title: Increased cardiac myocyte progenitors in failing human hearts.
abstract: BACKGROUND
  Increasing evidence, derived mainly from animal models, supports the existence of endogenous cardiac renewal and repair mechanisms in adult mammalian hearts that could contribute to normal homeostasis and the responses to pathological insults.
  
  
  RESULTS
  Translating these results, we isolated small c-kit+ cells from 36 of 37 human hearts using primary cell isolation techniques and magnetic cell sorting techniques. The abundance of these cardiac progenitor cells was increased nearly 4-fold in patients with heart failure requiring transplantation compared with nonfailing controls. Polychromatic flow cytometry of primary cell isolates (<30 microm) without antecedent c-kit enrichment confirmed the increased abundance of c-kit+ cells in failing hearts and demonstrated frequent coexpression of CD45 in these cells. Immunocytochemical characterization of freshly isolated, c-kit-enriched human cardiac progenitor cells confirmed frequent coexpression of c-kit and CD45. Primary cardiac progenitor cells formed new human cardiac myocytes at a relatively high frequency after coculture with neonatal rat ventricular myocytes. These contracting new cardiac myocytes exhibited an immature phenotype and frequent electric coupling with the rat myocytes that induced their myogenic differentiation.
  
  
  CONCLUSIONS
  Despite the increased abundance and cardiac myogenic capacity of cardiac progenitor cells in failing human hearts, the need to replace these organs via transplantation implies that adverse features of the local myocardial environment overwhelm endogenous cardiac repair capacity. Developing strategies to improve the success of endogenous cardiac regenerative processes may permit therapeutic myocardial repair without cell delivery per se.
authors.affiliation: Department of Physiology, Temple University School of Medicine, Philadelphia, PA, USA.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kubo
authors.forename: Naser
authors.initials: N
authors.lastname: Jaleel
authors.forename: Asangi
authors.initials: A
authors.lastname: Kumarapeli
authors.forename: Remus M
authors.initials: RM
authors.lastname: Berretta
authors.forename: George
authors.initials: G
authors.lastname: Bratinov
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Shan
authors.forename: Hongmei
authors.initials: H
authors.lastname: Wang
authors.forename: Steven R
authors.initials: SR
authors.lastname: Houser
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Margulies
mesh_terms: D000071916:AC133 Antigen; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism; D006333:Heart Failure / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000502:physiology; D010455:Peptides / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012038:Regeneration / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; D010455:Peptides; D019009:Proto-Oncogene Proteins c-kit; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human