LOS ANGELES, April 26(Xinhuanet)-- The US National Academies on Tuesday recommended guidelines for research involving human embryonic stem cells, which have shown promising therapeutic potential while arousing worldwide disputes.

The National Academies urged all institutions conducting such research to establish oversight committees to ensure that the new guidelines be followed, said a committee that wrote the guidelines.

"The oversight we call for will in many instances set a higher standard than required by existing laws or regulations. And while we were hesitant to recommend another bureaucratic oversight entity, the burden in this case is justified, given the novel and controversial nature of embryonic stem cell research," the committee said in a statement.

"A standard set of requirements for deriving, storing, distributing, and using embryonic stem cell lines-- one to which the entire U.S. scientific community adheres-- is the best way for this research to move forward."

Embryonic Stem Cell Research Oversight(ESCRO) committees should be established, but not as replacements for other research compliance bodies such as institutional review boards, the guidelines say. In addition to experts in biology and stem cell research, ESCRO committees should include legal and ethical experts as well as representatives of the public.

Stem cells usually are harvested after three to five days from a blastocyst-- an early stage of development before implantation in the uterus. The ESCRO committees should review proposals for research that takes stem cells from excess blastocysts.

They also should review any proposed use of blastocysts createdby nuclear transfer, often referred to as therapeutic cloning. Nuclear transfer must not be used for reproductive cloning, the guidelines committee noted.

Proposals to generate additional human embryonic stem cell lines by any means should be reviewed and approved by an ESCRO committee, the guidelines say. They add that human embryos used for research should not be grown in culture for longer than 14 days.

Although an ESCRO committee should approve new stem cell research, federal regulations already require institutional reviewboards to review the procurement of all eggs, sperm, or blastocysts to be used in generating new stem cell lines, and theyshould continue to do so, according to the new guidelines.

Donor consent must be obtained before a blastocyst is used to generate stem cells, and donors should be informed that they have the right to withdraw their consent at any point before a stem cell line is derived, the guidelines say.

The ESCRO committee should maintain a registry of stem cell lines banked at an institution. The registry should include a proof of informed consent, a medical history of the donors, and a characterization of any genetic markers on the cell lines. Repositories of stem cell lines also need a secure coding system to protect the identity of donors.

The Academies' guidelines also address how far scientists should go in mixing human and animal cells to create so-called chimeras, which researchers may need to do in order to test the therapeutic potential of human stem cells in animal models.

The guidelines say no animal embryonic stem cells should be transplanted into a human blastocyst, and approval by an ESCRO committee should be secured before any human embryonic stem cells are put into an animal.

Also, no animal into which human embryonic stem cells have been introduced should be allowed to breed. In addition, no human embryonic stem cells should be put into nonhuman primate blastocysts, the guidelines say. Enditem