Most stem cells mixed with mouse cells in lab WASHINGTON, Aug. 24 (UPI) -- Many or perhaps all of the embryonic stem cells approved for research funding by the Bush administration were mixed in the laboratory with mouse cells and "may create substantial hurdles" for scientists hoping to use the colonies in the search for cures for Parkinson's disease and other ailments, The Washington Post reported Friday. The stem cell lines were originally created for early stage research "with no thought they would become the only embryonic cells eligible for federal money," according to The Post. Extracting human cells from an embryo and placing them atop mouse cells is a standard technique for creating human embryonic stem cell lines. However, though the mouse "feeder" cells excrete unknown nutritional or growth factor that helps the human cells stay healthy, they may also pose a small risk of "transferring potentially deadly animal viruses into people," The Post reported. Also, inserting theses embryonic cells into people would be considered "xenotransplants," transplants of animal tissue. Under Food and Drug Administration guidelines, it would be difficult, but not impossible, to use the cells in human clinical tests. "The human embryonic stem cell lines reported in scientific literature were all grown in direct contact with mouse cells and might have picked up mouse viruses, which the government officials acknowledged will bring them under FDA policy," The Post added. Patient groups and those who work with the stem cells have expressed concern about the possible restrictions. "This would be the exclamation point" on an already lengthy list of questions about the quantity and quality of the cell lines eligible for research funding under the Bush policy, said Kevin Ryder, a consultant to the American Cell Therapy Research Foundation, reported The Post. -- Copyright 2001 by United Press International. All rights reserved. --