By Merritt McKinney

NEW YORK, Jan 03 (Reuters Health) - 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 Parkinson's 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.

"We can't take the embryonic (stem) cells that we have and transplant them into anything," said Dr. John D. Gearhart, of Johns Hopkins University in Baltimore, Maryland. They will "just as likely form a tumor as they will differentiate into some sort of tissue," he said.

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, Gearhart 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, Gearhart noted. "Once a cell commits, it won't become a tumor," he said.

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 fact that the embryoid body-derived cells contain the genes and other markers for several different cell types is intriguing, according to Gearhart. It suggests that the cells "share a cluster of genes," he said. If this proves to be the case, it may mean that the cells, although more differentiated than the earliest of stem cells, may have the capability to form different types of tissue depending on where in the body they are transplanted, Gearhart added.

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. Official results will not be available for several months, but preliminary findings look promising, he said.

Gearhart and his colleagues also note that growing embryoid body-derived cells is much easier and faster than growing early stem cells. The ease in growing the cells, as well as the ability to have a uniform population of the cells and the ability to freeze and thaw them--which is important for storage--may reduce the number of cells that need to be collected from embryos, according to Gearhart.

The research was funded by Geron, Inc. Gearhart and one of his colleagues, as well as Johns Hopkins, have a financial interest in the company.

SOURCE: Proceedings of the National Academy of Sciences 2001;98:113-118.

Several our patients asked us to comment this article.

The statement "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" disturbed them, 

We provide one of such comments below:

Dear Sir,
As I understand you mean the article
Michael J. Shamblott, Joyce Axelman, John W. Littlefield, Paul D. Blumenthal, George R. Huggins, Yan Cui, Linzhao Cheng, and John D. Gearhart
Human embryonic germ cell derivatives express a broad range of developmentally distinct markers and proliferate extensively in vitro
PNAS 2001 98: 113-118; published online before print December 26, 2000, 10.1073/pnas.021537998

You may see, that the scientists do not stress the problem of tumor. They start from this problem to say in the article that they have surmounted it.

We have never suggested to use stem cells of two weeks gestation. The well known article by Dr. Thompson is build on the analysis namely of contents of a tumor produced by such cells.

Remark in the article that "Differentiated cells are no longer immortal, so they do not run the risk of becoming cancerous, Gearhart noted. "Once a cell commits, it won't become a tumor," he said",

should be compared to our statement in the first page of our web-site:

"Embryonic Stem Cells of each certain type perform their specialized effects. The above mentioned results can be achieved by the sophisticated usage of different kinds of Stem Cells, according to the mechanisms of certain diseases, phases of the disease, etc. According to our experience, they should not be attributed to some universal cells and their generalized effects."

A you see, we use the stem cells, which are already "committed", "already specialized somewhat", differentiated, that have selected their tissue destiny. We never observed their malignization. On the contrary, they prevent malignization by means of reinforcement of inner immune control in the body of a recipient.

At the same time we see many questions and are aware of the fact, that only the first steps in Embryonic Stem Cell Transplantology have been made, and rigorous research will be carried out in this branch of medicine for many years.

Best regards,

Professor Alexey Karpenko.