Objective: The aim of this study is to investigate the effects of cardiac integrin-linked kinase (ILK) overexpression in a rat model of doxorubicin-induced heart failure and the underlying mechanisms.
Methods: Rat heart failure model was induced by intraperitoneal administration of doxorubicin (6 injections within 2 weeks: total dose = 15 mg/kg). Five weeks after the first injection, rats with heart failure were confirmed by echocardiography and then randomly divided into Ad-ILK group (intra-myocardial injected with adenoviral vector expressing ILK) and Ad-null group (intra-myocardial injected with empty ad-null, n = 20 each). After 4 weeks, ILK expression and activity were detected by Western blot, cardiac function was determined by echocardiographic and hemodynamic examinations. Apoptosis was measured by TUNEL analysis and cardiomyocyte proliferation was estimated by phospho-histone-H3 staining.
Results: Western blot analysis revealed higher expression of ILK as well as the phosphorylation levels of Akt in Ad-ILK hearts as compared with ad-null controls. Four weeks after transfection, LVEF and LVFS were significantly higher in Ad-ILK group as compared with control group [LVEF: (60.56 ± 2.61)% vs. (51.94 ± 2.28)%, P < 0.05; LVFS: (28.10 ± 1.83)% vs. (22.82 ± 1.68)%, P < 0.05]. The LVEDD and LVESD, as well as LVEDP were significantly lower in Ad-ILK group compared with control group [LVEDD: (6.22 ± 0.24) mm vs. (7.15 ± 0.21) mm, P < 0.05; LVESD: (4.42 ± 0.23) mm vs. (5.65 ± 0.25) mm, P < 0.05; LVEDP: (12.96 ± 2.10) mmHg vs. (21.45 ± 2.48) mmHg (1 mmHg = 0.133 kPa) , P < 0.05]. Reduced levels of serum BNP was also seen in the Ad-ILK group. TUNEL analysis showed that ILK treatment significantly inhibited the apoptosis of cardiomyocytes [(0.23 ± 0.02)% vs. (0.45 ± 0.04)%, P < 0.05]. Moreover, increased cardiomyocyte proliferation was found in Ad-ILK group through the phospho-histone H3 staining [(0.60 ± 0.07)% vs. (0.24 ± 0.03)%, P < 0.01].
Conclusion: ILK gene therapy improves cardiac function in this rat model of heart failure, and is associated with reduced apoptosis and increased cardiomyocyte proliferation.