动物实验,非转基因iPS细胞 z-bio 2021-01-20 303

　　Pluripotent stem cells (Ps) are the focus and focus of current stem cell research. It can differentiate into all cells in the body and form all tissues and organs in the body. Therefore, the study of pluripotent stem cells not only has important theoretical significance, but also has important application value in organ regeneration, repair and disease treatment. However, in the past it was thought that pluripotent stem cells could only be obtained from human embryos. In 2007, American and Japanese scientists used normal human and mouse skin cells to introduce four genes KLF4, OCT4, SOX2 and C-MYC, thereby converting normal somatic cells into pluripotent stem cells. I found it can be converted. The pluripotent stem cells induced by this gene are called induced pluripotent stem cells (iPSC). There is no doubt that this type of ips cell has important application value in the field of regenerative medicine, but the traditional induction method is to carry the OKSM 4 factor through retrovirus or lentiviral vector. , Making iPS cells potentially carcinogenic, and play a role in the field of human cell therapy. To solve this problem, in the past few years, scientists have developed a variety of methods to induce the production of iPS cells that do not contain exogenous factors. These methods include plasmid, piggyBac transposon, protein transformation, mRNA and micrornA transfection. Although these methods can generate iPS cells without exogenous factors, they cannot provide stable and reliable high-quality germ chimeric cells. In this study, researchers from China Agricultural University and the University of Utah in the United States successfully put 8 reprogramming factors and selectable marker genes into non-integrated plasmids, resulting in high-quality non-transgenic (non-transgenic iPS cells) This method has important applications in the field of stem cell research. The so-called transGENE-free iPS cells are iPS cells that can obtain or maintain pluripotency without external reprogramming factors. In order to obtain such iPS cells, the requirements for plasmids are higher than Ordinary classic four-factor reprogramming method. "The 8 reprogramming factors involved in this method are OCT4, SOX2, KLF4, MYC, NANOG, LIN28, NR5A2, MIR302/367. The positive selection marker gene is neo and the negative selection marker gene is tk. After reprogramming is completed, the plasmid It can be used to easily remove plasmids through negative selection. The researchers optimized the combination of reprogramming factors, selected the appropriate selection markers, and integrated the two into a non-integrating plasmid. More importantly, the researchers found that the pMaster12 plasmid can produce Gene-free iPS cells. This means that the cells can be used to manipulate embryos and produce healthy offspring after growing in 2i medium. Mice.

　　 Has the previous research achieved such an efficient reproductive channel? Professor Wu said: "This has never really been achieved. The main reason is that the quality of previously obtained iPS cells is insufficient. Embryonic stem cells (ES) are easy to reproduce. Inheritance can be achieved.

　　 Professor Wu also introduced the difference between this method and other methods. He said that this new method "the main difference is that more reprogramming factors are used, and eight reprogramming factors are added to the carrier. One of the benefits of this is reprogramming efficiency. Another advantage is that After programming, the foreign plasmid (factor) can be easily removed."

　　 This research is very important to solve the carcinogenicity problem of iPS cells. It can also be used to analyze the molecular mechanism of induced pluripotent stem cells. It is understood that the Wusen research team of China Agricultural University is trying to use the same method to obtain genetically modified iPS cells from large animals such as pigs and sheep.