The Biology Book: From the Origin of Life to Epigenetics, 250 Milestones in the History of Biology (2015)

Viktor Hamburger (1900–2001), Rita Levi-Montalcini (1909–2012), Stanley Cohen (b. 1922)

1952

Two years after Rita Levi-Montalcini received her medical degree from the University of Turin in 1938, Mussolini issued a decree preventing all non-Aryan Italians from pursuing professional careers in Italy. In response, she set up a small laboratory in her home and, inspired by the work of Viktor Hamburger, studied chick embryos. In 1947, she joined Hamburger at Washington University in St. Louis, Missouri, where he was studying the growth of nerve tissues. The following year, she found that when a piece of mouse tumor was grafted on chick embryos whose wing buds had been removed, the growth of nearby nerves was stimulated.

Stanley Cohen, a biochemist, joined Levi-Montalcini in 1953 and isolated the active protein from the tumor, which they named nerve growth factor (NGF). NGF was found essential for the normal growth and maintenance of nerves in the peripheral nervous system (outside the brain and spinal cord) and for cholinergic (acetylcholine-containing) nerves in the brain. After going to Vanderbilt University in 1959, Cohen found and isolated another growth factor in the NGF-containing tumor. This factor, which stimulated the growth of the epidermal layer of skin and caused newborn mice to open their eyes sooner than normal, was dubbed epidermal growth factor (EGF). In 1986, Cohen and Levi-Montalcini were co-recipients of the Nobel Prize for their discoveries of growth factors.

NGF was the first of approximately fifty growth-promoting agents that have been identified and that are secreted in the blood from many different tissues. They serve as signaling molecules between cells, with each promoting the growth of specific cells. In particular, these factors stimulate cellular growth, replication, and differentiation (specialization), and have been found in a wide variety of biological species including plants, insects, and vertebrates. Growth factors are used for the medical treatment of cancers and blood and cardiovascular diseases. Among the most familiar growth factors is erythropoietin (EPO), which is produced in the kidney and stimulates the production of red blood cells. EPO has since gained notoriety as a blood doping agent in cycling and other endurance sports.

SEE ALSO: Nervous System Communication (1791).

Among the fifty-or-so growth-promoting factors that have been discovered since 1953, perhaps the most well known is erythropoietin (EPO), which stimulates red blood cell production. EPO has gained a notorious reputation as a blood-doping agent, increasing oxygen delivery to muscles, which enhances endurance performance.