99mTc-GSA scintigraphy with SPECT for assessment of hepatic function and functional volume during liver regeneration in a rat model of partial hepatectomy.

UNLABELLED: Small-animal models are crucial to gain insights in the complex recovery mechanisms of liver function during liver regeneration. (99m)Tc-Mebrofenin hepatobiliary scintigraphy (HBS) has been introduced for noninvasive assessment of liver function in the clinical setting as well as in experimental research. However, HBS is restricted to planar modalities in small animals because hepatic kinetics are generally too fast for SPECT acquisition. (99m)Tc-DTPA-galactosyl serum albumin (where DTPA is diethylenetriaminepentaacetic acid) ((99m)Tc-GSA) scintigraphy is an alternative, receptor-mediated, noninvasive liver function test. After hepatic uptake, (99m)Tc-GSA remains trapped in the liver, which readily enables additional SPECT for the assessment of both liver function and liver functional volume within one test. In this study we evaluated the use of (99m)Tc-GSA scintigraphy combined with SPECT for the assessment of liver function and liver functional volume in normal and regenerating rat livers. METHODS: The reproducibility of (99m)Tc-GSA scintigraphy and SPECT was investigated by repeated measurements within the same rat. For the assessment in a regenerating liver, (99m)Tc-GSA scintigraphy with SPECT was performed on 1, 3, 5, and 7 d (n = 6 rats per time point) after 70% partial hepatectomy (PH). RESULTS: The correlation between repeated (99m)Tc-GSA measurements was strong (r = 0.75, P = 0.019). In normal rat livers, there was a strong, significant correlation between liver functional volume and conventional liver volume (r = 0.93; < 0.0001). The correlation between (99m)Tc-GSA uptake and liver volume was moderate (r = 0.62, P = 0.043). During the regeneration process, (99m)Tc-GSA uptake was significantly lower compared with both liver volume (P < 0.001) and liver functional volume (P < 0.001), when expressed as a percentage of baseline levels. There was a strong correlation between liver functional volume and conventional liver volume in the regenerating liver (r = 0.92, P < 0.0001). CONCLUSION: (99m)Tc-GSA scintigraphy combined with SPECT is a feasible, noninvasive method to assess hepatic functional volume in normal rat liver as well as in the regenerating rat liver. However, the hepatic (99m)Tc-GSA uptake as a liver function test seems to underestimate hepatic regeneration in comparison to liver volume.

IL-10 attenuates hepatic I/R injury and promotes hepatocyte proliferation.

BACKGROUND: One of the most important determinants of the outcome of hepatic ischemia and reperfusion (I/R) injury is the onset of the inflammatory response. Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine. It inhibits the production of interleukin-6 (IL-6), which however, also is involved in priming hepatocyte proliferation. The aim of this study was to examine the protective effects and the influence on the regenerative response of exogenous as well as endogenous IL-10 in a rat model of hepatic I/R injury. MATERIALS AND METHODS: Seventy percent Liver I/R was induced in male Wistar rats for 60 min followed by 24 h reperfusion. One group underwent a midline laparotomy with recombinant rat (rr)IL-10 administration (SHAM + IL-10). The other groups underwent 60 min ischemia with administration of saline (I/R + saline), rrIL-10 [at two different time-points, i.e., I/R + IL-10pre(ischemia) and I/R + IL-10end(ischemia)] or anti-rat IL-10 antibody (I/R + antiIL-10). RESULTS: Parenchymal damage, as assessed by plasma alanine aminotransferase and aspartate aminotransferase, was significantly reduced by rrIL-10 and by endogenous IL-10 (P < 0.05). Also, rrIL-10 significantly reduced IL-6 production and the accumulation of neutrophils in liver and lung tissue, as measured by myeloperoxidase activity. Necrosis and apoptosis were significantly reduced and hepatocyte proliferation was stimulated by rrIL-10. CONCLUSIONS: RrIL-10 and, to a lesser extent, endogenous IL-10, attenuate damage and inflammation, while rrIL-10 also promotes proliferation after hepatic I/R injury in rats. Therefore, rrIL-10 has potential use to prevent I/R injury and to promote liver regeneration after partial liver resection with temporary inflow occlusion.

Preservation of steatotic livers: a comparison between cold storage and machine perfusion preservation.

Liver grafts are frequently discarded due to steatosis. Steatotic livers can be classified as suboptimal and deteriorate rapidly during hypothermic static preservation, often resulting in graft nonfunction. Hypothermic machine perfusion (MP) has been introduced for preservation of donor livers instead of cold storage (CS), resulting in superior preservation outcomes. The aim of this study was to compare CS and MP for preservation of the steatotic donor rat liver. Liver steatosis was induced in male Wistar rats by a choline-methionine-deficient diet. After 24 hours hypothermic CS using the University of Wisconsin solution (UW) or MP using UW-Gluconate (UW-G), liver damage (liver enzymes, perfusate flow, and hyaluronic acid clearance) and liver function (bile production, ammonia clearance, urea production, oxygen consumption, adenosine triphosphate [ATP] levels) were assessed in an isolated perfused rat liver model. Furthermore, liver biopsies were visualized by hematoxylin and eosin staining. Animals developed 30 to 60% steatosis. Livers preserved by CS sustained significantly more damage as compared to MP. Bile production, ammonia clearance, urea production, oxygen consumption, and ATP levels were significantly higher after MP as compared to CS. These results were confirmed by histology. In conclusion, MP improves preservation results of the steatotic rat liver, as compared to CS.

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.