In 1999, Duke researchers led by Laura Niklason, M.D., reported in the journal Science on experiments in which they grew pig arteries in a novel "bioreactor" system that mimics the fetal environment, and then successfully implanted these bioengineered arteries back into the pig. Unfortunately, researchers found that human artery cells did not possess enough life cycles to be grown into functional arteries.
The key to overcoming this hurdle was found in a cancer research lab. Every time a cell divides, the ends of its chromosomes, or telomeres, erode until they become so short that the cell receives a signal to stop growing. While at the Massachusetts Institute of Technology, current Duke researcher Chris Counter, Ph.D., had previously cloned the hTERT (human telomerase reverse transcriptase subunit) component of the enzyme telomerase that stops telomeres from shortening, and had shown that expression of hTERT permitted some human cells to continue to divide indefinitely, in effect making them immortal.
Working with Niklason and Counter, then medical student Andy McKee found that when the hTERT gene was introduced into smooth muscle cells, key components of an artery, the life span of the cells were extended long enough to form arteries in the laboratory.
The results of the Duke experiments were published today (June 6, 2003) in EMBO Reports, the journal of the European Molecular Biology Organization.
"After introducing the human cells with hTERT, we found that the resulting cells not only proliferated long beyond their normal lifespan, but retained characteristics of normal smooth muscle cells," Niklason expla
Contact: Richard Merritt
Duke University Medical Center