Intravital assessment of angioarchitecture in rat hepatocellular nodules using in vivo fluorescent microscopy

Yi Liu, Tao Lu, Congcong Wang, Hui Li, Ke Xu, Peiling Li


Background: To prospectively evaluate the stepwise changes that occur in intra-nodular microvessels and microcirculation during the carcinogenesis process of hepatocellular nodules by using in vivo fluorescent microscopy, and to compare these with pathological changes.
Methods: Forty-five 10-week-old male Wistar rats received drinking water containing N-nitrosomorpholine at 10 mg/100 mL for 18weeks to develop multiple hepatocellular carcinomas (HCC) and dysplastic nodules (DN) in the liver; meanwhile, the non-lesion liver tissues become fibrotic. The microvascular morphological change and hemodynamic change of two lesion areas (HCC or DN) and one non-lesion area in each rat were observed with in vivo fluorescent microscope. After in vivo microscopy, 90 nodules and 45 non-lesion liver tissues that were observed were removed for pathological study. The microvessel density (MVD), branch density (BD), and cell density (CD) of these lesions were compared with the Kruskal-Wallis test and Mann-Whitney test, with an overall statistical significance of 0.05.
Results: The intra-nodular microvessels appeared tortuous, with irregular branching and abrupt diameter changes to form irregular convoluted networks in the HCC. This was distinctly different from the appearance of DN and non-lesion liver parenchyma. The MVD and BD of HCC were less than that of the DN and non-lesion liver parenchyma (P<0.01), and the BD of DN was also less than that of the non-lesion liver parenchyma (P<0.05). However, the MVD of the DN was similar to that of the non-lesion liver parenchyma (P>0.05). The CD of HCC was more than that of the DN and non-lesion liver parenchyma (P<0.05), and the CD of DN was also more than that of the non-lesion liver parenchyma (P<0.05).
Conclusions: Concurrent with the carcinogenesis process of the hepatocellular nodule, both the intra-nodular microvascular morphology and hemodynamics were stepwise changed, and the number of the intravascular lumen of intranodular microvessels decreased due to the infiltration and compression of intra-nodular parenchymal cells.