Abstract 14238: Label-free Imaging of Human Heart by Raman Microspectroscopy
Introduction: The accurate elucidation of myocardial viability is a critical issue in determining the resection region of cardiac tissue in surgical ventricular restoration (SVR). In general, the myocardial viability is evaluated before the operation by using MRI and myocardial scintigraphy. These methods are difficult to apply for real time evaluation of the myocardial viability during the SVR operation. Raman spectroscopy is an ideal and valuable analytical tool in biological and medical fields, allowing identification of states of tissue via detecting molecular vibrations of intrinsic molecules in the tissue without labels or extensive preparations. In this study, we evaluated a new method of human cardiac tissue to identify cardiomyocytes from fibrotic tissue by Raman microspectroscopy for the first time.
Method: Cardiac tissues were resected from five ischemic cardiomyopathy patients who underwent SVR. The resection stumps were immediately snap-frozen in liquid nitrogen and were sliced into 5-um-thick serial sections with a cryostat microtome. Raman spectra and 2D Raman images were acquired with a laser Raman confocal microscope (laser wavelength: 532 nm). Serial sections for staining were used to confirm histology. First, we analyzed the spectra of the regions of cardiomyocytes and fibrotic tissue. Second, we compared the acquired Raman images with the serial pathological images. This study was conducted after obtaining approval from the Ethics Committee of Kyoto Prefectural University of Medicine.
Result: In the region of cardiomyocytes, Raman peaks were mainly assigned to cytochrome. On the other hand, in the region of fibrotic tissue, Raman peaks were mainly assigned to collagen type I. The 2D Raman images almost coincided with the serial pathological images, in which the peaks at 751, 1130 and 1582 cm-1 corresponded to the cardiomyocytes, and the peak at 2943 cm-1 to the collagen type I.
Conclusion: By applying the Raman spectroscopy to the human heart, we visualized intact and infarcted myocardial regions at the cellular level without labeling for the first time. Raman microspectroscopy is a useful tool for the detection of myocardial viability. This feasible method is applicable to intraoperative non-invasive cardiac imaging.
- © 2013 by American Heart Association, Inc.