的研究进展

细胞移植技术治疗周围神经损伤已成为新兴的组织工程学研究热点。骨髓间充质干细胞(BMSCs),由于其具有扩增快、便于分离提纯、可以体外诱导分化成为雪旺细胞(SC)的特性,有可能成为雪旺细胞的有效替代品和组织T程化神经的新型种子细胞。就种子细胞雪旺细胞和骨髓间充质干细胞的生理功能、生物学特性、体外诱导骨髓间充质干细胞生成雪...     

神经干细胞分化影响因素的研究进展

神经干细胞（neural stem ceils，NSCs）在体外诱导条件下，可以分化成神经系统的三种主要细胞：神经元、星形胶质细胞、少突胶质细胞。移植入动物体内它也能分化成神经元和胶质细胞并能迁移到宿主中枢神经系统（CNS）的不同部位，与宿主细胞形成突触联系。其影响因素有外部因素和内在机制两个方面，文章对生长因子、细胞因子、局部微环境等外部因素和bHLH基因转录因子、Notch信号途径、DNA甲基化等内在机制对NSCs分化影响研究进展作一综述。     

2种诱导iPSC向神经干细胞分化方法的比较

目的:整体比较2种促进诱导性多能干细胞(induced pluripotent stem cells,i PSC)向神经干细胞(neural stem cells,NSC)分化的方法,确定一种稳定、高效的获得NSC的方法,并对NSC进行系统鉴定。方法:方法A:SB431542和drosomophorin的浓度均为5μmmol/L,诱导初始密度100%;方法 B:SB431542的浓度为5 mmol/L,drosomophorin的浓度为1 mmol/L,诱导初始密度为40%。比较及鉴定方法:镜下观察诱导获得NSC的状态;realtime PCR比较神经干细胞相关基因Pax6、nestin、Sox1、Sox2等表达量;流式细胞术分析诱导第16天Pax6阳性率;免疫荧光定性分析神经干细胞相关蛋白的表达及其自发分化的能力。结果:方法 A获得的NSC悬起后成球趋势明显,圆形,透明;方法 B诱导获得NSC形状不规则,色灰暗。Real-time PCR结果证明方法 A诱导获得的细胞神经干细胞相关基因的表达量高于方法 B。流式细胞术分析证明第16天,PAX6的阳性率,方法 A高于方法 B。经鉴定,方法 A获得的神经干细胞高表达Pax6、nestin、Sox2等基因自发分化30 d,形成明显的神经纤维束,表达TUJ-1、MAP2及GFAP等神经元和胶质细胞的特异性标志物。结论:方法 A整体优于方法 B,我们推荐方法 A作为诱导i PSC向神经干细胞分化的方法。     

神经干细胞分化调控机制的研究进展

神经干细胞（NSCs）是一类具有自我更新和多方向分化潜能的干细胞,可以分化为神经元,星形胶质细胞和少突胶质细胞。自从1992年Reynolds等从小鼠纹状体中分离到神经干细胞之后,相关的研究已经取得了很大的进展。然而由于中枢神经系统内神经干细胞数量较少,而神经系统损伤后移植的外源的神经干细胞大多分化为神经胶质细胞,进而形成瘢痕组织,限制了神经系统的恢复。因此,如何实现神经干细胞的定向诱导分化成为当前该领域的核心问题。     

神经干细胞分化调控的研究进展

神经干细胞 (NSC)多分化潜能的研究使人们对神经系统发生及中枢神经系统的损伤修复有了深入了解。NSC在体内的分化过程受各种信号分子的作用。干细胞在体内所受到的各类细胞因子的影响 ,最终将在基因水平的调控环节发挥作用。NSC的移植模型证明移植后干细胞保持着多分化潜能 ,且局部微环境信号在诱导分化方面起着重要作用     

The effect of enamel matrix derivative (Emdogain) on bone formation: a systematic review

This systematic review focused on the question, if and to what extent enamel matrix derivative (Emdogain) [EMD]) promotes the regeneration of bone. The influence of combinations with other biomaterials was additionally evaluated. Twenty histomorphometric studies were included in this systematic review. Main results of the reviewed articles were (i) guide tissue regeneration (GTR) of infrabony defects seems to result in a higher degree of bone regeneration compared to treatment with EMD; (ii) combined therapy (GTR + EMD) of infrabony defects might not lead to better results than GTR therapy alone; (iii) there seems to be no additional benefit of combined therapy (GTR + EMD) in furcation defects over GTR therapy alone; (iv) EMD seems to lead to more bone regeneration of infrabony defects compared to open flap debridement; (v) however, EMD application might result in more bone formation when applied in supporting defects compared to nonsupporting defects; and (vi) EMD does not seem to promote external jaw/parietal bone formation in the titanium capsule model. The results of one study that suggest that EMD increases the initial growth of trabecular bone around endosseous implants by new bone induction need to be confirmed by additional research.     

Effect of enamel matrix derivative on mouse fibroblasts and marrow stromal osteoblasts

There is increasing evidence that the cells of the epithelial root sheath synthesize enamel matrix proteins and that these proteins play a fundamental role in cementogenesis and periodontal tissue formation. Emdogain, enamel matrix derivative (EMD), is a porcine enamel matrix derived product used to enhance regeneration of the peridontium after inflammatory destruction. Today, little is known about EMD's potential regenerative properties on cell function. The purpose of this study was to investigate the effects of EMD on mouse fibroblasts (L 929 cells) and rat marrow stromal osteoblasts. For effects on cell proliferation, the L929 cell lines were plated in 24-well culture plates at an initial density of 10,000 cell/mL and allowed to attach. Following a 24-h incubation within Dulbecco's modified eagle medium (DMEM) enriched with 10% fetal bovine serum, DMEM supplemented with 0 (Control), 50 microg/mL and 100 microg/mL of EMD was added and cultures maintained for 96h. Cell proliferation was measured at 24, 48, 72 and 96 h as the total cell number per well and cell morphology was investigated. Osteoblasts were digested from mouse tibia marrow and were plated in similar manner as with L 929 cells, while the observation periods were 2, 6, 8 and 10 days in this group. Although both cell types were able to maintain their original cell morphology throughout the tests, in both cell groups the number of cells in the EMD groups at each observation period were not significantly different than that in the control group (ANOVA, p > 0.05). Moreover, EMD failed to show any impact on cell growth with higher concentration (ANOVA, p > 0.05). These results suggest that although EMD had no cytotoxic effect on mouse fibroblasts and stromal marrow osteoblasts, the same material failed to enhance the growth of both cell types.     

Effects of enamel matrix derivative to titanium implantation in rat femurs

The effects of enamel matrix derivative (EMD; Emdogain) on new trabecular bone induction after pure bioinert titanium (Ti) implantation in the rat femur were examined by means of routine light and transmission electron microscopy, immunohistochemistry, and backscattered electron image analysis. Newly designed mini-Ti implants (3.5 mm in length and 1.6 mm in diameter) were placed in the corticotrabecular area of the femur with either EMD or its carrier, propylene glycol alginate, as control. On post-implantation days 4, 7, 14, and 30, the dissected femur was examined in the transverse direction through Ti implants. In both control and EMD-applied femurs, trabecular bone formation was recognized over the implant surfaces and within medullary cavities even at 4 days post-implantation. These newly formed bone trabeculae around the Ti implants were immunoreactive for bone sialoproteins as a bone matrix marker, and osteoclastic bone resorption became evident in these bone trabeculae after 7 days post-implantation. Although trabecular bone area around the implants was markedly decreased at 30 days post-implantation compared with those at 14 days, the trabecular bone areas in EMD-applied femurs were significantly greater than those in propylene glycol alginate-applied femurs at both 14 and 30 days post-implantation. Our results suggest that EMD is an effective biological matrix for enhancing new trabecular bone induction and resulting attachment of orthopedic prostheses to the recipient bone.     

Beneficial effects of green tea: A literature review

The health benefits of green tea for a wide variety of ailments, including different types of cancer, heart disease, and liver disease, were reported. Many of these beneficial effects of green tea are related to its catechin, particularly (-)-epigallocatechin-3-gallate, content. There is evidence from in vitro and animal studies on the underlying mechanisms of green tea catechins and their biological actions. There are also human studies on using green tea catechins to treat metabolic syndrome, such as obesity, type II diabetes, and cardiovascular risk factors.     

Two new families with enamel renal syndrome: A novel FAM20A gene mutation and review of literature

Enamel renal syndrome (ERS) or so-called amelogenesis imperfecta type IG is a very rare disorder characterized by the triad of amelogenesis imperfecta, gingival enlargement and nephrocalcinosis. It is caused by biallelic mutations in the FAM20A gene. Herein, we report two unrelated patients with ERS. Our patients presented with the characteristic features of the syndrome, and amelogenesis imperfecta and gingival hyperplasia were the main complaint. Strikingly, they both had long face, thick lips, notched upper central incisors, and thick alveolar ridge which have never been reported before in patients with ERS. Gingival biopsy showed psammomatous calcifications, and renal ultrasound revealed bilateral nephrocalcinosis in the two patients. Mutational analysis of the FAM20A gene identified two homozygous mutations including a novel one (c.915_918delCTTT, p.Phe305Leufs*76 and c.1219 + 3_1219+6delAGGT). Our data expand the phenotypic and mutational spectrum of FAM20A gene and reinforce the importance of kidney examination and follow up for all patients with amelogenesis imperfecta unless FAM20A mutations were ruled out.     

Porcine enamel matrix derivative enhances trabecular bone regeneration during wound healing of injured rat femur

To elucidate the effects of enamel matrix derivative (EMD: Emdogain®) on bone regeneration in rat femurs after drill‐hole injury, defects in bone were filled with either EMD or its carrier, PGA, as control. On postoperative days 4 to 28, dissected femurs were examined by means of various morphological approaches. In both experimental groups, formation of trabecular bone, which was immunostained for bone sialoproteins (BSP), had occurred in the medullary cavities at cylindrical bone defects on Day 7 postoperatively. Cuboidal osteoblasts were clearly observed on these newly‐formed BSP‐positive bone trabeculae. On Days 7 and 14, many multinucleated giant cells, which strongly expressed cathepsin K, had appeared on these bone trabeculae, indicating active bone remodeling. In these bone trabeculae, Ca and P weight % and Ca/P ratio were similar to those of cortical bone, and there was no significant difference between the PGA‐ and EMD‐applied groups. Bone volume fraction of newly‐formed bone trabeculae on Day 7 postoperatively was significantly higher in the EMD‐applied group than in the PGA‐applied controls. Because of active bone remodeling and the marked decrease of bone volume, on Days 14 and 28 postoperatively, however, there was no longer a significant difference in trabecular bone volume fraction between the experimental groups. Our results suggest that EMD possesses an osteo‐promotive effect on bone and medullary regeneration during wound healing of injured long bones. Anat Rec 264:438–446, 2001. © 2001 Wiley‐Liss, Inc.     

Porcine enamel matrix derivative enhances trabecular bone regeneration during wound healing of injured rat femur.

To elucidate the effects of enamel matrix derivative (EMD: Emdogain) on bone regeneration in rat femurs after drill-hole injury, defects in bone were filled with either EMD or its carrier, PGA, as control. On postoperative days 4 to 28, dissected femurs were examined by means of various morphological approaches. In both experimental groups, formation of trabecular bone, which was immunostained for bone sialoproteins (BSP), had occurred in the medullary cavities at cylindrical bone defects on Day 7 postoperatively. Cuboidal osteoblasts were clearly observed on these newly-formed BSP-positive bone trabeculae. On Days 7 and 14, many multinucleated giant cells, which strongly expressed cathepsin K, had appeared on these bone trabeculae, indicating active bone remodeling. In these bone trabeculae, Ca and P weight % and Ca/P ratio were similar to those of cortical bone, and there was no significant difference between the PGA- and EMD-applied groups. Bone volume fraction of newly-formed bone trabeculae on Day 7 postoperatively was significantly higher in the EMD-applied group than in the PGA-applied controls. Because of active bone remodeling and the marked decrease of bone volume, on Days 14 and 28 postoperatively, however, there was no longer a significant difference in trabecular bone volume fraction between the experimental groups. Our results suggest that EMD possesses an osteo-promotive effect on bone and medullary regeneration during wound healing of injured long bones.     

The effect of fasting or calorie restriction on autophagy induction: A review of the literature

Autophagy is a lysosomal degradation process and protective housekeeping mechanism to eliminate damaged organelles, long-lived misfolded proteins and invading pathogens. Autophagy functions to recycle building blocks and energy for cellular renovation and homeostasis, allowing cells to adapt to stress. Modulation of autophagy is a potential therapeutic target for a diverse range of diseases, including metabolic conditions, neurodegenerative diseases, cancers and infectious diseases. Traditionally, food deprivation and calorie restriction (CR) have been considered to slow aging and increase longevity. Since autophagy inhibition attenuates the anti-aging effects of CR, it has been proposed that autophagy plays a substantive role in CR-mediated longevity. Among several stress stimuli inducers of autophagy, fasting and CR are the most potent non-genetic autophagy stimulators, and lack the undesirable side effects associated with alternative interventions. Despite the importance of autophagy, the evidence connecting fasting or CR with autophagy promotion has not previously been reviewed. Therefore, our objective was to weigh the evidence relating the effect of CR or fasting on autophagy promotion. We conclude that both fasting and CR have a role in the upregulation of autophagy, the evidence overwhelmingly suggesting that autophagy is induced in a wide variety of tissues and organs in response to food deprivation.     

Degradation of enamel matrix proteins in porcine secretory enamel

To elucidate the progressive disappearance of 25 kDa amelogenin occurring in a narrow space near the surface of enamel, the alkaline soluble fraction which contained 80% of the total proteins was extracted from a newly formed porcine enamel. When this fraction was incubated with the addition of Ca ions in an in vitro system, the degradation of the coexisting amelogenin and enamelin occurred without activation during the incubation period. Although the fraction contained mainly two kinds of metalloproteinases, 56 kDa and 61 kDa gelatinolytic, and 41 kDa and 46 kDa caseinolytic activities, it was demonstrated on amelogenin enzymography that the caseinolytic one was concerned with the conversion of the 25 kDa amelogenin into the 20 kDa amelogenin. The protein distribution of the newly formed enamel indicated that the metalloproteinases degraded the coexisting enamelin and amelogenin imperfectly. Nevertheless, during the next developing stage they demonstrated their full activities. It is suspected that these activities are regulated by Ca ions, which may be increased by a cascade system.