119 Bentley Lecture: Gene editing: A Japanese perspective

Abstract

Abstract Development of useful gene editing technologies, such as ZFN, TALEN and CRISPR/Cas9 systems, has made it possible to efficiently produce knock-out and knock-in mammals, including domestic animals. In particular, the number of scientific papers on gene editing by using the CRISPR/Cas9 system has increased rapidly since 2013, although it has begun to decline from 2022. Among those researchers, the contribution of Japanese scientists accounts for 5 to 10% of the total number of published papers in many species, including laboratory and domestic animals, while those in rats account for nearly 20 % of the total. Whereas research results in rodents, such as mice and rats, have been published from many Japanese institutions, those in domestic animals, such as pigs, appears to be from only limited numbers. With regard to the application of gene editing technology to livestock species, only pigs have different objectives compared with other species, and are used for xenotransplantation and disease models rather than for industrial applications. Whereas this trend is also true for research in Japan, publications on the attempts of new methodologies seem to stand out. A distinctive feature of Japanese research on mammalian gene editing may be the development of methods to introduce gene editors into oocytes with electroporation, for example, GEEP and iGonad, and the applications. These methods seem to be used to generate knock-out animals efficiently, and production of pigs with simultaneous knockout of two or three genes has been reported. To produce knock-in pigs, however, it seems that cloned animals still need to be produced by nuclear transplantation of somatic cells in which the interested gene has been previously modified. Although the attempts to introduce editing tools directly into zygotes by microinjection, which is much simpler than somatic cell nuclear transplantation, have been reported, it has not been controlled yet to reduce the occurrence of mosaics, and it would be necessary to wait for further improvement. In addition, some methods for gene editing chemically or by lipofection have also been attempted, but the efficiencies may still need to be improved. Arrangements for the proper handling of gene-edited animals and food products by Japanese government, especially whether or not such animals and food products are genetically modified organisms, etc. as defined by law, will have a significant impact on the direction and promotion of research on gene editing in Japan.