Embryonic Stem Cell Pioneer Dies

Leroy Stevens, who discovered pluripotent embryonic stem cells in mice, has passed away at age 94.

Apr 2, 2015
Jenny Rood

COURTESY OF ANNE STEVENS WHEELER

Former Jackson Laboratory researcher Leroy Stevens, whose work with mouse tumors led to the discovery of embryonic stem cells (ESCs), died last week (March 28) of congestive respiratory failure. He was 94.

A native of Kenmore, New York, Stevens earned an undergraduate degree from Cornell University and a PhD in embryology from the University of Rochester, both in New York. In 1953, he joined the Jackson Laboratory in Maine, where he investigated mouse models of cancer. He was promoted to the position of senior staff scientist in 1967.

In 1958, while examining a murine testicular tumor, Stevens found that part of the tumor contained many different types of tissue, including hair and teeth—a type of cancer known as a teratoma. Stevens’ further investigation of the teratoma revealed similarities to cells in the mouse embryo. When Stevens later transplanted embryonic cells into adult mice, some of them caused teratomas to grow. In their 1970 experiment, Stevens and his colleagues had identified the first ESCs. “Stevens’ contributions to stem cell biology built the road that led to current knowledge about the properties and potential of human embryonic stem cells,” Gail Martin of the University of California, San Francisco, said at the 75th anniversary of the Jackson Laboratory, The Ellsworth American reported.

After a long career using mouse models to study cancer, Stevens retired from the Jackson Laboratory in 1989.

He is survived by two children and seven grandchildren.