M1 macrophage infiltrations and histological changes in the liver after portal vein embolization using fibrinogen and OK432 in the rat.

The mechanism of anti-tumor effect of transarterial Immuno-Embolization (TIE) using OK-432 has not been well elucidated. In this study, we aimed to investigate the tissue injury and immune response after portal venous embolization (PVE) with/without OK-432. Embolic materials (L group: lipiodol, LF group: lipiodol+fibrinogen, LO group: lipiodol+OK-432, LFO group: lipiodol+fibrinogen+OK-432) were administered via the right portal vein in Wistar rats. The histological findings in LFO group demonstrated liver damage with severe architectural changes. The concentrations of CD68(+) cells were observed in a time-dependent manner; it was significantly increased in the LO group on day 1 and in the LFO group on day 3. CD68(+)CD163(-) macrophages significantly increased in the LFO group on day 7 (P<0.05). In conclusion, PVE with fibrinogen and OK-432 markedly increased the CD68(+)CD163(-) infiltrating macrophages around the peri-portal area in the liver. This novel technique could be applied as immune-enhanced chemo-embolization of liver tumors.