Contractile work directly modulates mitochondrial protein levels in human engineered heart tissues
Contractile work directly modulates mitochondrial protein levels in human engineered heart tissues
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DOI：
10.1152/ajpheart.00055.2020
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发表时间：
2020-06-01
影响因子：
4.8
通讯作者：
Campbell, Stuart G.
中科院分区：
文献类型：
--
作者：
Ng, Ronald;Sewanan, Lorenzo R.;Campbell, Stuart G.
工程心脏组织（EHT）已成为研究心脏生理学的强大体外模型。尽管已经开发出仿生培养环境以更好地模拟体内条件，但目前可用的方法不允许完全重现心动周期的四个阶段。我们开发了一种生物反应器，允许 EHT 进行模拟体内工作循环的循环加载序列。与等长培养的 EHT 相比，在这些工作条件下培养的 EHT 表现出增强的同心收缩，但等长收缩相似。在进行严格测试时，允许在培养物中周期性缩短的 EHT 会增加收缩做功的能力。工作量的增加与线粒体蛋白和线粒体生物发生水平的升高相关；当组织在肌球蛋白 ATP 酶抑制剂存在下周期性缩短时，这种效应就被消除了。利用我们新颖的体外方法在培养物中精确施加机械负载，我们在两种负载模式下培养 EHT，这两种负载模式规定相同的功输出，但具有不同的相关后负载。这些组的线粒体蛋白表达没有差异。在具有相同后负荷但不同功输出的负荷方案中，承受较高功需求的组织表现出线粒体蛋白水平升高。我们的研究结果表明，培养的人类 EHT 中线粒体质量的调节受到组织在培养物中允许执行的机械功的有效调节，大概是通过 ATP 需求来传达的。将机械载荷精确应用于培养中的工程心脏组织代表了一种研究生理和病理心脏适应的新型体外方法。新的和值得注意的在这项工作中，我们提出了一种新型生物反应器，它允许在扩展组织培养过程中主动控制工程心脏组织的长度。设计了特定长度的瞬变，以便工程心脏组织产生完整的心脏工作循环。具有各种工作循环的慢性培养表明，线粒体质量和生物发生直接受工作输出的调节。
Engineered heart tissues (EHTs) have emerged as a robust in vitro model to study cardiac physiology. Although biomimetic culture environments have been developed to better approximate in vivo conditions, currently available methods do not permit full recapitulation of the four phases of the cardiac cycle. We have developed a bioreactor which allows EHTs to undergo cyclic loading sequences that mimic in vivo work loops. EHTs cultured under these working conditions exhibited enhanced concentric contractions but similar isometric contractions compared with EHTs cultured isometrically. EHTs that were allowed to shorten cyclically in culture had increased capacity for contractile work when tested acutely. Increased work production was correlated with higher levels of mitochondrial proteins and mitochondrial biogenesis; this effect was eliminated when tissues were cyclically shortened in the presence of a myosin ATPase inhibitor. Leveraging our novel in vitro method to precisely apply mechanical loads in culture, we grew EHTs under two loading regimes prescribing the same work output but with different associated afterloads. These groups showed no difference in mitochondrial protein expression. In loading regimes with the same afterload but different work output, tissues subjected to higher work demand exhibited elevated levels of mitochondrial protein. Our findings suggest that regulation of mitochondrial mass in cultured human EHTs is potently modulated by the mechanical work the tissue is permitted to perform in culture, presumably communicated through ATP demand. Precise application of mechanical loads to engineered heart tissues in culture represents a novel in vitro method for studying physiological and pathological cardiac adaptation.NEW & NOTEWORTHY In this work, we present a novel bioreactor that allows for active length control of engineered heart tissues during extended tissue culture. Specific length transients were designed so that engineered heart tissues generated complete cardiac work loops. Chronic culture with various work loops suggests that mitochondrial mass and biogenesis are directly regulated by work output.