Stem cell research has quickened

DEAR DOCTOR K: People have been talking about stem cells as a revolutionary technique for a long time. Has anything come of it? And why has it been so controversial?

DEAR READER: You’re right; people have been excited about stem cells for nearly 25 years. Yet progress was quite slow, and some people had ethical concerns. But in the past eight years, progress has accelerated and the ethical issues largely have been circumvented.

Theoretically, stem cells could be used to replace cells that are killed by disease – heart cells killed in a heart attack, or brain cells killed by Alzheimer’s disease. But to explain the exciting potential of stem cells, I need first to define some terms and concepts.

Each human being is made of trillions of cells. They are grouped together into organs, such as the eye and the stomach. Each organ contains types of specialized cells, and each type looks and acts differently.

Each of these very different cells came from just one original cell: the fertilized egg. The egg keeps dividing until one cell has become trillions. Inside every human cell are a little over 20,000 genes. The genes inside a eye cell are the same as the genes in a stomach cell. So if both cells have the same genes, why are these two different types of specialized cells so different from each other?

What defines a specialized cell is what genes inside the cell are turned on.

About five days after the egg is fertilized, it has divided into several hundred cells. Some of these cells are called embryonic stem cells. They have the ability to turn into any type of specialized cell in the body.

With a few exceptions, once a cell has become specialized, it will stay that way until it dies.

Suppose you needed heart cells because of a heart attack. Until 2007, there were problems with using embryonic stem cells.

If only you could use your own cells, that would solve it. But of course your own embryonic stem cells existed only briefly, a long time ago.

Then, in 2007, a breakthrough changed everything. The breakthrough showed you can turn back the clock!