*Method could move quickly to human trials, company says

*Bypasses cancer-causing methods to make human stem cells

WASHINGTON, May 28 (Reuters) - U.S. researchers said on Thursday they had come up with the safest way yet to make stem-like cells using a patient's ordinary skin cells, this time by using pure human proteins.

The team at Harvard University and Massachusetts-based Advanced Cell Technology Inc

ACTC.PK

said their technique involves soaking cells in human proteins that turn back the clock biologically, making the cells behave like powerful embryonic stem cells.

Dr. Robert Lanza of Advanced Cell sees almost immediate commercial applications.

"After a few more flight tests -- in order to assure everything is working properly -- it should be ready for commercial use," Lanza said by e-mail.

He said the company would seek Food and Drug Administration permission to test the cells in people by next year -- a process unlikely to be quick, especially with a brand-new technology such as this one.

Stem cells are the body's master cells, giving rise to all the tissues, organs and blood. Embryonic stem cells are considered the most powerful kind, as each one is pluripotent, with the potential to morph into any type of tissue.

Doctors hope to someday use them to transform medicine, for instance, by regenerating the cells destroyed in type 1 diabetes or regrowing eye cells to reverse blindness.

But embryonic cells require the use of an embryo or cloning technology, and several countries, including the United States, limit funding for such experiments.

Several teams of scientists have homed in on four genes that can turn back the clock in ordinary cells, making them look and act like embryonic stem cells. These so-called induced pluripotent stem cells, or iPS cells, could in theory be made using a patient's own skin, allowing grow-your-own transplants with no risk of rejection.

DIFFICULT WORK

Getting these genes into the cells is not easy, however.

The first attempts used retroviruses, which integrate their own genetic material into the cells they infect. Others used loops of genetic material called plasmids or other genetically engineered molecules to reformat the cells.

And another team used the proteins made by the four genes and valproic acid to reprogram cells, but Lanza said these methods all have drawbacks.

His team, working with Kwang-Soo Kim of the Harvard Stem Cell Institute and a team at CHA Stem Cell Institute in South Korea used a peptide, a protein fragment, to drag the human proteins into the cells.

"These have been around for a long time," Lanza said. "The AIDS virus uses the peptide to get into the cells it infects," he said.

Using cells from the foreskins of newborn boys -- a common laboratory technique -- they showed they could transform the cells into iPS cells. They regrew them into a variety of mature new cell types, they reported in the journal Cell Stem Cell.

"This method eliminates the risks associated with genetic and chemical manipulation, and provides for the first time a potentially safe source of iPS cells for translation into the clinic," Lanza said.

"This is the ultimate stem cell solution -- you just add some proteins to a few skin cells and voila! Patient-specific stem cells!"

One question that is not clear is who owns the technology. Lanza said many groups have tried to patent the various steps in the process and it is not yet clear whose patents will prevail. (Editing by Anthony Boadle)