Self-replicating RNA-nanoplexes for programming monocytes to regenerate the heart

 描述：除了心脏移植，目前还没有能够恢复心肌梗死（MI）后心脏功能的治疗方法。心肌梗死会杀死数百万个心脏细胞， 减少氧气和血液供应。利用神经调节蛋白（NRG 1）等蛋白质刺激存活心肌细胞的有丝分裂来再生受损心脏细胞的策略可以部分恢复梗死心肌。然而，由于两个原因，使用常规方法将此类治疗剂递送至心脏是困难的：（1）心脏血管对大分子显示出非常低的渗透性，（2）到达心脏的分子被高血流快速冲走。在临床研究中，NRG 1的半衰期短，需要每天全身注射。此外，到达心脏的分数非常低，损害了其治疗功效。这种非靶向方法也可能导致心脏远端区域心肌细胞的不受控制的增殖，引起心肌增生和肥大。显然，迫切需要一种非侵入性和受控的递送方法，该方法可以特异性靶向梗死区和边缘区中存活的心肌细胞。我们建议开发一种新的交付策略，以满足这一需求。我们的方法将通过利用人体对MI的免疫反应来靶向梗死的心脏组织。具体来说，我们提出使用自然迁移到梗死部位的单核细胞来递送再生蛋白。由于与细胞外基质和其他蛋白质的特异性受体-配体相互作用，尽管血流量高，但单核细胞在心脏中显示出非凡的保留。我们假设（1）单核细胞可以被自我复制的RNA纳米复合物靶向和遗传编程以表达NRG 1，并且（2）单核细胞将归巢梗死组织并局部释放NRG 1，这是一种可以诱导心肌细胞增殖并促进组织再生的蛋白质。为了验证这些假设，我们将首先生成靶向单核细胞的自我复制RNA纳米复合物，并将其编程为表达NRG 1。其次，我们将量化MI归巢单核细胞的数量，这些单核细胞在MI小鼠模型中被遗传编程用于蛋白质生产。我们预计这些研究将导致一个活的药物库，是非侵入性的，并能够局部提供蛋白质治疗的梗死区及其边缘区。这对缺血性心脏病患者的治疗和梗死心肌的再生具有深远的意义。

 DESCRIPTION: There are currently no treatments capable of restoring cardiac function after myocardial infarction (MI) besides cardiac transplantation. MI kills millions of heart cells due to reduced oxygen and blood supply. Strategies to regenerate damaged heart cells that use proteins, such as neuregulin (NRG1), to stimulate mitosis of surviving cardiomyocytes could partially restore infarcted myocardium. However, delivering such therapeutics to the heart using conventional methods is difficult for two reasons: (1) heart blood vessels show very low permeability for large molecules, (2) molecules that do reach the heart are washed away rapidly by the high blood flow. In clinical studies, NRG1's short half-life necessitates daily systemic injections. Further, the fraction that reaches the heart is very low, compromising its therapeutic efficacy. This non-targeted approach can also lead to the uncontrolled proliferation of cardiomyocytes in the remote zone of the heart, causing myocardial hyperplasia and hypertrophy. Clearly there is an urgent need for a non-invasive and controlled delivery approach that can specifically target surviving cardiomyocytes in the infarcted area and border zone. We propose to develop a novel delivery strategy that fulfills this need. Our approach will target infarcted cardiac tissue by exploiting the body's immunological response to MI. Specifically, we propose to deliver regenerating proteins using monocytes that naturally migrate to the site of infarction. Monocytes show extraordinary retention in the heart in spite of high blood flow due to specific receptor-ligand interactions with the extracellular matrix and other proteins. We hypothesize that (1) monocytes can be targeted and genetically programmed with self-replicating RNA-nanoplexes to express NRG1 and that (2) monocytes will home to infarcted tissue and locally release NRG1, a protein that can induce cardiomyocyte proliferation and facilitate tissue regeneration. To test these hypotheses, we will first generate self-replicating RNA-nanoplexes that target monocytes and program them to express NRG1. Secondly, we will quantify the number of MI-homing monocytes that are genetically programmed for protein production in a mouse model of MI. We anticipate that these studies will lead to a living drug reservoir that is non-invasive and able to locally deliver protein therapeutics to the infarcted sie and its border zone. This has profound implications for the treatment of patients with IHD and the regeneration of infarcted myocardium.