Article
Intramyocardial Human Tissue Kallikrein Gene Transfer Stimulates Therapeutic Angiogenesis and Improves Cardiomyocyte Viability in a Mouse Model of Myocardial Infarction
Intramyokardialer humaner Gewebekallikrein Gentransfer stimuliert die therapeutische therapeutische Angiogenese und verbessert die Lebensfähigkeit von Cardiomyocyten in einem Maus Herzinfarktmodell
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Published: | August 10, 2005 |
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Background: The present study supported the hypothesis that human tissue kallikrein (hTK) gene transfer promotes myocardial neovascularization and cardiomyocyte survival, thus preventing post-ischemic left ventricle (LV) remodelling.
Methods: Myocardial infarction (MI) was performed in male CD-1 mice by permanent ligation of the left descending coronary artery, following gene transfer in the MI border zone with an adenoviral vector carrying the hTK gene (Ad.hTK, 107p.f.u.). Controls received NaCl or Ad.Null. Four days later, endothelial nitric oxide synthase (eNOS), VEGF-A, caspase 3, Bcl-2 and Bax expression were determined by real-time PCR. Phospho-Akt (p-Akt) and total Akt protein levels (tot.-Akt) were quantified by Western-Blot. Expression and localisation of the transgene were evaluated by ELISA and qualitative RT-PCR. At 14 days from MI, heart morphology was studied by formalin fixated sections. Capillary- and arteriole density (c.d. and a.d.) were evaluated on silver stained sections. Apoptosis was further examined on TUNEL-stained isolated cardiomyocytes. LV-function was characterised by intracaviter analyses.
Results: Transgenic mRNA was limited to the LV. Ad.hTK increased eNOS expression (2.1-fold, p<0.05 vs. Ad.Null) and Bcl-2/Bax ratio (p<0.01), while it did not affect VEGF-A expression (p=NS). Moreover, Ad.hTK decreased caspase3 expression (p<0.05). The p-Akt/tot-Akt ratio was 1.3-fold higher in the Ad.hTK group (p<0.05 vs. Ad.Null). Ad.hTK reduced LV and septum thickness (both by 14%) at 14 days. In the MI border zone, Ad.hTK increased c. d. and a.d. 1.2-fold (p<0.05) and 1.7-fold (p<0.05), respectively and reduced by 1.6-fold the number of isolated apoptotic cardiomyocytes (p<0.01). These findings correlated with an improved LV function.
Conclusion: Intramyocardial hTK stimulates reparative neovascularization and inhibits cardiomyocyte apoptosis in the area at risk, which correlates with an improved LV function.