WASHINGTON, D.C. (WTVO) — The U.S. Senate voted against Republican-led legislation aimed at preventing scientists from combining human and non-human DNA to possibly make embryos of an “uncertain” species.

Forbes reports the amendment was proposed by Sen. Mike Braun (R-Ind). It failed to pass, with 48 Republicans voting for it and 49 Democrats voting against it.

The amendment would have prevented creation of a “nonhuman life form” that is “engineered” to exhibit “human facial features or other bodily morphologies to resemble human features,” and would have imposed a fine or prison for even attempting to create a human-animal chimera.

“Human life is distinct and sacred, and research that creates an animal-human hybrid or transfers a human embryo into an animal womb or vice versa should be completely prohibited, and engaging in such unethical experiments should be a crime,” said Braun.

Scientists have combined human and animal DNA in an effort to improve drug testing and organ transplant research, but concerns have been raised about the ethics of such experiments.

“There is a way to genetically engineer both the embryo and the stem cells so that the stem cells will only make a particular organ,” bioethicist Insoo Hyun told NPR. “Nobody wants a chimeric embryo to grow into a part-human, part-animal thing that has human cells from head to toe mixed in.”

Currently, human-animal chimera research is prohibited from receiving federal funding, but still happens with limited regulation in university and private labs.