外泌体在骨重建以及骨质疏松中的研究进展

外泌体作为一种细胞间进行通讯的介质,既可以和靶细胞融合,将其中包裹的物质转移到靶细胞,介导细胞之间的信息交流,还可以修饰靶细胞的表型和功能,因此在临床诊断及治疗中具有重要的应用价值。目前外泌体被认为是细胞间信息交流的重要方式,同时也是疾病诊断的潜在生物标志物。最新研究发现,不同细胞来源的外泌体在骨重建中发挥了重要的调控作用。外泌体可以调控破骨细胞、成骨细胞以及骨髓间充质干细胞的增殖、分化和成熟,从而影响骨吸收和形成;同时外泌体在血管外再生以及组织新生方面可能起到重要作用。另外,外泌体在骨质疏松症的诊断、治疗以及作为疾病进展预后的预测指标方面也有很高的应用前景。本文将主要针对骨来源的外泌体生物学特性及其在骨重建以及骨质疏松中的相关研究进行简要综述。     

乳腺癌外泌体及相关miRNA的研究进展

正乳腺癌是中国女性最常见的肿瘤,同时是癌症致死的主要原因之一~([1])。近数十年,在乳腺癌的发病原因、发病机制的研究和诊断以及治疗方面取得极大进步。其诊断分级、预后的预测以及靶向治疗等方面也有许多新见解。然而,当前乳腺癌的治疗仍受药物毒性、治疗耐受性以及缺乏可靠的早期诊断和预后指标等因素的限制,因此,推动乳腺癌治疗的发展不仅需探索新的肿瘤标志物和治疗靶点,还需进一步挖掘影响其预后的潜在分子机制。     

骨源性外泌体在骨重建中的作用研究进展

骨代谢活动中骨吸收和骨形成在时间和空间上的紧密偶联过程称为骨重建。骨重建是一个非常精密并且程序化的过程,主要是由于骨吸收的破骨作用和骨形成的成骨作用之间在骨表面相继发生并配对调节的一过程,从而在骨损伤的相关部位产生新骨用以替代旧骨。通过这一方式,能够修复或靶向重建骨的微损伤,从而预防骨组织疲劳损伤的累积、保持骨损伤相关部位生物力学的功能及维持体内矿物质平衡。外泌体通常指的是30 nm~100 nm的细胞外囊泡,广泛存在于生物体之中,并能参与细胞间的物质与信息交换,能够调节细胞的增殖与分化,从而控制疾病的发生与发展。以往骨重建调节研究主要集中在骨组织的自分泌、旁分泌等方面,而本文通过整理中外学者对外泌体在骨重建相关细胞的研究报道,旨在简明阐述骨源性外泌体和骨重建之间的关系。     

外泌体治疗股骨头坏死的研究进展

股骨头坏死发病率逐年增高,是一种高致残率的骨科疾病,探索其早期非手术治疗方案是目前面临的巨大挑战。虽然关节置换等日趋成熟的手术技术帮助广大患者提高了功能恢复质量,但是如何治疗早期股骨头坏死、预防疾病进展,从而延缓关节置换的时间仍然困扰着广大学者。近年来,细胞治疗在治疗多种难治性疾病中的潜力被逐渐挖掘,外泌体在组织修复领域发挥了重要的作用。该文综述了当前外泌体在治疗股骨头坏死领域的研究现状和进展,为临床中股骨头坏死的治疗提供新思路和新方法,在股骨头坏死的临床防治领域开辟一条新的道路,实现新的突破,同时对其临床应用的推进具有重要意义。     

外泌体miRNA在骨质疏松中的调控作用及中医药干预研究

外泌体是一种直径为40~160 nm的细胞外囊泡,在细胞间通讯中发挥重要作用。其功能性组分miRNA可通过调控骨形成、骨吸收进程,影响血管生成,调节骨免疫等方式,参与骨质疏松症的发生发展。中医药防治骨质疏松症疗效显著,其作用机制可能与调控相关外泌体miRNA有关。本文就外泌体miRNA在骨重建中的作用及中药通过调节外泌体miRNA作用于骨质疏松症的机制进行综述。     

外泌体在前列腺癌中的研究进展

外泌体是一种富含多种生物活性物质的直径30～100 nm的细胞外囊泡。前列腺癌来源的外泌体调控着肿瘤微环境,介导肿瘤的侵袭转移、免疫逃逸和耐药等过程。随着研究的深入,外泌体在肿瘤的早期诊断、治疗等方面显示出巨大的潜力。本文主要对前列腺癌外泌体的生物学功能以及在前列腺癌诊断和治疗中的应用前景作一综述。     

卵巢功能减退患者卵泡液外泌体miRNA表达谱分析研究

目的利用高通量测序技术筛选卵巢储备功能减退(DOR)与卵巢功能正常卵泡液外泌体中差异表达的miRNAs,探讨其对DOR的发病影响。方法收集DOR患者和卵巢功能正常者(对照组)的卵泡液各15例,各组每5例卵泡液混合为均一样本提取外泌体,共进行3次生物学重复。使用Illumina HiSeq4000测序平台对DOR组和对照组卵泡液外泌体中的miRNAs进行测序分析,使用miRanda和TargetScanS软件、GO以及KEGG数据库对差异显著的miRNAs进行靶基因预测、生物学功能富集以及信号通路预测。结果与对照组相比,DOR卵泡液外泌体有80个显著差异表达的miRNAs,其中31个表达上调(包括hsa-miR-4792、hsa-let-7c-3p和hsa-miR-184等),49个表达下调(包括hsa-miR-136-3p、hsa-miR-296-3p和hsa-miR-337-5p等)(P<0.05);通过miRanda和TargetScanS的算法预测所有差异表达miRNA的靶基因共17159个,经GO和KEGG分析发现,这些靶基因主要富集的生物学功能有电离型谷氨酸受体信号通路、氨基酸转运调节、脂多糖介导信号通路及发育相关的凋亡过程等,主要参与调节的信号通路有趋化因子信号通路、环磷酸腺苷信号通路、肿瘤坏死因子信号通路及丝裂原活化蛋白激酶信号通路等。结论来源于DOR和卵巢功能正常者的卵泡液外泌体的miRNAs表达谱存在显著差异,差异表达的miRNAs可能在DOR的发生中起到重要的调控作用,这些miRNAs可能经过靶基因参与调节多种生物学功能以及信号通路进而影响DOR的病理生理过程。     

巨噬细胞来源外泌体成骨作用研究进展

骨骼完整性受到多种因素影响,其修复和再生是一个复杂过程。现有研究发现,外泌体能够调控骨髓间充质干细胞等成骨过程相关细胞的生物学行为,影响其成骨作用。该文回顾近年来巨噬细胞来源外泌体成骨作用相关研究文献,通过讨论巨噬细胞极化亚型影响、外界因素影响、骨组织工程应用和微RNA调控机制等,分析巨噬细胞外泌体的成骨调控作用,为后续基础研究和临床应用提供参考依据。     

骨组织细胞外泌体对骨代谢作用的研究现状

骨质疏松症是老年人的常见病和多发病,骨组织来源细胞可分泌外泌体,包装和运载多种活性物质,如蛋白质、miRNAs、各种活性因子等,进行细胞间物质交换和信息交流,根据骨组织来源细胞外泌体和内容物的特点,利用其调节骨形成和骨吸收平衡的作用,甚至作为生物或基因治疗的载体,为老年骨质疏松症的防治提供全新的思路。     

miRNA在骨重建中的作用

微小RNA(micro RNA,miRNA)是一类具有组织特异性或发育阶段特异性表达特征的非编码调控小RNA,近年来,miRNA与骨形成和代谢的关系已成为研究热点之一,许多研究发现miRNA在骨代谢中的调控作用巨大。部分miRNA能够调节骨重建过程中的血管生成以及成骨细胞、破骨细胞的分化,通过改变相关miRNA表达水平进而深入研究miRNA在骨重建中的调控作用,同时miRNA可作为早期检测骨代谢疾病的生物标志物。本文通过对已知的miRNA在骨重建中血管生成及成骨细胞、破骨细胞中生物学和骨病理学作用机制的总结,说明其在骨重建过程中的重要作用。基于miRNA在骨重建中的调控作用,并在骨代谢相关疾病的临床实践中开辟新的领域,进而对骨代谢疾病有治疗作用。     

Role of transforming growth factor-beta in bone remodeling

Transforming growth factor-beta (TGF-beta) plays a critical role in bone remodeling. TGF-beta stimulates matrix protein synthesis, has dramatic effects on the bone cells responsible for bone formation and resorption, and is abundant in bone and bone-conditioned media. Multiple sources of TGF-beta have been described. It was initially purified from platelets. Two distinct forms of TGF-beta have been purified from bone. The second form, TGF-beta II, was initially purified from bone but was then identified in platelets and also as the major TGF-beta in the monkey kidney BSC-1 cell line. The two bone-derived factors were called cartilage-inducing Factor A (CIF-A) and cartilage-inducing Factor B (CIF-B), based on their capacity to induce the formation of extracellular matrix proteins, which are characteristic of cartilage. CIF-A is identical to the TGF-beta purified from platelets, which is called TGF-beta I. CIG-B is the same as TGF-beta II, which was sequenced soon after CIF-B was discovered and characterized. There is 70% sequence homology between the two forms. The largest source of TGF-beta in the body is present in bone (200 micrograms/kg tissue), although the most concentrated source is in platelets. TGF-beta has multiple effects on bone cells depending on their phenotype and/or stage of differentiation. Osteoblasts, the cells responsible for formation of new bone and perhaps cellular control of bone remodeling, are directly affected by TGF-beta, which can induce differentiation or proliferation, depending on the osteoblastic cell type examined. TGF-beta inhibits the formation of osteoclast precursors and bone resorption and, in greater concentrations, has inhibitory effects on isolated osteoclasts, the cells responsible for bone resorption. TGF-beta may act as a bone-coupling factor linking bone resorption to bone formation.     

微小RNAs在骨与软骨组织中的调节作用

目的对微小RNAs(microRNAs,miRNAs)在骨与软骨组织中的调控作用和作用机制作一综述。方法广泛查阅近年来有关miRNAs在骨与软骨组织的调控作用及作用机制的文献,进行总结与分析。结果 miRNAs是近年来骨关节疾病研究的热点,越来越多研究显示其在骨与软骨组织形成和代谢过程中,对于细胞分化、细胞基质分泌等方面发挥重要的调控作用,但确切机制尚不清楚。结论 通过对miRNAs在骨与软骨组织中的调控作用及作用机制的研究,可能为了解退行性骨关节疾病开辟新的领域。     

Role of osteopontin in bone remodeling caused by mechanical stress.

Changes in the number and proportion of osteopontin mRNA (Opn) expressing osteocytes and osteoclasts caused by the mechanical stress applied during experimental tooth movement were examined in the present study. Opn expression was detected in the osteocytes on the pressure side at the early stage, and gradually spread to those on the tension side and also to the osteoblasts and bone-lining cells in the alveolar bone. Only 3.3% of the osteocytes located on the pressure side expressed Opn in the interradicular septum of control rats; in contrast, the value was increased to 87.5% at 48 h after the initiation of tooth movement. These results indicate that these cells responded to mechanical stress loaded on the bone with expression of the osteopontin gene. Following the increased expression of Opn in these cells, a 17-fold greater number of osteoclasts compared with the control and numerous resorption pits were observed on the pressure side of the alveolar bone. Injection of arginine-glycine-aspartic acid-serine peptide but not that of arginine-glycine-glutamic acid-serine peptide strongly inhibited the increase in the number of osteoclasts. Furthermore, an in vitro migration assay demonstrated the chemotactic activity of osteopontin (OPN) on the precursor of osteoclasts. Our study strongly suggests that OPN is an important factor triggering bone remodeling caused by mechanical stress.     

Role of prostaglandins in bone resorption in a synchronized remodeling sequence in the rat

The role of prostaglandins (PGs) in physiological remodeling has not yet been defined. The present study was undertaken to determine whether they intervene during the activation phase in a highly reproducible and synchronized model of bone remodeling. Indomethacin was employed to inhibit PG synthesis. This treatment throughout the entire activation period (4 days in this model) inhibited osteoclastic resorption completely. By modifying the treatment procedure, it appeared that PGs were operative mainly between the second and third day of activation. PGs did not seem to act on precursor recruitment, since off-bone osteoclasts (putatively inactive cells) were numerous in the treated groups. PGs might also be involved in osteoclast activity as the mean interface between osteoclasts and bone surface was reduced in the treated groups. However, indomethacin was unable to inhibit the remodeling sequence durably since a 6-day treatment resulted in a high profile of resorption. This suggests that factors other than PGs were responsible for activating resorption.     

Homocysteine mediated decrease in bone blood flow and remodeling: Role of folic acid

Deficiencies in folate lead to increased serum concentrations of homocysteine (Hcy), which is known as hyperhomocysteinemia (HHcy), is associated with bone disorders. Although, Hcy accumulates collagen in bone and contribute to decrease in bone strength. The mechanism of Hcy induced bone loss and remodeling is unclear. Therefore, the present study was aimed to determine the role of folic acid (FA) in genetically HHcy‐associated decrease in bone blood flow and remodeling. Wild type (WT) and cystathionine‐β‐synthase heterozygous (CBS+/?) mice were used in this study and supplemented with or without FA (300 mg/kg, Hcy reducing agent) in drinking water for 6 weeks. The tibial bone blood flow was measured by laser Doppler and ultrasonic flow probe method. The tibial bone density (BD) was assessed by dual energy X‐ray absorptiometry. The bone homogenates were analyzed for oxidative stress, NOX‐4 as oxidative marker and thioredoxin‐1 (Trx‐1) as anti‐oxidant marker, bone remodeling (MMP‐9) and bio‐availability of nitric oxide (eNOS/iNOS/NO) by Western blot method. The results suggested that there was decrease in tibial blood flow in CBS+/? mice. The BD was also reduced in CBS+/? mice. There was an increase in NOX‐4, iNOS, MMP‐9 protein as well as MMP‐9 activity in CBS+/? mice and decrease in Trx‐1, eNOS protein levels, in part by decreasing NO bio‐availability in CBS+/? mice. Interestingly, these effects were ameliorated by FA and suggested that FA supplementation may have therapeutic potential against genetically HHcy induced bone loss. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 1511–1516, 2011     

氧化应激对骨重建的影响

骨形成和骨吸收之间的协调平衡共同维持着骨重建的稳态。由于衰老、雌激素缺乏等因素引起体内氧化体系与抗氧化体系之间的平衡被打破,导致活性氧生成增多,发生氧化应激。近年来的研究发现活性氧所引起的氧化应激反应对骨重建过程中的骨形成和骨吸收均有重要的影响,机体内积累产生的过多活性氧通过对细胞因子、酶活性以及信号通路的调节,干预核内基因的转录表达,最终导致骨髓间充质干细胞、成骨细胞、骨细胞和破骨细胞增殖凋亡或分化功能的异常,使骨重建失衡,形成以骨吸收为主的代谢性骨病,从而引起骨质疏松症。因此,笔者就近年来氧化应激的产生及氧化应激对骨髓间充质干细胞、成骨细胞、骨细胞、破骨细胞的影响,骨质疏松症的抗氧化治疗等方面作一综述,对进一步认识氧化应激在骨重建中的生理病理学机制有着重要意义。     

Cyclic bone remodeling in deer

Biopsy samples of rib, metacarpus, metatarsus and tibia were obtained from deer at five intervals during the annual antler growth cycle. Tissues were examined by either histometric methods or by densitometric measurements followed by mineral analysis using atomic absorption spectrophotometry. Little remodelling occurred in bones during the period of antler quiescence, but during the peak of antler growth in June, internal bone remodelling reached a peak. The highest resorption of 22.99% occurred in ribs with lower levels of 13.10% for metacarpus and 10.37% for metatarsus. At the cessation of antler growth in the fall, remodelling again decreased to the low level found preceeding antler growth. In ribs lowest values of ash weight per unit volume occurred during the middle of antler growth but no cyclic variations were found for these values in metacarpus, metatarsus and tibia. Percentage of calcium, magnesium and phosphorus in bone ash did not vary during the antler growth cycle indicating no change in bone composition during periods of high remodelling.This work was supported by training grant 5-Tl-DEl 30 from the National Institute of Dental Research, National Institutes of Health, Bethesda, Md.