Adeno-associated viruses (AAV) have become one of the most promising tools for gene transfer in clinics. Among all the serotypes, AAV9 has been described as the most efficient for cardiac transduction. In order to achieve optimal therapeutic delivery in heart disease, we have explored AAV9 transduction efficiency in an infarcted heart using different routes of administration and promoters, including a cardiac-specific one. AAV9 vectors carrying luciferase or green fluorescence protein under the control of the ubiquitous elongation-factor-1-alpha or the cardiac-specific troponin-T (TnT) promoters were administered by intramyocardial or intravenous injection, either in healthy or myocardial-infarcted mice. The transduction efficacy and specificity, the time-course expression, and the safety of each vector were tested. High transgene expression levels were found in the heart, but not in the liver, of mice receiving AAV-TnT, which was significantly higher after intramyocardial injection regardless of ischemia-induction. On the contrary, high hepatic transgene expression levels were detected with the elongation-factor-1-alpha-promoter, independently of the administration route and heart damage. Moreover, tissue-specific green fluorescence protein expression was found in cardiomyocytes with the TnT vector, whereas minimal cardiac expression was detected with the ubiquitous one. Interestingly, we found that myocardial infarction greatly increased the transcriptional activity of AAV genomes. Our findings show that the use of cardiac promoters allows for specific and stable cardiac gene expression, which is optimal and robust when intramyocardially injected. Furthermore, our data indicate that the pathological status of the tissue can alter the transcriptional activity of AAV genomes, an aspect that should be carefully evaluated for clinical applications.

中文翻译：

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心脏缺血和给药途径对AAV9载体的生物分布和转导效率的影响。

腺伴随病毒（AAV）已成为临床上最有前途的基因转移工具之一。在所有血清型中，AAV9被描述为最有效的心脏转导。为了在心脏病中实现最佳的治疗效果，我们已经探索了使用不同的给药途径和启动子（包括心脏特异性启动子）在梗塞的心脏中进行AAV9的转导效率。在健康或心肌梗塞的小鼠中，通过心肌内或静脉内注射施用在普遍存在的延伸因子-1-α或心脏特异性肌钙蛋白-T（TnT）启动子控制下携带荧光素酶或绿色荧光蛋白的AAV9载体。测试了每种载体的转导功效和特异性，时程表达和安全性。在接受AAV-TnT的小鼠的心脏中发现高转基因表达水平，而在肝脏中则没有，在心肌内注射后无论缺血诱导如何，转基因表达水平均显着较高。相反，用延伸因子-1-α-启动子检测到高肝转基因表达水平，而与给药途径和心脏损害无关。此外，使用TnT载体在心肌细胞中发现了组织特异性绿色荧光蛋白表达，而在无处不在的心肌中仅检测到最小的心脏表达。有趣的是，我们发现心肌梗塞大大增加了AAV基因组的转录活性。我们的发现表明，使用心脏启动子可以实现特定且稳定的心脏基因表达，这在心肌内注射时是最佳且稳定的。