title: Repair of the injured adult heart involves new myocytes potentially derived from resident cardiac stem cells.
abstract: BACKGROUND
  The ability of the adult heart to generate new myocytes after injury is not established.
  
  
  OBJECTIVE
  Our purpose was to determine whether the adult heart has the capacity to generate new myocytes after injury, and to gain insight into their source.
  
  
  RESULTS
  Cardiac injury was induced in the adult feline heart by infusing isoproterenol (ISO) for 10 days via minipumps, and then animals were allowed to recover for 7 or 28 days. Cardiac function was measured with echocardiography, and proliferative cells were identified by nuclear incorporation of 5-bromodeoxyuridine (BrdU; 7-day minipump infusion). BrdU was infused for 7 days before euthanasia at days 10, 17, and 38 or during injury and animals euthanized at day 38. ISO caused reduction in cardiac function with evidence of myocyte loss from necrosis. During this injury phase there was a significant increase in the number of proliferative cells in the atria and ventricle, but there was no increase in BrdU+ myocytes. cKit+ cardiac progenitor cells were BrdU labeled during injury. During the first 7 days of recovery there was a significant reduction in cellular proliferation (BrdU incorporation) but a significant increase in BrdU+ myocytes. There was modest improvement in cardiac structure and function during recovery. At day 38, overall cell proliferation was not different than control, but increased numbers of BrdU+ myocytes were found when BrdU was infused during injury.
  
  
  CONCLUSIONS
  These studies suggest that ISO injury activates cardiac progenitor cells that can differentiate into new myocytes during cardiac repair.
authors: Cardiovascular Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA.
authors: David
authors: D
authors: Angert
authors: Remus M
authors: RM
authors: Berretta
authors: Hajime
authors: H
authors: Kubo
authors: Hongyu
authors: H
authors: Zhang
authors: Xiongwen
authors: X
authors: Chen
authors: Wei
authors: W
authors: Wang
authors: Barbara
authors: B
authors: Ogorek
authors: Mary
authors: M
authors: Barbe
authors: Steven R
authors: SR
authors: Houser
mesh_terms: D000367:Age Factors; D000818:Animals; D009202:Cardiomyopathies / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy*; D002415:Cats; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D007545:Isoproterenol / Q000633:toxicity; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000187:drug effects / Q000473:pathology; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000473:pathology
chemical_list: D007545:Isoproterenol