Pitt one of few to receive embryonic stem cells

Researchers at Pitt recently obtained human embryonic stem cell lines, something very few… Researchers at Pitt recently obtained human embryonic stem cell lines, something very few universities can claim.

In August 2001, President Bush said only 78 already existing embryonic stem cell lines would be approved for research with funding.

Gerald Schatten, head of the Pittsburgh Development Center, applied for the grant, and in April 2002 the grant was approved and Pitt received the money, said Christopher Navara, a cell biologist at the Pittsburgh Development Center and assistant professor of obstetrics, gynecology and reproductive sciences. In September, the University of California-San Francisco gave cell lines to the development center, which is part of the Magee-Women’s Research Institute at Pitt, Navara said.

Only 78 cell lines are allowed for research because of the controversy surrounding human embryonic stem cells, according to Navara. Some consider an embryo a human life, and cannot be morally destroyed. The acceptance of human embryonic stem cell research depends on an individual’s definition of when actual life starts, Navara said.

Bush’s proclamation was a compromise that allowed researchers to only use cell lines that had previously existed because in-vitro fertilization, Navara said.

In-vitro fertilization involves fertilizing eggs outside of a woman’s body. If more embryos begin to develop than is necessary, the extra embryos are removed and are donated for research if the donor consents, Navara said. This usually occurs about one week after fertilization, when the embryo is in the form of a blastocyst. A blastocyst is a cluster of cells with an outer cell layer, called the trophectoderm, and a cluster of cells inside, called the inner cell mass.

The inner cell mass can be removed from the blastocyst and cultured in a Petri dish. In the cultured dish, the cells divide to grow increasing amounts of embryonic stem cells. All of these cells make up one cell line, she said.

According to the National Institute of Health, which researched the exact number of pre-existing cell lines, there are 78 cell lines. According to Navara, in actuality, there are only 10 cell lines. Some of these cell lines are exact replicates.

For example, Geron Corporation in California is listed as having seven cell lines, but five of these cell lines are exact replicates of other cell lines.

Cell lines are replicates when they are grown from the same blastocyst. Some cell lines grow so much that they overcrowd the Petri dish, and the researchers have to divide the cells into two dishes. Even though they are essentially the same cell line for research purposes, NIH refers to them as separate cell lines, Navara said. He said this problem is compounded by the fact that Geron isn’t giving the cell lines to anybody else and that very little is known about the actual structure of human embryonic stem cells.

Research performed on mouse embryonic stem cells have revealed that the stem cells are totipotent, meaning the cells can develop into a complete organism.

When stem cells from a blastocyst of a white mouse were cultured, and then injected into a black mouse’s blastocyst, the result was a white mouse with black spots. This showed researchers that the embryonic stem cells eventually differentiated into all the specialized cells needed to form a complete organism.

But this process cannot be done with human embryonic stem cells, for obvious ethical reasons, Navara said. So researchers cannot find out if human embryonic stem cells are totipotent in this method. Instead, researchers have manipulated the stem cells to see if they can form various types of specialized cells.

Researchers have also injected embryonic stem cells into mice to determine if the cells will grow various types of tissue, Navara said. The result was a tumor of various tissue types, Navara said. The tumor can even have teeth or hair, for example.

These methods, however, do not prove that the embryonic stem cells can form all types of specialized cells, and thus be totipotent. According to Navara, these methods only prove the cells are pluripotent, meaning the cells can form various types of other cells, but not necessarily a complete organism.

Human embryonic stem cells have the potential to treat diseases, such as Parkinson’s disease, if researchers can manipulate the stem cells to form certain cell types, he said.

Some people feel research should only be done on adult stem cells, but adult stem cells cannot form any type of specialized cell.

“I kind of take the middle ground [on the issue],” he said.

Navara said researchers do not know for sure if human embryonic stem cells can form all types of specialized cells like mouse embryonic stem cells can. But he added, human embryonic stem cells are “possibly very important for research.”

He said he personally cannot support destroying human embryos, because “potential research is just that: potential.”

But he added that research on already-existing stem cell lines from in-vitro fertilization is ethical to him, because the stem cells already exist and their potential value to research and disease treatment shouldn’t be wasted.

The Pittsburgh Development Center is interested in the “basic biology of these cells,” Navara said. For example, “we want to say that this particular stem cell expresses these proteins,” he added.

The development center will also focus on comparing the human embryonic stem cells to that of mice embryonic stem cells. Reports from other researchers already state that the human cell lines are growing more slowly than the mouse cell lines did.

According to Navara, researchers of human embryonic stem cells will probably begin announcing their findings in about six months to one year.