"So far as I know, this will be the first study reported in the USA", said Jun Wu, a collaborator at the Salk Institute in La Jolla, California, who played a role in the project.
OPB was not immediately able to independently confirm the breakthrough.
According to OHSU spokesperson Eric Robinson, the result of the peer-reviewed study are expected to be published soon in a scientific journal.
American Scientists have managed to edit and improve the DNA of human embryos in an effort to correct the gene defects that cause inherited diseases.
Successfully altering genes in embryos could theoretically allow scientists to cures diseases, including cancer.
For now, federal regulations have banned allowing a genetically-modified human embryo to develop into a baby.
Last year, Britain said some of its scientists could edit embryo genes to better understand human development.
Speaking to Technology Review, a scientist familiar with the project said: 'It is proof of principle that it can work. In a report this year, National Academy of Sciences (NAS) and the National Academy of Medicine said scientific advances made gene editing in human reproductive cells "a realistic possibility that deserves serious consideration".
The earlier Chinese publications, although limited in scope, found CRISPR caused editing errors and that the desired DNA changes were taken up not by all the cells of an embryo, only some.
Researchers from Oregon Health and Science University (OHSU) in Portland carried out the study, according to MIT's Technology Review. The NIH also does not fund any use of gene-editing technologies in human embryos. 'They significantly reduced mosaicism. "I don't think it's the start of clinical trials yet, but it does take it further than anyone has before". It's like using a molecular scissors to cut and paste DNA, and is much more precise than some types of gene therapy that can not ensure that desired changes will take place exactly where and as intended.