Mechanobiology of Engineered Heart Tissue

该项目的总体目标是检查机械提示是否可以改善工程心脏组织（EHT）结构的收缩功能。EHT结构是通过使用人类细胞来源的心肌细胞的组织工程方法制成的。这些结构可以作为心脏病学和药理学研究的伦理试验平台，在某些情况下可以减少对动物研究的依赖。EHT结构体是功能性组织，因为它们产生在体外可见的肌肉收缩。然而，在目前最先进的EHT结构中，它们的收缩性和生理学并不完全类似于成人心脏组织。因此，该项目将使EHT结构在一个新型生物反应器中动态变化的外部负荷下，通过心脏运动建立更强壮的肌肉组织。如果成功，该项目将实现一个“盘子里的心脏”平台，用于评估心脏病的新药物治疗，了解遗传性肌病，或研究心脏病变的进展。本项目的研究机会将提供给本科生和代表性不足的少数群体。我们将在华盛顿大学的拓展活动中向K-12学生宣传我们的研究，让他们了解工程和医学交叉领域可能出现的创新。该项目将为心脏组织工程提供一种革命性的方法，通过磁性测量EHT结构的生物力学性能，并提供机械生物学线索，推动其成熟到成人水平。EHT结构的收缩力和抽搐频率的实时测量将通过在磁性硅柱上生长结构来实现，硅柱会部分偏转结构的作用力。磁柱的运动将使用多井板下的新型磁力计阵列进行测量，这使得EHT结构可以长时间连续地以平行的方式进行监测。磁场对磁柱的拉动作用会对EHT结构体施加外力，使其在收缩前（预加载）得到强力拉伸，在收缩时（后加载）得到强力约束。利用磁力进行胎儿负荷模式的前负荷和后负荷的应用，将通过机械生物学线索，复制胎儿发育过程中人类心脏所经历的不断增加的负荷，改善EHT构建中hPSC-CM的肌原纤维结构、成熟标记和收缩输出。从更广泛的意义上说，本项目的方法旨在模拟人类心脏发育中的前负荷和后负荷的发育模式，以提高在EHT结构中生长的hPSC-CM的成熟度，并通过监测细胞的收缩功能来评估这种改善。

The overall goal of this project is to examine whether mechanical cues can improve the contractile function of engineered heart tissue (EHT) constructs. EHT constructs are made by tissue engineering approaches that use human cell derived cardiomyocytes. These constructs can serve as an ethical testbed for cardiology and pharmacology studies and can reduce the reliance on animal studies in some cases. EHT constructs are functional tissues for they produce muscle contractions that are visible in vitro. However, in the current state-of-the-art for EHT constructs, their contractility and physiology does not fully resemble that of adult heart tissue. As such, this project will subject EHT constructs to dynamically changing external loads in a novel bioreactor in order to build stronger muscle tissue through cardiac exercise. If successful, this project would achieve a "hearts-in-a-dish" platform for assessing new pharmacological treatments for heart disease, understanding inheritable myopathies, or studying the progression of cardiac pathologies. Research opportunities with this project will be provided to undergraduates and underrepresented minority groups. We will publicize our research to K-12 students at outreach events at the University of Washington to educate them on the innovations that are possible at the intersection of engineering and medicine.This project will provide a transformative approach to cardiac tissue engineering by magnetically measuring the biomechanical performance of EHT constructs and providing mechanobiological cues that drive their maturation towards adult levels. Real-time measurements of the contractile force and twitch frequency of EHT constructs will be achieved by growing the constructs on magnetic silicone posts, which deflect in portion to the applied force of the constructs. The motion of the magnetic posts will be measured using a novel array of magnetometers underneath a multi-well plate, which enable the EHT constructs to be monitored continually over a long period of time and in a parallel manner. Application of magnetic fields that pull on the magnetic posts will impart external forces on the EHT constructs to forcibly stretch the constructs before their contraction (preload) and forcibly restrain the constructs during a contraction (afterload). Application of fetal loading patterns of preload and afterload using magnetic forces will improve the myofibril structure, maturation markers, and contractile output of hPSC-CM in the EHT constructs through mechanobiological cues that replicate the increasing loads that the human heart experiences during fetal development. In broader terms, the approaches in this project are intended to mimic to the developmental loading patterns of preload and afterload in a developing human heart in order to improve the maturation of hPSC-CM grown in EHT constructs and assess the improvements by monitoring the contractile function of the cells.