Chicago: Genetically engi¬neered stem cells from bone marrow showed promise as a potential new way to deliver a cancer-killing protein to tu¬mors, British researchers said on Tuesday.

Experiments in cell cul¬tures and in mice showed the adult stem cells — a type known as mesenchymal stem cells could home in on cancer cells and deliver a lethal protein that attacked only the cancer while sparing normal healthy tissue. “We've devel¬oped cells which specifically target cancer through the body and deliver an anti-can¬cer protein to where it is need¬ed in a seek-and-destroy ap¬proach,” said Dr Michael Loebinger of University Col¬lege London, who presented his findings at the American Thoracic Society conference in San Diego. "Essentially, we've combined two pieces of research. The first is that me¬senchymal stem cells have an innate ability to seek out tu¬mors throughout the body," Loebinger said in a telephone interview. Loebinger, Dr.S.M. Janes and colleagues altered the cells to express or make the cancer-killing protein called TNF-related apoptosis-inducing ligand or TRAIL.

“This protein has the ability to cause the death only of cancer cells. By combining these two approaches, we have a cell which has the abili¬ty to go around the body and find and destroy tumors,” Loebinger said. Studies in cell cultures showed the cells were able to find and kill cells from lung, squamous, breast and cervical cancer. “Lots of cancer have sensitivity to this TRAIL protein,” Loebinger said. They injected the cells into mice with breast tumors and showed they were able to safely kill the tumors but leave healthy tissue intact.

“When we delivered this therapy, 38% of the tumors were completely eliminated.” He said the goal would be to de¬velop a cell-based cancer treatment for humans that specifically targets cancer cells. An attractive property of these cells is that they are “immunoprivileged,” mean¬ing the body will not reject them as foreign invaders. That means they can be made in batches instead ofhaving to make custom stem cell treat¬ments for each patient, Loeb¬inger said. He said the team hopes human trials could be¬gin in two or three years.

Stem cells have been iden¬tified in many organs and tis¬sues, including brain, bone marrow, peripheral blood, blood vessels, skeletal mus¬cle, skin^ teeth, heart, gut, liv¬er, ovarian epithelium, and testis. They are thought to re¬side in a specific area of each tissue. In many tissues, cur¬rent evidence suggests that some types of stem cells are pericytes, cells that compose the outermost layer of small bloodvessels, REUTERS