Nature relies upon a spectrum of stem cells.

Adult stem cells are capable of producing different types of related cells, such as platelets and lymphocytes.

Embryonic stem cells theoretically can be persuaded to form any type of cell.

Fetal stem cells fall in between, capable of producing more types than adult stem cells but fewer than embryonic stem cells.

Theoretically, because an adult stem cell contains the full DNA blueprint, it could be persuaded to produce any other type of cell.

In reality, once a cell starts down the path toward specialization, protein switches within that cell become unavailable. It’s difficult to force stem cells to revert to an earlier version.

Maintaining embryonic stem cells as stem cells actually is far easier than maintaining adult stem cells, said David Crouse, Ph.D., of the University of Nebraska Medical Center in Omaha. Adult stem cells want to change. Without careful controls, they quickly get away from researchers.

Opponents of embryonic stem cell research claim that 72 diseases or conditions have benefited from adult stem cell research, and there is no need to mess with embryonic stem cells.

“The actual number is far below the 72,” Crouse said. “It’s closer to nine or 10.”

And most of those are bone marrow or metabolic diseases. Much of that research occurred at UNMC.

“We know a lot about adult stem cells,” Crouse said.

Many diseases so far have eluded treatment using adult stem cells, said Sanford Goodman, public policy director of Nebraskans for Research.

Much of what opponents say about stem cell research is “a misuse of science and an abuse of the scientific process,” he said.

The argument that no cures have come directly from embryonic stem cell research is misleading, Goodman said. Research is necessary to learn all that can be learned about how stem cells work.

“Eliminating embryonic stem cell research would be like a puzzle where you throw some of the pieces away,” he said. “You’ll never get the big picture.”

Reach Mark Andersen at 473-7238 or mandersen@journalstar.com.