Kinetics of Hepatic Volume Evolution and Architectural Changes after Major Resection in a Porcine Model.

BACKGROUND: The hepatic volume gain following resection is essential for clinical recovery. Previous studies have focused on cellular regeneration. This study aims to explore the rate of hepatic regeneration of the porcine liver following major resection, highlighting estimates of the early microarchitectural changes that occur during the cellular regeneration. METHODS: Nineteen large white pigs had 75% resection with serial measurements of the hepatic volume, density, blood flow, and architectural changes. RESULTS: The growth rate initially was 45% per day, then rapidly decreased and was accompanied by a similar pattern of hepatic fat deposition. The architectural changes showed a significant increase in the Ki67 expression (p < 0.0001) in the days following resection with a peak on the 2nd day and nearly normalized on day 7. The expression of CD31 increased significantly on the 2nd and 3rd days compared to the pre-resection samples (p = 0.03). Hepatic artery flow per liver volume remained at baseline ranges during regeneration. Portal flow per liver volume increased after liver resection (p < 0.001), was still elevated on the 1st postoperative day, then decreased. Correlations were significantly negative between the hepatic volume increase on day 3 and the hepatic oxygen consumption and the net lactate production at the end of the procedure (r = -0.82, p = 0.01, and r = -0.70, p = 0.03). CONCLUSION: The volume increase in the first days - a fast process - is not explained by cellular proliferation alone. The liver/body weight ratio is back to 50% of the preoperative value after 3 days to close to 100% volume regain on days 10-15.

Modulating Portal Hemodynamics With Vascular Ring Allows Efficient Regeneration After Partial Hepatectomy in a Porcine Model.

OBJECTIVE: To investigate safety and efficacy of temporary portal hemodynamics modulation with a novel percutaneously adjustable vascular ring (MID-AVR) onto a porcine model of 75% hepatectomy. BACKGROUND: Postoperative liver failure is a leading cause of mortality after major hepatectomy. Portal flow modulation is an increasingly accepted concept to prevent postoperative liver failure. Nonetheless, the current strategies have shortcomings. METHODS: Resection was performed under hemodynamic monitoring in 17 large, white pigs allocated into 2 groups. Eight pigs had ring around the portal vein for 3 days with the aim of reducing changes in hemodynamics due to hepatectomy. Analysis of hemodynamics, laboratory, and histopathological parameters was performed. RESULTS: Percutaneous inflation, deflation, and removal of the MID-AVR were safe. Two (25%) pigs in the MID-AVR group and 4 (45%) controls died before day 3 (P = NS). A moderate increase of portal flow rate per liver mass after resection was associated with better survival (P = 0.017). The portocaval pressure gradient was lower after hepatectomy in the MID-AVR group (P = 0.001). Postoperative serum bilirubin levels were lower in the MID-AVR group (P = 0.007 at day 5). In the MID-AVR group, the Ki67 index was significantly higher on day 3 (P = 0.043) and the architectural derangement was lower (P < 0.05). Morphometric quantification of the bile canaliculi revealed a significantly lower number of intersection branches (P < 0.05) and intersection nodes (P < 0.001) on day 7 compared with the preoperative specimen, in the control group. These differences were not found in the ring group. CONCLUSIONS: MID-AVR is safe for portal hemodynamics modulation. It might improve liver regeneration by protecting liver microarchitecture.

Computerized tomography-based anatomic description of the porcine liver.

BACKGROUND: The knowledge of the anatomic features is imperative for successful modeling of the different surgical situations. This study aims to describe the anatomic features of the porcine using computerized tomography (CT) scan. METHODS: Thirty large, white, female pigs were included in this study. The CT image acquisition was performed in four-phase contrast study. Subsequently, analysis of the images was performed using syngo.via software (Siemens) to subtract mainly the hepatic artery and its branches. Analysis of the portal and hepatic veins division pattern was performed using the Myrian XP-Liver 1.14.1 software (Intrasense). RESULTS: The mean total liver volume was 915 ± 159 mL. The largest sector in the liver was the right medial one representing around 28 ± 5.7% of the total liver volume. Next in order is the right lateral sector constituting around 24 ± 5%. Its volume is very close to the volume of the left medial sector, which represents around 22 ± 4.7% of the total liver volume. The caudate lobe represents around 8 ± 2% of the total liver volume.The portal vein did not show distinct right and left divisions rather than consecutive branches that come off the main trunk. The hepatic artery frequently trifurcates into left trunk that gives off the right gastric artery and the artery to the left lateral sector, the middle hepatic artery that supplies both the right and the left medial sectors and the right hepatic artery trunk that divides to give anterior branch to the right lateral lobe, branch to the right medial lobe, and at least a branch to the caudate lobe. Frequently, there is a posterior branch that crosses behind the portal vein to the right lateral lobe. The suprahepatic veins join the inferior vena cava in three distinct openings. There are communications between the suprahepatic veins that drain the adjacent sectors. The vein from the right lateral and the right medial sectors drains into a common trunk. The vein from the left lateral and from the left medial sectors drains into a common trunk. A separate opening is usually encountered draining the right medial sector. The caudate lobe drains separately into inferior vena cava caudal to the other veins. CONCLUSIONS: Knowledge of the anatomic features of the porcine liver is crucial to the performance of a successful surgical procedure. We herein describe the CT-depicted anatomic features of the porcine liver.

Protocols for staining of bile canalicular and sinusoidal networks of human, mouse and pig livers, three-dimensional reconstruction and quantification of tissue microarchitecture by image processing and analysis.

Histological alterations often constitute a fingerprint of toxicity and diseases. The extent to which these alterations are cause or consequence of compromised organ function, and the underlying mechanisms involved is a matter of intensive research. In particular, liver disease is often associated with altered tissue microarchitecture, which in turn may compromise perfusion and functionality. Research in this field requires the development and orchestration of new techniques into standardized processing pipelines that can be used to reproducibly quantify tissue architecture. Major bottlenecks include the lack of robust staining, and adequate reconstruction and quantification techniques. To bridge this gap, we established protocols employing specific antibody combinations for immunostaining, confocal imaging, three-dimensional reconstruction of approximately 100-µm-thick tissue blocks and quantification of key architectural features. We describe a standard procedure termed 'liver architectural staining' for the simultaneous visualization of bile canaliculi, sinusoidal endothelial cells, glutamine synthetase (GS) for the identification of central veins, and DAPI as a nuclear marker. Additionally, we present a second standard procedure entitled 'S-phase staining', where S-phase-positive and S-phase-negative nuclei (stained with BrdU and DAPI, respectively), sinusoidal endothelial cells and GS are stained. The techniques include three-dimensional reconstruction of the sinusoidal and bile canalicular networks from the same tissue block, and robust capture of position, size and shape of individual hepatocytes, as well as entire lobules from the same tissue specimen. In addition to the protocols, we have also established image analysis software that allows relational and hierarchical quantifications of different liver substructures (e.g. cells and vascular branches) and events (e.g. cell proliferation and death). Typical results acquired for routinely quantified parameters in adult mice (C57Bl6/N) include the hepatocyte volume (5,128.3 ± 837.8 µm(3)) and the fraction of the hepatocyte surface in contact with the neighbouring hepatocytes (67.4 ± 6.7 %), sinusoids (22.1 ± 4.8 %) and bile canaliculi (9.9 ± 3.8 %). Parameters of the sinusoidal network that we also routinely quantify include the radius of the sinusoids (4.8 ± 2.25 µm), the branching angle (32.5 ± 11.2°), the length of intersection branches (23.93 ± 5.9 µm), the number of intersection nodes per mm(3) (120.3 × 103 ± 42.1 × 10(3)), the average length of sinusoidal vessel per mm(3) (5.4 × 10(3) ± 1.4 × 10(3)mm) and the percentage of vessel volume in relation to the whole liver volume (15.3 ± 3.9) (mean ± standard deviation). Moreover, the provided parameters of the bile canalicular network are: length of the first-order branches (7.5 ± 0.6 µm), length of the second-order branches (10.9 ± 1.8 µm), length of the dead-end branches (5.9 ± 0.7 µm), the number of intersection nodes per mm(3) (819.1 × 10(3) ± 180.7 × 10(3)), the number of dead-end branches per mm(3) (409.9 × 10(3) ± 95.6 × 10(3)), the length of the bile canalicular network per mm(3) (9.4 × 10(3) ± 0.7 × 10(3) mm) and the percentage of the bile canalicular volume with respect to the total liver volume (3.4 ± 0.005). A particular strength of our technique is that quantitative parameters of hepatocytes and bile canalicular as well as sinusoidal networks can be extracted from the same tissue block. Reconstructions and quantifications performed as described in the current protocols can be used for quantitative mathematical modelling of the underlying mechanisms. Furthermore, protocols are presented for both human and pig livers. The technique is also applicable for both vibratome blocks and conventional paraffin slices.

New paradigms in post-hepatectomy liver failure.

INTRODUCTION: Liver failure after hepatectomy remains the most feared postoperative complication. Many risk factors are already known, related to patient's comorbidities, underlying liver disease, received treatments and type of resection. Preoperative assessment of functional liver reserve must be a priority for the surgeon. METHODS: Physiopathology of post-hepatectomy liver failure is not comparable to fulminant liver failure. Liver regeneration is an early phenomenon whose cellular mechanisms are beginning to be elucidated and allowing most of the time to quickly recover a functional organ. In some cases, microscopic and macroscopic disorganization appears. The hepatocyte hyperproliferation and the asynchronism between hepatocytes and non-hepatocyte cells mitosis probably play a major role in this pathogenesis. RESULTS: Many peri- or intra-operative techniques try to prevent the occurrence of this potentially lethal complication, but a better understanding of involved mechanisms might help to completely avoid it, or even to extend the possibilities of resection. CONCLUSION: Future prevention and management may include pharmacological slowing of proliferation, drug or physical modulation of portal flow to reduce shear-stress, stem cells or immortalized hepatocytes injection, and liver bioreactors. Everything must be done to avoid the need for transplantation, which remains today the most efficient treatment of liver failure.

Treatment of severe iatrogenic quadriceps retraction in children.

We assessed the results of the treatment of severe iatrogenic infantile quadriceps retraction in a pediatric surgery department, which still admits such cases. We used two different surgical techniques of quadricepsplasty: one based on the Judet technique and the other based on the Payr and Thompson techniques. We selected the technique to perform according to the initial rate of limitation of the range of movement of the knee. We followed 76 patients operated on with one of the two techniques for at least 3 years. There were 94 cases operated on with a modified Judet technique and 34 according to the Payr-Thompson technique. After 3 years, maximal knee flexion improved from an average of -3 to 81 degree in the first group and from 37 to 115 degree in the second group. The most frequent complications were skin necrosis after the Judet quadricepsplasty and active extension lag after the Payr-Thompson procedure.