Healing the heart from within.

While some scientists work toward repairing injured hearts with stem cells, others wonder if they can coax human hearts into fixing themselves. After all, some nonmammalian animals regenerate heart tissue (SN: 11/1/97, p. 280).

Challenging the dogma that human-heart cells don't divide, a research group reported in the June 7 NEW ENGLAND JOURNAL OF MEDICINE that such cells proliferate in people who have suffered a heart attack, albeit not enough to heal the organ (SN: 7/7/01, p. 13). Now, through studies of a mouse strain with unusual powers to regenerate tissue, scientists have found that some mammals can indeed heal their own hearts.

Several years ago, Ellen Heber-Katz of the Wistar Institute in Philadelphia accidentally discovered that a certain strain of mouse heals holes punched into its ears, and leaves no scars (SN: 2/21/98, p. 118). In the Aug. 14 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, they report that these mice also extensively regenerate heart tissue damaged by surgical means, whereas other mice don't.

Heber-Katz and her colleagues continue to look for genetic differences in the mice that might be behind the tissue regeneration. They're also finding hints that the rodents can regenerate nerve cells and bone.