Stem cell transplant eyed warily

A Korean research team said yesterday that it started a study on the development of human stem cells by inserting them into the embryos of mice. Civic and religious groups said they were concerned at the implications. Park Se-pill, who heads Maria Biotechnology Research Institute, said his research team implanted human stem cells into fertilized mice eggs that had been developing for four to five days. After an additional six hours of cell replication, researchers planted the embryos in four female mice, who delivered 11 babies. The stem cells had been tagged with a marker to allow researchers to trace their development in the baby mice. The results will be known in a month, according to the team. “The human stem cells are before the stage where they are directed to develop into individual organs,” Mr. Park said. When asked whether he expects human stem cells to be directed by the genetic programs of mice, Mr. Park said: “That is part of what we have to study.” Civil activists and religious leaders complained that moral and technical standards related to such experiments have not yet been established. Mr. Park said such experiments are necessary to find ways to treat incurable human diseases. “To find the best conditions under which human stem cells develop into organs outside of human bodies, we need to understand the mechanisms of their development,” he said. by Kim Hyo-jin