As they matured from prenatal to adult, heart cells reduced the number of nuclear pores by more than 60%. That decrease protected them from the consequences of stress, but also impaired their ability to regenerate. “These findings are an important advance in fundamental understanding of how the heart develops with age and how it has evolved to cope with stress,” senior author Bernhard Kühn, professor of pediatrics and director of the Pediatric Institute for Heart Regeneration and Therapeutics at the University of Pittsburgh School of Medicine, said in a press release. Kühn and his colleagues published those findings in the Oct. 24, 2022, issue of Developmental Cell.