For years the stem cell research community has been slowly overcoming obstacles that have prevented it from advancing their efforts . And they may have just accomplished one of their most significant feats to date: obtaining the green light from the federal government to continue developing chimeras, according to NPR. Chimeras are animals that have some sort of human condition or aspect to them – it could be a tumor or immune system, for example. To form chimeras, scientists develop animals from human stem cells.

As you might imagine, this is an extremely controversial subject within and outside of the medical community. Questions about the ethical practice of the experiments had raised serious concerns about the science's future. Now, with the lift of a moratorium on federal funding for chimera stem cell research, scientists can go forward with their plans as normal.

What are the concerns?
The main concern surrounding chimera research is the human element involved in it. Many are concerned that breeding between chimera animals could result in the production of human embryos or fetuses.

"NIH has set up a number of policies to regulate chimera

creation and experimentation."

While scientists aren't looking to make hybrid animals, people are concerned these animals may be able to feel and think like humans. NPR didn't address deeper moral concerns (such as chimeras' potential rights), but this is also a question we can comfortably say lingers over the practice. 

"At the end of the day, we want to make sure this research progresses because it's very important to our understanding of disease. It's important to our mission to improve human health," Carrie Wolinetz, the National Institutes of Health's associate director for science policy, said in an interview with NPR. "But we also want to make sure there's an extra set of eyes on these projects because they do have this ethical set of concerns associated with them."

The National Institutes of Health has set up a number of policies to regulate chimera creation and experimentation. For example, NIH's regulation bars researchers from placing some stem cells into monkeys and chimps. The reason, NPR reported, is because humans and apes are too close together on the evolutionary tree.

In a blog post, NIH stated that the new regulations are "consistent with recently updated guidelines from the International Society for Stem Cell Research."

In general, many are happy with the news because it'll allow scientists to progress their research.

"It's very, very welcome news that NIH will consider funding this type of research," Pablo Ross, a developmental biologist at the University of California, said, according to NPR. "We need funding to be able to answer some very important questions."

NIH's approval will now allow scientists to conduct research that may allow them to one day treat serious diseases or make transplants.