从胎儿胰腺组织建立单克隆胰腺前体细胞的研究

目的 探索一种新的人胰腺干细胞分离纯化体系。方法 从胎儿胰腺中分离获得巢蛋白阳性细胞群体，荧光激活细胞分选(FACS)技术分选单个side population(SP)细胞后进行单克隆细胞培养。应用逆转录-聚合酶链反应(RT-PCR)及放射免疫分析(RIA)方法，研究单克隆SP细胞在体外增殖和向胰岛内分泌细胞分化的能力。结果 胎儿胰腺组织经过分离和体外培养后，可获得巢蛋白阳性细胞，对其进行Htoechst 33342染色，分析显示SP细胞约占0．1％；RT-PCR证实SP细胞有ATP结合盒转运子G2(ABCG2)表达，而非SP细胞则未见表达；SP细胞的克隆形成率约为2．7％，而非SP细胞没有克隆形成。在多种细胞因子和无血清的条件下，单克隆SP细胞经诱导后出现胰岛素、胰升糖素和胰十二指肠同源盒基因-1(PDX-1)mRNA的表达，而巢蛋白、neurogenin3 (Ngn3)和ABCG2 mRNA表达消失；RIA分析可检测到诱导后的细胞内有胰岛素产生。结论 首次报道从胎儿胰腺组织中分离并建立了单克隆胰腺前体细胞。该细胞在体外具有很强的增殖能力，并可分化为胰岛内分泌细胞。     

Characterization of CD133^＋ parenchymal cells in the liver： Histology and culture

AIM: To reveal the characteristics of CD133~+ cells in the liver.METHODS: This study examined the histological characteristics of CD133~+ cells in non-neoplastic and neoplastic liver tissues by immunostaining, and also analyzed the biological characteristics of CD133~+ cells derived from human hepatocellular carcinoma (HCC) or cholangiocarcinoma cell lines.RESULTS: Immunostaining revealed constant expression of CD133 in non-neoplastic and neoplastic biliary epithelium, and these cells had the immunophenotype CD133~+/CK19+/HepPar-1~-. A small number of CD133~+/CK19~-/HepPar-1~+ cells were also identified in HCC and combined hepatocellular and cholangiocarcinoma. In addition, small ductal structures, resembling the canal of Hering, partly surrounded by hepatocytes were positive for CD133. CD133 expression was observed in three HCC (HuH7, PLC5 and HepG2) and two cholangiocarcinoma cell and HepG2) and two cholangiocarcinoma cell lines (HuCCT1 and CCKS1). Fluorescence-activated cell sorting (FACS) revealed that CD133~+ and CD133~-cells derived from HuH7 and HuCCT1 cells similarly produced CD133~+ and CD133~-cells during subculture. To examine the relationship between CD133~+ cells and the side population (SP) phenotype, FACS was performed using Hoechst 33342 and a monoclonal antibody against CD133. The ratios of CD133~+/CD133~-cells were almost identical in the SP and non-SP in HuH7. In addition, four different cellular populations (SP/CD133~+, SP/CD133~-, non-SP/CD133~+, and non-SP/CD133~-) could similarly produce CD133~+ and CD133~-cells during subculture. CONCLUSION: This study revealed that CD133 could be a biliary and progenitor cell marker in vivo. However, CD133 alone is not sufficient to detect tumor-initiating cells in cell lines.     

人胰腺癌细胞系SW1990中肿瘤干细胞样侧群细胞的分离及生物学特性研究

目的 从人胰腺癌细胞系SW1990中分离肿瘤干细胞样侧群(side population,SP)细胞,并进一步研究其生物学特性.方法 细胞常规培养后应用Hoechst 33342和PI染色、荧光激发流式细胞仪检测并分选SP细胞,MTT法检测细胞活性,流式细胞仪分析干细胞标志物CD133的表达,克隆平板测定细胞克隆形成能力,Western blot检测细胞ABC超家族成员G2(ABCG2)蛋白表达.结果 人胰腺癌细胞系SW1990中SP细胞比例为2.70%,可完全被维拉帕米阻断.培养9 d后,SP细胞的A492值为2.1,克隆形成率为(38.7±6.8)%,CD133阳性率为69.63%,均显著高于非SP细胞的0.5,(15.5±2.8)%,16.71%;SP细胞ABCG2表达也较非SP细胞强.结论 胰腺癌细胞系SW1990存在SP细胞.     

Left atrium of the human adult heart contains a population of side population cells

Cardiac “side population” (SP) cells have previously been found to differentiate into both endothelial cells and cardiomyocytes in mice and rats, but there are no data on SP cells in the human adult heart. Therefore, human cardiac atrial biopsies were dissociated, stained for SP cells and analyzed with FACS. Identified cell populations were analyzed for gene expression by quantitative real-time PCR and subjected to in vitro differentiation. Only biopsies from the left atrium contained a clearly distinguishable population of SP cells (0.22 ± 0.08%). The SP population was reduced by co-incubation with MDR1 inhibitor Verapamil, while the ABCG2 inhibitor FTC failed to decrease the number of SP cells. When the gene expression was analyzed, SP cells were found to express significantly more MDR1 than non-SP cells. For ABCG2, there was no detectable difference. SP cells also expressed more of the stem cell-associated markers C-KIT and OCT-4 than non-SP cells. On the other hand, no significant difference in the expression of endothelial and cardiac genes could be detected. SP cells were further subdivided based on CD45 expression. The CD45−SP population showed evidence of endothelial commitment at gene expression level. In conclusion, the results show that a SP population of cells is present also in the human adult heart.     

Persistence of side population cells with high drug efflux capacity in pancreatic cancer

AIM： To investigate the persistence of side population （SP） cells in pancreatic cancer and their role and mechanism in the drug resistance. METHODS： The presentation of side population cells in pancreatic cancer cell line PANC-1 and its proportion change when cultured with Gemcitabine, was detected by Hoechst 33342 staining and FACS analysis. The expression of ABCB1 and ABCG2 was detected by real- time PCR in either SP cells or non-SP cells. RESULTS： SP cells do exist in PANC-1, with a median of 3.3% and a range of 2.1-8.7%. After cultured with Gemcitabine for 3 d, the proportion of SP cells increased significantly （3.8% ± 1.9%, 10.7% ± 3.7%, t = 4.616, P = 0.001 〈 0.05）. ABCB1 and ABCG2 expressed at higher concentrations in SP as compared with non-SP cells （ABCB1： 1.15 ± 0.72, 5.82 ± 1.16, t = 10.839, P = 0.000 〈 0.05; ABCG2： 1.16 ± 0.75, 5.48 ± 0.94, t = 11.305, P = 0.000 〈 0.05）, which may contribute to the efflux of fluorescent staining and drug resistance. CONCLUSION： SP cells with inherently high resistance to chemotherapeutic agents do exist in pancreatic cancers, which may be candidate cancer stem cells contributing to the relapse of the tumor.     

侧群细胞与消化系恶性肿瘤干细胞研究

侧群(side population,SP)细胞是利用Hoechst33342染料和流式细胞术进行造血干/祖细胞分离时发现的一群特殊细胞,既有干细胞样自我更新和多向分化潜能,而且具有独特的SP表型标志,为干细胞研究提供了新的方向。侧群细胞在正常组织和恶性肿瘤细胞中均有表达,且其有与肿瘤干细胞相似的生物学特性。近年来在消化系肿瘤干细胞的研究中发现侧群细胞对于分选鉴定肿瘤干细胞意义重大。本文就侧群细胞与消化系肿瘤干细胞的关系进行研究。     

Side population purified from hepatocellular carcinoma cells harbors cancer stem cell-like properties

Recent advances in stem cell biology enable us to identify cancer stem cells in solid tumors as well as putative stem cells in normal solid organs. In this study, we applied side population (SP) cell analysis and sorting to established hepatocellular carcinoma (HCC) cell lines to detect subpopulations that function as cancer stem cells and to elucidate their roles in tumorigenesis. Among four cell lines analyzed, SP cells were detected in Huh7 (0.25%) and PLC/PRF/5 cells (0.80%), but not in HepG2 and Huh6 cells. SP cells demonstrated high proliferative potential and anti-apoptotic properties compared with those of non-SP cells. Immunocytochemistry examination showed that SP fractions contain a large number of cells presenting characteristics of both hepatocyte and cholangiocyte lineages. Non-obese diabetic/severe combined immunodeficiency (NOD/SCID) xenograft transplant experiments showed that only 1 x 10(3) SP cells were sufficient for tumor formation, whereas an injection of 1 x 10(6) non-SP cells did not initiate tumors. Re-analysis of SP cell-derived tumors showed that SP cells generated both SP and non-SP cells and tumor-initiating potential was maintained only in SP cells in serial transplantation. Microarray analysis discriminated a differential gene expression profile between SP and non-SP cells, and several so-called "stemness genes" were upregulated in SP cells in HCC cells. In conclusion, we propose that a minority population, detected as SP cells in HCC cells, possess extreme tumorigenic potential and provide heterogeneity to the cancer stem cell system characterized by distinct hierarchy.     

肝细胞生长因子及葡萄糖对人胰腺干细胞向胰岛素分泌细胞分化的影响

目的 探讨人胰腺干细胞体外扩增及其向胰岛素分泌细胞分化的影响因素.方法 应用剪碎消化法从孕4～6月龄引产的人胎儿胰腺中获得胰岛组织,选用差速贴壁法从胰岛中分离胰腺干细胞,经扩增后定向诱导成具有胰岛素分泌功能和胰岛样结构的胰岛样细胞团,观察肝细胞生长因子和葡萄糖对胰腺干细胞向胰岛素分泌细胞诱导分化以及胰岛样细胞团胰岛素分泌功能的影响.采用流式细胞仪和免疫组织化学法检测扩增前后nestin阳性细胞和ABCG2阳性细胞.行葡萄糖刺激的胰岛素释放试验,以酶联免疫吸附法（ELISA）检测每1×105个扩增细胞经定向诱导后形成的胰岛样细胞团释放的胰岛素量,比较肝细胞生长因子和葡萄糖对定向分化的影响.采用单因素方差分析或多样本均数两两比较进行统计学分析.结果 经过15代连续扩增,nestin阳性细胞和ABCG2阳性细胞分别扩增了27.9倍和37.8倍.扩增后的细胞经15 d定向诱导后形成具有胰岛素分泌功能和胰岛样结构的细胞团.葡萄糖刺激的胰岛素分泌试验显示,当诱导培养基中肝细胞生长因子浓度为0、5、10、15μg/L时,5.6 mmol/L葡萄糖刺激后,胰岛素分泌量分别为5.00、12.93、14.91和11.23μU;25.0 mmol/L葡萄糖刺激后,胰岛素分泌量分别为19.91、35.53、47.43和23.33 μU.诱导培养基中的葡萄糖浓度为0、2.8、5.6和11.2 mmol/L时,5.6 mmol/L葡萄糖刺激后,胰岛素分泌量分别为9.07、14.21、6.91和3.53 μU;25.0 mmol/L葡萄糖刺激后,胰岛素分泌量分别为26.64、48.97、37.63和34.20 μU.结论 人胰腺中nestin和ABCG2阳性胰腺干细胞具有很强的体外扩增能力.扩增后的胰腺干细胞仍然具有形成胰岛素分泌细胞的功能,经体外诱导后能形成胰岛样细胞团.在胰腺干细胞向胰岛素分泌细胞分化诱导过程中,适当浓度的肝细胞生长因子和葡萄糖有利于胰岛样细胞团的形成和胰岛素分泌.     

Non-side-population hematopoietic stem cells in mouse bone marrow

Most hematopoietic stem cells (HSCs) are assumed to reside in the so-called side population (SP) in adult mouse bone marrow (BM). We report the coexistence of non-SP HSCs that do not significantly differ from SP HSCs in numbers, capacities, and cell-cycle states. When stained with Hoechst 33342 dye, the CD34(-/low) c-Kit(+)Sca-1(+)lineage marker(-) (CD34(-)KSL) cell population, highly enriched in mouse HSCs, was almost equally divided into the SP and the main population (MP) that represents non-SP cells. Competitive repopulation assays with single or 30 SP- or MP-CD34(-)KSL cells found similar degrees of repopulating activity and frequencies of repopulating cells for these populations. Secondary transplantation detected self-renewal capacity in both populations. SP analysis of BM cells from primary recipient mice suggested that the SP and MP phenotypes are interconvertible. Cell-cycle analyses revealed that CD34(-)KSL cells were in a quiescent state and showed uniform cell-cycle kinetics, regardless of whether they were in the SP or MP. Bcrp-1 expression was similarly detected in SP- and MP-CD34(-)KSL cells, suggesting that the SP phenotype is regulated not only by Bcrp-1, but also by other factors. The SP phenotype does not specify all HSCs; its identity with stem cell function thus is unlikely.