非转基因iPS细胞 z-bo 2020-11-05 322

　　Pluripotent stem cell (Ps) is the current 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 of the body. Therefore, the study of pluripotent stem cells not only has important theoretical significance, but also has great application value in organ regeneration, repair and disease treatment. But in the past it was thought that pluripotent stem cells could only be obtained from human embryos. In 2007, American and Japanese scientists discovered that using normal human and mouse skin cells to introduce four genes, KLF4, OCT4, SOX2 and C-MYC, can transform normal somatic cells into pluripotent stem cells. The pluripotent stem cells induced by this gene are called induced pluripotent stem cells (iPSC).

　　Undoubtedly, 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 four factors through retrovirus or lentiviral vector, which makes iPS cells potentially carcinogenic and cannot be applied to human cells. Treatment field.

　　In order to solve this problem, in the past few years, scientists have developed various methods to induce the production of iPS cells without exogenous factors. These methods include plasmid, piggyBac transposon, protein transduction, mRNA and micrornA transfection, etc. Although these methods can produce iPS cells without exogenous factors, they cannot stably and reliably obtain high-quality, reproductive chimeric cells.

　　In this study, researchers from the China Agricultural University and the University of Utah in the United States successfully put 8 reprogramming factors and selectable marker genes into a non-integrating plasmid, thereby obtaining high-quality non-transgenic (transgene- free) iPS cells. This method will have important applications in the field of stem cell research.

　　The so-called transGENE-free iPS cells refer to 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 general classical four-factor reprogramming method.

　　"The eight 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. In order to easily remove the plasmid by negative selection after the reprogramming is completed,” explained Professor Wu Sen of China Agricultural University.

　　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 transgene-free iPS cells, which means that the cells can be used for embryo manipulation and can produce healthy offspring after being grown in 2i medium. Mice.

　　Has the previous research also achieved this kind of efficient reproduction?

　　Professor Wu said, “It has not been possible to achieve this reliably before. The main reason is that the quality of the iPS cells obtained before is not good enough to achieve reproductive passage as easily as embryonic stem cells (ES).”

　　Professor Wu also introduced the difference between this method and other methods. He said that this new method "mainly differs in that we use more reprogramming factors and put 8 reprogramming factors on a carrier. This is done. One advantage is that the reprogramming efficiency is higher, and the other advantage is that the foreign plasmid (factor) can be easily removed after the reprogramming is completed."

　　This research is of great significance for solving the problem of carcinogenicity in iPS cells, and will also help to analyze the molecular mechanism of induced pluripotent stem cells. It is understood that Wu Sen's research team at China Agricultural University is trying to use the same method to obtain genetically modified iPS cells from large animals such as pigs and sheep.