New Heart Cells

Seems the medical textbooks will need a bit of a rewrite.  It has always been believed that heart cells cannot regenerate.  Thus, while the cells may enlarge as you grow, it was believed that you died with the same heart cells with which you were born.

Not so.  A new study has shown that heart cells can replicate, although not that quickly.  Jonas Frisen and others have just reported in the journal Science that the heart replaces about 1% of all cells per year at age 25, falling to about 0.5% per year at age 75.

Two interesting aspects about this research. 

First, it establishes that a mechanism controlling heart cell replacement must exist.  Once that mechanism is understood there may be new hope for heart attack patients who have lost functional heart muscle.

Second, the methodology used was fascinating.  The standard technique used to determine cellular replacement in other animals is to radiolabel them (i.e., expose them to a radioactive chemical that the cells will incorporate into their strucure) and then look for new unlabelled cells. This can't be done in humans for ethical/health reasons.  Indirectly though, the world superpowers did this anyway.  Above ground nuclear testing created an abnormally high level of radioactive carbon (C-14) that anyone born before 1963 would have been exposed to.  It was following this radioisotope that allowed the measurements in this study to be made.

Photo Credit: New York Times