多能干细胞,非转基因iPS细胞 z-bo 2020-08-18 543

　　Pluripotent stem cells (Ps) are currently attracting attention in stem cell research. They can differentiate into all cells of the human body and form all tissues and organs of the human body. Therefore, the study of pluripotent stem cells is not only of great significance in theory, but also of important application value in organ regeneration, repair and disease treatment. However, it was previously thought that pluripotent stem cells can only be obtained from human embryos. In 2007, American and Japanese scientists introduced four genes, namely KLF4, OCT4, SOX2 and C-MYC, to increase the number of normal somatic cells in normal human and mouse skin cells.. We found that it can be transformed into competent stem cells . 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 four elements of OKSM through retrovirus or lentiviral vector. .. In order to solve this problem in the field of human cell therapy, in the past few years, scientists have developed a variety of methods to induce the production of iPS cells without exogenous factors. These methods include plasmid, piggyBac transposon, protein transduction, mRNA and micrornA transfection. Although these methods can produce iPS cells without exogenous factors, they cannot provide stable, reliable and high-quality replicable chimeric cells.

　　In this study, researchers from the China Agricultural University and the University of Utah introduced 8 reprogramming factors and a selection marker gene into a non-integrating plasmid to produce high-quality non-transgenes (including transgenes). ) Has been generated. iPS unit. 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, plasmid requirements are higher than conventional classical four-factor reprogramming methods. The eight reprogramming elements included 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 complete, the unincorporated plasmid can be used to easily remove the plasmid by negative selection. “Professor Wu Sen from China Agricultural University explained that the researchers optimized the combination of reprogramming factors, selected appropriate selection markers, and integrated the two into a non-integrating plasmid. More importantly, the plasmid produced by pMaster12 does not contain Transgenic iPS cells, which means they can grow cells in 2i medium to produce embryos and produce healthy offspring. The main reason is that the quality of the iPS units obtained previously is not good enough. He introduced the difference from other methods and the new method "The main difference between the two when using more reprogramming elements is. ", and then place 8 reprogramming elements in the vector. One advantage of this is higher reprogramming efficiency, and another advantage is that it is easy to remove foreign plasmids (factors) after reprogramming is completed.

　　This research is very important for solving the carcinogenicity problem of iPS cells, and it is also very useful for analyzing the molecular mechanism of induced pluripotent stem cells. Use the same method to understand the large animals (such as pigs and sheep) they are trying to use.