人骨髓间充质干细胞来源外泌体分离、鉴定及卵巢摄取

目的 提取及鉴定人骨髓间充质干细胞(hBMSC)来源外泌体，探讨颗粒细胞及自身免疫性早发性卵巢功能不全(POI)小鼠卵巢摄取外泌体的情况。方法 取P3至P9代hBMSC培养上清液，倒置显微镜下观察P4代hBMSC细胞形态，超高速离心法提取外泌体；纳米流式仪测外泌体粒径；透射电镜观察外泌体形态；Western blot检测外泌体标志蛋白CD63、CD9、肿瘤易感基因(TSG)101表达。外泌体采用DiR进行荧光标记；共聚焦显微镜观察人卵巢颗粒细胞(KGN)共孵育24 h和48 h摄取外泌体的情况；用ZP3蛋白多肽构建自身免疫性POI小鼠模型，在建模成功后的第1、7天腹腔注射150μg DiR标记的外泌体。在第2次注射外泌体后的第14天通过活体成像仪监测小鼠卵巢摄取情况。结果 h BMSC呈纺锤状，大小均一，提取出的外泌体平均直径为(81.12±17.23)nm。透射电镜显示外泌体结构为双层膜状；外泌体表面相关特异性蛋白CD63、CD9和TSG101呈阳性。共聚焦显微镜下观察到KGN细胞能够摄取外泌体，并与共孵育24 h比，48 h摄取的外泌体量更多。在自身免疫性POI小鼠模型中观察到小鼠...     

A549细胞对单硬脂酸甘油酯固体脂质纳米粒的摄取作用A549细胞对单硬脂酸甘油酯固体脂质纳米粒的摄取作用

目的考察单硬脂酸甘油酯固体脂质纳米粒(monostearin solid lipid nanoparticles，MSLN)经PEG2000修饰后，对A549细胞摄取MSLN及J774A1细胞吞噬MSLN的影响。方法采用溶剂扩散法制备MSLN，测定其粒径和zeta电位；以罗丹明B(Rhodamine B)为荧光标记物，研究A549细胞对MSLN的摄取作用和J774A1细胞对MSLN的吞噬作用。结果MSLN的细胞毒性较低，A549细胞对MSLN的摄取可快速接近饱和，其摄取百分率与MSLN在细胞外的浓度呈负相关。结论MSLN经PEG2000修饰，可显著抑制J774A1细胞对MSLN的吞噬，但可增加A549细胞对MSLN的摄取。     

外泌体传递miR-139调控卵巢癌顺铂敏感性的机制研究

目的探讨外泌体介导的miR-139传递对卵巢癌顺铂(cDDP)敏感性的影响。方法分别提取卵巢癌cDDP敏感细胞及耐药细胞分泌的外泌体,透射电镜观察外泌体形态,Western blotting检测外泌体标志蛋白的丰度,qPCR定量检测miR-139水平,MTT检测cDDP敏感细胞、miR-139敲低敏感细胞源性外泌体对耐药细胞cDDP敏感性的影响。结果卵巢癌细胞培养基上清液中存在大量椭圆形或圆形、粒径50~100 nm且高表达外泌体标志因子Alix、CD63、CD9的囊状结构。相较于卵巢癌cDDP耐药细胞源性外泌体,cDDP敏感细胞源性外泌体中miR-139的丰度更高,且将cDDP敏感细胞源性外泌体与耐药细胞株共同孵育可增强后者的cDDP敏感性,而下调外泌体中miR-139的表达可削弱其对耐药细胞的cDDP敏感性诱导作用。结论卵巢癌cDDP敏感细胞可通过外泌体传递miR-139,增强耐药细胞对cDDP的敏感性。     

BMSCs外泌体来源miR-133a对大鼠脊髓损伤修复的影响

目的 探讨骨髓间充质干细胞(BMSCs)外泌体来源miR-133a对大鼠脊髓损伤(SCI)修复的影响。方法 原代分离和培养BMSCs,测定BMSCs细胞表面标记物(CD90,CD45)表达;提取BMSCs外泌体,观察外泌体形态及外泌体标记分子(Alix、CD63)表达;建立SCI大鼠模型,随机将大鼠分为假手术组、SCI组、外泌体组、外泌体-抑制剂对照(NC)组、外泌体-miR-133a抑制剂组,28 d后,对各组大鼠进行BBB评分评估脊髓损伤程度;分离大鼠骨髓组织,检测该组织病理学变化、细胞凋亡状况;同时检测相关蛋白[胶质纤维酸性蛋白(GFAP)、神经元核抗原(NeuN)、炎性小体3(NLRP3)、半胱氨酸天冬氨酸酶(caspase)-1]及miR-133a表达水平。双荧光素酶实验验证miR-133a、NLRP3靶向关系。结果 BMSCs细胞中CD90、CD45表达率分别为98.07%、0.09%。外泌体呈球形,Alix、CD63呈阳性表达。与假手术组比较,SCI组BBB评分、NeuN、miR-133a表达显著降低,细胞凋亡率、GFAP、NLRP3、caspase-1表达显著增加(P&...     

姜黄素纳米胶束的制备及体外抗肿瘤作用研究

目的 制备姜黄素(Cur)/甲氧基聚乙二醇-聚己内酯(MP)载药纳米胶束,并研究其体外抗肿瘤作用。方法 采用薄膜分散法制备Cur/MP纳米胶束,筛选不同药材质量比优化处方,在扫描电镜下观察载药纳米胶束的形态;采用CCK-8法考察Cur、Cur/MP胶束对人非小细胞肺癌A549细胞的抑制率;以香豆素6为荧光探针考察细胞对胶束的摄取行为。结果 按最优处方制备3批胶束的平均粒径为35.71±0.2 nm,平均电位为-16.8±0.2 mV,平均包封率为97.52%±1.00%,平均载药量5.25%±0.80%;Cur/MP胶束在72 h内释放度最大可达74.16%,释放缓慢,无突释现象,遵循一级动力学方程;与Cur溶液比较,Cur/MP纳米胶束对A549细胞的抑制作用增强;荧光显微镜下可观察到,随着时间的延长,细胞对药物的摄取增加。结论 Cur/MP胶束制备工艺简单,可增强药物对A549细胞的抑制作用;聚合物纳米胶束的pH敏感性有利于其在体内肿瘤组织中的蓄积及肿瘤细胞内的摄取。     

干扰素γ刺激hUC-MSCs分泌外泌体促进调节性T细胞生成

目的探讨生理和炎性微环境下人脐带间充质干细胞(human umbilical cord derived mesenchymal stem cells,h UCMSCs)能否通过外泌体诱导调节性T细胞的生成来发挥免疫抑制功能。方法胶原酶消化法分离h UC-MSCs,应用流式细胞术鉴定h UC-MSCs。IFN-γ模拟体内炎性微环境,以未预处理为对照,分别提取外泌体,得到Nor-h UC-exo和IFN-γ-stimulated h UC-exo,分析其浓度及粒径分布等特征、并鉴定表面标记蛋白CD63的表达。采用h UC-MSCs、Nor-h UCexo、IFN-γpretreated-h UC-MSCs、IFN-γstimulated h UC-exo与人外周血单个核细胞共培养5 d后,流式细胞术检测T细胞的增殖、调节性T细胞的比例变化。结果 h UC-MSCs高表达CD73、CD44等间充质干细胞标志物。IFN-γ刺激前后外泌体粒径无明显变化,但IFN-γ刺激后分泌量和CD63增加(P<0.05)。CFSE染料示踪结果显示,h UC-MSCs来源的外泌体抑制PBMCs增殖(P<0.01),且IFN-γ刺激后明显提高外泌体的免疫抑制能力(P<0.01)。在活化T细胞中,IFN-γ-stimulated h UC-exo组Treg比例(11.53±0.88%)与IFN-γpretreated-h UC-MSCs组(7.54±0.50%)(P<0.05)、Norh UC-exo组(6.60±0.56%)(P<0.01)、对照组(3.87±0.73%)(P<0.01)相比升高。结论 h UC-MSCs可通过分泌外泌体来发挥免疫调节作用,在炎症因子刺激下h UCMSCs分泌的外泌体明显促进调节性T细胞的生成,h UC-exo可能是潜在的免疫抑制载体。     

比较两种方法提取人脐带间充质干细胞外泌体的效果

目的 比较两种方法提取人脐带间充质干细胞来源外泌体的效果。方法 分别采用超速离心法和组合优化法提取人脐带间充质干细胞上清液中外泌体，获得的外泌体设为外泌体A和外泌体B,采用透射电镜观察外泌体形态，纳米颗粒跟踪分析法检测外泌体浓度和粒径，BCA法测定外泌体蛋白含量以及Western blot法检测外泌体表面标志物的蛋白表达。结果 两种方法提取的外泌体均具有茶托形或椭圆形的双膜性结构，且边界清晰，但是外泌体B背景中存在其他聚合物。外泌体A浓度与外泌体B相仿(P>0.05)。外泌体A、B粒径峰值分别为128、101 nm。外泌体A蛋白含量高于外泌体B,且外泌体A表面特异性标志物CD9、CD63、CD81和TSG101蛋白表达高于外泌体B(P<0.05)。结论 两种方法均可以提取人脐带间充质干细胞来源的外泌体，但超速离心法提取的外泌体纯度更高。     

缺氧心肌细胞来源外泌体对Gli1~+细胞纤维化表型转换的作用机制

目的观察缺氧心肌细胞来源外泌体对Gli1~+细胞纤维化过程的影响,并探讨其可能的机制。方法分离Gli1~+细胞和SD乳鼠心肌细胞。心肌细胞分别进行常氧和缺氧培养,收集培养基并提取外泌体,用透射电镜、Nanosight、Western blot等方法对其鉴定。两种外泌体分别与Gli1~+细胞共培养。RT-qPCR法检测这两种外泌体并对比分析,明确其中起关键调控作用的miRNA。转染miRNA模拟物观察Gli1~+细胞中纤维化相关蛋白的表达水平。结果 Gli1~+细胞强阳性表达CD29、CD105和Gli1,不表达CD31、CD34和CD45。心肌细胞表达cTnT和α-Actinin,其外泌体直径约100 nm,并检测到Flotillin-1、Alix、HSP-70和CD63。缺氧处理外泌体中miR-223明显上调(P<0.01);Gli1~+细胞经缺氧外泌体和miR-223 mimic处理,纤维化相关的蛋白α-SMA(P<0.01,P<0.05)、DDR-2(P<0.01,P<0.01)和collagen I(P<0.05,P<0.01)的表达都明显升高。结论缺氧心肌细胞外泌体能促进Gli1~+细胞内纤维化相关蛋白的表达,使其向纤维化表型转换,这一作用可能与外泌体中高表达的miR-223有关。     

巨噬细胞来源的外泌体不同提取方法的比较

目的根据聚乙二醇(polyethylene glycol,PEG)沉淀原理,结合超高速离心改进一种简便、快速的细胞外泌体分离方法。方法采用超高速离心法、PEG6000沉淀结合超高速离心和EXO Quick试剂盒,分别提取巨噬细胞外泌体。通过透射电镜、NanoSight ZS及Nanoparticle tracker(NTA)分析外泌体的形态和粒径;蛋白印迹法鉴定细胞外泌体标志物Alix、TSG101的表达情况。结果 PEG6000沉淀结合超高速离心法获得的外泌体,其粒径分布和差速离心法相当,小于商品化的EXO Quick试剂盒。而外泌体表面蛋白Alix、TSG101在3种方法提取的沉淀物中都有表达。透射电镜结果显示,3种方法均获得典型的盘状囊泡。结论实验改进的细胞外泌体提取方法操作简洁、效率高,并且成本较低。     

RGD修饰紫杉醇脂质体的制备及其肺癌靶向治疗研究

目的:制备RGD修饰载紫杉醇(paclitaxel,PTX)脂质体(RGDLP-PTX),研究其理化性质,并探究其肺癌靶向治疗作用。方法:采用薄膜分散法制备RGDLP-PTX。荧光分光光度法研究A549细胞和NCI-H446细胞对普通脂质体(LP)和RGD修饰脂质体(RGDLP)的摄取效率。噻唑蓝实验研究不同紫杉醇浓度对A549细胞和NCI-H446细胞的细胞毒性;流式细胞仪检测RGDLP-PTX对A549细胞和NCI-H446细胞的凋亡诱导作用。用A549细胞构建肺癌裸鼠异位肿瘤模型,研究RGDLP-PTX的体内抗肿瘤作用。结果:RGDLP-PTX的粒径为(106.3±15.2)nm,电位为(6.23±2.2)mV;A549细胞对RGDLP-PTX的摄取效率是LP-PTX的4.4倍,差异有统计学意义(P<0.01);NCI-H446细胞对RGDLP-PTX的摄取效率是LP-PTX的3.8倍,差异有统计学意义(P<0.01);RGDLP-PTX对A549细胞和NCI-H446细胞的增殖抑制率具有浓度依赖性;在相同紫杉醇浓度下,RGDLP-PTX对A549细胞和NCI-H446细胞的增殖抑制率显著强于LP-PTX和游离紫杉醇,差异有统计学意义(P<0.01);RGDLP-PTX,LP-PTX和游离紫杉醇诱导肺癌A549细胞的凋亡率分别为48.3%,27.4%和35.5%,与生理盐水组比较,差异有统计学意义(P<0.01);NCI-H446细胞凋亡率分别为41.3%,22.8%和34.1%,与生理盐水组比较,差异有统计学意义(P<0.01)。RGDLP-PTX,LP-PTX和游离紫杉醇对肺癌肿瘤的抑制率分别为69.3%,47.5%和24.4%,差异有统计学意义(P<0.01)。结论:RGD修饰载紫杉醇脂质体能够高效抑制肺癌细胞的增殖和肿瘤的生长,是一种有效的肺癌靶向给药系统。     

Dendritic Cells-based Vaccine and Immune Monitoring for Hepatocellular Carcinoma

Human tumors, including those of the hepatobiliary system, express a number of specific antigens that can be recognized by T cells, and may provide potential targets for cancer immunotherapy. Dendritic cells (DCs) are rare leucocytes that are uniquely potent in their ability to capture, process and present antigens to T cells. The ability to culture sufficient numbers of DCs from human bone marrow or blood progenitors has attracted a great deal of interest in their potential utilization in human tumor vaccination. CD34⁺ peripheral blood stem cells (PBSCs) were obtained from a patient with a hepatocellular carcinoma. The PBSCs were cultured in the X-VIVO 20 medium supplemented with the Flt-3 Ligand (FL), GM-CSF, IL-4 and TNF-α for 12 days. The morphology and functions of the cells were examined. The generated cells had the typical morphology of DCs. When the DCs were reinjected into the same patient, an augmentation of the cytotoxic T lymphocyte (CTL) activity was observed. Concomitantly, an increase in the natural killer (NK) cell activity was also detected in the patient. These results suggest that DCs-based cancer immunotherapy may become an important treatment option for cancer patients in the future.     

The Influence of Alpha-fetoprotein on Natural Suppressor Cell Activity and Ehrlich Carcinoma Growth

The influence of alpha-fetoprotein (AFP) on the bone marrow (BM) natural suppressor (NS) cells of intact Ehrlich carcinoma -bearing CBA mice was studied. Bone marrow NS cells were fractionated into three fractions by isopycnic centrifugation on percoll gradients: NS1 (ρ=1.080 g/ml), NS2 (ρ=1.090 g/ml) and NS3 (1.100>ρ>1.090 g/ml). These fractions were highly different in their sensitivity to known NS cell inductors (interleukin (IL)-2, IL-3 or histamine). None of the NS fractions isolated from the intact mice spontaneously produced antiproliferative activity, however, they showed a high level of NS (antiproliferative and natural killer cell inhibitory) activity under the influence of AFP. A single injection of AFP to intact mice led to an increase of spontaneous NS activity and the inhibition of natural killer cell activity. NS activity, especially NS2, was increased in when tumor cells were subcutaneously inoculated three days after AFP injection. In the AFP-treated mice, the tumor mass at 14 days was 60% larger than that in the untreated mice. Our data confirmed that AFP is a tumor marker that can inhibit cancer immunity and plays a role in cancer pathogenesis.     

槲寄生凝集素对肿瘤细胞细胞周期的影响

目的通过体外实验研究槲寄生凝集素对肿瘤细胞的细胞毒性作用。方法采用MTT比色分析法测定槲寄生凝集素注射液对肿瘤细胞生长曲线的影响 ;采用流式细胞仪技术检测槲寄生凝集素注射液对肿瘤细胞细胞周期的影响。结果和结论槲寄生凝集素注射液对肿瘤细胞有剂量依赖性杀伤作用     

Identification of inducible genes during mast cell differentiation

Mast cells play an important role in allergic inflammation by releasing their bioactive mediators. The function of mast cells is enhanced by stimulation because of the induction of specific genes and their products. While many inducible genes have been elucidated, we speculated that a significant number of genes remain to be identified. Thus, we applied differential display (dd) PCR to establish a profile of the induced genes in bone marrow-derived mast cells (BMMCs) after they were co-cultured with 3T3 fibroblasts. To date, 150 cDNA fragments from the connective-type mast cells (CTMCs) were amplified. Among them, thirty cDNA fragments were reamplified for cloning and sequencing. The ddPCR strategy revealed that serine proteases were the most abundant genes among the sequenced clones induced during the maturation. Additionally, unknown genes from the co-culture of BMMCs with 3T3 fibroblasts were identified. We confirmed their induction in the CTMCs by Northern blot analysis and RT-PCR. Characterization of these induced genes during the maturation processes will provide insight into the functions of mast cells.     

肿瘤干细胞miRNA及miRNA作为肿瘤标志物的研究和临床应用进展

肿瘤干细胞(CSCs)理论为肿瘤的研究开辟了一个新的方向,CSCs学说认为肿瘤细胞具有异质性,肿瘤中存在干细胞样细胞,该群细胞是一种增殖失控、可形成肿瘤的细胞,只占肿瘤细胞很少部分,具有干细胞特性,是形成不同分化程度肿瘤细胞和肿瘤增长、复发及转移的根源。微小核糖核酸(miRNA)是广泛存在的非编码小RNA,调节着人类1/3的基因,越来越多的证据显示miRNA在肿瘤的发生发展中起着重要的作用,作为重要的转录后调控因子,广泛参与肿瘤相关基因调控的生物程序,使不同类型的肿瘤表现出特异的miRNA表达谱。近年来,CSCs的miRNA研究日益成为热点,已经发现多种CSCs中存在特异性表达的miRNA,对CSCs的生物学行为有了更进一步的认识。有研究发现肿瘤患者血浆中表达某些特异的miRNA,这些miRNA可以作为肿瘤的标志物对患者的病情及预后进行预测和判断。本文就近来CSCs中miRNA研究进展及miRNA作为肿瘤标志物研究进展进行综述。     

补骨脂定对骨髓间充质干细胞向癌相关成纤维细胞分化的抑制作用

目的探讨不同来源的间充质干细胞(MSCs)在癌细胞诱导下分化成癌相关成纤维细胞(CAFs)的情况,观察补骨脂定对人骨髓间充质干细胞(h BMSCs)和人脐带间充质干细胞(h UCMSCs)向CAFs分化的影响。方法利用Transwell小室,建立h BMSCs和h UCMSCs与4种女性特发恶性肿瘤细胞(BT-549、HEC-1B、Hela和SK-OV-3)共培养模型。梯度浓度的补骨脂定处理h BMSCs和h UCMSCs后,用Compu Syn软件计算半数抑制浓度(IC50),后续用10μmol·L-1补骨脂定处理各组细胞。用细胞增殖毒性(CCK-8法)检测细胞的增殖活性;流式细胞术分析细胞中α-平滑肌肌动蛋白(α-SMA)表达水平;用免疫印迹检测细胞中p-JAK2和p-STAT3表达水平。结果补骨脂定对h BMSCs和h UCMSCs的IC50分别是477.34和364.83μmol·L-1;在10μmol·L-1浓度下,对两种细胞活性的抑制率分别为(3.77±1.65)%和(3.70±2.11)%,均小于5%。h BMSCs与4种癌细胞共培养后,h BMSCs中α-SMA表达阳性率上升,肿瘤细胞的增殖活性增强,其p-JAK2和p-STAT3的表达水平上升;补骨脂定能显著抑制共培养体系中的上述现象。在共培养体系中,h UCMSCs中α-SMA表达阳性率不变,癌细胞的增殖活性却受抑制,其p-JAK2和p-STAT3的表达下降;补骨脂定不影响h UCMSCs中α-SMA、p-JAK2和p-STAT3的表达,但能增强h UCMSCs对癌细胞活性的抑制作用。结论在Transwell共培养环境中,补骨脂定可抑制h BMSCs向CAFs分化,降低癌细胞恶性增殖活性。     

Analysis of receptor-G protein interactions in permeabilized cells

Receptor-induced binding of the stable GTP analogue, guanosine 5-[-thio]triphosphate (GTP [S]), to guanine nucleotide-binding regulatory proteins (G proteins) was measured in various permeabilized cells. In myeloid differentiated human leukemia (HL-60) cells, permeabilized with either digitonin, streptolysin O or Staphylococcus aureus -toxin, binding of GTP [S] induced by three distinct chemoattractant receptors was observed. The extent of receptor-stimulated GTP [S] binding (maximally about 2-fold) was independent of the type of permeabilizing agent used. In human erythroleukemia cells permeabilized with digitonin, agonist activation of thrombin and neuropeptide Y receptors increased GTP [S] binding by 1.8- and 1.5-fold, respectively. Finally, in adherently grown human embryonic kidney cells permeabilized with digitonin, activation of the stably expressed human muscarinic m3 receptor increased GTP[S] binding by about 1.6-fold. In digitonin-permeabilized HL-60 cells, a quantitative analysis of formyl peptide receptors and interacting G proteins was performed. About 50,000 formyl peptide receptors per cell were detected. Agonist binding to these receptors was fully sensitive to regulation by guanine nucleotides and pertussis toxin. The number of high-affinity GTP [S] binding sites, most likely representing heterotrimeric G proteins, was calculated to be about 670,000 per cell. Stimulation of formyl peptide receptors led to the activation of about 130,000 of high-affinity GTP [S] binding sites, indicating a ratio of about three activated G proteins per one agonist-activated receptor.Overall, this study indicates that receptor-stimulated GTP [S] binding to G proteins in permeabilized cells is a sensitive and rapid method for analyzing receptor-G protein interactions, which can be applied to a variety of cultured cells and for various receptor systems.     

铜对培养心肌细胞电活动的影响

本文观察了不同剂量铜对培养心肌细胞动作电位的作用,2～5ppm可使APA、OS、RP降低,而Vmax、DDR、BR减慢,APD缩短,认为铜影响到细胞膜上酶的活性,而对Na~+、Ca~(2+)、K~+等离子导产生作用。     

碱性成纤维细胞生长因子对非贴壁骨髓基质前体细胞增殖及分化作用的研究

目的　探讨碱性成纤维细胞生长因子 (bFGF)对非贴壁骨髓前体细胞的增殖及分化作用。方法　分离骨髓前体细胞体外培养 ,用碱性磷酸酶化学染色及图像分析仪测定细胞克隆数 ;采用免疫组化 (ABC法 )检测PCNA、Ⅰ型胶原、钙及骨钙素。研究bFGF对非贴壁前体细胞的促增殖及分化作用。结果　骨髓细胞中许多基质前体细胞以非贴壁前体细胞 (NASP)形式存在 ,bFGF不仅能促进其增殖 ,而且能诱导其向成骨细胞分化。结论　bFGF主要作用于非贴壁生长的基质前体细胞 :能增加骨细胞的数量 ,促进骨样组织形成 ,为临床用bFGF治疗骨折、骨不连提供理论依据。     

[125I]Tyr10-cortistatin14 labels all five somatostatin receptors

The recently cloned rat preprocortistatin, which shows homology to the preprosomatostatin peptide, is thought to be enzymatically cleaved to cortistatin₁₄ (CST₁₄) similarly to somatostatin₁₄ (SRIF₁₄). High structural similarity of cortistatin₁₄ compared to SRIF₁₄ suggested binding properties to somatostatin receptors similar to SRIF₁₄. In the present study, we expressed stably the five human somatostatin receptor subtypes (hsst₁–hsst₅) in CCL39 cells (Chinese hamster lung fibroblast cells). The receptors were labelled with an iodinated analogue of CST₁₄ ([¹²⁵I]Tyr¹⁰-cortistatin₁₄, [¹²⁵I]Tyr¹⁰-CST) to establish the pharmacological profile of hsst₁–hsst₅ sites labelled with [¹²⁵I]Tyr¹⁰-CST. In parallel, [Leu⁸,D-Trp²²,¹²⁵I-Tyr²⁵]-SRIF₂₈ ([¹²⁵I]LTT-SRIF₂₈) was used as a control at the five recombinant SRIF receptors stably expressed in CCL39 cells. High affinity [¹²⁵I]Tyr¹⁰-CST binding could be demonstrated to all five recombinant somatostatin receptor subtypes. The pK_d (–log mol/l) and B_max values (fmol/mg) for hsst_1–5 receptors were: 10.02±0.04, 220±30; 9.45±0.09, 340±70; 10.06±0.11, 340±50; 9.67±0.14, 340±110 and 10.33±0.03, 5630±330, respectively. The pharmacological profiles determined with [¹²⁵I]Tyr¹⁰-CST and [¹²⁵I]LTT-SRIF₂₈ were very similar at every receptor studied. These data suggest that cortistatin and somatostatin have similar high affinity for SRIF receptors. None of the receptors showed marked selectivity for either CST₁₄/CST₁₇ or the somatostatins. In conclusion, the data show that cortistatin and somatostatin have very similar high affinity to all five recombinant somatostatin receptors. It remains to be seen whether there are specific receptors which bind only somatostatins or cortistatins. Received: 7 October 1997 / Accepted: 11 February 1998