成人骨髓间充质干细胞对造血干细胞体外增殖的影响

目的研究骨髓间充质干细胞（MSC）对脐带血（CB）CD34^＋细胞体外增殖和造血重建能力的影响。方法取人骨髓单个核细胞贴壁培养．梭形细胞完全融合后传代，用流式细胞仪检测免疫表型；将CBCD34^＋细胞接种到MSC或其他培养液中．比较不同培养条件对造血干细胞扩增能力、集落形成能力及黏附分子表达的影响。结果在加入IL-3的培养体系中．在MSC和细胞因子作用下，CD34^＋细胞扩增7d和14d后，有核细胞（NC）、CD34^＋细胞和CDl33^＋细胞数，实验组均显著多于对照组。CD34＋细胞在未加入IL-3的培养体系中培养8d后，实验组NC、CD34^＋细胞、CD34^＋CD38-细胞和造血祖细胞集落扩增倍数均显著高于对照组。扩增后CD34^＋细胞的ALCAM、VLA-α4、VLA-α5、VLA-β1、HCAM、PECAM和LFA-1表达较扩增前无显著变化。结论MSC可为造血干细胞（HSC）体外扩增提供适宜的微环境，有助于CD34^＋细胞体外增殖并抑制HSC分化，保持其造血重建潜能和归巢能力。     

休克期大面积切痂对严重烧伤大鼠细胞免疫功能影响的研究

目的 观察休克期大面积切痂对严重烧伤大鼠细胞免疫功能的影响，探索改善烧伤后机体免疫功能紊乱的有效方法。方法 将大鼠分成休克期切痂组（A组）、常规切痂组（B组）和正常对照组（C组）。A、B组造成30％TBSAⅢ度烫伤，C组不烫伤。A组伤后第6h、B组伤后第4d切痂，并于伤后第1、5、9d各活杀10只，取材送检，观察其免疫指标的变化。结果 （1）A、B组与C组比较：A、B组烫伤大鼠各时相点CD3^＋T细胞变化不大（P〉0．05），但CD4^＋T细胞、CD4^＋／CD8^＋比值明显下降、CD8^＋T细胞增高（P〈0．05或P〈0．01）。NK细胞活性明显下降（P〈0．05或P〈0.01），外周血CD25^＋T淋巴细胞表达及经活化后脾脏CD25^＋T淋巴细胞表达明显下降（P〈0．05或P〈0．01）。（2）A组与B组比较：A组CD4^＋T细胞、CD4^＋／CD8^＋比值明显升高、CD8^＋T细胞降低（P〈0．05或P〈0．01），NK细胞活性明显升高（P〈0．05或P〈0．01），外周血CD25^＋T淋巴细胞表达及经活化后脾脏CD25^＋T淋巴细胞表达均明显升高（P〈0．05或P〈0．01）。结论 （1）大鼠烫伤后细胞免疫状况发生了明显变化。（2）休克期切痂可以改善烫伤大鼠T淋巴细胞亚群分布，提高NK细胞活性，增加外周血CD25^＋T淋巴细胞的表达。提高经活化后脾脏CD25^＋T淋巴细胞数。从而改善烫伤大鼠伤后机体的细胞免疫功能。     

多细胞因子组合对人脐血单个核细胞体外扩增及粘附分子和CXCR4表达的影响

目的：探讨不同细胞因子组合对人脐血单个核细胞体外扩增及扩增后粘附分子和CXCR4表达的影响。方法：将新鲜脐血标本分离的单个核细胞接种于含有不同细胞因子组合的无血清无基质培养体系中培养7天,在0、7天检测有核细胞数（TNC）、CD34^＋细胞数及CD34^＋CXCR4^＋、CD34^＋CD49d^＋、CD34^＋CD62L^＋的细胞数和集落形成单位（CFU）数。根据不同细胞因子组合实验分组为：对照组;SCF＋FL（简称SF）组;SFT（SCF＋FL＋TPO）组;SFT6（SCF＋FL＋TPO＋IL-6）组;SFTs（SCF＋FL＋TPO＋sIL-6R）组;SFT6s（SCF＋FL＋TPO＋IL-6/sIL-6R）组。结果：和对照组相比,SF、SFT、SFT6、SFTs、SFT6s组均可有效地扩增脐血造血细胞（P〈0.05）,SFT、SFT6、SFTs、SFT6s四组扩增效果优于SF,差异有显著性（P〈0.05）,但SFT和SFT6、SFTs三组之间却无明显区别（P〉0.05）,在SFT6组合基础上加入sIL-6R后,即SFT6s组能有效地扩增脐血细胞,并优于SFT、SFT6、SFTs三组（P〈0.05）;SF、SFT、SFT6、SFTs四组细胞因子组合均可提高脐血CD34＋细胞上CD49d、CD62L和CXCR4的表达,但四组之间差异无显著性（P〉0.05）,SFT6s组可明显促进脐血CD34＋细胞上CD49、CD62L和CXCR4的表达,并优于SF、SFT、SFT6、SFTs四组,差异有显著性（P〈0.05）。结论：IL-6/sIL-6R可协同SCF、FL和TPO有效地扩增脐血细胞并能促进和归巢有关的CD49d、CD62L及CXCR4表达     

中国HIV感染者细胞毒性淋巴细胞内穿孔素的差异性表达

目的 了解中国HIV感染者细胞毒性相关的NK细胞及CD8^＋T细胞内穿孔素表达水平，探讨HIV感染过程中穿孔素表达与机体免疫功能的关系。方法 采集31例未经抗病毒治疗的HIV感染者和经过高效抗逆转录病毒疗法（HAAS）治疗的17例HIV／AIDS患者以及15例健康对照的抗凝全血，应用流式细胞仪胞内染色法检测CD56^＋／CD3^-、CD3^-／CD16^＋NK细胞及CD8^＋／CD3^＋内穿孔素表达的百分数，分析其与NK细胞绝对值、NK细胞百分数、CD4^＋T、CD8^＋T淋巴细胞绝对值及血浆病毒载量的相关性。结果 中国HIV感染者的NK细胞CD56^＋／CD3^-及CD3^-／CD16^＋亚群穿孔素表达百分数（平均13．17％，平均24．05％）高于CD8^＋T细胞穿孔素表达百分数（平均9．03％）；NK细胞内穿孔素表达低于健康对照（P〈0．05，P〈0．05），CD8^＋T细胞内穿孔素表达高于健康对照（P〈0．05）；NK细胞及CD8^＋T细胞内穿孔素表达水平与其绝对计数显著相关，与疾病进展不相关。HAART治疗组NK细胞内穿孔素表达升高，CD8T^＋细胞内穿孔素表达无显著变化。结论 中国HIV感染者NK细胞内穿孔素表达降低，抗病毒治疗后升高；CD8^＋T细胞内穿孔素表达升高，抗病毒治疗后无显著变化。     

T淋巴细胞亚群检测在肾移植排斥反应与环孢霉素A中毒鉴别诊断中的应用

目的探讨外周血淋巴细胞亚群检测在人类同种异体肾移植术后急性排斥反应与免疫抑制剂环孢霉素A（cyclosporine A，CSA）中毒的诊断与鉴别诊断中的价值。方法采用四色流式细胞技术对26例肾移植术后肾功能正常、11例急性排斥反应、10例环孢霉素A中毒患者外周血淋巴细胞亚群中CD3^＋、CD3^＋CD4^＋、CD3^＋CD8^＋细胞的百分比进行检测。结果肾功能正常组、急性排斥反应组与环孢霉素A中毒组外周血淋巴细胞中CD3^＋细胞的百分比分别为71．83％±9．65％、73．29％±8．85％、72．06％±12．04％，3组比较差异无统计学意义；CD3^＋CD4^＋细胞的百分比分别为38．69％±9．21％、49．58％±8．41％、40．15％±9．98％，急性排斥反应组与正常组和CSA中毒组比较差异有显著统计学意义（P〈0．01）；CD3^＋CD8^＋细胞百分比分别为29.28％±9．02％、19．18％±5.35％、30．86％±9．19％，急性排斥反应组与正常组和CSA中毒组比较差异有显著统计学意义（P〈0．01）；CD3^＋CD4^＋／CD3^＋CD8^＋分别为1．76±0．97、2．92±0．71、1．81±0．92，急性排斥反应组与正常组和CSA中毒组比较差异有显著统计学意义（P〈0．01）。结论检测外周血淋巴细胞亚群的变化，对肾移植术后急性排斥反应和环孢霉素A中毒有鉴别诊断的价值。     

烫伤对大鼠免疫功能的影响及药膳饮食对其的调理作用观察

目的观察烫伤对大鼠免疫功能的影响及药膳饮食对其的调理作用。方法健康Wistar大鼠70只，体质量（200±20）g，雌雄各半，随机分成正常对照组（A组，n=10）、烧伤常规喂养组（B组，n=30）和烧伤药膳喂养组（C组，n=30）。A组37℃造成假伤后全部处死取材，B、C组大鼠造成30％TB-SAⅢ度烧伤伤后B组常规饲养，C组伤后2h开始以复温至37℃的药膳饮食灌胃，2ml/次，2次／d＋常规饲养。B、C组于伤后3、7、14d各取10只，无菌条件下取材送检，观察T淋巴细胞亚群和NK细胞活性、血浆IgA、IgG、IgM、C3、C4、含量、肠道sIgA含量的变化。结果①B、C组伤后CD3^＋、CD4^＋、CD4^＋／CD8^＋、NK细胞活性、IgA、IgG、IgM、C3、C4水平及肠道sIgA含量均低于A组，CD8^＋高于A组（P〈0．05或P〈0．01）；②C组与B组比较，各免疫指标均恢复快（P〈0．05或P〈0．01）。结论严重烫伤大鼠细胞免疫和体液免疫功能发生了改变；药膳饮食可以改善烫伤大鼠T淋巴细胞亚群分布，提高NK细胞活性，促进血浆IgA、IgM、IgG、C3、C4的恢复和肠黏膜细胞sIgA的分泌，从而改善机体的免疫功能。     

脐带血造血前体细胞在间质干细胞微环境中的增殖和分化特性研究

目的： 用间质干细胞（MSC）体外模拟造血微环境，探讨脐带血造血前体细胞在MSC微环境中的增殖和分化特性。方法： 实验组（CK+MSC组）以MSC为基质层细胞，建立基于MSC的体外造血细胞扩增体系，接种脐带血单个核细胞，培养体系中加入外源性造血生长因子SCF、Flt3L、TPO和IL-6，培养第1、2、3、4周对扩增的细胞进行细胞计数、集落培养，对照组为单纯细胞因子组（CK组，无MSC基质层细胞）和单纯MSC组（无脐带血单个核细胞）。结果： (1)第4周时CK+MSC组的细胞数扩增108倍，而CK组只有7.8倍。(2)CK+MSC组和CK组扩增的集落形成细胞（CFC）数量在第3周时达高峰，第4周时CFC数量已迅速下降。(3)红系CFC和高增殖潜能集落形成细胞（HPP-CFC）均于扩增1周后到达高峰，CK+MSC组的扩增效率要优于CK组，到第3周时两组均降为零。(4)粒单系CFC则在扩增第3周时到达高峰，CK+MSC组扩增效率优于CK组，从第4周开始出现回落。(5)扩增1周后，单位细胞（10⁴个MNC）中的CFC数到达高峰，CK+MSC组优于CK组，从第2周开始每104个MNC中的CFC数迅速呈下降趋势，到第4周时已降至低于扩增前水平。(6)单纯MSC组无造血细胞生长。结论： (1)体外扩增脐带血造血前体细胞时，基于MSC的扩增体系要优于单纯细胞因子体系。(2)MSC在体外有利于脐带血造血前体细胞扩增的同时，并不能阻止其分化。(3)红系扩增出现在体外扩增的早期，粒单系扩增持续的时间比红系长，扩增的CFC数量更多。     

初发系统性红斑狼疮患者外周血CD4~+CD25~+Foxp3~+和CD4~+CD25~-Foxp3~+T细胞

目的：研究初发系统性红斑狼疮患者（Systemic lupus elythematosus，SLE）外周血CD4^＋T细胞中CD25和Foxp3表达及其在SLE发病中的意义。方法：根据SLE疾病活动积分（SLEDAI）将初发SLE患者分为活动组（10例）和不活动组（11例），流式细胞仪检测治疗前后外周血CD4^＋T细胞中CD25、Foxp3和CD127表达百分率，并对其与SLE临床活动度、尿蛋白、补体和anti-ds-DNA相关性进行研究。结果：初发活动组和不活动组SLE患者CD4^＋CD25^＋Foxp3^＋T细胞表达百分率分别为（1．91％～6．75％）和（2．74％～7．01％），与正常对照（2．11％～9．90％）相比没有统计学差异（P=0．524，P=0．794）；且初发SLE患者外周血CD4^＋CD25^＋T细胞在体外增殖反应和增殖抑制功能与正常对照相比无明显差别（P=0．174，P=0．689）；外周血CD4^＋CD25^-Foxp3^＋T细胞百分率在初发活动组（3．71％～10．94％）和不活动组（2．97％～7．69％）SLE患者均比正常对照（1．01％～3．62％）显著增高（P〈0．01和P〈0．01）；而CD4^＋CD2^＋Foxp34^-T百分率在初发活动组SLE患者（1．19％～9．23％）显著低于正常对照（2．67％～11．26％）和初发不活动组SLE患者（3．73～8．27％）（P=0．039，P=0．048）；与CD4^＋CD25^＋Foxp3^＋T细胞类似，90％左右的CD4^＋CD25一Foxp3^＋T细胞不表达或低表达CD127，其百分率与anti-ds-DNA浓度呈正相关，且尽管未达到统计学意义，但激素和免疫抑制治疗后其水平下降。结论：初发未经治疗的SLE患者CD4^＋CD25^＋Foxp3^＋T细胞数量和功能无明显异常，而CD4^＋CD25^-Foxp3^＋T细胞数量增多，与SLE疾病活动相关，可能具有调节功能。     

慢性乙型肝炎患者外周血淋巴细胞CD8+CD38+的检测意义

目的：通过测定慢性乙型肝炎患者外周血淋巴细胞CD8^＋CD38^＋的表达及门冬氨酸氨基转移酶（AST）、总胆红素（TBIL）、凝血酶原时间（PT），旨在为治疗慢性乙型肝炎提供有用的参考指标。方法：流式细胞术检测38例慢性乙型肝炎、14例肝硬化患者外周血淋巴细胞CD8^＋CD38^＋细胞的百分率；同时测定AST、TBIL和PT。结果：（1）慢性乙型肝炎组CD8^＋CD38^＋、CD38^＋细胞均明显高于正常组（P〈0．01，P〈0．01），肝硬化组CD8^＋CD38^＋、CD38^＋细胞均明显高于正常组（P〈0．05，P〈0．05）。肝硬化组CD8^＋CD38^＋、CD8^＋细胞均明显低于慢性乙型肝炎组（P〈0．05，P〈0．05）。（2）慢性乙型肝炎轻、中、重各组之间比较，中度组CD8^＋CD38^＋高于轻度组（P〈0．05），重度组CD8^＋CD38^＋、CD8^＋、CD38^＋均高于轻度组（P〈0．05，P〈0．05，P〈0．05）；重度组CD38^＋高于中度组（P〈0．05）；肝硬化组CD8^＋CD38‘均明显低于轻、中、重各组（P〈0．05，P〈0．01，P〈0．01），肝硬化组CD8^＋低于重度组（P〈0．01）。（3）慢性乙型肝炎患者AST、TBIL、PT不正常组CD8^＋CD38^＋均高于AST、TBIL、PT正常组。结论：慢性乙型肝炎患者CD8^＋CD38^＋细胞明显升高，表明慢性乙型肝炎患者细胞免疫处于异常激活状态，并与肝功能损伤有一定的相关性。慢性乙型肝炎患者外周血淋巴细胞CD8^＋CD38^＋的测定，对病情分析和诊断有一定的临床参考价值。     

中国HIV-1暴露未感染者及感染者趋化因子受体CX3CR1的表达研究

目的 通过分析中国HIV-1暴露未感者（exposed semnegative individuals，ESN）及HIV-1感染者外周血中CX3C1^＋CD8^＋／CD3^＋、CX3CR1^＋CD16^＋／CD3^-、CX3CR1^＋CD56^＋／CD3^-细胞百分率及绝对值的变化，探讨CX3CR1受体与HIV-1感染及疾病进展的关系。方法 采集19例ESN、34例未经治疗的HIV-1感染者及18例健康人抗凝静脉血，采用流式细胞仪检测技术，分析计算三色荧光抗体标记的全血中CX3CR1^＋CD8^＋／CD3^＋、CX3CR1^＋CD16^＋／CD3^-、CX3CR1^＋CD56^＋／CD3^-细胞百分率及绝对值。结果 ESNCX3CR1^＋CD8^＋／CD3^＋细胞的百分率是11．05％±6．52％，绝对值是81．16±13．67个／山，显著高于正常对照组（百分率是5．69％±3．94％，绝对值是37．36±8．28个/μl）；HIV-1感染组CX3CR1^＋CD8^＋／CD3^＋细胞的百分率是20．98％±11．88％，绝对值是166．38±138．38个/μl，显著高于正常对照组。ESN的CX3CR1^＋CD16^＋／CD3^-细胞的绝对值是312．49±159．45个／m，显著高于HIV-1感染组（108．83±119．35个／ta）。ESN的CX3CR1^＋CD56^＋／CD3^-细胞的绝对值是316．98±162．56个叫，显著高于HIV-1感染组（100．27±114．57个／ta）。HIV．1感染者的CX3CR1^＋CD16^＋／CD3^-、CX3CR1^＋CD56^＋／CD3^-细胞的绝对值与CIM^＋T淋巴细胞的绝对值呈明显正相关（P〈0．05）。结论CX3CR1^＋CD8^＋／CD3^＋细胞在中国ESN体内起保护作用，而在HIV-1感染者体内发挥有限的保护作用。表达CX3CR1受体的NK细胞可以作为监测HIV-1感染者免疫状况的一个指标。     

脐血造血干/祖细胞移植SCID小鼠的实验研究

目的 :检测扩增后脐血造血干 祖细胞的体内移植能力和造血活性 ,建立脐血细胞体外扩增优化方案和体内移植的SCID小鼠模型。方法 :采用无基质接触的液体悬浮培养方法扩增脐血CD34 细胞 ,将扩增前后的细胞移植给预先经过亚致死量辐照的SCID小鼠 ,4w后通过免疫荧光标记、PCR等检测存活小鼠体内的人源细胞。结果 :连续培养一定时间后 ,FL TPO SCF IL 6组脐血细胞得到持续扩增 ,并能维持一定比例的CD34 细胞 ;SCF IL 3 IL 6 GM CSF EPO组在第 2周时集落形成数已降低 ,第 4周时集落形成的细胞、CD34 细胞已基本检测不到。移植至少 4w后 ,在存活小鼠体内检测到人CD4 5 细胞和Alu基因。结论 :因子组合FL TPO CSF IL 6可以有效扩增脐血CD34 细胞 ,而且扩增后的细胞具有较高的移植效率和造血活性     

重组人Delta-like 1蛋白表达及其对脐带血CD34+细胞扩增作用

目的构建pET32a(+)-hDll1DSL原核表达载体,表达、纯化hDll1DSL蛋白,观察其对脐带血CD34+细胞的体外扩增作用。方法克隆hDll1DSL,构建pET32a(+)-hDll1DSL重组表达载体。转化大肠杆菌BL21,异丙基-β-D-硫代吡喃半乳糖苷(IPTG)诱导蛋白表达,镍珠亲合层析纯化蛋白。重组信号结合蛋白(RBP-J)报告基因实验及Notch下游分子Hes1检测证实hDll1DSL活性。磁珠分选脐带血CD34+细胞,加入hDll1DSL或联合干细胞因子(SCF)、Flt3配体(FL)、血小板生成表(TPO)孵育1周,观察体外扩增作用。结果成功克隆hDll1DSL,并构建了pET32a(+)-hDll1DSL重组表达载体。在大肠杆菌BL21成功表达Trx-hDll1DSL融合蛋白,经镍珠亲合层析纯化蛋白,成功获得高纯度的Trx-hDll1DSL融合蛋白。配体活性实验显示,可溶性的Trx-hDll1DSL蛋白可以激活RBP-J报告基因,并且能上调Notch下游分子Hes1的表达,证明其能够激活Notch信号通路。此外,Trx-hDll1DSL融合蛋白与SCF、FL及TPO联用,具有协同刺激CD34+细胞体外扩增的作用。结论成功构建了pET32a(+)-hDll1DSL重组表达载体,表达、纯化了具有生物学活性的Trx-hDll1DSL融合蛋白,具有协同刺激CD34+细胞体外扩增的作用,为造血干/祖细胞体外扩增体系的优化研究奠定了基础。     

Interleukin 3 improves the ex vivo expansion of primitive human cord blood progenitor cells and maintains the engraftment potential of scid repopulating cells.

In umbilical cord blood (UCB) transplantation, the number of nucleated cells per kilogram is a major predictive and critical factor of hematopoietic recovery. Thus, ex vivo expansion of hematopoietic UCB progenitors could potentially accelerate engraftment. Whereas Flt-3 ligand (FL), stem cell factor (SCF), and thrombopoietin (TPO) are considered indispensable, the role of interleukin 3 (IL-3) is still controversial: it has been reported either to support or abrogate the reconstituting ability of stem cells. By adding IL-3 we aimed to enhance the amplification of early and committed progenitor cells without impairing the long-term engraftment of stem cells. Demonstrating a positive impact of IL-3 on the proliferation of all progenitor subsets, the amplification of CD34+ UCB cells was increased 20.9-fold +/- 5.4 (mean +/- standard error) in serum-free culture with FL, SCF, TPO, and IL-3 as opposed to 9.3-fold +/- 3.2 without IL-3 after 7 days. If IL-3 was included, primitive long-term culture-initiating cells and committed colony-forming cells were expanded 16.3-fold +/- 5.5 and 18.1-fold +/- 2.4, respectively, compared to 12.6-fold +/- 5.6 and 9.1-fold +/- 2.0 without IL-3. Analysis of cultured CD34+ UCB cells in sublethally irradiated nonobese diabetic/severe combined immunodeficient mice confirmed that cultured cells had preserved their repopulating potential. After 6 weeks, all mice showed multilineage engraftment with their bone marrow containing an average of 45% human CD45+ cells of the unmanipulated sample, 43% of cells after culture in the presence of IL-3, and 27% of cells after culture without IL-3. In combination with early acting cytokines, IL-3 therefore improves the ex vivo expansion of UCB stem and progenitor cells without impairing their engraftment potential.     

Cotransplantation of cord blood hematopoietic stem cells and culture-expanded and GM-CSF-/SCF-transfected mesenchymal stem cells in SCID mice

Mesenchymal stem cells (MSC) are multipotent in nature and believed to facilitate the engraftment of hematopoietic stem cells (HSC) when transplanted simultaneously in animal studies and even in human trials. In this study, we transfected culture-expanded MSC with granulocyte macrophage-colony stimulating factor (GMCSF) and stem cell factor (SCF) cytokine genes and then cotransplanted with mononuclear cells (MNC) to further promote HSC engraftment. MNC were harvested from cord blood and seeded in long-term culture for ex vivo MSC expansion. A total of 1 x 10(7) MNC plus MSC/microL were introduced to the tail vein of nonobese diabetic/severe combined immunodeficiency mice. After 6-8 weeks later, homing and engraftment of human cells were determined by flow cytometry and fluorescence in situ hybridization studies. The total nucleated cell count and the engraftment of CD45+/CD34+ cells and XX or XY positive human cells were significantly increased in cotransplanted mice and even higher with the cytokine gene-transfected MSC (GM-CSF>SCF, p<0.05) than in transplantation of MNC alone. These results suggest that MSC transfected with hematopoietic growth factor genes are capable of enhancing the hematopoietic engraftment. Delivering genes involved in homing and cell adhesions, CXCR4 or VLA, would further increase the efficiency of stem cell transplantation in the future.     

Fast but durable megakaryocyte repopulation and platelet production in NOD/SCID mice transplanted with ex-vivo expanded human cord blood CD34+ cells

We have previously established a stroma-free culture with Flt-3 ligand (FL), stem cell factor (SCF), and thrombopoietin (TPO) that allows the maintenance and the expansion for several weeks of a cord blood (CB) CD34+ cell population capable of multilineage and long-lasting hematopoietic repopulation in non-obese diabetic/ severe combined immunodeficient (NOD/SCID) mice. In this work the kinetics of megakarocyte (Mk)-engraftment that is often poor and delayed in CB transplantation, and human platelet (HuPlt) generation in NOD/SCID mice of baseline CD34+ cells (b34+), and of CD34+ cells reisolated after a 4-week expansion with FL+SCF+TPO (4w34+) were compared. With b34+ cells Mk-engraftment was first seen at week 3 (CD41+: 0.4%); 4w34+ cells allowed a more rapid Mk-engraftment (at weeks 2 and 3 the CD41+ cells were 0.3% and 0.8%). Circulating HuPlts were first seen at weeks 2 and 1, respectively. Mk-engraftment levels of b34+ and 4w34+ cells 6-8 weeks after transplantation were similar (12 +/- 3.5 versus 15 +/- 5% CD45+; 1.3 +/- 0.5 versus 1.8 +/- 0.5% CD41+ cells). Also serial transplant experiments were performed with expanded and reselected CB cells. In secondary and tertiary recipients the Mk population was detected with bone marrow fluorescence-activated cell sorter analysis; these experiments indicate the effective long-term repopulation of expanded cells. Selected CD34+ cells after a 4-week expansion with FL+SCF+TPO are more efficient in Mk engraftment than the same number of unmanipulated cells.     

Ex vivo expansion of megakaryocyte progenitor cells: cord blood versus mobilized peripheral blood

Thrombocytopenia is a problematic and potentially fatal occurrence after transplantation of cord blood stem cells. This problem may be alleviated by infusion of megakaryocyte progenitor cells. Here, we compared the ability of hematopoietic progenitor cells obtained from cord blood and expanded in culture to that of mobilized peripheral blood cells. The CD34(+) cells were plated for 10 days in presence of thrombopoietin (TPO) alone and combined with stem cell factor (SCF), Flt3-ligand (FL), interleukin-3 (IL-3), IL-6, and IL-11. Cells were analyzed for the CD41 and CD42b expression and for their ploidy status. Ex vivo produced platelets were enumerated. We show that (1) TPO alone was able to induce differentiation of CD34(+) cells into CD41(+) cells, with limited total leucocyte expansion; (2) the addition of SCF to TPO decreased significantly CD41(+) cell percentage in CB, but not in MPB; and (3) in CB, the addition of FL, IL-6, and IL-11 to TPO increased the leukocyte expansion with differentiation and terminal maturation into MK lineage. In these conditions, high numbers of immature CD34(+)CD41(+) MK progenitor cells were produced. Our results thereby demonstrate a different sensitivity of CB and MPB cells to SCF, with limited CB MK differentiation. This different sensitivity to SCF (produced constitutively by BM stromal cells) could explain the longer delay of platelet recovery after CB transplant. Nevertheless, in CB, the combination of TPO with FL, IL-6, and IL-11 allows generation of a suitable number of immature MK progenitor cells expressing both CD34 and CD41 antigens, which are supposed to be responsible for the platelet recovery after transplantation.     

Small peptide analogue of SDF-1alpha supports survival of cord blood CD34+ cells in synergy with other cytokines and enhances their ex vivo expansion and engraftment into nonobese diabetic/severe combined immunodeficient mice

The SDF-1/CXCR4 axis has been implicated in the chemotaxis, homing, mobilization, and expansion of hematopoietic stem and progenitor cells. We studied the effects of a SDF-1 peptide analogue CTCE-0214 on the survival of cord blood CD34+ cells in culture, expansion, and engraftment of expanded cells in the nonobese diabetic/severe combined immunodeficient (NOD/SCID) mouse model. Our results demonstrated that CTCE-0214 synergized with thrombopoietin (TPO), stem cell factor (SCF), or flt-3 ligand (FL) on the survival of stem and progenitor cells in culture. Adding CTCE-0214 at a low concentration (0.01 ng/ml) for 4 days together with TPO, SCF, and FL significantly enhanced ex vivo expansion of CD34+ cells to subsets of primitive (CD34+CD38- cells, colony-forming unit-mixed [CFU-GEMMs]), erythroid (CFU-Es), myeloid (CFU-GMs), and megakaryocytic (CD61+CD41+ cells, CFU-MKs) progenitors, as well as their multilineage engraftment in NOD/SCID mice. Interestingly, the short exposure of expanded cells to CTCE-0214 (100 and 500 ng/ml) for 4 hours did not increase the quantity of progenitor cells but enhanced their engraftment capacity. The proportion of CD34+ cells expressing surface CXCR4 was decreased, but the overall number of this population increased upon expansion. The small peptide analogue of SDF-1 could be developed for ex vivo expansion and improving engraftment of cord blood transplantation.     

Primary cells as feeder cells for coculture expansion of human hematopoietic stem cells from umbilical cord blood--a comparative study

Although umbilical cord blood (UCB) has been widely accepted as an alternative source of hematopoietic stem cells (HSC) for transplantation, its use in adults is restricted because of low absolute HSC numbers. To overcome this obstacle, expansion of HSC in coculture with feeder cells is a promising possibility. In this study, we compared the potential of three human primary cell types, namely, mesenchymal stem cells (MSC), human umbilical cord vein endothelial cells (HUVEC), and Wharton's jelly cells (WJC), for use as feeder cells in a potentially clinically applicable coculture system. In first experiments, we evaluated procedures needed to obtain feeder cells, the possibility to separate them from cells derived from CD34(+) cells after coculture, their ability to activate allogeneic T cells, and their survival in CD34(+)-adapted medium. Finally, we compared their support for UCB-derived CD34(+) expansion. MSC and WJC were superior to HUVEC in terms of ease and reliability of isolation procedures needed. None of the potential feeder cells expressed CD34 or CD45, thus providing markers for cell sorting after coculture. Other markers (CD31, CD90, CD105, CD166) were expressed differently on feeder cell types. While MSC in higher concentrations did not activate allogeneic T cells, those were stimulated by lower concentrations of MSC as shown by CD25, CD69, and CD71 expression. In contrast, HUVEC and WJC were proven to activate T cells at all ratios tested. Feeder cells survived a 7-day culture in CD34(+)-adapted medium. In cocultures of UCB CD34(+)cells with primary feeder cells, mononuclear cell expansion was 30- to 60-fold, colony-forming cell expansion 20- to 40-fold, and cobblestone area-forming cell expansion 10- to 50-fold. We conclude that after a careful further evaluation especially of their immunological properties, all three primary cell types might possibly be suitable for use in a potentially clinically applicable system for expansion from UCB CD34(+)cells, with WJC being best choice and MSC still superior to HUVEC.