IN-VIVO MICROSCOPY OF HEPATIC METASTASES - DYNAMIC OBSERVATION OF TUMOR-CELL INVASION AND INTERACTION WITH KUPFFER CELLS

In vivo microscopy was used in the study of the biological behavior of tumor cells and of the activity of Kupffer cells in hepatic tumors in situ. Three tumor models, Friend erythroleukemia inoculated into Dilu te Brown Aguti (DBA)/2 mice, murine colon adenocarcinoma (CT)-26 in Ba gg Albino inbred albino (BALB)/c mice, and mammary cancer 13762 NF in Fischer rats, were investigated. Tumor cells showed a strong tendency to adhere to the sinusoidal endothelium, most frequently in the sinuso ids near the tumors. Mechanical trapping of tumor cells in the narrow portion of hepatic sinusoids, a phenomenon suggested by previous inves tigators as a predominant pattern for tumor cells to arrest in the liv er, was not confirmed. Our study documented that in tumor-bearing live rs, as compared with normal control livers, the population size and th e phagocytic capacity of Kupffer cells are increased in nontumorous ar eas but are significantly decreased inside the tumors. In vivo microsc opic images showed that Kupffer cells are not only attracted to tumor cells in the hepatic circulation but also have the ability to phagocyt ose those tumor cells. In vivo microscopy has been shown to be a usefu l tool for dynamic studies in tumor biology, pathology, and pharmacolo gy.