Transmission of transgene to the offspring in the common marmoset

A team of Japanese researchers, led by Dr. Erika Sasaki of the Central Institute for Animal Experiments, managed to raise genetically modified common marmosets capable of transmitting the transgene to their offspring. This is the first time that such a result is obtained with primates.

It describes a transgenic as, animal or plant from which a gene has been added, removed or replaced. The methods to generate a line of transgenic mice are now well established, making it possible to use this animal model in biomedical research. However, genetic and physiological differences between mice and primates make it very uncertain extrapolation of the results obtained for the model to clinical applications. The common marmoset has several characteristics that make a potentially interesting closer to humans than mice, the species has a short gestation time (about 5 months), quickly reached sexual maturity (between one year and a year and a half), and females give birth to up to 80 young in a lifetime.

The researchers injected a viral vector carrying a protein called EGFP in 91 marmoset embryos. Several original features of the method should be mentioned. First, the EGFP protein is characteristic of being fluorescent, allowing easy monitoring of expression throughout the process. Most marmoset embryos used were obtained by natural reproduction, as researchers found in a pilot study that they were more likely to express a transgene that embryos obtained by in vitro fertilization. In addition, a high titer viral vector was injected. Finally, the majority of the embryos was placed in a solution of sucrose, which had the effect of increasing their volume and to facilitate the injection phase.

The embryos were then implanted in surrogate mothers. In the end, 5 ouististis were born healthy. Four of them expressed the EGF protein in different tissues - roots of the hair, skin, blood cells. When they reached the age of sexual consent, two of them also expressed the protein in their germ cells. Finally, one of them transmitted the gene coding for the protein to a descendant born by in vitro fertilization.

The study suggests that the method will provide lines of transgenic primates for research in regenerative medicine and gene therapy. Researchers, however, will probably have to pay attention to ethical issues raised by the generation of a line of marmosets carrying a defective gene.

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