11 January 2001
Scientists may have found a way to overcome some of the obstacles preventing the use of embryo-derived stem cells, a type of immature cell thought to hold great promise in the treatment of illnesses such as Parkinsons disease and diabetes.
While the cells can be grown in the laboratory after they are collected from embryos, the characteristics of stem cells make it difficult to move them from the laboratory to the clinic. Stem cells never stop dividing, so if the cells were to be transplanted before they had begun to form more specialized cells, they might form a tumor instead of normal tissue, Dr. John D. Gearhart, of Johns Hopkins University in Baltimore, Maryland, explained.
The key to overcoming this problem is to transplant cells that have already specialized somewhat, a process known as differentiation, according to the Johns Hopkins researcher. Differentiated cells are no longer immortal, so they do not run the risk of becoming cancerous.
In a report in the January 2nd issue of the Proceedings of the National Academy of Sciences, Gearhart and his colleagues detail their successful efforts to produce cells that can still form many different types of cells, but do not carry a risk of forming tumors.
The researchers started by coaxing embryonic stem cells to form clusters of cells known as embryoid bodies. From these small masses, the scientists then isolated cells called embryoid body-derived cells, which they grew in culture dishes to form different types of cells.
When they analyzed the embryoid body-derived cells, the researchers detected genes for several different cell types, including neurons and blood cells, Gearhart stated. The researchers also found that, unlike the most immature stem cells, embryoid-derived cells are not immortal. They will divide 70 to 80 times and then die, Gearhart said, which is enough to grow tissue but not to form tumors.
The next step, Gearhart pointed out, is to place the cells in animals to see whether they can treat disease or heal spinal cord injuries.
Proceedings of the
National Academy of Sciences 2001;98:113-118