Efficient targeting of heart lesions with cardiac myofibroblasts: Combined gene and cell therapy enhanced by magnetic steering

1 The cardiac scar is a collagen-rich area, which is populated by myofibroblasts and has proven little amenable for therapeutic interventions. Herein, we have established an efficient targeting strategy for cardiac lesions by genetically manipulating embryonic cardiac myofibroblasts (mFB) in vitro , load the cells with magnetic nanoparticles and inject these into infarcted mouse hearts using magnetic steering. This yields strongly increased numbers (∼4 fold compared to other cell types) of engrafted mFB. The injected mFB and endogenous myofibroblast (endoFB) population remain separate in the scar, but grafted mFB enhance the proliferation rate of endoFB by ∼4 fold. We also tested the functional impact of this approach by grafting lentiviral (LV)-transduced Connexin43 (Cx43) overexpressing mFB into the cardiac lesion. Prominent engraftment of Cx43 + mFB provides strong protection against post-infarct ventricular tachycardia (VT) in vivo , as VT incidence is reduced by ∼50 % at two and eight weeks after cell injection. Thus, ex vivo gene and subsequent in vivo cell therapy combined with magnetic steering of cardiac mFB enable efficient functional targeting of the cardiac scar.