J Korean Surg Soc.  2012 Apr;82(4):238-245. 10.4174/jkss.2012.82.4.238.

Splenectomy affects the balance between hepatic growth factor and transforming growth factor-beta and its effect on liver regeneration is dependent on the amount of liver resection in rats

• Kim J
• Kim CJ
• Ko IG
• Joo SH
• Ahn HJ

• KMID: 1820072
• DOI: http://doi.org/10.4174/jkss.2012.82.4.238

Abstract

PURPOSE
Small-for-size syndrome (SFSS) is a major problem in liver surgery, and splenectomy has been used to prevent SFSS. However, it is unknown whether splenectomy has the same effect on liver regeneration in both standard and marginal hepatectomy. The aim of this study is to see a difference in effect of splenectomy on liver regeneration according to the amount of liver resection.
METHODS
Thirty male Sprague-Dawley rats (220 to 260 g) were divided into the following five groups: control (n = 6), 70% hepatectomy (n = 6), 70% hepatectomy with splenectomy (n = 6), 90% hepatectomy (n = 6), and 90% hepatectomy with splenectomy (n = 6). The animals were euthanized 24 hours after surgery and liver specimens were obtained. To assess liver regeneration, we performed immunohistochemistry of liver tissue using 5-bromo-2-deoxyuridine (BrdU) labeling and Western blot analysis of hepatic growth factor (HGF) and transforming growth factor-beta (TGF-beta) in the liver tissue.
RESULTS
The splenectomized subgroup had a higher BrdU-positive cell count in the 90% hepatectomy group, but not in the 70% hepatectomy group (P < 0.001). Splenectomy significantly decreased TGF-beta expression (P = 0.005) and increased the HGF to TGF-beta ratio (P = 0.002) in the 90% hepatectomy group, but not in the 70% hepatectomy group.
CONCLUSION
The positive effect of splenectomy on liver regeneration was greater in the group with the larger liver resection. This phenomenon may be related to the relative balance between HGF and TGF-beta in the liver.

Keyword

Liver regeneration; Splenectomy; Hepatectomy; HGF; Transforming growth factor beta

MeSH Terms

Animals
Blotting, Western
Cell Count
Hepatectomy
Humans
Immunohistochemistry
Liver
Liver Regeneration
Male
Rats
Rats, Sprague-Dawley
Splenectomy
Transforming Growth Factor beta
Transforming Growth Factor beta

Figure

• 

  Fig. 1 (A) Liver weight index (the percent of remnant liver weight measured 24 hours after the first surgery divided by body weight) was significantly different according to the amount of liver resection (P < 0.001). (B) The differences between subgroups according to the splenectomy were not significant. 70 (90)% ± S, 70 (90)% hepatectomy with and without splenectomy; 70 (90)%, 70 (90)% hepatectomy without splenectomy; 70 (90)% + S, 70 (90)% hepatectomy with splenectomy. NS, non-significant.

• 

  Fig. 2 Liver regeneration index measured by the number of 5-bromo-2'-deoxyuridine (BrdU)-positive hepatocytes. (A) Photomicrographs showed liver sections stained for BrdU (A-a, arrows) and hepatocytic nuclei. Scale bar 400 mm (A) and 50 mm (a). (B) Liver regeneration indexes were significantly different according to the amount of liver resection (P < 0.001). (C) The differences between subgroups according to the splenectomy were significant only in 90% hepatectomy group (P < 0.001). 70 (90)% ± S, 70 (90)% hepatectomy with and without splenectomy; 70 (90)%, 70 (90)% hepatectomy without splenectomy; 70 (90)%±S, 70 (90)% hepatectomy with splenectomy; NS, non-significant.

• 

  Fig. 3 Western blot analysis of hepatic growth factor (HGF) and transforming growth factor-β (TGF-β). (A) The intensities of α-chain of HGF and TGF-β were calculated by using densitometry. (B) Relative protein expressions of HGF were significantly higher in hepatectomized groups than the control group, and it was higher in 90% hepatectomy group than in 70% hepatectomy group. (C) However, those were not significant between subgroups according to the splenectomy. (D) The expressions of TGF-β were also significantly higher in hepatectomized groups. However, the difference was not significant between 70% and 90% hepatectomy groups. (E) Subgroup analysis showed that TGF-β expressions were significantly lower in the splenectomy group, in 90% hepatectomy groups but not in 70% hepatectomy groups. (F) To show the relative balance between HGF and TGF-β, the relative ratio of HGF to TGF-β was also analyzed. Difference of the ratio was not significant between the control group and the 70% hepatectony group but it was significantly higher in the 90% group. (G) The subgroup analysis showed that splenectomy significantly increased HGF to TGF-β ratio only in the 90% hepatectomy group. Among subgroups without splenectomy (bars marked with asterisks), there were no significant differences. Values are presented as mean ± standard error of the mean. 70 (90)% ± S, 70 (90)% hepatectomy with and without splenectomy; 70 (90)%, 70 (90)% hepatectomy without splenectomy; 70 (90)% + S, 70 (90)% hepatectomy with splenectomy; NS, non-significant.

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