In a series of bold experiments, scientists have created laboratory mice with tiny human organ structures -- lungs, intestines, pancreases, lymph nodes, thymuses, livers and immune systems. The purpose is to study the viruses of human diseases in living human tissues.
The animals, whose organ tissues are derived from those of human fetuses, provide a singular opportunity to gauge the effectiveness of various antiviral drugs. The mice have been successfully infected with the AIDS virus and with two cancer viruses that cause leukemia.
Researchers plan next to infect the mice with cytomegalovirus, which can damage the brains of unborn children. After that will come infections with the viruses of influenza, chronic infant diarrhea, genital warts and hepatitis. Because these viruses attack only humans, it has been impossible hitherto to study them in animals.
The organ structures are not miniature carbon copies of adult organs but contain complete structural subunits of each organ and carry out the organ's normal functions in duplicate with the mouse's own.
The novel mice were developed by Dr. J. Michael McCune, an immunologist who treats patients with acquired immune deficiency syndrome at San Francisco General Hospital.
A second kind of mouse, carrying adult human blood cells, has been developed by Dr. Donald E. Mosier, an immunologist from the Medical Research Institute, a private research laboratory in La Jolla, Calif.
Many experiments are being carried out by companies recently formed by Dr. Mosier and Dr. McCune. Researchers at Duke University, Stanford University and the University of California at Los Angeles have also replicated the work.
Because human fetal tissues are being implanted into animals and not humans, Dr. McCune and his colleagues are not subject to the federal ban on the use of such tissues in medical research.
The humanized mouse "is potentially quite an important model" for studying AIDS and other viral diseases, said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md.