Chimpanzees who've spent their existence in research labs will soon reach a new chapter in life when more than 300 chimps from medical research facilities around the country will be retired over the next few years, the National Institutes of Health said Wednesday.

The nation's medical research agency said the chimps "deserve special respect" as our closest relatives, though it will retain but not breed about 50 of the apes for future research, just in case there is a crucial need to use them in research for human health.

"Americans have benefitted greatly from the chimpanzees' service to biomedical research, but new scientific methods and technologies have rendered their use in research largely unnecessary," Dr. Francis Collins, the director of the NIH, said in a statement.

"Their likeness to humans has made them uniquely valuable for certain types of research, but also demands greater justification for their use. After extensive consideration with the expert guidance of many, I am confident that greatly reducing their use in biomedical research is scientifically sound and the right thing to do."

The decision to retire the chimpanzee from medical research stems from a 2010 investigation into whether there was a continued scientific need for chimpanzees in NIH-funded research and the resulting recommendations that the practice was no longer needed.

Wednesday's news comes on the heels of a recent move by the U.S. Fish and Wildlife Service to list captive chimpanzees as endangered species.

As the NIH-owned chimps are retired they will be moved to what the NIH calls "ethologically appropriate facilities" that would be suitable substitute environments for the chimps' natural habitat. The agency said it will also establish a review panel to consider research projects proposing the use of chimps, as well as wind down most research projects that use NIH-owned or -supported chimpanzees.