Intramyocardial Transplantation of Bone Marrow-Derived Stem Cells: Ultrasonic Strain Rate Imaging in a Model of Hibernating Myocardium

BackgroundThe aim of this study was to evaluate potential cardioprotective effects of bone marrow-derived stem cells in chronic ischemic myocardium regarding strain rate parameters during dobutamine stress echocardiography.MethodsAn ameroid constrictor was placed around the circumflex artery in 23 pigs to induce hibernating myocardium. Pigs received autologous mesenchymal stem cells (auto MSCs), allogeneic MSC (allo MSC), autologous mononuclear cells (auto MNCs), or placebo injections into the ischemic region. During dobutamine stress echocardiography, peak systolic strain rates (SRsys) and systolic and postsystolic strain values (ɛsys, ɛps) were determined. The animals were evaluated regarding myocardial fibrosis, neovascularization, apoptosis, and myocardial β-adrenergic receptor density.ResultsThe median ejection fraction was reduced in the control group compared with the auto MSC-, allo MSC-, and auto MNC-treated pigs (36.5% vs 46.0% vs 46.0% vs 41.5%; P = .001, respectively). Histopathology revealed a decreased myocardial fibrosis in auto MSC- (16.3%), allo MSC- (11.3%), and auto MNC- (16.7%) treated pigs compared with controls (31.0%; P = .004). The fibrosis and echocardiographic deformation data correlated in the posterior walls: rest peak SRsysr = −0.92; ɛsysr = −0.86; 10 μg dobutamine stimulation peak SRsysr = −0.88, ɛsys, r = −0.87 (P = .0001).ConclusionEndocardial injection of stem cells may induce cardioprotective effects in chronic ischemic myocardium and helps to keep the ischemic myocardium viable.