人白血病抑制因子在果蝇细胞S2中的表达

目的 克隆人白血病抑制因子基因并将其在果蝇细胞中表达.方法 以人6w胚胎绒毛的总RNA为模板,利用RT-PCR方法扩增人白血病抑制因子cDNA,测序后将其克隆到真核表达载体C,经电穿孔法将构建的重组人白血病抑制因子质粒转染果蝇细胞S2,48h后用免疫斑点法检测人白血病抑制因子的瞬时表达情况.结果 从人早孕胚胎组织获得了长度为543bp的白血病抑制因子cDNA片段,新构建的人白血病抑制因子真核表达载体中,有人白血病抑制因子cDNA的正确插入,转染人白血病抑制因子cDNA的S2细胞培养上清中含有人白血病抑制因子蛋白.结论 成功地构建了人白血病抑制因子真核表达载体,人白血病抑制因子可在果蝇细胞中呈分泌性表达.     

Ad-hLIF转基因饲养层细胞对CD34+造血干/祖细胞增殖和分化的影响

目的 用腺病毒载体介导的人白血病抑制因子基因(Ad-hLIF)感染WI-38人胚肺成纤维细胞制备饲养层细胞,体外观察转基因细胞对CD34+造血干/柑细胞增殖和分化的影响,体内研究对辐射损伤SCID小鼠造血功能恢复的效果.方法 用RT-PCR和ELISA法鉴定Ad-hLIF转基因饲养层细胞目的 基因的表达后,将经免疫磁珠法分离和流式细胞术检测后的CD34+细胞在饲养层和/或细胞因子培养体系中扩增28 d,检测不同时间点的单个核细胞(MNC)数量及CD34+细胞阳性率;扩增后的MNC经CFDA SE荧光标记后移植入辐射损伤SCID小鼠体内,RT-PCR和细胞荧光标记法检测小鼠内含Alu基因人源细胞的门巢情况.结果 感染50MOI(multiplicity of infection)Ad-hLIF的饲养层细胞均有绿色荧光,RT-PCR和ELISA法结果 显示hLIF目的 基因能在WI-38饲养层细胞中表达,免疫磁珠法分离的CD34+造血干/祖细胞经流式细胞术检测其纯度可达95.60%±2.58%,MNC在Ad-hLIF转基因饲养层培养体系持续扩增,最高可达356.95±0.87倍,其中CD34+细胞仪在0～14 d能维持较高水平,最高可扩增52.11±1.13倍,以后逐渐降低.将其移植辐射损伤SCID小鼠后,可明显提高小鼠存活率,4周内小鼠骨髓中不仅可观察到CFDA SE荧光标记的细胞,而且经RT-PCR法搭定后.还可检测到表达Alu人源基因的人脐血造血归巢细胞.结论 成功建立的Ad-hLIF转基因饲养层细胞不仅体外可以有效地扩增CD34+造血干/祖细胞,并延缓其分化.扩增的CD34+细胞对辐射损伤SCID小鼠具有造血功能恢复的功能.     

CD34~＋造血干/祖细胞在转hLIF基因腺病毒载体饲养层细胞中的扩增及其移植SCID小鼠的实验研究

目的:建立转hLIF基因腺病毒载体的饲养层细胞,观察对CD34+造血干/祖细胞的扩增作用,并研究移植辐射损伤模型SCID小鼠的效果.方法:建立转hLIF基因腺病毒载体的饲养层细胞,并用RT-PCR法鉴定目的基因;采用免疫磁珠法分离脐带血CD34+造血干/祖细胞,流式细胞术检测纯度;将CD34+造血干/祖细胞与饲养层细胞共培养,流式细胞术检测各组增殖效果,建立辐射损伤模型SCID小鼠,将扩增后的CD34+造血干/祖细胞经CFDA SE荧光标记后移植入SCID小鼠体内,通过RT-PCR和观察荧光标记细胞来检测小鼠内的人源细胞.结果:建立的转基因饲养层细胞均有绿色荧光,RT-PCR法证实有目的基因表达,免疫磁珠法分离的CD34+造血干/祖细胞纯度可达(95.6±2.58)%,与饲养层细胞共培养后CD34+造血干/祖细胞可扩增13.2倍,表面粘附分子CXCR4和CD54表达量仍较高,移植入SCID小鼠四周后,仍可见带有荧光标记的人源细胞,RT-PCR证明人源基因Alu的存在.结论:建立的转hLIF基因腺病毒载体饲养层细胞可以有效地扩增CD34+造血干/祖细胞,延缓其分化,并且有较高的移植效率和造血活性.     

Generation of mutant leukaemia inhibitory factor (LIF)-IgG heavy chain fusion proteins as bivalent antagonists of LIF

Two leukaemia inhibitory factor (LIF) mutants, designated MH35-BD and LIF05, have been shown to have a capacity to inhibit the biological activities of not only human LIF (hLIF) but also other interleukin-6 (IL-6) subfamily cytokines such as human oncostatin M (hOSM). These cytokines share the same receptor complex in which the glycoprotein 130 (gp130) subunit is a common constituent. However, at low concentrations and in their monomeric forms, such molecules have a relatively short plasma half-life due to rapid clearance from the kidneys. Here, to prolong their serum half-lives, we have used a multi-step polymerase chain reaction (PCR) to fuse each of the LIF05 and MH35-BD cDNA fragments to a sequence encoding the Fc portion, and the hinge region, of the human immunoglobulin G (hIgG) heavy chain. The linking was achieved through an oligomer encoding a thrombin-sensitive peptide linker thus generating MH35-BD:Fc and LIF05:Fc, respectively. Both Fc fusion constructs were expressed in insect cell Sf21 and the proteins were purified by two successive affinity chromatography steps using nickel-nitrilotriacetic acid (Ni-NTA) agarose and protein A beads. The Ba/F3 cell-based proliferation assay was used to confirm that the proteins were biologically active. In addition, preliminary pharmacokinetics indicates that the Fc fusion constructs have a longer serum half-life compared to their non-fusion counterparts.