Kupffer cell and hepatocyte function in rat transplanted liver

Mild steatosis impairs functional recovery after liver resection in an experimental model

BACKGROUND

Mild steatosis has been thought not to affect outcome after liver resection. However, recent studies have reported impaired postoperative recovery of patients with mild steatosis. This study evaluated the recovery of hepatic functional reserve during regeneration in a rat model of mild steatosis and liver resection.

METHODS

Male Wistar rats had a standard methione- and choline-deficient diet to induce mild steatosis before 70 per cent liver resection. Evaluation of hepatobiliary function was by (99m)Tc-labelled mebrofenin scintigraphy. Mebrofenin uptake rate, the time for maximum uptake (T peak) and the time required for peak activity to decrease by 50 per cent (T(1/2) peak) were assessed 1, 2, 3 and 7 days after liver resection, along with regeneration of the remnant liver, hepatocellular and sinusoidal damage, and hepatic adenosine 5'-triphosphate (ATP) levels.

RESULTS

Liver regeneration and proliferative response in mild steatotic rats were no different from those in controls. However, the mebrofenin uptake rate was lower (P < 0.050) and the recovery of hepatic ATP impaired (P < 0.050) in animals with mild steatosis. Hepatocellular damage was increased (P < 0.050) but sinusoidal endothelial cell function was not affected after liver resection in mildly steatotic rats.

CONCLUSION

Mild steatosis impaired functional recovery and increased hepatocellular damage after liver resection.

Hepatobiliary function assessed by 99mTc-mebrofenin cholescintigraphy in the evaluation of severity of steatosis in a rat model

PURPOSE

This study evaluated the utility of non-invasive assessment of hepatobiliary function by 99mTc-mebrofenin cholescintigraphy in a rat model of diet-induced steatosis.

METHODS

Male Wistar rats (250-300 g) were fed a standard methionine- and choline-deficient (MCD) diet for up to 5 weeks, thereby inducing hepatic fat accumulation, progressive inflammation and fibrogenesis corresponding with clinical steatosis. 99mTc-mebrofenin pinhole scintigraphy was used to evaluate the hepatocyte mebrofenin uptake rate, the time of maximum hepatic uptake (T(peak)) and the time required for peak activity to decrease by 50% (T(1/2peak)). Scintigraphic parameters were correlated with biochemical and serological parameters and with liver histopathology.

RESULTS

MCD diet induced mild steatosis after 1 week and severe steatosis with prominent inflammation after 5 weeks. T(peak), T(1/2peak) prolonged and the uptake rate decreased significantly, while the severity of steatosis increased (p<0.05). There was a strong, significant correlation between the severity of steatosis (histopathology, hepatic triglyceride content) and the 99mTc-mebrofenin uptake rate (r2=0.83, p<0.0001 and r2=0.82, p<0.0001, respectively). In addition, the uptake rate correlated significantly with the increased inflammation (plasma and hepatic TNF-alpha, r2=0.72, p<0.0001 and r2=0.52, p=0.001, respectively). The correlation of the uptake rate with hepatocellular damage was weak (AST and ALT, r2=0.29 and 0.32, respectively), but correlation with synthetic function was strong (prothrombin time, r2=0.70, p<0.001).

CONCLUSION

Hepatobiliary function assessed by 99mTc-mebrofenin scintigraphy correlates with the extent and progression of steatosis. These results suggest a potential role for mebrofenin scintigraphy as a non-invasive functional follow-up method for disease progression in steatotic patients.

Imaging of liver function with dedicated animal dynamic pinhole scintigraphy in rats

BACKGROUND

Non-invasive evaluation of liver function in small animal models remains a challenge. Hepatobiliary scintigraphy (HBS) enables the assessment of total and regional liver function for both uptake and excretion in larger species.

AIM

To validate quantitative liver function assessment with dedicated pinhole HBS in rats. To illustrate an application of this technique, liver function was assessed in two surgical models of liver regeneration.

METHODS

HBS was performed in 12 rats with 99mTc-mebrofenin on a dedicated animal pinhole gamma camera. The hepatic uptake rate was calculated twice by different observers to establish a normal range and the reproducibility of processing. The degree of hepatocellular injury and synthesis function were assessed by serum liver tests. Liver function was compared with liver weight. Subsequently, three groups of three rats were scanned on three separate days to assess the reproducibility of HBS. Finally, to illustrate an application of this technique, liver function was assessed in two surgical models of liver regeneration.

RESULTS

HBS in rats was feasible without mortality. The mean liver uptake rate was 77.29+/-1.29% . min(-1). Calculation of the liver uptake (% . min(-1)) was highly reproducible (r=0.95, P<0.001). There was a good correlation between liver weight and function measured by HBS at baseline and after partial resection (r=0.94, P<0.001).

CONCLUSION

HBS offers a unique combination of functional liver uptake and excretion assessment with the ability to determine the liver function reserve before and after an intervention in rats.