OHSU Scientists Use Embryo Splitting Technique to Clone Identical Monkeys

01/13/00    Portland, Ore.

Scientists at Oregon Health Sciences University announce they have replicated the naturally occuring birth of a non-human primate twin using a lab technique called embryo splitting. The method, which has produced a healthy, female monkey named Tetra shows promise for researchers hoping to safely and speedily move discoveries from the laboratory bench to the patient's bedside. The study was conducted by Anthony Chan, Ph.D., a staff scientist at OHSU's Oregon Regional Primate Research Center, and his colleagues in a lab coordinated by Gerald Schatten, Ph.D., professor of obstetrics and gynecology, and cell and developmental biology in the OHSU School of Medicine. The results of this research will be published in the Jan. 14 edition of the journal Science.

In the past, investigators have used identical mice as human disease models to help conquer disorders now cured. However, as research moves to more complex diseases like Alzheimer's, AIDS, and cancer, many scientists agree a model closer to humans is needed. In addition, mice are not always effective test subjects for human illness therapies due to the fact that some human diseases do not surface when genetically introduced into mice. For years, scientists have considered the use of monkeys to study these forms of illnesses. However, the lack of identical, non-human primate models has posed a hurdle to researchers - until now.

"This research is an encouraging step that could accelerate the work of thousands of scientists looking for cures to hundreds of diseases," said Schatten. "While many researchers agree that mice will continue to prove useful in the study of some illnesses, most admit another model for human disease is needed to bridge the gap between mice and sick people. We believe identical monkeys are the next logical step in finding these life-saving answers."

Schatten points to the Human Genome Project when explaining the benefits of this research. He and other scientists believe efforts to break the genetic codes for diseases may lead to cures in the very near future. "Gene and cell therapies, including stem cell treatments, promise remedies to rebuild hearts damaged by attacks, spinal cord injuries and diabetes," said Schatten. " Identical monkeys are the most reliable and appropriate models in which to perfect these cures before clinical trials. Also, since these monkeys are identical, the environmental influences in causing disease can be discovered."

Schatten also suggests monkeys like Tetra could answer very important questions regarding the effect a mother has on her developing child during pregnancy. This could be accomplished by observing the birth of twins in two different mothers. Additionally, scientists could learn more about physical effects of the embryo-splitting technique itself.

Tetra is the first monkey born using this cloning method. The monkey was produced by separating an eight-cell embryo into four sets of two-cell embryos. Scientists used microscopic instruments to perform the delicate procedure. The scientists first removed the eight-cell embryo's eggshell and split the eight cells apart. Next, two of the individual cells were injected into an empty eggshell. An egg was implanted in a female rhesus monkey, resulting in Tetra's birth.

The research was conducted through funding by the National Center for Research Resources, a component of the National Institutes of Health, along with funding from the National Institute for Child Health and Human Development. Judith Vaitukaitis, M.D., the director of the NCRR, says in addition to an improved model for human disease there are other benefits to the Schatten lab's research. "When the experimental subjects' genetics are identical, defined and invariable, data will be more accurately obtained, thus reducing the number of animals necessary for study and allowing investigators to more rapidly discern immune mechanisms of disease," said Vaitukaitis.