Stable therapeutic effects of mesenchymal stem cell-based multiple gene delivery for cardiac repair

Aims: We have previously shown that transplantation of mesenchymal stem cells (MSCs) co-overexpressing angiopoietin-1 (Ang-1) and Akt prevented cell apoptosis, enhanced angiogenesis, and improved left ventricular heart function. The present study was designed to determine the persistence of therapeutic benefits on longer term basis. Methods and results: Acute myocardial infarction model was developed in 30 young female Fischer-344 rats by permanent ligation of the left anterior descending coronary artery. The animals were grouped (n = 10) to receive 70 μL Dulbecco's modified Eagle's medium (DMEM) without cells (DMEM group 1) or containing 3 × 10⁶ non-transduced male MSCs (MSC group 2) or transduced MSCs co-overexpressing Ang-1 and Akt (MAA group 3). The injections were carried out intramyocardially in the free wall of left ventricle at multiple sites. Three months after cell transplantation, real-time polymerase chain reaction for the rat sry gene, confocal imaging, and immunohistochemical studies revealed the extensive survival and myogenic differentiation of the PKH67-labelled cell graft. Blood vessel density was significantly higher in the MAA group (P < 0.05) at 3 months compared with the other groups. Blood vessel maturation index as determined by double-fluorescent immunostaining for vWFactor VIII and smooth muscle actin showed that most of the newly formed vessels matured to develop a smooth muscle covering in MAA group. Sonographic assessment of heart function showed that heart function deteriorated in the DMEM group, whereas the functional benefits were stable over a period of 3 months following transplantation of transfected cells. Conclusion: Engraftment of genetically modified MSCs co-overexpressing Ang-1 and Akt produced long-term histological and functional benefits in an infarcted heart.