Characterisation of normal and cancer stem cells: One experimental paradigm for two kinds of stem cells

The characterisation of normal stem cells and cancer stem cells uses the same paradigm. These cells are isolated by a fluorescence‐activated cell sorting step and their stemness is assayed following implantation into animals. However, differences exist between these two kinds of stem cells. Therefore, the translation of the experimental procedures used for normal stem cell isolation into the research field of cancer stem cells is a potential source of artefacts. In addition, normal stem cell therapy has the objective of regenerating a tissue, while cancer stem cell‐centred therapy seeks the destruction of the cancer tissue. Taking these differences into account is critical for anticipating problems that might arise in cancer stem cell‐centred therapy and for upgrading the cancer stem cell paradigm accordingly.     

一种新型干细胞--侧群细胞

侧群细胞(side population cell)是利用Hoechst染料和流式细胞术进行造血千／祖细胞分离时发现的一群特殊细胞,广泛分布于多种成体组织、胚胎和某些肿瘤细胞系中;它既具有类似千细胞的自我更新和多向分化潜能,还具有独特的表型标记和生物学特征,代表了一种新的千细胞类型。对侧群细胞的研究,不仅有助于人们增加对千细胞增殖、分化及其发育调控机制的理解,同时还提供了一种从不同组织中分离纯化和利用多能干细胞的新策略,为组织工程和细胞治疗提供新的千细胞材料来源。现就侧群细胞的组织分布、生物学特征、表型标记、信号转导机制及其与肿瘤发生相关性等方面的研究进展进行了综述,并对侧群细胞的进一步研究和应用作了展望。     

CD90过表达影响胃癌细胞AGS的干性特征

2019年中国癌症报告显示,胃癌发病率仅次于肺癌,位列第二,其死亡率排在所有肿瘤的第三位,严重危害人们健康.筛查和鉴定胃癌的早期检测标志物、寻找胃癌治疗的分子靶点,对于降低胃癌致死率至关重要.CD90 (THY1)是一种细胞表面糖蛋白,在肿瘤细胞增殖、转移以及血管生成中发挥重要作用.CD90异常表达与干细胞特性有关,促...     

Unraveling stem cell and progenitor subsets in autologous grafts according to methods of mobilization: implications for prediction of hematopoietic recovery

Background aimsIn the autologous setting, granulocyte colony-stimulating factor (G-CSF) (G), or, when failing, G plus plerixafor (G+P), are common regimens for mobilization of stem cells into peripheral blood. To delineate mobilization effects on graft composition and hematopoietic recovery, we compared contents of stem cells and progenitor cells in products of G+P- and G patients. Paired samples of G+P patients and prior insufficient G mobilization were available for analyses.MethodsSubset analyses of grafts were performed by flow cytometry and myeloid colony-forming assay. In search of new markers to ascertain graft quality, we determined the fractions of aldehyde dehydrogenase bright (ALDH^br) cells.ResultsG grafts contained higher percentages of CD34+ cells, CD34+CD38- cells, and committed progenitors (CD34+CD38+) compared with G+P grafts. A detailed characterization of the mobilized CD34+ cell subset showed higher percentages of CD38– among the CD34+ cells of the G+P group (P = 0.032). In contrast, the CD34+ cell subset in G grafts was characterized by a higher percentage of ALDH^br cells (P < 0.0001). Studying engraftment and day +100 graft function the G and G+P transplanted patients were comparable with respect to neutrophils, whereas in platelets they differed. In the prediction of engraftment and hematopoietic recovery, the dose of infused ALDH^br cells correlated best to both platelet (r = 0.565, P = 0.002) and neutrophil reconstitution (r = 0.366, P = 0.06).ConclusionsBesides showing dissimilar distributions of CD34+CD38– cells and progenitors in G and G+P grafts, this study further designated ALDH^br as a promising marker in determination and prediction of graft quality and hematopoietic recovery.     

CD44+CD24-/low乳腺癌干细胞的流式分选及其肿瘤干细胞特性的初步鉴定

目的:通过表面标志分选法富集乳腺癌干细胞,并初步鉴定其肿瘤干细胞特性。方法:采用流式细胞分选术从人乳腺癌细胞系MCF-7中分选CD44+CD24-/low乳腺癌干细胞,并进行干细胞比例分析;用免疫荧光法检测、比较分选获得的细胞和对照细胞的干性和分化标记物Oct-4、SOX-2、CK-18和α-SMA的表达状态。结果:分选获得的CD44+CD24-/low乳腺癌干细胞阳性比例达90%以上;免疫荧光检测结果显示,CD44+CD24-/low细胞亚群比non-CD44+CD24-/low细胞亚群高表达干细胞转录因子Oct-4、SOX-2,低表达分化因子CK-18、α-SMA;体外实验表明,CD44+CD24-/low细胞亚群具有更强的成球生长能力,并具有双向分化潜能。结论:CD44+CD24-/low表面标记物分选的方法可以富集高纯度的乳腺癌干细胞,且呈现干性因子Oct-4和SOX-2高表达。     

miRNA-148b suppresses hepatic cancer stem cell by targeting neuropilin-1

The existence of cancer stem cells (CSCs) is considered as a direct reason for the failure of clinic treatment in hepatocellular carcinoma (HCC). Growing evidences have demonstrated that miRNAs play an important role in regulation of stem cell proliferation, differentiation and self-renewal and their aberrances cause the formation of CSCs and eventually result in carcinogenesis. We recently identified miRNA-148b as one of the miRNAs specifically down-regulated in side population (SP) cells of PLC/PRF/5 cell line. However, it remains elusive how miRNA-148b regulates CSC properties in HCC. In the present study, we observed that overexpression or knockdown of miR-148b through lentiviral transfection could affect the proportion of SP cells as well as CSC-related gene expression in HCC cell lines. In addition, miR-148b blocking could stimulate cell proliferation, enhance chemosensitivity, as well as increase cell metastasis and angiogenesis in vitro. More importantly, miR-148b could significantly suppress tumorigenicity in vivo. Further studies revealed that Neuropilin-1 (NRP1), a transmembrane co-receptor involved in tumour initiation, metastasis and angiogenesis, might be the direct target of miRNA-148b. Taking together, our findings define that miR-148b might play a critical role in maintenance of SP cells with CSC properties by targeting NRP1 in HCC. It is the potential to develop a new strategy specifically targeting hepatic CSCs (HCSCs) through restoration of miR-148b expression in future therapy.     

Identification and characterization of a resident vascular stem/progenitor cell population in preexisting blood vessels

Vasculogenesis, the in-situ assembly of angioblast or endothelial progenitor cells (EPCs), may persist into adult life, contributing to new blood vessel formation. However, EPCs are scattered throughout newly developed blood vessels and cannot be solely responsible for vascularization. Here, we identify an endothelial progenitor/stem-like population located at the inner surface of preexisting blood vessels using the Hoechst method in which stem cell populations are identified as side populations. This population is dormant in the steady state but possesses colony-forming ability, produces large numbers of endothelial cells (ECs) and when transplanted into ischaemic lesions, restores blood flow completely and reconstitutes de-novo long-term surviving blood vessels. Moreover, although surface markers of this population are very similar to conventional ECs, and they reside in the capillary endothelium sub-population, the gene expression profile is completely different. Our results suggest that this heterogeneity of stem-like ECs will lead to the identification of new targets for vascular regeneration therapy.     

乳腺癌肿瘤干细胞的研究进展

干细胞(stem cell,SC)是一类具有自我更新、多向分化潜能的特殊细胞群体.而肿瘤干细胞(cancer stem cell,CSC)不仅具备了干细胞方面的特征,同时还有其自身特殊性.乳腺癌中肿瘤干细胞的发现为乳腺癌的治疗提供了创新性策略.近年来,有关乳腺癌肿瘤干细胞的筛选标记和方法以及信号转导通路方面的研究颇多,但其中也不乏争议.就乳腺癌干细胞研究的最新进展作一端述.     

肿瘤干细胞起源及其生物学特性

肿瘤干细胞与正常成体干细胞在自我更新与增殖分化能力、表型标记和强耐药性等诸多方面存在着相类似的生物学特征,所以肿瘤干细胞被推测为肿瘤发生的细胞起源。基于肿瘤干细胞与正常干细胞之间的相似性质和肿瘤发生的分子机制,科学家建立了一系列从肿瘤组织或肿瘤细胞系分离肿瘤干细胞的实验方法和研究肿瘤干细胞起源的动物实验模型。现就目前在肿瘤干细胞起源和生物学特性领域的研究作概括阐述。     

Isolation of Stem Cells from Human Pancreatic Cancer Xenografts

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal and produce differentiated progeny¹. These properties allow CSCs to recapitulate the original tumor when injected into immunocompromised mice. CSCs within an epithelial malignancy were first described in breast cancer and found to display specific cell surface antigen expression (CD44⁺CD24^low/-)². Since then, CSCs have been identified in an increasing number of other human malignancies using CD44 and CD24 as well as a number of other surface antigens. Physiologic properties, including aldehyde dehydrogenase (ALDH) activity, have also been used to isolate CSCs from malignant tissues^3-5.Recently, we and others identified CSCs from pancreatic adenocarcinoma based on ALDH activity and the expression of the cell surface antigens CD44 and CD24, and CD133^6-8. These highly tumorigenic populations may or may not be overlapping and display other functions. We found that ALDH⁺ and CD44⁺CD24⁺ pancreatic CSCs are similarly tumorigenic, but ALDH⁺ cells are relatively more invasive⁸. In this protocol we describe a method to isolate viable pancreatic CSCs from low-passage human xenografts⁹. Xenografted tumors are harvested from mice and made into a single-cell suspension. Tissue debris and dead cells are separated from live cells and then stained using antibodies against CD44 and CD24 and using the ALDEFLUOR reagent, a fluorescent substrate of ALDH¹⁰. CSCs are then isolated by fluorescence activated cell sorting. Isolated CSCs can then be used for analytical or functional assays requiring viable cells.     

Magnetic activated cell sorting allows isolation of spermatogonia from adult primate testes and reveals distinct GFRa1‐positive subpopulations in men

Background Isolation of spermatogonial stem cells (SSCs) could enable in vitro approaches for exploration of spermatogonial physiology and therapeutic approaches for fertility preservation. SSC isolation from adult testes is difficult due to low cell numbers and lacking cell surface markers. Glial cell‐derived neurotrophic factor family receptor alpha‐1 (GFRα1) plays a crucial role for the maintenance of SSCs in rodents and is expressed in monkey spermatogonia. Methods Magnetic activated cell sorting was employed for the enrichment of GFRα1+ spermatogonia from adult primate testes. Results Magnetic activated cell sorting of monkey cells enriched GFRα1+ cells threefold. 11.4% of GFRα1+ cells were recovered. 42.9% of GFRα1+ cells were recovered in sorted fractions of human testicular cells, representing a fivefold enrichment. Interestingly, a high degree of morphological heterogeneity among the GFRα1+ cells from human testes was observed. Conclusions Magnetic activated cell sorting using anti‐GFRα1 antibodies provides an enrichment strategy for spermatogonia from monkey and human testes.