Ultrasound mediated nitric oxide microbubbles enhance the therapeutic efficacy of bone marrow mesenchymal stem cell transplantation on myocardial infarctions / 中国组织工程研究

ABSTRACT

BACKGROUND: Recent experimental studies have found ultrasound mediated microbubbles potentiate stem cell therapy in myocardial infarction (MI)-induced heart failure, indicating a good application prospect. But whether ultrasound mediated nitric oxide (NO) microbubbles also have the same effect in the intracoronary transplantation of bone marrow mesenchymal stem cells (BMSCs) for treatment of large animals with MI is still unknown. OBJECTIVE: To investigate the effectiveness and possible mechanism of ultrasound mediated NO microbubbles in potentiating intracoronally transplanted BMSCs homing to the infarcted area in a MI pig model.METHODS: Density gradient centrifugation culture method was used in the isolation and cultivation of BMSCs. CM-Dil was used to label BMSCs in vitro. Twenty-four pigs were used to make MI models by blocking the left anterior descending coronary artery, and then were divided into PBS group, BMSCs group, ultrasound+microbubbles+BMSCs(MB) group, ultrasound+NO microbubbles+BMSCs (NO-MB) group(n=6 per group). In the PBS group, 10 mL of PBS was intracoronally injected. In the BMSCs group, about 1×107 BMSCs were diluted in 10 mL of PBS and then intracoronally infused. In the MB group, 0.1 mL/kg sulphur hexafluoride microbubbles (Sono Vue) was intracoronally injected together with ultrasound treatment (1 MHz, 2 W/cm2, 2 minutes), followed by intracoronary infusion of about 1×107 BMSCs that were diluted in 10 mL of PBS. In the NO-MB group, all methods and conditions were identical to those in the MB group except only 0.1 mL/kg of Sono Vue was replaced by 0.1 mL/kg NO microbubbles. Three pigs were sacrificed in each group 48 hours after CM-Dil positive BMSCs transplantation. The labeled BMSCs were observed and counted by fluorescent microscope after frozen sectioning of the infarct area. We assessed and compared left ventricular systolic function with M-mode ultrasound among groups at 4 weeks after intervention. After cardiac function test, the rest pigs were sacrificed and capillary density in the myocardial ischemic area was counted and compared after hematoxylin-eosin staining. RESULTS AND CONCLUSION: (1) The number of CM-Dil positive cells in the area of MI in the NO-MB group was much more than that in the MB group and BMSCs group with statistical significance (P < 0.05). (2) The left ventricle systolic function was significantly improved in the NO-MB group as compared with the MB group (P < 0.05). The same trend was observed between NO-MB group and BMSCs group as well as between NO-MB group and PBS group (P < 0.05). (3) The density of capillaries increased significantly in the NO-MB group compared with the MB group, BMSCs group and PBS group, respectively. To conclude, ultrasound mediated NO microbubble combined with intracoronary BMSCs transplantation can improve the left ventricular systolic function. The possible mechanism could be that ultrasoundmediated NO mocrobubbles promote the homing of transplanted BMSCs to the myocardial ischemia area as well as improve local angiogenesis.