Stem cells and the new future of medicine.

• Author: Herold, Eve
• Position: Medicine & Health

DIABETES, cancer, heart disease, Alzheimer's--all are deadly and often incurable, until now. In the near future, stem cell treatments could relegate them to history. Those aren't the only conditions that may end up being cured by the groundbreaking research--there also are kidney disease, Parkinson's, spinal paralysis, amyotrophic lateral sclerosis (Lou Gehrig's disease), and severe burns. Then there are a slew of debilitating and often fatal autoimmune disorders like lupus, multiple sclerosis, and Crohn's disease. The list of cell-based diseases that could be eradicated through stem cell treatments encompasses almost anything you can think of, including age-related conditions and the process of aging itself In fact, if and when stem cell treatments become available to Americans, they could end up extending people's life spans well beyond anything one could have dreamed possible a mere 10 years ago.

It is hard to believe that a single field in science could produce such a quantum leap, but stem cell therapies promise to overcome one of the central limitations of biological life--the fact that, over a lifetime, the body has at its disposal a finite number of cells. Sooner or later, we no longer are able to repair and replace these cells with anything like the rate of their loss through disease or injury. Once we lose that race, disease and the assaults of aging take their toll. Too few beating cardiac cells and the heart enlarges and grows weak. Too few functioning neurons in the hippocampus and the brain declines into dementia. Cancer can wipe out normal cells much faster than the body can replace them at any age, possibly resulting in organ failure and death.

In all of these conditions, it is not just the number of cells that pose a devastating loss to the body, but the specific function of each cell type. (There are hundreds in the body.) Our cells perform indispensable functions. Each is a little biochemical factory continuously convening energy, eliminating waste products, communicating with other cells, and producing its own special molecules. What is more, only our bodies know how to make these brilliant little units. Modern pharmaceuticals are but a blunt instrument compared to the vast array of chemical reactions that can occur throughout our bodies every microsecond of every day. Only live, functioning human cells can perform such an assortment of life-giving and life-maintaining roles. However, it seems that with every miracle, there has to be a catch, and the catch here is that the body can just make so many of each precious cell type.

Replacing dead brain cells with healthy new ones could cure Alzheimer's, Parkinson's, and stroke-related brain damage. Replacing dead pancreatic cells with young, insulin-producing islet cells could banish diabetes, and an infusion of fresh liver cells could rejuvenate a sick liver from the inside out. The list of potential cures goes on and on. It would be great if doctors could just reach for the kind of cells we need and give us an infusion when we need one. If stem cell science pans out as researchers hope, that, in principal, is what they will be able to do.

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