Thorac Cardiovasc Surg 2012; 60 - PP29
DOI: 10.1055/s-0031-1297676

Protective effects of different fibroblast phenotypes on the hypoxia induced cardiac myocyte injury

M Franz 1, M Ditze 2, R Heller 3, M Kiehntopf 4, M Fritzenwanger 1, BR Brehm 1, I Petersen 2, HR Figulla 1, A Berndt 2
  • 1Universitätsklinikum Jena, Klinik für Innere Medizin I, Jena, Germany
  • 2Universitätsklinikum Jena, Institut für Pathologie, Jena, Germany
  • 3Friedrich-Schiller-Universität Jena, Center for Molecular Biomedicine, Jena, Germany
  • 4Universitätsklinikum Jena, Institut für Klinische Chemie und Laboratoriumsdiagnostik, Jena, Germany

Objectives: Cardiac tissue remodelling in response ischemia/reperfusion is characterized by the interaction of cardiac myocytes (CM) and fibroblasts (cFb). Thereby, activation of Fb leads to different phenotypes, i.e. the alpha-smooth muscle actin (ASMA) positive myofibroblasts (MyoFb) which contribute to interstitial fibrosis and scar formation. For non-activated cFb, a protective effect has been shown for CM injury due to simulated ischemia reperfusion in vitro. Our study was aimed to analyse the influence of activated MyoFb compared to non-activated cFb on the hypoxia induced CM injury and the associated changes in the ECM gene expression profile.

Methods: The HL-1 mouse cardiomyocyte tumour cell line was used as a model for adult CM and the hTERT-BJ-1 human immortalized fibroblast cell line as a model for cFb. The MyoFb phenotype was generated by stimulation of BJ-1 cells with transforming growth factor-beta 1 (TGF-beta1). HL-1 cells were cultivated in unconditioned medium and Fb or MyoFb supernatant under hypoxic conditions (1% pO2 to simulate ischemia) and subsequently under normoxic conditions (to simulate reperfusion) and/or in presence of 2-Deoxy-D-glucose (2-DG). Lactate dehydrognase (LDH) and Troponin-I (TnI) levels were measured in the HL-1 supernatant by ELISA technique. Moreover, real-time PCR based ECM gene expression profiler arrays were performed.

Results: CM like phenotype of HL-1 and MyoFb phenotype of stimulated BJ-1 cells was confirmed by real-time PCR and immunohistochemistry for typical marker molecules. LDH and TnI levels in the HL-1 cell supernatant after ischemia/reperfusion were significantly reduced in presence of fibroblasts. There was further remarkable decrease in LDH and TnI liberation when MyoFb conditioned medium was added. Furthermore, the presence of different cFb phenotypes is associated by distinct changes in the ECM gene expression profile of injured HL-1 cells.

Conclusions: CM damage due to ischemia/reperfusion can be significantly reduced in the presence of Fb or MyoFb secretome. Thus, a protective effect especially of activated MyoFb can be postulated. Also the ECM gene expression profile possibly contributing to fibrosis and scar formation can be modulated by activated fibroblasts. Our data suggest that not only CM but also the cFb/MyoFb should be considered as functionally important in the process of cardiac tissue remodelling and thereby evaluated as therapeutic targets.