title: c-kitpos GATA-4 high rat cardiac stem cells foster adult cardiomyocyte survival through IGF-1 paracrine signalling.
abstract: BACKGROUND
  Resident c-kit positive (c-kitpos) cardiac stem cells (CSCs) could be considered the most appropriate cell type for myocardial regeneration therapies. However, much is still unknown regarding their biological properties and potential.
  
  
  RESULTS
  We produced clones of high and low expressing GATA-4 CSCs from long-term bulk-cultured c-kitpos CSCs isolated from adult rat hearts. When c-kitpos GATA-4 high expressing clonal CSCs (cCSCs) were co-cultured with adult rat ventricular cardiomyocytes, we observed increased survival and contractility of the cardiomyocytes, compared to cardiomyocytes cultured alone, co-cultured with fibroblasts or c-kitpos GATA-4 low expressing cCSCs. When analysed by ELISA, the concentration of IGF-1 was significantly increased in the c-kitpos GATA-4 high cCSC/cardiomyocyte co-cultures and there was a significant correlation between IGF-1 concentration and cardiomyocyte survival. We showed the activation of the IGF-1 receptor and its downstream molecular targets in cardiomyocytes co-cultured with c-kitpos GATA-4 high cCSCs but not in cardiomyocytes that were cultured alone, co-cultured with fibroblasts or c-kitpos GATA-4 low cCSCs. Addition of a blocking antibody specific to the IGF-1 receptor inhibited the survival of cardiomyocytes and prevented the activation of its signalling in cardiomyocytes in the c-kitpos GATA-4 high cCSC/cardiomyocyte co-culture system. IGF-1 supplementation or IGF-1 high conditioned medium taken from the co-culture of c-kitpos GATA-4 high cCSCs plus cardiomyocytes did extend the survival and contractility of cardiomyocytes cultured alone and cardiomyocytes co-cultured with c-kitpos GATA-4 low cCSCs.
  
  
  CONCLUSIONS
  c-kitpos GATA-4 high cCSCs exert a paracrine survival effect on cardiomyocytes through induction of the IGF-1R and signalling pathway.
authors.affiliation: International Research and Educational Institute for Integrated Medical Sciences (IREIIMS), Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Nanako
authors.initials: N
authors.lastname: Kawaguchi
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Smith
authors.forename: Cheryl D
authors.initials: CD
authors.lastname: Waring
authors.forename: Md Kamrul
authors.initials: MK
authors.lastname: Hasan
authors.forename: Shinka
authors.initials: S
authors.lastname: Miyamoto
authors.forename: Rumiko
authors.initials: R
authors.lastname: Matsuoka
authors.forename: Georgina M
authors.initials: GM
authors.lastname: Ellison
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods; D002470:Cell Survival; D064987:Cell- and Tissue-Based Therapy / Q000379:methods*; D050991:GATA4 Transcription Factor / Q000378:metabolism*; D006321:Heart / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology*; D032383:Myocytes, Cardiac / Q000166:cytology*; D019899:Paracrine Communication; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D051381:Rats; D012038:Regeneration / Q000502:physiology*; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism*
chemical_list: D050991:GATA4 Transcription Factor; C084365:Gata4 protein, rat; D007334:Insulin-Like Growth Factor I; D019009:Proto-Oncogene Proteins c-kit