Benjamin Struecker

Liver support strategies: cutting-edge technologies

The treatment of end-stage liver disease and acute liver failure remains a clinically relevant issue. Although orthotopic liver transplantation is a well-established procedure, whole-organ transplantation is invasive and increasingly limited by the unavailability of suitable donor organs. Artificial and bioartificial liver support systems have been developed to provide an alternative to whole organ transplantation, but despite three decades of scientific efforts, the results are still not convincing with respect to clinical outcome. In this Review, conceptual limitations of clinically available liver support therapy systems are discussed. Furthermore, alternative concepts, such as hepatocyte transplantation, and cutting-edge developments in the field of liver support strategies, including the repopulation of decellularized organs and the biofabrication of entirely new organs by printing techniques or induced organogenesis are analysed with respect to clinical relevance. Whereas hepatocyte transplantation shows promising clinical results, at least for the temporary treatment of inborn metabolic diseases, so far data regarding implantation of engineered hepatic tissue have only emerged from preclinical experiments. However, the evolving techniques presented here raise hope for bioengineered liver support therapies in the future.

Porcine liver decellularization under oscillating pressure conditions: a technical refinement to improve the homogeneity of the decellularization process.

Decellularization and recellularization of parenchymal organs may facilitate the generation of autologous functional liver organoids by repopulation of decellularized porcine liver matrices with induced liver cells. We present an accelerated (7 h overall perfusion time) and effective protocol for human-scale liver decellularization by pressure-controlled perfusion with 1% Triton X-100 and 1% sodium dodecyl sulfate via the hepatic artery (120 mmHg) and portal vein (60 mmHg). In addition, we analyzed the effect of oscillating pressure conditions on pig liver decellularization (n=19). The proprietary perfusion device used to generate these pressure conditions mimics intra-abdominal conditions during respiration to optimize microperfusion within livers and thus optimize the homogeneity of the decellularization process. The efficiency of perfusion decellularization was analyzed by macroscopic observation, histological staining (hematoxylin and eosin [H&E], Sirius red, and alcian blue), immunohistochemical staining (collagen IV, laminin, and fibronectin), and biochemical assessment (DNA, collagen, and glycosaminoglycans) of decellularized liver matrices. The integrity of the extracellular matrix (ECM) postdecellularization was visualized by corrosion casting and three-dimensional computed tomography scanning. We found that livers perfused under oscillating pressure conditions (P(+)) showed a more homogenous course of decellularization and contained less DNA compared with livers perfused without oscillating pressure conditions (P(-)). Microscopically, livers from the (P(-)) group showed remnant cell clusters, while no cells were found in livers from the (P(+)) group. The grade of disruption of the ECM was higher in livers from the (P(-)) group, although the perfusion rates and pressure did not significantly differ. Immunohistochemical staining revealed that important matrix components were still present after decellularization. Corrosion casting showed an intact vascular (portal vein and hepatic artery) and biliary framework. In summary, the presented protocol for pig liver decellularization is quick (7 h) and effective. The application of oscillating pressure conditions improves the homogeneity of perfusion and thus the outcome of the decellularization process.

Improved rat liver decellularization by arterial perfusion under oscillating pressure conditions

One approach of regenerative medicine to generate functional hepatic tissue in vitro is decellularization and recellularization, and several protocols for the decellularization of livers of different species have been published. This appears to be the first report on rat liver decellularization by perfusion under oscillating pressure conditions, intending to optimize microperfusion and minimize damage to the ECM. Four decellularization protocols were compared: perfusion via the portal vein (PV) or the hepatic artery (HA), with (+P) or without (–P) oscillating pressure conditions. All rat livers (n = 24) were perfused with 1% Triton X‐100 and 1% sodium dodecyl sulphate, each for 90 min with a perfusion rate of 5 ml/min. Perfusion decellularization was observed macroscopically and the decellularized liver matrices were analysed by histology and biochemical analyses (e.g. levels of DNA, glycosaminoglycans and hepatocyte growth factor). Livers decellularized via the hepatic artery and under oscillating pressure showed a more homogeneous decellularization and less remaining DNA, compared with the livers of the other experimental groups. The novel decellularization method described is effective, quick (3 h) and gentle to the extracellular matrix and thus represents an improvement of existing methodology. Copyright

CD44 and CXCL9 serum protein levels predict the risk of clinically significant allograft rejection after liver transplantation

The diagnosis of acute cellular rejection (ACR) after liver transplantation is based on histological analysis of biopsies because noninvasive biomarkers for allograft rejection are not yet established for clinical routines. CD31, CD44, and chemokine (C‐X‐C motif) ligand (CXCL) 9 have previously been described as biomarkers for cross‐organ allograft rejection. Here, we assessed the predictive and diagnostic value of these proteins as serum biomarkers for clinically significant ACR in the first 6 months after liver transplantation in a prospective study. The protein levels were measured in 94 patients immediately before transplantation, at postoperative days (PODs) 1, 3, 7, and 14 and when biopsies were performed during episodes of biochemical graft dysfunction. The CD44 serum protein levels were significantly lower at POD 1 in patients who experienced histologically proven ACR in the follow‐up compared with patients without ACR (P < 0.001). CXCL9 was significantly higher before transplantation (P = 0.049) and at POD 1 (P < 0.001) in these patients. Low CD44 values (cutoff, <200.5 ng/mL) or high CXCL9 values (cutoff, >2.7 ng/mL) at POD 1 differentiated between rejection and no rejection with a sensitivity of 88% or 60% and a specificity of 61% or 79%, respectively. The combination of both biomarker cutoffs at POD 1 had a positive predictive value of 91% and a negative predictive value of 67% for clinically significant ACR. Moreover, CD44 was significantly lower at the time of ACR (P < 0.001) and differentiated the rejection group from patients with graft dysfunction due to other reasons. Our results suggest that CD44 and CXCL9 may serve as predictive biomarkers to identify liver allograft recipients at risk for clinically significant ACR. Liver Transpl 21:1195–1207, 2015.

Predictive Factors for Extrahepatic Recurrence of Hepatocellular Carcinoma Following Liver Transplantation.

Recurrence of hepatocellular carcinoma (HCC) in patients treated with liver transplantation (LT) is associated with diminished survival. Particularly, extrahepatic localization of HCC recurrence contributes to poor prognosis.

Hepatotoxicity following systemic therapy for colorectal liver metastases and the impact of chemotherapy-associated liver injury on outcomes after curative liver resection

Patients with colorectal liver metastases (CLM) have remarkably benefited from the advances in medical multimodal treatment and surgical techniques over the last two decades leading to significant improvements in long-term survival. More patients are currently undergoing liver resection following neoadjuvant chemotherapy, which has been increasingly established within the framework of curative-indented treatment strategies. However, the use of several cytotoxic agents has been linked to specific liver injuries that not only impair the ability of liver tissue to regenerate but also decrease long-term survival. One of the most common agents included in modern chemotherapy regimens is oxaliplatin, which is considered to induce a parenchymal damage of the liver primarily involving the sinusoids defined as sinusoidal obstruction syndrome (SOS). Administration of bevacizumab, an inhibitor of vascular endothelial growth factor (VEGF), has been reported to improve response of CLM to chemotherapy in clinical studies, concomitantly protecting the liver from the development of SOS. In this review, we aim to summarize current data on multimodal treatment concepts for CLM, give an in-depth overview of liver damage caused by cytostatic agents focusing on oxaliplatin-induced SOS, and evaluate the role of bevacizumab to improve clinical outcomes of patients with CLM and to protect the liver from the development of SOS.

Genetic variants of STAT-4 affect the development of graft fibrosis after liver transplantation for HCV-induced liver disease.

Background Hepatitis C virus (HCV) reinfection after liver transplantation may lead to recirrhosis and seems to be influenced by genetic factors. The aim of our study was to evaluate the role of STAT-4-polymorphisms in the development of HCV-related graft disease based on protocol biopsies. Methods One hundred sixty transplant patients with HCV recurrence were genotyped for STAT-4 (rs7574865) by polymerase chain reaction. Fibrosis stages were determined based on Desmet and Scheuer classification. SPSS was used for the statistical analysis of genotype distribution and of time to the development of advanced fibrosis among the genotypes. Results During a comparable observation period of 86.2 months (P=0.654), 65 patients (46.5%) developed advanced fibrosis. Advanced fibrosis was observed significantly more frequent in patients (n=34) with at least one T-allele (53.1 vs. 32.3%; P=0.013) compared with homozygotes for G-allele (n=31). Significant differences in the duration of advanced fibrosis development were detected between patients with at least one T-allele compared with G-allele (34.4 vs. 49.0 months; P=0.022). No impact was observed regarding the outcome of interferon-based antiviral treatment (P=0.297) and the occurrence of acute cellular rejection (P=0.365). Conclusion Present results indicate a possible impact of genetic confounders in the recipient on graft fibrogenesis, thus explaining significantly different graft behavior observed after transplantation for HCV-associated liver disease. STAT-4-T-allele is identified as fibrogenic factor and seems to have a negative impact on HCV-induced fibrosis development.

Comparison of Single-Port Versus Standard Multiport Left Lateral Liver Sectionectomy

It remains unclear if single incision laparoscopic liver surgery is superior to standard multiport resections and in what regard patients might benefit from this approach. We retrospectively analyzed the course of all patients undergoing laparoscopic left lateral sectionectomy at our center between 2009 and 2017. In total, 11 single incision and 31 multiport left lateral sectionectomies were performed at our center between July 2009 and May 2017. Six patients were excluded due to multivisceral resections. Indications included adenoma (n = 7 vs n = 2), focal nodular hyperplasia (n = 4 vs n = 3), hepatocellular carcinoma (n = 4 vs n = 4), colorectal liver metastasis (n = 4 vs n = 0), noncolorectal metastasis (n = 2 vs n = 1), hemangioma (n = 3 vs n = 0), abscess (n = 1 vs n = 0), and cysts (n = 1 vs n = 0). Length of operation was significantly shorter in the single incision group (206 vs 137 minutes, P = .003). One complication was observed in the single incision group (grade IIIb, n = 1) while 3 patients in the multiport group suffered from postoperative complications (grade II, n = 1; grade IIIa, n = 2), resulting in a morbidity rate of 12.5% and 11.5%, respectively. No mortality was observed in both groups. Length of hospital stay did not significantly differ in both groups (median 7 vs 7 days, P = .513). The single incision approach is safe and has become the standard approach for the left lateral sectionectomy at our center. Shorter operation times technique might well be due to the easy retrieval of the liver specimen via the umbilical incision with no need for a Pfannenstiel incision.

Evolution of graft morphology and function after recellularization of decellularized rat livers

Decellularization of livers is a well‐established procedure. Data on different reseeding techniques or the functional evolution and reorganization processes of repopulated grafts remains limited. A proprietary, customized bioreactor was established to repopulate decellularized rat livers (n = 21) with primary rat hepatocytes (150 × 106 cells) via the hepatic artery and to subsequently evaluate graft morphology and function during 7 days of ex vivo perfusion. Grafts were analysed at 1 h, 6 h, 12 h, 24 h, 3 days, 5 days and 7 days after recellularization (all n = 3) by immunohistological evaluation, hepatocyte‐related enzyme (aspartate transaminase, alanine transaminase and lactate dehydrogenase) and albumin measurement in the perfusate. This appears to be the first available protocol for repopulation of rat livers via the hepatic artery. Within the first 24 h after repopulation, the hepatocytes seemed to migrate out of the vascular network and form clusters in the parenchymal space around the vessels. Graft function increased for the first 24 h after repopulation with a significantly higher function compared to standard two‐dimensional culture after 24 h. Thereafter, graft function constantly decreased with significantly lower values after 6 days and 7 days of perfusion, although histologically viable hepatocytes were found even after this period. The data suggests that, owing to a constant loss of function, repopulated grafts should potentially be implanted as soon as cell engraftment and graft re‐organization are completed. Copyright

Liver Transplantation and Liver Resection for Cirrhotic Patients with Hepatocellular Carcinoma: Comparison of Long-Term Survivals

BackgroundBoth liver transplantation (LT) and liver resection (LR) represent curative treatment options for hepatocellular carcinoma (HCC) in patients with liver cirrhosis. In this study, we have compared outcomes between historical and more recent patient cohorts scheduled either for LT or LR, respectively.MethodsClinicopathological data of all patients with HCC and cirrhosis who underwent LT or LR between 1989 and 2011 were evaluated. Overall survival of patients with HCC within the Milan criteria (MC) was analyzed focusing on changes between different time periods.ResultsIn total, 364 and 141 patients underwent LT and LR for HCC in cirrhosis, respectively. Among patients with HCC within MC, 214 and 59 underwent LT and LR, respectively. Postoperative morbidity (37 vs. 11%, P < .0001), but not mortality (3 vs. 1%, P = .165), was higher after LR than after LT for HCC within MC. In the period 1989–2004, overall survival (OS) was significantly higher in patients who underwent LT compared to LR for HCC within MC (5-year OS: 77 vs. 36%, P < .0001). Interestingly, in the more recent period 2005–2011, OS was comparable between LT and LR for HCC within MC (5-year OS: 73 vs. 61%, P = .07).ConclusionWe have noted an improvement of outcomes among patients selected for partial hepatectomy in recent years that were comparable to stable results after LT in cirrhotic patients with HCC. Whether those improvements are due to advances in liver surgery, optimized perioperative managament for patients with liver cirrhosis, and the development of modern multimodal treatment strategies for the recurrent lesions appears plausible.