7 The 100 Most Influential Inventors of All Time 7Wilmut was not interested in cloning simply for the
sake of producing cloned animals, and neither was his
team of scientists at Roslin. They still had problems to
solve concerning their work on pharming. In 1997 Wilmut
and his colleagues generated Polly, a Poll Dorset clone
made from nuclear transfer using a fetal fibroblast nucleus
genetically engineered to express a human gene known as
FIX. This gene encodes a substance called human factor
IX, a clotting factor that occurs naturally in most people
but is absent in people with hemophilia, who require
replacement therapy with a therapeutic form of the sub-
stance. Polly—along with two other sheep engineered to
produce human factor IX that also were born in 1997—
represented a major advance in pharming. The successful
birth of Polly marked Wilmut’s last major cloning
experiment.
Later Career
Throughout Wilmut’s career at Roslin, he had been slowly
moving away from research relying on embryonic stem
cells, primarily because culturing embryonic stem cells
from sheep embryos was extraordinarily difficult and
impractical in terms of cost and time. In 2000 Wilmut was
promoted to head of the department of gene expression
and development at the Roslin Institute, and his research
interests shifted from animals to humans. He was particu-
larly interested in uncovering the genetic mechanisms
that control embryonic development and the role that
these mechanisms play in human disease. In 2005 he
accepted a position as chair of reproductive science at the
University of Edinburgh. He maintained a relationship
with the Roslin Institute, acting as a visiting scientist.
Wilmut also directed the Medical Research Council’s