Objective    To evaluate the effect of different cold preservation time on liver regeneration after partial liver transplantation in rats

and study the role of IL-6/STAT3.      Methods    SD rats were divided into 3 groups: group Ⅰ underwent liver resection

group Ⅱ received partial liver transplantation after one-hour cold preservation and group Ⅲ received partial liver transplantation after 8-hour cold preservation. Radioimmunoassay was used to measure the levels of TNF-α and IL-6 in liver tissues. The protein expressions of PCNA and STAT3 were assessed by immunohistochemical staining in paraffin sections. The liver regeneration ratio and the expressions of the proliferative cell nuclear antigen (PCNA) and STAT3 were compared among three groups at 1

6

12

24

48

72 and 168 h after operation.     Results    The remnant liver in group Ⅰ and grafts in group Ⅱ grew rapidly; The regeneration ratio in group Ⅲ was significantly lower than that in group Ⅰ and group Ⅱ during postoperative day 2 to 3 (P0.05). The levels of TNF-α and IL-6 in group Ⅰ and group Ⅱ were markedly higher than those in group Ⅲ in postoperative 12 h (P0.05). The maximum levels of TNF-α and IL-6 appeared at postoperative 12 h in group Ⅰ and group Ⅱ

at 24 h in groupⅢ. PCNA expressions in group Ⅰ and group Ⅱ were increased and reached the peak value at postoperative 24 h. PCNA expressions in group Ⅲ were markedly lower than groups Ⅰ and Ⅱ during postoperative 12 h (P0.05)

and reached the peak at 48 h. STAT3 expression reached the peak at postoperative 1 h in groups Ⅰ and Ⅱ

then decreased gradually to undetectable at postoperative day 7. In group Ⅲ

STAT3 expressions were detected at 6 h and reached the peak at postoperative 12 h

still more at 7 d.     Conclusion    Longer cold preservation time leads to more impairment of the regenerative ability of liver after partial liver transplantation. The abnormal changes of TNF-α

IL-6 and STAT3 in the early period of regeneration may be the main mechanism for impaired partial graft regeneration after long-time cold preservation.