Chinese Journal of Tissue Engineering Research ›› 2010, Vol. 14 ›› Issue (36): 6785-6789.doi: 10.3969/j.issn.1673-8225.2010.36.030

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Relationship of microvillus-like protrusions to extracellular membrane particles and tunneling nanotubes on the surfaces of human fetal and hepatocellular carcinoma cells revealed by a scanning electron microscope

Zhao Xiang1, Hu Bai-he2, Zhao Xin-rong2, Zhang Ye1   

  1. 1 Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing  100191, China; 2 Electron Microscope Laboratory, Health and Medical Analysis Center, Peking University, Beijing  100191, China
  • Online:2010-09-03 Published:2010-09-03
  • Contact: Zhang Ye, Associate professor, Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing 100191, China zhangye@bjmu.edu.cn
  • About author:Zhao Xiang, Technician-in-charge, Department of Cell Biology, School of Basic Medical Sciences, Peking University, Beijing 100191, China xiangzh@bjmu.edu. cn
  • Supported by:

    the National Natural Science Foundation of China, No. 30570413; the Key Subject Construction Project of 985 Cell Biology of Peking University

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Abstract:

BACKGROUND: Liver-derived extracellular membrane particles can mediate cell-cell communication and regulate proliferation/differentiation of hepatocytes, and therefore have important application values in diagnosis of liver diseases, in prevention and treatment of liver cancers, and in development of techniques for liver regeneration and cell transplantation. However, progress in the field is hampered by limited knowledge about the origination and typological classification of liver-derived membrane particles. Tunneling nanotube (TNT) is anther newly discovered structure that also mediates cell-cell communication. However, the question whether TNT exists in hepatocytes remains unanswered.
OBJECTIVE: By comparing ultrastructural characteristics of the cell surfaces of human normal fetal liver and hepatocellular carcinoma cells, the study is aimed to find the differences between normal and cancerous cells, to uncover the biogenesis of membrane particles so as to accurately classify the particles, and to assure the existence of TNT in liver cells.
METHODS: A scanning electron microscope (SEM) was used to probe the samples prepared from cycling adhered fetal hepatocytes L02 and hepatocellular carcinoma BEL-7402 cells to analyze the commonness and difference of cell surface ultrastructure.
RESULTS AND CONCLUSION: Extensive microvillus-like protrusions were revealed for the first time on the cell surfaces of both L02 and BEL-7402 cells. The protrusions were characteristically different with the typical microvilli on resting cells. Compared with the BEL-7402 cells, however, the average length and density of the microvillus-like protrusions were longer and higher on the L02 cells, which could be used as a guide to differentiate the two cells. Microvillus-like protrusions from the two cells could either generate nanoparticles or transform into TNT. Two types of nanoparticle biogenesis, budding and pearl-forming constriction, were observed. Taken together, high-resolution SEM images can be served as gold standard to characterize the surface ultrastructures on liver-derived cells, and to pinpoint the sources of extracellular membrane particles.

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