Abstract 4374: G-CSF Treatment Improves Cardiac Function In postmyocarditic Cardiomyopathy By Enhanced Circulation And Homing Of CD34+ Progenitor Cell Populations

Abstract

Objective : Recently, it was shown that the physiologic repair mechanism of mobilization and homing of bone marrow-derived stem cells (BMCs) is impaired in dilated cardiomyopathy. In our study we aimed to analyze circulation and homing of CD34 + progenitor cell populations in a murine model of dilated cardiomyopathy due to coxsackie virus B3 (CVB3) induced myocarditis and the influence of G-CSF treatment on BMC homing and cardiac function. Methods and Results : First, SWR/J (H-2q)-mice were infected by intraperitoneal injection of 10 5 pfu CVB3. Healthy, age-matched SWR/J (H-2q)-mice served as controls. 12 weeks after infection, DCM was verified by MRI/Millar-tip-catheter and histology. In DCM mice, CD34 + BMC populations (CD34 + CD31 + , CD34 + Sca-1 + , CD34 + c-kit + and CD34 + CXCR-4 + ) measured by flow cytometry were significantly increased in peripheral blood, decreased in bone marrow and remained unchanged in the hearts in comparison to controls. Different from ischemic heart diseases, myocardial homing factors (SDF-1, SCF, HIF-1a, VCAM and HGF) assessed by real-time PCR were not upregulated in the CVB3-DCM group. Finally, 18 DCM-CVB3 mice were analyzed by MRI 8 weeks after CVB3 infection and randomized into G-CSF-or saline-treatment (100 μg/20μl s.c. daily for 2× 5 days). 12 weeks after infection, cardiac function was assessed using MRI: Change of ejection fraction was significantly better in the G-CSF-group compared to the controls (4.1±1.8 vs. −2.5±2.2%; p=0.03). The improvement of cardiac function was associated with enhanced homing of BMC subpopulations. Conclusions : We have shown that postmyocarditic cardiomyopathy is associated with a reduced migration of BMCs to the cardiomyopathic hearts due to a lack of increase of homing factors. This defect can partly be overcome by G-CSF-administration resulting in an increased number of stem cells in the myocardium and leading to a moderately improved cardiac function. Therefore our data provides new insights in the pathogenesis of dilated cariomyopathy and presents a promising non-invasive approach to ameliorate heart failure.