人骨髓间质干细胞中的端粒调控机制

目的：〖HT5"SS〗研究人骨髓来源间充质干细胞(MSCs)端粒长度的调控机制。方法：以贴壁培养法从人骨髓中分离MSCs并用MSCs及造血干细胞相关表面抗体作表型鉴定,用Southern blotting检测MSCs的端粒长度;应用免疫荧光染色技术检测端粒重复序列结合因子1（TRF1）和早幼粒细胞白血病蛋白小体（PML）的定位;以端粒重复序列扩增法（TRAP）和/或Western blotting法检测传代及分化成脂肪细胞的MSCs和经同步化处理被阻断在S期的MSCs的端粒酶表达。结果：与端粒酶阴性ALT细胞株WI-38-2RA细胞相比,MSCs的端粒长度较短并且端粒长度变异度不大;端粒调控相关蛋白TRF1和PML在MSCs中的定位则与端粒酶阳性细胞HeLa细胞相同,两者呈非共定位,而在端粒酶阴性WI-38-2RA细胞中两者呈共定位状态。MSCs中不存在有染色体外端粒重复序列DNA（ECTR DNA）。TRAP法检测传代培养的MSCs端粒酶呈阴性表达,但分化成脂肪的MSCs端粒酶呈阳性表达。Western blotting 检测同步化处理前MSCs端粒酶呈微弱表达,经同步化处理被阻断在S期时,MSCs的端粒酶表达明显增高,并且与S期的细胞比例呈正相关。结论：MSCs中不存在ALT相关的早幼粒细胞白血病蛋白小体(APBs)、染色体外端粒重复序列DNA(ECTR DNA)和端粒长度较长、端粒长度变异度大等ALT机制相关分子特征;非同步化在S期处理的MSCs,端粒酶呈微弱表达,但诱导向脂肪细胞分化或处在S期时,MSCs的端粒酶表达明显增高,并且与S期的细胞比例呈正相关。本研究提示MSCs是通过端粒酶机制而不是端粒延长旁路途径（ALT）机制调控其端粒末端。     

Telomere length and telomerase activity: effect of ageing on human NK cells

Telomeres are repeats of TTAGGG sequences located at the end of eukaryotic chromosomes. They are essential for stabilisation and protection of chromosomal ends and for the regulation of cell replicative capacity. Due to the end-replication defect of DNA polymerase, telomeres shorten progressively with each cell division and telomere length may be an indicator of the replicative history of a cell. Compensatory mechanisms for the telomere loss have been identified. The most widely studied one is mediated by telomerase a ribonuclear protein-enzyme complex that synthesise telomeric repeats. In this study we have investigated whether NK cells, derived from a group of old healthy subjects, underwent the modifications of telomere length and telomerase activity observed in other sub-populations of lymphocytes with advancing age. We demonstrated that: (a) telomere shortening occurred and telomerase activity decreased in human NK cells with ageing; (b) the rate of telomere loss was different under and over 80 years of age; (c) similarly to telomere shortening, the modification of telomerase activity was particularly evident in octogenarians; (d) subjects with the most evident modifications of telomeres and telomerase were the oldest and those with increased NK cell numbers.     

端粒与肿瘤细胞耐药关系的研究进展

端粒是人类染色体末端结构,在维持基因组稳定性中发挥重要作用.有丝分裂导致的端粒长度的进行性缩短是细胞衰老的标志,肿瘤细胞则克服了这种现象,保留了无限增殖的能力,故端粒成为临床治疗的靶点.肿瘤细胞对化疗药物的耐受现象是临床治疗的难题.如何克服肿瘤的耐药性一直是肿瘤治疗研究的重点.该文从端粒的基本组成结构人手,对端粒与肿瘤细胞获得性耐药的关系以及端粒如何介导肿瘤细胞耐药性的产生进行综述,旨在为克服肿瘤耐药性提供新的治疗思路.     

The telomere world and aging: Analytical challenges and future perspectives

Telomeres, the terminal nucleoprotein structures of eukaryotic chromosomes, play pleiotropic functions in cellular and organismal aging. Telomere length (TL) varies throughout life due to the influence of genetic factors and to a complex balancing between “shortening” and “elongation” signals. Telomerase, the only enzyme that can elongate a telomeric DNA chain, and telomeric repeat-containing RNA (TERRA), a long non-coding RNA involved in looping maintenance, play key roles in TL during life. Despite recent advances in the knowledge of TL, TERRA and telomerase activity (TA) biology and their measurement techniques, the experimental and theoretical issues involved raise a number of problems that should carefully be considered by researchers approaching the “telomere world”. The increasing use of such parameters – hailed as promising clinically relevant biomarkers – has failed to be paralleled by the development of automated and standardized measurement technology. Consequently, associating given TL values to specific pathological conditions involves on the one hand technological issues and on the other clinical-biological issues related to the planning of clinically relevant association studies. Addressing these issues would help avoid major biases in association studies involving TL and a number of outcomes, especially those focusing on psychological and bio-behavioral variables. The main challenge in telomere research is the development of accurate and reliable measurement methods to achieve simple and sensitive TL, TERRA, and TA detection. The discovery of the localization of telomeres and TERRA in cellular and extracellular compartments had added an additional layer of complexity to the measurement of these age-related biomarkers. Since combined analysis of TL, TERRA and TA may well provide more exhaustive clinical information than a single parameter, we feel it is important for researchers in the various fields to become familiar with their most common measurement techniques and to be aware of the respective merits and drawbacks of these approaches.     

原发性胃癌组织中的端粒及端粒酶表达

目的观察端粒（ＴＲＦ）及端粒酶在胃癌形成及发展中的作用。方法采用ＤＮＡ琼脂糖凝胶杂交技术及端粒重复扩增ＰＣＲ方法检测１７例早期胃癌、８９例进展期胃癌组织及邻近正常组织中的平均ＴＲＦ长度及端粒酶活性。结果早期、进展期胃癌的ＴＲＦ长度及端粒酶活性表达均显著短于或高于邻近胃组织（Ｐ＜０．０５～０．０１），且端粒酶活性的表达主要表现在ＴＲＦ缩短或延长的胃癌组织中，而ＴＲＦ缩短与胃癌的分化程度相一致。结论端粒及端粒酶的异常状态可能与胃癌的发生发展密切相关，端粒酶活性及端粒缩短可以作为胃癌的诊断标志     

IGF-1 rescues human intervertebral annulus cells from in vitro stress-induced premature senescence

The aging human intervertebral disc contains a sizeable population of senescent cells. Since senescent cells cannot divide, senescence reduces the disc's ability to generate new cells to replace existing ones lost to necrosis or apoptosis. The objectives of the present work were: (1) to develop a reliable in vitro model for stress-induced premature senescence in human annulus cells, and (2) to investigate the potential for insulin-like growth factor-1 (IGF-1) to prevent or ameliorate senescence in vitro. The developed experimental model employs a 2 h exposure to 50 μM hydrogen peroxide; immunocytochemical localization of senescence associated-beta-galactosidase at pH 6.0 was used as the marker for senescent cells, and the percentage of senescent cells quantified after 3 days of culture. Nine sets of annulus cells were obtained from eight human surgical disc specimens; cells were tested with 0, 50, 100 or 500 ng/ml IGF-1. Although 50 or 100 ng/ml IGF-1 did not significantly alter the percentage of senescent cells, a significant reduction was present following exposure to 500 ng/ml IGF-1 (control, 56.3% ± 8.5 (9); mean ± SEM, (n) vs. treated, 39.6% ± 6.6 (9), p = 0.0009). These novel findings point to the value of continued research towards development of future biologic therapies designed to reduce cell senescence in degenerating human discs.     

Telomere length and telomerase activity during expansion and differentiation of human mesenchymal stem cells and chondrocytes

Chondrocyte ex vivo expansion currently performed to replace damaged articular surfaces is associated with a loss of telomeric repeats similar to decades of aging in vivo. This might affect the incidence or time of onset of age-related disorders within transplanted cells or tissues. This study examined whether more immature progenitor cells, such as mesenchymal stem cells (MSC), which can be expanded and subsequently differentiated into chondrocytes is advantageous regarding telomere-length related limitations of expansion protocols. Primary chondrocytes and bone-marrow-derived MSC were isolated from 12 donors, expanded separately to 4 x 10(6) cells, and (re-)differentiated as three-dimensional chondrogenic spheroids. Cells were collected during expansion, after three-dimensional culturing and chondrogenic differentiation, and sequential analyses of telomere length and telomerase activity were performed. Surprisingly, telomeres of expanded MSC were significantly shorter than those from expanded chondrocytes from the same donor (11.4+/-2.5 vs. 13.4+/-2.2 kb) and tended to remain shorter after differentiation in chondrogenic spheroids (11.9+/-1.8 vs. 13.0+/- kb). While telomere lengths in native chondrocytes and MSC were not related to the age of the donor, significant negative correlations with age were observed in expanded (136 bp/year), three-dimensionally reconstituted (188 bp/year), and redifferentiated (229 bp/year) chondrocytes. Low levels of telomerase activity were found in MSC and chondrocytes during expansion and after (re-)differentiation to chondrogenic spheroids. In terms of replicative potential, as determined by telomere length, ex vivo expansion followed by chondrogenic differentiation of MSC did not provide a benefit compared to the expansion of adult chondrocytes. However, accelerated telomere shortening with age during expansion and redifferentiation argues for an "age phenotype" in chondrocytes as opposed to MSC and suggests an advantage for the use of MSC especially in older individuals and protocols requiring extensive expansion     

Rb1延缓人脐静脉内皮细胞早熟性衰老与caveolin-1表达的关系

目的:血管内皮细胞衰老是动脉粥样硬化发生的病理生理机制之一。本研究旨在探讨人参皂苷Rb1延缓人脐静脉内皮细胞(HUVECs)早熟性衰老与窖蛋白1(caveolin-1)表达的关系,为延缓HUVECs衰老提供新的靶点。方法:建立60μmol/L过氧化氢(H_2O_2)诱导的HUVECs早熟性衰老模型,根据细胞形态学的变化、衰老相关β-半乳糖苷酶(SA-β-Gal)染色阳性率和细胞周期评估内皮细胞衰老,采用Western blot和激光共聚焦显微成像的方法检测caveolin-1的变化,观察人参皂苷Rb1对HUVECs衰老的作用及其相关的分子机制。结果:60μmol/L H_2O_2可成功地诱导内皮细胞衰老,早熟性衰老的HUVECs体积变大,SA-β-Gal活性明显增加,细胞发生G_1期阻滞,细胞增殖受抑制,caveolin-1表达增多。与H_2O_2处理组相比,人参皂苷Rb1预处理延缓HUVECs早熟性衰老,SA-β-Gal染色阳性细胞百分比降低,G_0/G_1期细胞比例下降,caveolin-1表达减少。结论:人参皂苷Rb1可通过抑制caveolin-1的表达延缓H_2O_2诱导的HUVECs早熟性衰老。     

EB病毒对人胚鼻咽上皮细胞的转化

为观察EBV和／或促癌物四癸酸佛波醇二酯（TPA）对其的转化作用，以人胚鼻咽上皮作体外原代组织培养，采用自B95－8细胞分离的EB病毒直接感染或结合TPA处理体外培养的人胚鼻咽上皮细胞，着重观察感染细胞在半固体培养基中的集落形成率；并采用PCR扩增法探讨EB病毒是否直接进入鼻咽上皮细胞。结果显示：单独EB病毒或灭活（56℃，30分钟）EB病毒加TPA感染时，病毒不能进入细胞导致表型改变；活性EB病毒结合TPA同时处理或先用EB病毒后用TPA处理时，EB病毒能直接进入细胞并导致细胞集落形成率明显增高（P＜0．05）。从而表明EB病毒体外能部分转化人胚鼻咽上皮细胞，其转化作用依赖于TPA的存在和病毒基因组的完整。     

Endogenous oxidative stress prevents telomerase-dependent immortalization of human endothelial cells

Introduction

With aging, oxidative stress accelerates vascular endothelial cell (EC) telomere shortening-induced senescence, and may promote atherosclerosis in humans. Our aim was to investigate whether an antioxidant treatment combined with telomerase (hTERT) over-expression would prevent senescence of EC isolated from patients with severe atherosclerosis.

Methods

Cells were isolated from internal mammary arteries (n = 11 donors), cultured until senescence with or without N-acetylcystein (NAC) and infected, or not, with a lentivirus over-expressing hTERT.

Results

Compared to control EC, hTERT-NAC cells had increased telomerase activity, longer telomeres and underwent more cell divisions. According to the donor, hTERT-NAC either delayed (n = 5) or prevented (n = 4) EC senescence, the latter leading to cell immortalization. Lack of cell immortalization by hTERT-NAC was accompanied by an absence of beneficial effect of NAC alone in paired EC. Accordingly, lack of EC immortalization by hTERT-NAC was associated with high endogenous susceptibility to oxidation. In EC where hTERT-NAC did not immortalize EC, p53, p21 and p16 expression increased with senescence, while oxidative-dependent DNA damage associated with senescence was not prevented.

Conclusion

Our data suggest that irreversible oxidative stress-dependent damages associated with cardiovascular risk factors are responsible for senescence of EC from atherosclerotic patients.     

体外传代培养成体大鼠骨髓间充质干细胞生物学特性的观察

目的观察成体大鼠骨髓间充质干细胞（MSC）体外培养过程中生物学特性的改变,为骨髓间充质干细胞的应用研究提供实验依据。方法成体大鼠骨髓MSC的分离培养,流式细胞仪观察MSC免疫表型及细胞周期,检测细胞的诱导分化能力以及细胞的生长曲线,TRAP—ELISA方法检测其端粒酶活性。结果体外培养的成体大鼠MSC,随着传代次数的增加,长梭形细胞的体积逐渐增大。第4代时免疫表型阳性细胞率分别为CD29：（94．75±3．68）％,CD71：（95．43±2．23）％,CD90：（98．08±3．88）％;当传到第7代时,阳性细胞率仅为CD29：（50．00±3．35）％,CD71：（50．70±2．43）％,CD90：（48．60±2．83）％;第9代时MSC检测不到任何阳性免疫表型。前5代MSC增殖较快,第3代时处于S期和G2／M期的细胞比例为（38．36±2．01）％,处于G0／G1期细胞为（61．64±2．13）％;第7代以后细胞增殖能力明显降低,第12代时处于S期和G2／M期的细胞为（10．83±1．63）％,而G0／G1期的细胞为（89．17±1．96）％,此时MSC已经基本停止增长。当体外培养的MSC传到第9代以后,在成骨和成脂肪诱导体系作用下,细胞丧失了分化为Von Kossa法染色和油红O染色阳性细胞的能力;同时其端粒酶活性也随着传代次数的增多由最初的（52．7±0．78）％逐渐降低为阴性。结论体外培养的成体大鼠骨髓MSC随着传代次数的增加,其生物学特性发生明显改变。     

A new insight into cell biological and biochemical changes through aging

After several years of extensive research, the main cause of aging is yet elusive. There are some theories about aging, such as stem cell aging, senescent cells accumulation, and neuro-endocrine theories. None of them is able to explain all changes that happen in cells and body through aging. By finding out the main cause of aging, it will be much easier to control, prevent and even reverse the aging process. Our cells, regardless of their replicative capacity, get old through aging and they have almost the same epigenetic age. Different cell signaling pathways contribute to aging. The most important one is mTORC1 that becomes hyperactive in cells that undergo aging. Other significant changes with age are lysosome accumulation, impaired autophagy, and mitophagy. Immune system undergoes gradual changes through aging including a shift from lymphoid to myeloid lineage production as well as increased IL-6 and TNF-α which lead to age-related weight loss and meta-inflammation. Additionally, our endocrine system also experiences some changes that should be taken into consideration when looking for the main cause of aging in the human body. In this review, we planned to summarize some of the changes that happen in cells and the body through aging.     

Resveratrol induces senescence-like growth inhibition of U-2 OS cells associated with the instability of telomeric DNA and upregulation of BRCA1

Resveratrol decreases cancer risk and improves health of laboratory animals. However, it can also promote genomic instability. Part of the beneficial activity of resveratrol may result from the activation of SIRT1 deacetylase. We examined how resveratrol influenced the growth of human cancer cell lines of different origin: osteosarcoma (U-2 OS) and lung adenocarcinoma (A549) and how it modulated the expression as well as the localization of key proteins, involved in DNA repair and cell cycle regulation. Resveratrol-induced growth arrest was associated with signs of stress-induced senescence. Differential expression of BRCA1, cyclin B1, pRb and p21 in U-2 OS and A549 cells indicates that resveratrol can engage various molecular mechanisms to arrest cell cycle progression. In subset of U-2 OS cells, the upregulated BRCA1 formed foci closely associated with WRN and the telomeric protein (TRF1). Moreover, resveratrol induced telomeric instability in U-2 OS cells and the activation of DNA damage signaling in both cell lines, manifested as the phosphorylation of histone H2AX at serine 139 and of p53 at serines 15 and 37. Our data are consistent with the hypothesis that resveratrol inhibits cell growth and induces senescence by altering DNA metabolism.     

不同浓度血清对大鼠骨髓基质细胞生长的影响

目的：探讨不同浓度血清对大鼠原代培养骨髓基质细胞(BMSCs)功能的影响，寻求培养所需的适宜血清浓度。 方法： 利用MTT法绘制细胞生长曲线、流式细胞仪分析细胞生长周期及细胞凋亡的变化，PCR-ELISA法分析细胞端粒酶活性的改变。 结果： ①血清能明显促进BMSCs增殖，表现为G0/G1期细胞减少，S期细胞增加，群体细胞倍增时间缩短。②在组成BMSCs的Ⅰ型和Ⅱ型细胞发育生长过程中，血清对Ⅱ型细胞的增殖无明显促进作用；对Ⅰ型细胞，血清能明显促进细胞增殖。③短时间内血清对于BMSCs端粒酶活性无明显影响。 结论： ①对于BMSCs中不同类型的细胞采用的培养条件应因类而异。②血清对Ⅰ型细胞的增殖具有明显促进作用。③血清并不能促进Ⅱ型细胞增殖，但在短时间内对其分化亦无明显影响。     

Telomerase activity in hybrids between telomerase-negative and telomerase-positive immortal human cells is repressed in the different complementation groups but not in the same complementation group of immortality

The expression of telomerase is essential for cells to be immortalized, and most immortal cell lines possessed telomerase activity. Using the cell fusion technique, it has been shown that mortal and telomerase-negative phenotypes of normal cells are dominant over immortal and telomerase-positive phenotypes, suggesting that the normal cells possessed dominant repressor-type activity for telomerase expression. Several telomerase-negative immortal human cell lines were reported, in which telomerase-independent mechanisms was supposed to maintain telomere length. We aimed at seeing whether the telomerase-negative phenotype of these immortal cells is dominant over telomerase-positive phenotype of other immortal cells in correlation with cellular mortality. Results showed that, when telomerase-positive and -negative immortal parental cell lines belonging to the different complementation groups were fused, telomerase-negative mortal hybrid clones arose, i.e. telomerase-negative phenotype was dominant as well as mortal phenotype. However, when immortal hybrid cells arose from telomerase-positive and -negative immortal parents belonging to either the same or different complementation groups, they were all telomerase-positive, i.e. telomerase-negative phenotype appeared to be recessive. Telomerase-negative immortal hybrid was never established from any combinations between telomerase-negative and -positive immortal parental cells.     

Age-dependent alterations of the T cell repertoire and functional diversity of T cells of the aged

The aging immune system is characterized by the contraction of T cell receptor (TCR) diversity and the de novo expression of NK-related receptors (NKR) on oligoclonal T cells. NKR⁺T cells likely represent a secondary immune diversification as a biological adaptation of aging to ensure host defense despite shrinkage of the TCR repertoire. NKRs are expressed in various combinations even among TCR-identical cells, and are capable of triggering effector pathways in either TCR-independent or TCR-dependent fashion. Understanding the biology of NKR⁺ T cells will be pivotal to the development of strategies to enhance immunity in the elderly.     

低温保存脂肪间充质干细胞的生物学特性评价

目的 探讨低温保存对小鼠脂肪间充质干细胞（ADMSCs)体外培养的生物学特性和分化潜能的影响。方法 分离、培养小鼠ADMSCs,取第3代细胞置于液氮深低温（-196℃）冻存 12个月后复苏。MTT 法测定ADMSCs的增殖活性;β-半乳糖苷酶(SA-β-Gal)染色检测衰老;免疫细胞化学方法检测细胞表面分子CD73、CD90和CD105;条件培养基诱导后,免疫荧光法检测心肌特异性肌钙蛋白（cTnT）,茜素红、碱性磷酸酶和油红 O 染色检测成骨、成脂诱导分化潜能,Real time-PCR检测cTnT、Gata4、Ost和Runx2。未经低温保存的第3代ADMSCs为对照。 结果 低温保存的ADMSCs其增殖活性、衰老率与未冻存细胞比较差异无显著性（P>0.05）。诱导后ADMSCs的cTnT阳性表达、茜素红、碱性磷酸酶和油红O染色呈阳性反应,冻存组与对照组比较差异无显著性(P>0.05）。结论 低温保存对ADMSCs体外生长特性和成心肌、成脂肪细胞、成骨细胞的分化潜能差异无显著性。     

P> 不同年龄小鼠脂肪源间充质干细胞体外原代培养衰老和凋亡的变化/P>

目的 探讨小鼠脂肪源间充质干细胞(ADMSCs)体外原代培养过程中衰老和凋亡变化。方法 用差速贴壁法对1月和24月龄小鼠（各30只）腹股沟脂肪组织的ADMSCs进行原代培养,免疫荧光技术检测第3代ADMSCs表面抗原CD73、CD90和CD105的表达,比较两组细胞的形态差异和生长情况,β-半乳糖苷酶(SA-β-Gal)染色检测ADMSCs衰老情况,PI-Hoechst33342双染色观察ADMSCs的凋亡变化。 结果 两组体外原代培养的ADMSCs均贴壁生长,具有典型干细胞的形态和生长特征,两组ADMSCs CD73、CD90和CD105的表型一致。SA-β-Gal染色显示：原代培养的老年组ADMSCs衰老比例比幼年组多,1月组原代培养2~7d的ADMSCs阳性率分别为（3.87±1.34）%、（4.21±1.22）%、（9.00±0.98）%、（11.20±1.24）%、（9.50±2.19）%和（13.20±2.93）%;24月组分别为（8.67±1.05）%、（10.23±0.98）%、（12.80±0.78）%、（17.10±1.13）%、（19.80±1.59）%和（24.70±1.86）%。PI-Hoechst 33342染液双染显示：1月组原代培养2~7d的ADMSCs凋亡率分别为(22.1±1.4)%、(36.7±1.62)%、(11.7±1.45)%、(38.4±1.57)%、(6.5±1.32)%和(11.3±1.63)%;24月组4~7d的ADMSCs凋亡率分别为(29.4±1.72)%、(37.6±1.64)%、(19.4±1.29)%和(18.9±1.25)%。 结论 老龄ADMSCs增殖能力下降,衰老、凋亡和坏死的细胞比例增加;随着ADMSCs原代培养时间的延长,其衰老增加,但凋亡和坏死无规律性变化。     

粘附性NK细胞的制备及免疫学特性初探

目的：初步探讨粘附NK细胞的制备方法及免疫学特性。方法：首先经淋巴细胞分离液，贴壁粘附及尼龙毛柱粘附对外周血NK细胞进行初步分离，然后联合使用Percoll不连续密度梯度离心法和T细胞Panning法进一步纯化NK细胞，应用流式细胞仪鉴定NK细胞并检测其纯度，rhIL-2(6000IU/ml)诱导纯化的NK细胞（R－NK）转变为粘附NK（A－NK）细胞，然后利用细胞计数法，MTT法和RT－PCR方法检测A－NK细胞的增殖和杀伤等免疫学特性。结果：经过纯化，诱导获得较高纯度，较高活性的A－NK细胞。结论：初步建立了利用人外周血NK细胞制备A－NK细胞的方法。