Artikel
Intramyocardial Human Tissue Kallikrein Gene Transfer increases Cardiomyocyte Progenitor Cells in a Mouse Model of Myocardial Infarction
Intramyokardialer humaner Gewebekallikrein Gentransfer erhöht kardial gewebeständige Stammzellen in einem experimentellen Myokardinfarktmodell der Maus
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Veröffentlicht: | 8. August 2006 |
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Background: The kallikrein-kinin system is known to be cardioprotective under ischemic conditions. The present investigation aimed to test the original hypothesis that hTK delivery to the peri-infarct (I) myocardium would increase the myocardial abundance of cardiomyocyte progenitor cells (CPCs).
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, expression and localisation of the transgene were evaluated by qualitative RT-PCR and immunostaining. Moreover, phosphorylated (p)-Akt and total (tot.) Akt, p-endothelial nitric oxide synthase (eNOS) and tot.-eNOS protein levels were quantified by Western-Blot. At 4 and 14 days from MI, the density of CD45+ and CD68+ cells in the peri-I and remote areas were analyzed by immunohistochemistry. CPCs were analyzed in the peri-I and remote zone of the LV by immunofluorescence by their double positivity for c-kit and GATA-4 and the absence of _-sarc expression. LV-function was characterised by a 1.4F Millar Tip-catheter intracaviter 5 weeks after MI.
Results: HTK mRNA presence was restricted to the LV, where it was higher in the peri-I. HTK protein was variably expressed by cardiomyocytes, with maximal hTK immunostaining in proximity to the injection site and almost undetectable in the remote zone. The p-Akt/tot-Akt ratio and the p-eNOS/tot.eNOS ratio were significantly higher in the Ad.hTK group (p<0.05 vs. Ad.Null) 4 days after MI. MI increased CD45+ and CD68+ cells, which, at 4 days from MI, were both more abundant in the peri-I vs. the remote zone (p<0.01). Ad.hTK did not further increase the number of CD45+ and CD68+ cells. MI increased the abundance of resident CPCs as compared with sham-operation (p<0.01 at 4 or 14 days). In addition, in the Ad.Null controls, CPCs were more abundant in the peri-I than in the remote zone (p<0.01 at 4 or 14 days). At 4 days from MI, Ad.hTK enhanced the CPC abundance in the peri-I, albeit the difference was lost at 14 days. These findings correlated with an improved LV function 5 weeks after MI.
Conclusion: Intramyocardial hTK increases CPC abundance, which correlates with an improved LV function.