開發微探針技術應用於藥物影響對心肌收縮功能之檢測

Abstract

心臟的主要功能在於收縮促使血液流動，藉由血液將養分、氧氣及新陳代謝物質運至或運離組織。心臟的基本功能單位為心肌細胞。心肌細胞功能異常會導致心輸出下降甚至心臟衰竭。釐清引起心臟疾病的機制以及評估治療心臟衰竭的療法需要更進一步了解心臟的功能特性。有別於活體動物或器官層次的研究，研究體外培養的心肌細胞可以排除組織結構和體內激素調節的影響，更能在細胞層次了解心肌細胞功能異常的原因以及量測收縮力，進而收集資訊幫助擬定預防與治療心臟衰竭之方針。以往心肌細胞的相關研究包括量測心肌收縮過程的細胞機械性質變化，或是心肌細胞在藥物處理下之跳動頻率的改變，較少同時量測心肌細胞收縮過程之收縮能力以及細胞內鈣離子變化。文章中開發微探針技術，對雞胚胎心肌細胞以非侵入方式即時追蹤細胞膜位移，獲得脈動強度以及脈動頻率。並將此技術應用於量測荷爾蒙以及藥物作用下心肌細胞跳動行為的動態變化。並結合細胞內鈣離子量測，偵測細胞內興奮-收縮偶合作用。此技術對於細胞層次藥物效力測試以及心臟毒性評估提供一新的檢測方法。

Cardiomyocytes comprise the fundamental contractile unit of a heart. Dysfunction of cardiomyocytes can lead to deadly pathological conditions. Detailed characterization of cardiac functions on primarily cultured cardiomyocytes can help assess interventions against heart failure and elucidate the pathogenesis of contractile dysfunction of the heart. We have demonstrated the employment of microcantilever technology based on an atomic force microscope to characterize the pulsation dynamics of chicken embryo cardiomyocytes under various pharmacological interventions. We showed that the displacement of the cardiomyocyte membrane, during cardiomyocytes contraction can be kinetically and noninvasively monitored at nanometer resolution. Through short-time Fourier transformation, the dynamic intervention of the contractile behavior of cardiomyocytes by hormones and drugs was intuitively and quantitatively demonstrated on spectrogram. At the end, we have demonstrated our first attempt to simultaneously probe the intracellular Ca2+ and the contraction mechanics of cardiomyocytes treated with doxorubicin on the same platform. Our approach should prove useful for in vitro assessment of efficacies and cardiotoxicity of new drugs. The ability to measure the intracellular level of Ca2+ and the rhythm of contraction simultaneously may also bring new insight into the excitation-contraction coupling.