2002-12-05 17:00:39 -0400
By Maggie Fox
Cloning technology may someday be able to give patients "re-booted" immune systems, offering new treatments for diseases ranging from pneumonia to multiple sclerosis, US researchers said on Thursday.
Stem cells made from cattle traveled throughout their blood, and out-competed the animals' older, native cells, researchers at a Massachusetts biotechnology company told a conference.
The research has not been reviewed by other scientists, a standard procedure in medical science, but the team at Advanced Cell Technology has reported regularly on cloning experiments, including the first reported attempt to clone a human embryo.
The privately held firm, which has herds of cloned cattle, is also testing the use of so-called therapeutic cloning, which uses cloning technology for medical experiments.
The idea is to help a patient grow new cells and tissues using his or her own cells, eventually leading to "grow-your-own" transplants and other treatments. But the approach is controversial because an embryo must be created and then taken apart in the procedure.
"We used the therapeutic cloning procedure to give old cows new immune cells," Robert Lanza, medical director at ACT, said in an interview conducted by E-mail.
They found the oldest cattle they could and cloned them.
"These animals were the equivalent of 70-year-old humans," Lanza told the Third Annual Conference on Regenerative Medicine, held in Washington this week. Cattle allowed to live natural lives can survive 24 years and longer.
The clones were not grown to calves but instead stopped when the embryos were just a few days old and still in the lab dish. They were used as a source of embryonic stem cells, which have the potential to become any kind of cell in the body.
"We gave an 1,800-pound (800 kg) animal a thimbleful of cells," Lanza said.
It was hoped these embryonic stem cells would respond to the body's own signals and start to produce immune system cells as needed. Earlier experiments suggest the cells can be directed to migrate to needed areas, producing a variety of different types of cells.
RE-BOOTING THE IMMUNE SYSTEM
"If this approach works in humans, it could not only be used to treat cancer and immunodeficiencies, but to 'reboot' the immune system in patients with various autoimmune diseases," Lanza said.
"There are over 40 autoimmune diseases in humans, including multiple sclerosis, rheumatoid arthritis, juvenile diabetes, lupus, inflammatory bowel disease and dozens of others."
He said that 170 days later the injected cells had survived and were thriving in the blood of the cattle. When put into lab dishes, they grew abundantly, much as young fetal cells do.
Immune cells from the bone marrow are already widely used to treat cancer and some auto-immune diseases. But when a patient receives these "adult" stem cells, even from a close relative, he or she usually must take immune-suppressing drugs to keep them from attacking the body in what is known as graft versus host disease.
Therapeutic cloning, also known as somatic cell nuclear transfer, offers a way around this problem. "The nuclear transfer procedure generates cells that are more youthful, and potentially of far greater therapeutic value," Lanza said.
"The ability to regenerate an aged or defective immune system without the need for drugs, tissue matching or the risk of graft-versus-host disease would have important implications for medicine. For instance, an injection of new immune cells might prevent elderly patients from dying of pneumonia."
Lanza, along with other scientists in the field, fears Congress may soon block the research. One of two competing bills would ban all cloning research involving humans, while the second would allow work such as Lanza's.
But US federal policy, backed by President Bush, is to ban federal funding of such work, which scientists complains slows it down.
"We're all a bit frustrated by the lack of progress--we should be on
the verge of clinical trials by now," Lanza said.
Copyright © 2002 Reuters Limited