非转基因iPS细胞 z-bio 2021-09-28 460

　　Pluripotent stem cells (Ps) are currently the hotspot and focus of stem cell research. It can differentiate into all the cells in the body, and then form all the 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 believed that pluripotent stem cells could only be obtained from human embryos. In 2007, scientists in the United States and Japan used normal human and mouse skin cells to introduce the four genes KLF4, OCT4, SOX2, and C-MYC to convert normal somatic cells into pluripotent stem cells. I found that I could do it. The pluripotent stem cells induced by this gene are called induced pluripotent stem cells (iPSCs).

　　There is no doubt that this type of ips cell has important application value in the field of regenerative medicine, but the conventional induction method is to carry OKSM 4 factor through retrovirus or lentiviral vector. IPS cells may cause cancer. Used in the field of human cell therapy.

　　In order to solve this problem, scientists have developed various methods in the past few years to induce the production of exogenous factor-free iPS cells. 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 and reliable high-quality reproduction chimeric cells.

　　In this study, researchers from the China Agricultural University and the University of Utah succeeded in putting eight reprogramming factors and selectable marker genes into a non-integrating plasmid, producing high-quality non-transgenic (transgenic) genes. ) I got iPS. cell. This method has important applications in the field of stem cell research.

　　"Transgenic-free iPS cells" are iPS cells that can obtain or maintain pluripotency without the need for exogenous reprogramming factors. To obtain such iPS cells, the requirements for plasmids are higher than the common classical four-factor reprogramming methods.

　　\"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. The integrated plasmid is used in After the reprogramming is completed, the plasmid is easily removed by negative selection,” explained Professor Wu Sen of China Agricultural University.

　　The researchers optimized the combination of reprogramming factors, selected the appropriate selectable markers, and integrated the two into a non-integrating plasmid. More importantly, the researchers found that the pMaster12 plasmid can produce iPS cells without transgenes. This means that after cells are grown in 2i medium, they can be used to manipulate embryos and produce healthy offspring.

　　Has the previous research achieved such an efficient reproductive channel? Professor Wu said, "It has never really been achieved. The main reason is that the quality of the iPS cells obtained before is not good.

　　Wu also said this method. He also introduced the difference between other methods, he said, "The main difference is that more methods are used to reprogram factors. And eight reprogramming factors are placed in the profession. One advantage of this is that the reprogramming efficiency is high. Another One advantage is that foreign plasmids (factors) can be easily removed after reprogramming."

　　This research is very important for solving the carcinogenicity problem of iPS cells, and it is also very helpful for analyzing the molecular mechanism of induced pluripotent stem cells. It is understood that the research team of China Agricultural University Wu Sen is trying to use the same method to obtain genetically modified iPS cells from large animals such as pigs and sheep.