Ryuzo Yanagimachi, a renowned University of Hawaii fertility researcher who created the technique to develop the world’s first cloned mouse, died last week at the age of 95.
In his 38-year tenure at UH and 18 years as professor emeritus, Yanagimachi won many awards, pioneered cloning and made numerous fertilization breakthroughs, including intracytoplasmic sperm injection (ICSI) and other techniques that are used around the world in fertility clinics.
“He was an innovative scientist and a great mentor,” said Mariana Gerschenson, associate dean of research at UH’s John A. Burns School of Medicine, in a statement. “He was an inspiration to the faculty, staff, post-doctoral fellows, and students. He will always be part of our ohana.”
Yanagimachi was born in 1928 in Hokkaido, Japan. He earned a bachelor’s in zoology and a doctorate of science in animal embryology in 1960, both from Hokkaido University, then spent two years teaching high school.
In 1960 Yanagimachi accepted a position at the Worcester Foundation for Biomedical Research in Massachusetts, where he developed the techniques to fertilize hamster eggs “in vitro,” a breakthrough that provided the foundation for his work the rest of his life.
In 1964 the researcher returned to Hokkaido University as a temporary lecturer but then he landed a full-time position at UH’s medical school in 1966.
Three decades later, at the age of 69, Yanagimachi led a team that cloned the world’s first mouse. A year later, in 1998, the groundbreaking research appeared in the journal Nature, describing how the nucleus from a somatic cell was removed and injected it into an egg that also had its nucleus removed.
After the egg was cultured and developed into an embryo, it was implanted into a surrogate, where it developed.
The first mouse born through what would be known as the “Honolulu Technique” was named Cumulina, for the cumulus cells whose nuclei were used to clone her.
Unlike the sheep that was cloned in Scotland the previous year, Yanagimachi’s mice were able to produce offspring over several generations, representing a significant step forward in cloned animal research.
Last year the taxidermy remains of “the most celebrated mouse in scientific history” found a new home at the Smithsonian’s National Museum of American History in Washington, D.C.
In 2000, Yanagimachi founded and led the Institute for Biogenesis Research at the University of Hawaii, which focused on the study of embryogenesis, stem cell development and transgenesis technology.
Four years later the faculty, staff, and students cloned the first male animal from adult cells. Yanagimachi’s team used ICSI techniques to produce pups from an infertile male mouse.
Yanagimachi retired in 2005 but not before receiving numerous honors over the years. They include the 1996 International Prize for Biology and the 1999 Carl G. Hartman Award, the Society for the Study of Reproduction’s top honor. He was inducted into the National Academy of Sciences in 2001.
This year the reproductive biologist was honored with the Kyoto Prize, an international award for lifetime achievement in the arts and sciences. Yanagimachi was recognized in the biotechnology and medical technology category for his contributions to the development of reproductive technologies.
Yanagimachi was scheduled to accept the award in November.
When the Kyoto Prize was announced, Yanagimachi wrote humbly that, “Although I was rarely directly involved in clinical investigations, I am very happy that some of the work we did played a role in bringing joy to many infertile couples.”
Dr. Lee Buenconsejo-Lum, interim dean of the UH medical school, said Yanagimachi’s research into cloning and in vitro fertilization changed the world.
“Yana’s breakthroughs in cloning and IVF helped make the world a happier place for millions of families. His legacy is etched in history and at the University of Hawaii John A. Burns School of Medicine. We are so honored that he was part of our ohana for so many years,” she said in a news release.