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Mending broken hearts

Typically, when a muscle is damaged, cells are stimulated to divide. This type of division, however, is rare in adult mammals. Many different approaches have been tried to address this problem particularly for the human heart as it has poor regenerative potential. 

Prof. Eldad Tzahor and his team at the Weizmann Institute recently made two groundbreaking discoveries in mice, whose hearts can heal after injury through the first week of life, which have the potential to impact human healing 

First, by studying the mechanisms of cardiac regeneration in mice, Prof. Tzahor discovered that a type of cell division (called cardiomyocyte proliferation), seemed to diminish one week after birth due to a reduction of the NRG1 co-receptor, ERBB2.  

The team found an increase in ERBB2 in adult mice was sufficient to trigger regeneration response following a heart attack. This discovery has great clinical and scientific implications for future heart health treatments.  

Second, the component agrin within the tissue surrounding heart cells— is present during embryonic development, but is no longer present around the time of birth. Prof. Tzahor and his team suspected that the secret to embryonic heart tissue regeneration lies here, since many cell-to-cell messages pass through it while others are stored within it.  

When they introduced agrin into mice with a heart attack, this protein appeared to unlock a regenerative process that enables the repair of the heart tissue. After about a month, the injured hearts almost completely healed and became fully functional. At the end of the recovery period, the scar tissue was dramatically reduced and was replaced by living heart tissue that restored the heart’s pumping function. 

Prof. Tzahor’s discoveries uncovered two separate molecular mechanisms—agrin and ERBB2—that are key in cardiac regeneration. His research reveals that cardiac regeneration can be awakened and activated, and gives hope to the possibility of heart repair in mammals.  

Preclinical studies are ongoing, and the results are encouraging.  

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