Scientists at the Harvard Stem Cell Institute on Tuesday announced that they would begin cloning disease-specific human stem cell lines, marking the first such effort in the United States after the scandal of South Korea’s Hwang Woo-suk.

Because U.S. President George W. Bush strictly prohibited federal budget funding for human embryonic stem cell research, the study would be "entirely supported with private funds," the Harvard Stem Cell Institute noted in a telephone briefing.

"If successful, it will mark a major step forward in the effort to use stem cells to treat chronic diseases," the institute said.

The work will be conducted by two groups: one led by Douglas Melton, Co-Director of the Harvard Stem Cell Institute and a Harvard professor, and the other led by George Daley at the Children’s Hospital in Boston, who is also an associate professor at the Harvard Medical School.

Melton’s team will focus on diabetes-targeting stem cell lines, and then shift to neurodegenerative diseases such as Lou Gehrig’s Disease. Daley’s group will focus on blood disorders.

University leaders said they had carefully considered the ethical debates around stem cell study before approving the project.

Lawrence Summers, president of Harvard University, called the approvals "a seminal event in the University’s effort to advance this tremendously promising area of science."

Steven Hyman, provost of the University, said the work had been the subject of "more than two years of thoughtful, intensive review by as many as eight different Institutional Review Boards and Stem Cell oversight committees at five different institutions."

The clone technology, more formally known as Somatic Cell Nuclear Transfer, involves removing nuclei that contains the cellular DNA from egg cells, and replacing them with the nuclei of donor cells.

The resulting cell is subject to a chemical, or electrical, charge that triggers cell division and the creation of an embryo genetically identical to the donor of the nuclei. In the Harvard experiments, the nuclei will be taken from skin cells donated by patients suffering from different diseases.

Theoretically, embryonic stem cells are capable of developing into any tissue type. Scientists believe that many chronic diseases can be cured if the patients’ sick tissue is replaced with healthy tissue developed from cloned embryonic stem cells.

However, the research involving human embryonic stem cells is controversial because extracting the cells requires the destruction of a human embryo. Opponents of the work argue that no potential medical benefit can justify the destruction of what they view as a human life, or even as a person.

The study has also been heavily hit by the scandal of Hwang, who claimed to have created disease-specific human embryonic stem cell lines using Somatic Cell Nuclear Transfer technology in 2005. Hwang’s claim, published in the highly-regarded journal Science, proved to be the largest hoax in science history later that year.

In spite of that Harvard scientists said they would not be discouraged by the debate and scandal.

"While we understand and respect the sincerely held beliefs of those who oppose this research, we are equally sincere in our belief that the life-and-death medical needs of countless suffering children and adults justifies moving forward with this research," Summers said.

"From the scientific perspective, this work holds enormous potential to save lives, cure diseases, and improve the health of millions of people," echoed Melton.

"The reality of the suffering of those individuals far outweighs the potential of blastocysts that would never be implanted and allowed to come to term even if we did not do this research."