Genetically modified animals refer to animal strains obtained through artificial mutation. It can be achieved either by transferring foreign genes, or by mutating the genes of the animal itself. Tool animal models refer to animal models established by modifying known genes, which can be used as tools to help achieve other target gene modifications. In mice, a large number of gene modification tool models have been established and used, such as stem cell marker mouse models (OG2 transgenic mice), Cre/loxP genetically modified mice, immunodeficient mice, etc. These tool mouse models have greatly promoted Research progress in life sciences and biomedicine.
Pig is not only one of the main economic animals in agriculture, but also has a wide range of uses in the field of biomedicine. First of all, pigs are a good animal model of human diseases. The cardiovascular system, digestive system, skin, nutritional requirements, bone development, and mineral metabolism of pigs are very similar to those of humans. The size and taming habits of pigs allow repeated iterations. Sampling, and the breeding cycle is short, the productivity is high, and the litter produces many litters. Genetically modified experimental animal models play an important role in studying human disease-related gene functions, the relationship between disease phenotypes and genotypes, and disease diagnosis and treatment. They can also be used as important drug evaluation models. Thirdly, pigs are ideal donors for xenogeneic organ transplantation. Using transgenic technology to transform the hereditary characteristics of xenogeneic organs to make them suitable for human organ or tissue transplantation is the most effective way to solve the shortage of organ transplantation.
Through genetic modification, just like mice, the establishment of tool pigs for different application purposes will promote the rapid realization of the above application value of pigs. The establishment of genetic engineering tool animals often involves the application of multi-gene transfer and multi-step gene targeted targeting technology. However, porcine embryonic stem cells have not been successfully established so far. Porcine induced pluripotent stem cells prepared by induced pluripotent stem cell technology do not have germline mosaic ability. The preparation of genetically modified pigs mainly depends on somatic cell gene modification and somatic cell nuclear transfer The technology is combined to complete. The proliferation capacity of somatic cells is limited, and genetic modification, especially the low efficiency of gene targeting, makes it very difficult to establish a pig model with genetic modification tools. In recent years, artificial endonucleases ZFN, TALEN and RNA-mediated Cas9 nucleic acid The development of enzymes has brought a revolutionary breakthrough in gene knockout technology, solved the problem of difficult targeted modification of pig genes, and made it possible to establish pig models with genetic modification tools. Thanks to this, the genetic engineering tool pig’s The establishment shows a trend of rapid development.