As was mentioned earlier, a little-understood "on-off" mechanism in a gene decides which cells become what, and produces birth defects or cancer by turning on the right (or wrong) genes. If some way could be found to govern that switch -- that is, to control the process of cell differentiation -- we might be able to prevent a broad range of human ailments, maybe even grow new organs or limbs in people to replace lost or diseased ones.
Recently the University of Chicago's Dr. Charles Huggins and a colleague, Haridara Reddi, reported that they had discovered an electrochemical method of working the "on-off" switch. Using bone matrix -- a protein that is able to change soft fibrous cells called fibroblasts to cartilage, bone, and bone marrow, in a sort of biological chain reaction -- the researchers stopped or started cell differentiation in adult rats. They did this by changing the electrical charge on the material. In their experiments, bone matrix (which remains behind after the powdered