The Study Of MCD-microRNAs Interfere Plasmids Mediated By Ultrasound Microbubble On Cardiac Function Of Rats With Myocardial Infarction

Backgroud: Myocardial infarction is an important reason in leading toheart failure. It has great significance in improving cardiac dysfunctionafter myocardial infarction. It is suggested that myocardial energymetabolism plays an important role in the development and progression ofheart failure. Most studies suggest that the inhibition of fatty acid oxidationor increasing glucoseoxidation will help to improve heart function. Largenumber of studies have confirmed that the ultrasoundmicrobubble-mediated exogenous gene in the rat’s heart has a strongtargeted carrying capacity, and will not lead to irreversible myocardialinjury and cardiac dysfunction.The objective of this study is to construct and select the optimalmicroRNA interference plasmid for MLYCD gene. And then theinterference plasmid mixed with lipid microbubbles were co-transfectedinto wista rats with myocardial infarction to silent myocardial MLYCDgene, resulting in improving the content of malonyl coenzyme A and inhibiting fatty acid oxidation, so that to investigate its influence on cardiacfunction and the possible mechanism for a new target from the metabolictreatment of heart failure Objective: To observe the inhibition of microRNA interferingplasmids for rat’s MLYCD on MLYCD gene in vitro and select the optimalmicroRNA interference sequence.Methods: The microRNA interfering plasmids targeting on rat’sMLYCD gene were constructed and co-transfected with eukaryoticexpression vector for MLYCD gene into HEK293cells, respectively. Therelative expression of mRNA in MLYCD gene was detected by real timePCR.Results: DNA sequencing showed that the microRNA interferingplasmids for rat’s MLYCD gene and the eukaryotic expression vector forMLYCD gene were constructed successfully. The results of real-time PCRshowed that the expression of mRNA in interference group1(MCD-microRNA-1) was significantly lower than the negative control group, positive control group and other interference groups (P<0.05).Conclusion: MCD-microRNA-1was the optimal microRNAinterference sequence, laying a foundation for further study. Objective： To evaluate the effect of the targeted inhibition ofmyocardial malonyl-coa decarboxylase(MCD) MCD-microRNAinterference plasmids mediated by ultrasound-microbubble on cardiacfunction of rats with myocardial infarction and the possible mechanism.Methods：The models of myocardial infarction were constructed byligating the rat ramus descendens anterior arteriae coronariae sinistraepermanently. Twenty-eight rats with myocardial infarction were randomlyassigned into four experimental groups: myocardial infarction (MI)+saline;myocardial infarction+plasmid; myocardial infarction+ultrasound+plasmid; myocardial infarction+ultrasound+microbubble+plasmid, n=7.An alternative group of sham-operated+saline served as control. A goodmixture of the selected interference plasmid and lipid microbubbles wereco-transfected into myocardial infarction rats mediated by ultrasound every four days at the fourth week. After continuous intervention until28days,the changes of left ventricular ejection fraction intervention (LVEF),fractional shrinkage (FS%), left ventricular end-diastolic diameter size(LVIDd), malonyl COA and lactic acid were investigated.Results：The MCD-microRNAs interfering plasmids were transfectedinto rats with myocardial infarction mediated by ultrasound-microbubble.After8weeks, the levels of LVEF%and FS%in the group of myocardialinfarction+ultrasound+microbubble+plasmid were both higher thanthose in other interfering groups of myocardial infarction (P <0.05), butsignificantly lower than those in the group of sham-opearated+saline (P <0.05). The level of lactic acid was lower than that in other myocardialinfarction intervention groups (allP<0.05), but significantly higher thanthat in the group of sham-opearated+saline (P <0.05). The level of LVIDdin rats with myocardial infarction in the interference group was notsignificant different (P>0.05)，but significantly lower than that in the groupof sham-opearated+saline (P<0.05).Conclusion：That the MCD-microRNA interference plasmids mediatedby ultrasound microbubble which targetedly transfected into rats withmyocardial infarction, can increase the level of malonyl COA, reduce thelevel of lactic acid and delay the deterioration of cardiac function althoughit has no effect on the inhibition of ventricular dilatation.