Scientists in Shanghai say they’ve produced two cloned macaque monkeys by taking the DNA from the nuclei of fetal monkey cells and putting the genes into monkey eggs that had their own DNA removed. The scientists then stimulated the eggs to develop into embryos, which were placed into the wombs of female surrogate monkeys to develop into baby monkeys. It’s the first time the technology, called somatic cell nuclear transfer, has been used to clone any close relative of humans.
Scientists cloned rhesus monkeys using a different method known as embryo splitting. But that technique isn’t considered useful for producing large numbers of genetically modified clones for medical research.
Researchers have also created cloned human embryos, even after earlier claims of doing so were determined to have been fraud. But that work was done to obtain human embryonic stem cells for research.
Despite decades of trying, no one had ever succeeded in using the same method used to create Dolly to clone a primate.
•Somatic cell nuclear transfer (SCNT) using fetal fibroblasts yielded two live monkeys
•Epigenetic modulators promoted development and pregnancy rate of SCNT embryos
•SCNT using adult cumulus cells yielded live births of monkeys that were short-lived
•Genetic analysis confirmed the clonal origin of the SCNT monkey offspring
Generation of genetically uniform non-human primates may help to establish animal models for primate biology and biomedical research. In this study, we have successfully cloned cynomolgus monkeys (Macaca fascicularis) by somatic cell nuclear transfer (SCNT). We found that injection of H3K9me3 demethylase Kdm4d mRNA and treatment with histone deacetylase inhibitor trichostatin A at one-cell stage following SCNT greatly improved blastocyst development and pregnancy rate of transplanted SCNT embryos in surrogate monkeys. For SCNT using fetal monkey fibroblasts, 6 pregnancies were confirmed in 21 surrogates and yielded 2 healthy babies. For SCNT using adult monkey cumulus cells, 22 pregnancies were confirmed in 42 surrogates and yielded 2 babies that were short-lived. In both cases, genetic analyses confirmed that the nuclear DNA and mitochondria DNA of the monkey offspring originated from the nucleus donor cell and the oocyte donor monkey, respectively. Thus, cloning macaque monkeys by SCNT is feasible using fetal fibroblasts.