Preservation of Myocardial Structure Is Enhanced by Pim-1 Engineering of Bone Marrow Cells

Rationale: Bone marrow-derived cells to treat myocardial injury improve cardiac function and support beneficial cardiac remodeling. However, survival of stem cells is limited due to low proliferation of transferred cells. Objective: To demonstrate long-term potential of c-kit(+) bone marrow stem cells (BMCs) enhanced with Pim-1 kinase to promote positive cardiac remodeling. Methods and Results: Lentiviral modification of c-kit(+) BMCs to express Pim-1 (BMCeP) increases proliferation and expression of prosurvival proteins relative to BMCs expressing green fluorescent protein (BMCe). Intramyocardial delivery of BMCeP at time of infarction supports improvements in anterior wall dimensions and prevents left ventricle dilation compared with hearts treated with vehicle alone. Reduction of the akinetic left ventricular wall was observed in BMCeP-treated hearts at 4 and 12 weeks after infarction. Early recovery of cardiac function in BMCeP-injected hearts facilitated modest improvements in hemodynamic function up to 12 weeks after infarction between cell-treated groups. Persistence of BMCeP is improved relative to BMCe within the infarct together with increased recruitment of endogenous c-kit(+) cells. Delivery of BMC populations promotes cellular hypertrophy in the border and infarcted regions coupled with an upregulation of hypertrophic genes. Thus, BMCeP treatment yields improved structural remodeling of infarcted myocardium compared with control BMCs. Conclusions: Genetic modification of BMCs with Pim-1 may serve as a therapeutic approach to promote recovery of myocardial structure. Future approaches may take advantage of salutary BMC actions in conjunction with other stem cell types to increase efficacy of cellular therapy and improve myocardial performance in the injured myocardium. (Circ Res. 2012;111:77-86.)