Liver regeneration: a spotlight on the novel role of platelets and serotonin

The development of novel approaches in liver surgery in the last decade has saved the lives of a large number of patients via resection of liver tumours previously thought to be non-resectable. Concurrently, living donor liver transplantation has emerged as one of the ways of lowering mortality on the waiting lists. These breakthroughs demanded a rigorous understanding of the mechanisms of liver regeneration after partial hepatectomy. Based on our previous studies on blood platelets and cold ischaemic injury, platelets and serotonin have attracted attention due to their theoretical potential contribution to liver regeneration. Both platelets and serotonin have been proven to be crucially involved in liver regeneration after partial hepatectomy. This review article provides an overview on the process of liver regeneration, with emphasis on its molecular basis and the coordinate contribution of several cells to restoring the organ's original volume and function. The role of platelets and serotonin is highlighted as novel contributors in this process.

Cancer testis antigen expression in gastrointestinal stromal tumors: new markers for early recurrence

Cancer testis antigens (CTAs) are expressed in a variety of malignant tumors but not in any normal adult tissues except germ cells and occasionally placenta. Because of this tumor-associated pattern of expression, CTAs are regarded as potential vaccine targets. The expression of CTAs in gastrointestinal stromal tumors (GIST) has not been analyzed systematically previously. The present study was performed to analyze the expression of CTA in GIST and to determine if CTA expression correlates with prognosis. Thirty-five GIST patients were retrospectively analyzed for their expression of CTAs by immunohistochemistry using the following monoclonal antibodies (mAb/antigen): MA454/MAGE-A1, M3H67/MAGE-A3, 57B/MAGE-A4, CT7-33/MAGE-C1 and E978/NY-ESO-1. Fourteen tumors (40%) expressed 1 or more of the 5 CTAs tested. Fourteen percent (n = 5/35) were positive for MAGE-A1, MAGE-A3 or MAGE-A4, respectively. Twenty-six percent (n = 9/35) stained positive for MAGE-C1 and 20% (n = 7/35) for NY-ESO-1. A highly significant correlation between CTA expression and tumor recurrence risk was observed (71% vs. 29%; p = 0.027). In our study population, the high-risk GIST expressed CTAs more frequently than low-risk GIST (p = 0.012). High-risk GISTs which stained positive for at least 1 CTA, recurred in 100% (n = 25) of the cases. This is the first study analyzing CTA expression in GIST and its prognostic value for recurrence. The CTA staining could add information to the individual patient prognosis and represent an interesting target for future treatment strategies.

Contrast-enhanced 18F-FDG PET/CT: 1-stop-shop imaging for assessing the resectability of pancreatic cancer

Patients with pancreatic cancer continue to have a poor prognosis, with a 5-y survival rate of less than 5%. Surgery is the only treatment that offers a potential cure. Determining resectability is the principal goal of staging in pancreatic cancer patients. Our objective was to evaluate the value of combined contrast-enhanced (18)F-FDG PET/CT in assessing the resectability of pancreatic cancer and to compare enhanced PET/CT with the performance of PET alone and unenhanced PET/CT.

METHODS

Fifty patients (25 women and 25 men; mean age, 64.3 y; range, 39-84 y) with biopsy-proven pancreatic adenocarcinoma underwent enhanced (18)F-FDG PET/CT for the evaluation of resectability. Criteria for unresectability were distant metastases, peritoneal carcinomatosis, arterial infiltration, or invasion of neighboring organs other than the duodenum. The performance of enhanced PET/CT regarding resectability was compared with that of PET alone and unenhanced PET/CT. Histology, intraoperative findings, and follow-up CT with clinical investigations were used as the reference standard.

RESULTS

According to the reference standard, 27 patients had disease that was not resectable because of distant metastases (n=17), peritoneal carcinomatosis (n=5), or local infiltration (n=5). In the assessment of resectability, PET alone had a sensitivity of 100%, specificity of 44%, accuracy of 70%, positive predictive value of 61%, and negative predictive value of 100%; unenhanced PET/CT had respective values of 100%, 56%, 76%, 66%, and 100%; and enhanced PET/CT, 96%, 82%, 88%, 82%, and 96%. In 5 patients, unresectability was missed by all imaging methods and was diagnosed intraoperatively. Enhanced PET/CT was significantly superior to PET alone (P=0.035), and there was a trend for enhanced PET/CT to be superior to unenhanced PET/CT (P=0.070).

CONCLUSION

The use of enhanced PET/CT as a 1-stop-shop imaging protocol for assessing the resectability of pancreatic cancer is feasible and accurate. Enhanced PET/CT is significantly superior to PET alone.

Rare PIK3CA hotspot mutations in carcinomas of the biliary tract

Somatic mutations of the PIK3CA gene, which encodes the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3K), are frequent in various cancer types. The majority of mutations cluster at hotspots within exons 9 and 20, which encode the helical and kinase domains of p110alpha. PIK3CA mutations in bile duct and gallbladder carcinomas have not been reported yet. In this study, we analysed 118 carcinomas of the biliary tract and the liver (45 intra- and extrahepatic cholangiocarcinomas (CCA), 23 gallbladder carcinomas, 50 hepatocellular carcinomas) for PIK3CA hotspot mutations using polymerase chain reaction and direct DNA sequencing. PIK3CA missense mutations were found in one of 11 intrahepatic CCA (E545K, 9%), one of 23 gallbladder carcinomas (E542K, 4%), and one of 50 hepatocellular carcinomas (H1047R, 2%). All three mutations represent hotspot mutations, which also occur in other cancer types. PI3K pathway activation in hepato-biliary carcinomas was analyzed using immunohistochemistry for the downstream targets eIF4-E and phosphorylated 4E-BP1 on tissue microarrays. eIF4-E expression was found in 3/13 intrahepatic CCA (23%), 9/38 extrahepatic CCA (24%), 12/34 gallbladder carcinomas (35%), and 9/61 hepatocellular carcinomas (15%). 4E-BP1 phosphorylation was observed in 1/13 intrahepatic CCA (8%), 8/38 extrahepatic CCA (21%), 15/34 gallbladder carcinomas (44%), and 16/61 hepatocellular carcinomas (26%). These results indicate that somatic PIK3CA mutations contribute to the frequent activation of the PI3K/AKT pathway in carcinomas of the biliary tract and liver.

Ischemic preconditioning and intermittent clamping confer protection against ischemic injury in the cirrhotic mouse liver

Surgery on cirrhotic livers is fraught with complications, and many surgeons refrain from operating on patients with cirrhosis. Surgical procedures include temporal occlusion of blood flow resulting in ischemia. The mechanisms of protective strategies to prevent ischemic injury in patients with cirrhosis are not fully understood. The aim of this study was to evaluate how the cirrhotic liver tolerates an ischemic insult, whether mechanisms other than those observed in the normal liver are active, and whether intermittent clamping and preconditioning, which are known as safe surgical strategies in normal and steatotic livers, confer protection to the cirrhotic liver. We applied partial hepatic inflow occlusion to cirrhotic mice fed carbon tetrachloride according to different vascular occlusion protocols: intermittent clamping with 15 or 30 minute cycles of ischemia or ischemic preconditioning prior to 60 or 75 minutes of ischemia. Continuous ischemia (60 or 75 minutes) served as controls. The results showed that the cirrhotic liver was significantly more susceptible to 60 minutes of ischemia than the normal liver. Apoptosis was higher in the normal liver, whereas necrosis was a predominant feature in the cirrhotic liver. Both protocols of intermittent vascular occlusion and ischemic preconditioning dramatically prevented injury compared to continuous occlusion for 60 minutes. This protection was associated with reduced necrosis and apoptosis, and particularly reduced activation of the apoptotic pathway through mitochondria. In conclusion, this study extends the protective effects of ischemic preconditioning and intermittent clamping to the cirrhotic liver, highlighting a diminished apoptotic pathway with dramatic improvement in the development of necrosis.

Liver regeneration: a spotlight on the novel role of platelets and serotonin

The development of novel approaches in liver surgery in the last decade has saved the lives of a large number of patients via resection of liver tumours previously thought to be non-resectable. Concurrently, living donor liver transplantation has emerged as one of the ways of lowering mortality on the waiting lists. These breakthroughs demanded a rigorous understanding of the mechanisms of liver regeneration after partial hepatectomy. Based on our previous studies on blood platelets and cold ischaemic injury, platelets and serotonin have attracted attention due to their theoretical potential contribution to liver regeneration. Both platelets and serotonin have been proven to be crucially involved in liver regeneration after partial hepatectomy. This review article provides an overview on the process of liver regeneration, with emphasis on its molecular basis and the coordinate contribution of several cells to restoring the organ's original volume and function. The role of platelets and serotonin is highlighted as novel contributors in this process.

Impact of clinical pathways in surgery

BACKGROUND

One strategy to reduce the consumption of resources associated to specific procedures is to utilize clinical pathways, in which surgical care is standardized and preset by determination of perioperative in-hospital processes. The aim of this prospective study was to establish the impact of clinical pathways on costs, complication rates, and nursing activities.

METHOD

Data was prospectively collected for 171 consecutive patients undergoing laparoscopic cholecystectomy (n = 50), open herniorrhaphy (n = 56), and laparoscopic Roux-en-Y gastric bypass (n = 65).

RESULTS

Clinical pathways reduced the postoperative hospital stay by 28% from a mean of 6.1 to 4.4 days (p < 0.001), while the 30-day readmission rate remained unchanged (0.5% vs. 0.45%). Total mean costs per case were reduced by 25% from euro 6,390 to euro 4,800 (p < 0.001). Costs for diagnostic tests were reduced by 33% (p < 0.001). Nursing hours decreased, reducing nursing costs by 24% from euro 1,810 to euro 1,374 (p < 0.001). A trend was noted for lower postoperative complication rates in the clinical pathway group (7% vs. 14%, p = 0.07).

CONCLUSIONS

This study demonstrates clinically and economically relevant benefits for the utilization of clinical pathways with a reduction in use of all resource types, without any negative impact on the rate of complications or re-hospitalization.

Reconstruction of the gastric passage by a side-to-side gastrogastrostomy after failed vertical-banded gastroplasty: a case report

Introduction

Vertical-banded gastroplasty, a technique that is commonly performed in the treatment of morbid obesity, represents a nonadjustable restrictive procedure which reduces the volume of the upper stomach by a vertical stapler line. In addition, a textile or silicone band restricts food passage through the stomach.

Case presentation

A 71-year-old woman presented with a severe gastric stenosis 11 years after vertical gastroplasty. We describe a side-to-side gastrogastrostomy as a safe surgical procedure to restore the physiological gastric passage after failed vertical-banded gastroplasty.

Conclusion

Occasionally, restrictive procedures for morbid obesity cannot be converted into an alternative bariatric procedure to maintain weight control. This report demonstrates that a side-to-side gastrogastrostomy is a feasible and safe procedure.

Aggravation of viral hepatitis by platelet-derived serotonin

More than 500 million people worldwide are persistently infected with hepatitis B virus or hepatitis C virus. Although both viruses are poorly cytopathic, persistence of either virus carries a risk of chronic liver inflammation, potentially resulting in liver steatosis, liver cirrhosis, end-stage liver failure or hepatocellular carcinoma. Virus-specific T cells are a major determinant of the outcome of hepatitis, as they contribute to the early control of chronic hepatitis viruses, but they also mediate immunopathology during persistent virus infection. We have analyzed the role of platelet-derived vasoactive serotonin during virus-induced CD8(+) T cell-dependent immunopathological hepatitis in mice infected with the noncytopathic lymphocytic choriomeningitis virus. After virus infection, platelets were recruited to the liver, and their activation correlated with severely reduced sinusoidal microcirculation, delayed virus elimination and increased immunopathological liver cell damage. Lack of platelet-derived serotonin in serotonin-deficient mice normalized hepatic microcirculatory dysfunction, accelerated virus clearance in the liver and reduced CD8(+) T cell-dependent liver cell damage. In keeping with these observations, serotonin treatment of infected mice delayed entry of activated CD8(+) T cells into the liver, delayed virus control and aggravated immunopathological hepatitis. Thus, vasoactive serotonin supports virus persistence in the liver and aggravates virus-induced immunopathology.

Prospective Phase II Trial of Neoadjuvant Chemotherapy With Gemcitabine and Cisplatin for Resectable Adenocarcinoma of the Pancreatic Head

Purpose

To test the safety of neoadjuvant chemotherapy for resectable pancreatic cancer.

Patients and Methods

Patients with cytologically proven resectable adenocarcinoma of the pancreatic head were eligible for this prospective phase II trial. After confirmation of resectability by contrast-enhanced computed tomography (ceCT), positron emission tomography/CT, laparoscopy, and endoscopic ultrasound, patients received four biweekly cycles of gemcitabine 1,000 mg/m2and cisplatin 50 mg/m2. Thereafter, staging was repeated and patients underwent surgery. Quality of life (QoL) and prealbumin serum levels were determined pre- and postchemotherapy. Follow-up included 3-month CA 19-9 measurements and ceCT after 6, 12, 18, and 24 months. Histologic tumor response was assessed by two scoring systems.

Results

Twenty-eight patients entered this study. Adverse effects were mainly gastrointestinal and hematologic, most often mild, and never of grade 4. Twenty-six patients (93%) had resectable cancer on restaging examinations, and the R0 resection rate was 80%. Histologic tumor response and cytopathic effects were documented in 54% and 83% of patients, respectively. On intention-to-treat analysis, disease-free and overall survival were 9.2 months (95% CI, 5.6 to 12.9 months) and 26.5 months (95% CI, 11.4 to 41.5 months) and 9 months (95% CI, 6.99 to 10.1 months) and 19.1 months (95% CI, 15 to 23.1 months) for ductal adenocarcinoma, respectively. QoL improved in two items and was unchanged in all other items. Moreover, prealbumin serum levels significantly improved during chemotherapy (P = .008).

Conclusion

Neoadjuvant chemotherapy with gemcitabine and cisplatin is well tolerated and does not impair resectability of pancreatic cancer. Furthermore, it improves the QoL and the nutritional status of affected patients with favorable overall and disease-free survival.

Selective portal vein embolization and ligation trigger different regenerative responses in the rat liver

Two strategies are clinically available to induce selective hypertrophy of the liver: portal vein embolization (PVE) and portal vein ligation (PVL). The aim of this study was to compare the impact of PVE and PVL on liver regeneration. Rats were subjected to 70% PVL, 70% PVE, 70% partial hepatectomy (PH) (positive control), or sham operation (negative control). PVL and PVE of liver segments were validated by portography and histology, demonstrating obstruction of the involved portal branches. Liver weight and markers of regeneration were assessed at 24, 48, and 72 hours, and 7 days after surgery (n = 5). Sinusoidal perfusion was examined by intravital microscopy. The weight of the regenerating liver segments increased continuously in all groups, with the highest weight gain after PH, which also disclosed the strongest proliferative activity. In Ki-67 and PCNA stainings, hepatocyte proliferation after PVL was more pronounced than after PVE (P = 0.01). Volumetric blood flow and functional sinusoidal density were lower after PVE than after PVL (P = 0.006, P = 0.02, respectively). The accumulation of Kupffer cells 24 hours after the intervention was highest after PH. Transcript levels of cytokines (interleukin-1beta, tumor necrosis factor-alpha, interleukin-6) peaked at 24 hours and were highest after PH. The embolized part of the liver after PVE showed prominent foreign body reaction in the portal triad with accumulation of macrophages.

CONCLUSION

PVL is superior to PVE in inducing a regenerative response of the remnant liver. The impairment of liver regeneration after PVE may be a consequence of macrophage trapping in the occluded segment due to a foreign body reaction. Lower blood flow and lower accumulation of macrophages, particularly Kupffer cells, in the regenerating part of the liver likewise causes impaired liver regeneration after PVE.

Immunologic ignorance of vascular endothelial cells expressing minor histocompatibility antigen

Endothelial cells (ECs) presenting minor histocompatibility antigen (mhAg) are major target cells for alloreactive effector CD8(+) T cells during chronic transplant rejection and graft-versus-host disease (GVHD). The contribution of ECs to T-cell activation, however, is still a controversial issue. In this study, we have assessed the antigen-presenting capacity of ECs in vivo using a transgenic mouse model with beta-galactosidase (beta-gal) expression confined to the vascular endothelium (Tie2-LacZ mice). In a GVHD-like setting with adoptive transfer of beta-gal-specific T-cell receptor-transgenic T cells, beta-gal expression by ECs was not sufficient to either activate or tolerize CD8(+) T cells. Likewise, transplantation of fully vascularized heart or liver grafts from Tie2-LacZ mice into nontransgenic recipients did not suffice to activate beta-gal-specific CD8(+) T cells, indicating that CD8(+) T-cell responses against mhAg cannot be initiated by ECs. Moreover, we could show that spontaneous activation of beta-gal-specific CD8(+) T cells in Tie2-LacZ mice was exclusively dependent on CD11c(+) dendritic cells (DCs), demonstrating that mhAgs presented by ECs remain immunologically ignored unless presentation by DCs is granted.

Dearterialization of the liver causes intrahepatic cholestasis due to reduced bile transporter expression

BACKGROUND

Bile duct injury after hepatic artery thrombosis (HAT) in liver transplantation is believed to be caused by ischemia predominantly. We aimed to define the involvement of bile secretory dysfunction in the pathogenesis of liver injury after HAT.

METHODS

In a murine model, the main hepatic artery, the extrahepatic peribiliary plexus, or both arterial connections to the liver were interrupted (n=5 for each group). After 1, 14, or 28 days, hepatobiliary function was assessed by analysis of bile transporter expression, serum bile acids and bilirubin, and hepatic ATP content. In addition, cellular injury was assessed by light microscopy and biochemical markers.

RESULTS

There were no signs of hepatobiliary dysfunction or injury in sham-operated animals or in mice with interruption of the hepatic artery or the extrahepatic peribiliary plexus alone. However, as early as 24 hr after complete dearterialization, bile transporter expression was significantly reduced and intrahepatic cholestasis started to progress the following weeks. Histologic studies at 28 days after complete dearterialization showed severe hepatobiliary injury.

CONCLUSIONS

This study indicates that arterial blood supply is critical for normal bile secretion. Bile duct injury after complete arterial deprivation is preceded by a loss of bile secretory function and subsequent intrahepatic cholestasis.

A novel approach for treatment of sacrococcygeal pilonidal sinus: less is more

BACKGROUND

The surgical management of sacrococcygeal pilonidal sinus (PS) is still a matter of discussion. Therapy ranges from complete wide excision with or without closure of the wound to excochleation of the sinus with a brush. In this paper, we introduce a novel limited excision technique. The aim of this study was to assess the morbidity and recurrence rate of this technique.

MATERIALS AND METHODS

Limited excision consisted of a selective extirpation of the sinus after tagging the tract with methylene blue. Ninety-three consecutive patients, who underwent surgery between 2001 and 2004, were analyzed. The patients' survey was performed by mail questionnaire and telephone interview inquiring recurrence, time off work, and time to wound healing.

RESULTS

Seventy-three percent of the patients were treated in an outpatient setting. With a median follow-up of 2 years, the recurrence rate was 5%. The median time off work was 2 weeks. The median wound healing time was 5 weeks.

CONCLUSION

Limited excision for PS can be done in an outpatient setting with a low recurrence rate and short time off work.

Use of severely steatotic grafts in liver transplantation: a matched case-control study

BACKGROUND

Although there is a worldwide need to expand the pool of available liver grafts, cadaveric livers with severe steatosis (>60%) are discarded for orthotopic liver transplantation (OLT) by most centers.

METHODS

We analyzed patients receiving liver grafts with severe steatosis between January 2002 and September 2006. These patients were matched 1:2 with control patients without severe steatosis according to status the waiting list, recipient age, recipient body mass index (BMI), and model for end-stage liver disease (MELD) score. Primary end points were the incidence of primary graft nonfunction (PNF), and graft and patient survival. Secondary end points included primary graft dysfunction (PDF), the incidence of postoperative complications, and histologic assessment of steatosis in follow-up biopsies. We also conducted a survey on the use of grafts with severe steatosis among leading European liver transplant centers.

RESULTS

During the study period, 62 patients dropped out of the waiting list and 45 of them died due to progression of disease. Of 118 patients who received transplants 20 (17%) received a graft with severe steatosis during this period. The median degree of total liver steatosis was 90% (R = 65%-100%) for the steatotic group. The steatotic (n = 20) and matched control group (n = 40) were comparable in terms of recipient age, BMI, MELD score, and cold ischemia time. The steatotic group had a significantly higher rate of PDF and/or renal failure. Although the median intensive care unit (ICU) and hospital stay were not significantly different between both groups, the proportion of patients with long-term ICU (> or =21 days) and hospital (> or =40 days) stay was significantly higher for patients with a severely steatotic graft. Sixty-day mortality (5% vs. 5%) and 3-year patient survival rate (83% vs. 84%) were comparable between the control and severe steatosis group. Postoperative histologic assessment demonstrated that the median total amount of liver steatosis decreased significantly (median: 90% to 15%, P < 0.001). Our survey showed that all but one of the European centers currently reject liver grafts with severe steatosis for any recipient.

CONCLUSION

Due to the urgent need of liver grafts, severely steatotic grafts should be no longer discarded for OLT. Maximal effort must be spent when dealing with these high-risk organs but the use of severely steatotic grafts may save the lives of many patients who would die on the waiting list.

Prospective evaluation of vacuum-assisted closure in abdominal compartment syndrome and severe abdominal sepsis

BACKGROUND

Open abdomen treatment because of severe abdominal sepsis and abdominal compartment syndrome remains a difficult task. Different surgical techniques are available and are often used according to the surgeon's personal experience. Recently, the abdominal vacuum-assisted closure (VAC) system has been introduced, providing a new possibility to treat an open abdomen. In this study, we evaluate the role of this treatment option.

STUDY DESIGN

This prospective observational cohort study includes 37 consecutive patients who were temporarily treated with VAC for severe abdominal sepsis or abdominal compartment syndrome, or both. Patients with abdominal trauma were excluded from the study. Thirty-seven patients undergoing major elective laparotomy and primary abdominal closure served as control group. Primary end points were fascial closure rate, physicoemotional recovery, and appearance outcomes 1 year after closure. Secondary end points included mortality, duration of open abdomen, length of ICU stay, and hospitalization time.

RESULTS

Abdomens were left open for 23 days (range 3 to 122 days) with 3.8 dressing changes (range 1 to 22) per patient. Abdominal closure was achieved in 70% (n = 26), with no marked relation to duration of open abdomen treatment (p > 0.05). After 3 months, patients with VAC treatment recovered to a physical and mental health status similar to patients in the control group (p > 0.05). This status remained stable until the end of the study. Aesthetic outcomes (according to the Vancouver Scar Scale) were considerably poorer in the VAC group compared with controls (p < 0.01).

CONCLUSIONS

Treatment of laparostomy with VAC for abdominal sepsis and abdominal compartment syndrome results in a high rate of successful abdominal closure. In addition, patients recover more rapidly, although hypertrophic scars might interfere with body perception. We recommend abdominal VAC system as first option if open abdomen treatment is indicated.