四环素调控基因(TetO)诱导重编程的猪体细胞系建立

建立含有TetO-FUW-OSKM和FUW-M2rtTA的第二代猪(Sus scrofa domesticus)成纤维细胞,使其在添加强力霉素(doxycycline,DOX)而无需再次感染病毒的条件下可以重编程。将慢病毒(Lentiviral)质粒四环素调控基因(TetO)-FUW-OSKM和FUW-M2rtTA同时感染猪胎儿成纤维细胞(porcine embryonic fibroblasts,PEF),在添加DOX的培养条件下,形成诱导多能干细胞(induced pluripotent stem cells,iPSCs)。随后,将iPSCs通过形成拟胚体(embryoid body,EB)再分化为成纤维样细胞,即TetO-PEF细胞。TetO-PEF携带TetO-FUW-OSKM和FUW-M2rtTA两个载体,且外源四因子拷贝数一致,在+DOX条件下调控四因子表达,直接驱动细胞重编程。本研究建立了TetO-PEF细胞系,为优化猪iPSCs培养条件提供了新的细胞资源。     

Factors Affecting the Development of Somatic Cell Nuclear Transfer Embryos in Cattle

Nuclear transfer is a complex multistep procedure that includes oocyte maturation, cell cycle synchronization of donor cells, enucleation, cell fusion, oocyte activation and embryo culture. Therefore, many factors are believed to contribute to the success of embryo development following nuclear transfer. Numerous attempts to improve cloning efficiency have been conducted since the birth of the first sheep by somatic cell nuclear transfer. However, the efficiency of somatic cell cloning has remained low, and applications have been limited. In this review, we discuss some of the factors that affect the developmental ability of somatic cell nuclear transfer embryos in cattle.     

诱导多能干细胞新进展

对近几年来多能干细胞（iPS细胞）的研究进展和安全性问题进行了论述,并对iPS细胞的应用前景进行了展望。     

哺乳动物体细胞异种核移植胚胎早期发育的研究进展

体细胞异种核移植是指将一个物种的体细胞移植到另一物种的去核卵母细胞中,移入的体细胞核在受体胞质中重编程并发育成新个体的实验方法。该方法为拯救濒危物种和获取灵长类胚胎干细胞提供了可能的途径。但这方面的研究目前还只获得初步的进展,核重编程不完全以及异种胚胎的囊胚率低仍是其面临的主要难点。本文从基因表达、表观重编程、线粒体异质性、核重塑和核移植体系优化等方面入手,介绍近年来哺乳动物体细胞异种核移植的研究进展,并探讨异种重构胚重编程所面临的关键问题和可能获得成功的方法。     

影响哺乳动物克隆效率因素研究进展

哺乳动物克隆效率低下,克隆后代发育异常已成为目前制约动物克隆技术发展和应用的瓶颈.概述哺乳动物克隆中供体细胞的选择、供体核再编程和重构胚的培养等因素对克隆效率的影响,以及提高克隆效率的策略.     

山羊诱导性多能干细胞培养体系的筛选

[目的]使用多种培养成分组合,筛选出一个适合山羊诱导性多能干细胞(induced pluripotent stem cells,i PSCs)的培养体系。[方法]采用慢病毒作为载体,携带多能因子,采用多种培养成分(培养基、血清和细胞因子)的组合培养山羊i PSCs,优化其培养体系。[结果]用FBS代替KSR可以提高克隆的形成效率以及克隆的质量,而用DMEM/F12代替KNOCKOUT-DMEM,i PSCs克隆的形成效率和克隆质量没有明显的改善。带有β-FGF的培养体系可以保持i PSCs未分化的状态,而培养体系中只加LIF不能维持i PSCs未分化的状态。[结论]该研究成功诱导出山羊i PSCs,且能在体外传代培养。     

Collagen complexes increase the efficiency of iPS cells generated using fibroblasts from adult mice

Different interventions are being tested for restoration of the youthfulness of adult mouse-derived fibroblasts. However, fundamental issues, such as the decline of adult mouse-derived fibroblast activity with age, remain unresolved. Therefore, in this study, we examined whether treatment with collagen complexes has beneficial effects on the rejuvenation or reprogramming of adult mouse-derived fibroblasts. Further, we investigated the mechanisms of rejuvenation of adult mouse-derived fibroblasts during treatment with total collagen complexes. We isolated total collagen complexes from the tails of young mice and cultured adult mouse-derived fibroblasts with or without the collagen complexes. When compared with fibroblasts cultured without collagen complexes, adult-derived fibroblasts cultured with collagen complexes over five consecutive passages showed a more youthful state, expanded at a higher rate, and exhibited reduced spontaneous cell death. The fibroblasts cultured in the presence of collagen complexes also showed extensive demethylation in the promoter regions of cell cycle-related genes such as PCNA, increased proliferation, and decreased senescence. In addition, the efficiency of reprogramming of fibroblasts to become induced pluripotent stem (iPS) cells was significantly higher in young- and adult-derived fibroblasts cultured with collagen complexes than in adult-derived fibroblasts cultured alone. Furthermore, mechanistic evidence shows that genes involved in anti-proliferative pathways, including Ink4a/Arf locus genes and p53, were downregulated in fibroblasts exposed to collagen complexes. Interestingly, our results suggest that the rejuvenation process was mediated via the α2β1 integrin-dependent Bmi-1 pathway. Thus, collagen complexes both stimulate proliferation and inhibit cell death and growth arrest in fibroblasts, which appears to be a promising approach for improving the efficiency of reprogramming.     

不同病毒感染方法对山羊体细胞重编程效率的影响

[目的]检测2种病毒感染方法(悬浮感染和贴壁感染)对体细胞重编程效率的影响。[方法]采用慢病毒作为载体携带多能因子分别使用悬浮感染和贴壁感染2种方法感染正常山羊体细胞,统计克隆形成率。[结果]悬浮感染和贴壁感染的平均克隆率分别为0.44‰和0.31‰,悬浮感染的效果要显著地优于贴壁感染。[结论]悬浮感染的方式更利于山羊成纤维细胞重编程。