Worldwide, about 23 million people have heart attacks each year.  Half of them die within five years.  In the United States alone, heart failure costs $40 billion a year. 

While we’ve made a lot of progress in preventing heart attacks over the past 50 years, there has been no way to undo the damage a heart attack leaves behind in survivors.  Fortunately that’s all changing. 

The field of adult stem cell research and therapy is exploding right now, and its advances promise to change the way medicine is practiced and to improve the lives of millions — not just heart patients but people with a wide range of diseases.

Stem cells are the precursors of all the tissues in the body.  In theory, a stem cell could grow and change to become anything from nerve tissue to heart muscle to skin or bone or blood.  In fact, all our tissues start out as stem cells.  Although this has been known in theory for a long time, until fairly recently no one was sure if it could be useful in replacing or repairing damaged tissues in living bodies. 

First let’s review the relevant history: 

Scientists in the early 1900s noticed that a simple cell in bone marrow would transform itself into a more complex one, producing blood cells.  They called these stem cells.  In fact, a bone marrow transplant — used to treat leukemia, among other diseases — is simply a transplant of stem cells.

Physicians have long suspected that stem cells might have curative properties.  A century ago they were giving leukemia patients bone marrow by mouth.  Although it had no effect, their thinking eventually led them to inject bone marrow into the bloodstream of mice, which did have therapeutic effects.  The first successful human treatments that might be termed “stem cell therapy” were bone marrow transplants conducted in France in the late 1950s. 

By 1958, a French researcher discovered human histocompatibility antigens, known as HLA antigens.  Those are the proteins on the outside of a cell that are responsible for the immune response that causes rejection, and their discovery led to great strides in stem cell research.  For one thing, scientists came to understand that for bone marrow transplants or any other stem cell therapy to work, the HLA antigens had to be...