The Adult Heart Lacks Stem Cells Capable of Regenerating Damaged Muscle

A recent study conducted on mice has shown that stem cells present in the hearts of new born animals can be induced to regenerate heart muscle following a heart attack but that these stem cells no longer function in the hearts of adult animals.

Investigators at Cornell University (Ithaca, NY, USA) and their colleagues at the University of Bonn (Germany) examined the ability of neonatal and adult mice to regenerate heart muscle tissue following heart attack (infarction) to determine the role of the stem cells known as c-kit+ cardiovascular precursor cells (CPCs) that are known to be present in early heart development.

They reported in the July 30, 2012, online edition of the journal Proceedings of the National Academy of Sciences of the USA (PNAS) that undifferentiated precursor cells matured into new heart muscle cells in two-day-old mice, but not in adult animals. While the young mice were able to regenerate functional myocytes, infarction of adult mice resulted in only a modest induction of c-kit+ cells within the infarct, which did not undergo myogenic differentiation, but adopted a vascular role within the infarction, indicating a lack of authentic CPCs.

“While the existence of these cells in adults is controversial, if one did have fully capable stem cells in adults, why are there no new heart cells after an infarct? Whether this is due to a lack of stem cells or to something special about the infarct that inhibits stem cells from forming new heart cells is the question we addressed, taking advantage of the fact that the newborn mouse has these cells,” said senior author Dr. Michael Kotlikoff, professor of veterinary medicine at Cornell University. “The stem cells found in the adult heart have lost the ability to become heart cells, and are only capable of forming new vessels.”

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University of Bonn