Gaitas Angelo, Malhotra Ricky, Li Tao, Herron Todd, Jalife José
Kytaro, Inc., 11200 SW 8th Street, MARC 430, Miami, Florida 33199, USA.
Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109, USA.
Rev Sci Instrum. 2015 Mar;86(3):034302. doi: 10.1063/1.4915500.
Cardiac contractility is the hallmark of cardiac function and is a predictor of healthy or diseased cardiac muscle. Despite advancements over the last two decades, the techniques and tools available to cardiovascular scientists are limited in their utility to accurately and reliably measure the amplitude and frequency of cardiomyocyte contractions. Isometric force measurements in the past have entailed cumbersome attachment of isolated and permeabilized cardiomyocytes to a force transducer followed by measurements of sarcomere lengths under conditions of submaximal and maximal Ca(2+) activation. These techniques have the inherent disadvantages of being labor intensive and costly. We have engineered a micro-machined cantilever sensor with an embedded deflection-sensing element that, in preliminary experiments, has demonstrated to reliably measure cardiac cell contractions in real-time. Here, we describe this new bioengineering tool with applicability in the cardiovascular research field to effectively and reliably measure cardiac cell contractility in a quantitative manner. We measured contractility in both primary neonatal rat heart cardiomyocyte monolayers that demonstrated a beat frequency of 3 Hz as well as human embryonic stem cell-derived cardiomyocytes with a contractile frequency of about 1 Hz. We also employed the β-adrenergic agonist isoproterenol (100 nmol l(-1)) and observed that our cantilever demonstrated high sensitivity in detecting subtle changes in both chronotropic and inotropic responses of monolayers. This report describes the utility of our micro-device in both basic cardiovascular research as well as in small molecule drug discovery to monitor cardiac cell contractions.
心脏收缩力是心脏功能的标志，也是健康或患病心肌的一个预测指标。尽管在过去二十年中取得了进展，但心血管科学家可用的技术和工具在准确可靠地测量心肌细胞收缩的幅度和频率方面的效用有限。过去的等长力测量需要将分离并通透的心肌细胞繁琐地连接到力传感器上，然后在次最大和最大钙（Ca2+）激活条件下测量肌节长度。这些技术存在劳动强度大且成本高的固有缺点。我们设计了一种带有嵌入式挠度传感元件的微机械悬臂传感器，在初步实验中已证明其能够实时可靠地测量心脏细胞收缩。在此，我们描述这种新型生物工程工具在心血管研究领域的适用性，以有效且可靠地定量测量心脏细胞收缩力。我们测量了原代新生大鼠心脏心肌细胞单层的收缩力，其搏动频率为3 Hz，还测量了人胚胎干细胞衍生的心肌细胞的收缩力，其收缩频率约为1 Hz。我们还使用了β-肾上腺素能激动剂异丙肾上腺素（100 nmol l(-1)），并观察到我们的悬臂在检测单层变时性和变力性反应的细微变化方面表现出高灵敏度。本报告描述了我们的微型设备在基础心血管研究以及小分子药物发现中监测心脏细胞收缩的效用。
