4-dimensional intravital microscopy: a new model for studies of leukocyte recruitment and migration in hepatocellular cancer in mice.
BACKGROUND
Although it is accepted that the immune system plays a role in the prognosis of hepatocellular carcinoma (HCC), the exact mechanisms of leukocyte recruitment into HCC are poorly understood. Progress in the study of this aspect has been hindered by technical limitations.


METHODS
In the present study, we describe the use of 4D intravital microscopy which represents an advantageous technology for the investigation of the microvascular system and leukocyte migration in HCC. To establish 4D intravital microscopy, we used a HCC tumor model in transgenic mice expressing enhanced green fluorescent protein in specific leukocyte subpopulations and combined digital time-lapse recording, laser scanning confocal microscopy, and 3D reconstruction. Using this technology, we studied the intra- and extravascular leukocyte adhesion and migration in HCC in vivo at the single-cell level.


RESULTS
We showed that although vessel density in HCC was lower than in normal liver, tumor tissue was moderately infiltrated with leukocytes of lymphoid and myeloid origin. Most tumor-infiltrating leukocytes migrated in a random manner frequently changing direction of migration in the tumor tissue. The migration velocity of myeloid and lymphoid leukocytes in HCC tissue was not different.


CONCLUSIONS
These results demonstrated that 4D intravital microscopy has potential to be a powerful tool in the study of mechanisms of leukocyte recruitment and intratumoral migration in HCC.
Department of Surgery, University of Heidelberg, Im Neuenheimer Feld 110, 69120 Heidelberg, Germany. ttakeichi@fc.kuh.kumamoto-u.ac.jp
Takayuki
T
Takeichi
Guido
G
Engelmann
Paulius
P
Mocevicius
Jan
J
Schmidt
Eduard
E
Ryschich
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D002634:Chemotaxis, Leukocyte / Q000276:immunology / Q000502:physiology*; D003287:Contrast Media; D003952:Diagnostic Imaging / Q000295:instrumentation*; D004195:Disease Models, Animal; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007090:Image Interpretation, Computer-Assisted; D007275:Injections, Intravenous; D007962:Leukocytes / Q000473:pathology* / Q000502:physiology; D008113:Liver Neoplasms / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D036641:Microscopy, Fluorescence, Multiphoton; D009374:Neoplasms, Experimental; D011897:Random Allocation; D012235:Rhodamines; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric
D003287:Contrast Media; D012235:Rhodamines; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C009434:tetramethylrhodamine isothiocyanate