Spatiotemporal dynamics of self-organized branching in pancreas-derived organoids.

The development dynamics and self-organization of glandular branched epithelia is of utmost importance for our understanding of diverse processes ranging from normal tissue growth to the growth of cancerous tissues. Using single primary murine pancreatic ductal adenocarcinoma (PDAC) cells embedded in a collagen matrix and adapted media supplementation, we generate organoids that self-organize into highly branched structures displaying a seamless lumen connecting terminal end buds, replicating in vivo PDAC architecture. We identify distinct morphogenesis phases, each characterized by a unique pattern of cell invasion, matrix deformation, protein expression, and respective molecular dependencies. We propose a minimal theoretical model of a branching and proliferating tissue, capturing the dynamics of the first phases. Observing the interaction of morphogenesis, mechanical environment and gene expression in vitro sets a benchmark for the understanding of self-organization processes governing complex organoid structure formation processes and branching morphogenesis.

De-novo Upper Gastrointestinal Tract Cancer after Liver Transplantation: A Demographic Report.

BACKGROUND: Immunosuppression is essential after liver transplantation (LT). It, however, increases the risk for cancer. OBJECTIVE: To evaluate the prevalence and outcome of upper gastrointestinal (GI) tract cancer in LT patients and assess the perioperative risk of surgery for the upper GI malignancies post-LT. METHODS: 2855 patients underwent LT at our clinic from 1988 to 2018. 20 patients developed upper GI cancer. Data were retrospectively extracted from our database. Analysis included patients' specific data, tumor histopathology and stage, the treatment given and survival. RESULTS: 23 patients developed upper GI malignancies (2 gastric and 18 esophageal cancers; 3 excluded), translating to a incidence of 26.4 per 100,000 population per year. All patients were male. 80% showed alcohol-induced cirrhosis before LT. Most of the tumors were diagnosed at a stage ≥III. 70% underwent surgery and 78.6% developed postoperative complications. One-year-survival was 50%. Total survival rate was 28.6% with a median follow-up of 10 months (range: 0-184). CONCLUSION: Upper GI malignancies are more common after LT compared to the general population. Men after LT, due to alcohol-induced liver cirrhosis, are at a higher risk. Upper GI surgery after LT can be safe, but the severe risk for complications and a poor survival require strict indications.

[High donor age for liver transplantation : Tackling organ scarcity in Germany]. / Hohes Spenderalter bei Lebertransplantation : Wie begegnen wir dem Organmangel in Deutschland?

BACKGROUND: Liver transplantation is the only curative treatment option for patients with end-stage liver disease; however, the 40% decline of available organ donors in recent years in Germany necessitates the optimization of available resources and possibly extending the criteria to older donors. MATERIAL AND METHODS: All 2652 livers made available to the Charité Universitätsmedizin Berlin from 2010 to 2016 were retrospectively analyzed and the clinical outcome of 526 liver transplantations during this time frame were evaluated. RESULTS: The median age of donors of transplanted organs increased from 49.3 years in 2010 to 57.3 years in 2016 (p = 0.02). Organs from donors ≥65 years were more frequently discarded than organs from younger donors (n = 344, 18.4% vs. n = 220, 28.1%; p = 0.005). Moreover, the older donors had higher rates of diabetes mellitus and hepatic steatosis. Organs from older donors had a higher donor risk index (2.8 vs. 2.2; p < 0.001) and were transplanted more often in patients with preserved liver function and hepatocellular carcinoma and liver cirrhosis (n = 121, 74.7% of indications). The 3­year survival after liver transplantation from donors ≥65 and ≥80 years old was not significantly reduced in comparison to younger donors; however, there was an increased retransplantation rate (28.6%; p = 0.005) after transplantation of organs from donors ≥80 years old. CONCLUSION: Despite conservative organ acceptance there were higher rates of retransplantation after transplantation from very old donors. In the light of an increasing scarcity of suitable organs this mandates caution and highlights the need for adequate assessment instruments for marginal donor organs before transplantation.

[Frontiers in liver transplantation in indication and techniques]. / Grenzbereiche der Lebertransplantation in Indikation und Technik.

BACKGROUND: The frontiers in liver transplantation are intrinsically expansions of indications, e.g. hepatocellular carcinoma and (perihilar) cholangiocarcinoma, recipients with more severe concomitant diagnoses or "soft" contraindications and technically demanding reconstruction procedures of vascular structures (for portal vein thrombosis or aorto-hepatic conduits). In addition, an extension of the donor pool with suboptimal donor organs (old donors and steatotic livers) is of interest. METHODS: This article presents the current situation based on personal experiences in daily practice and an appropriate literature review. RESULTS: A significant reduction of 1­year patient survival has been reported in Germany. The percentage of so-called marginal donor organs is inversely proportional to the very low donation rate and parallel to the waiting list mortality. Simultaneously, the proportion of inpatients with multiple organ failure is rising. CONCLUSION: Results-oriented and controlled liver transplantation currently prohibits making inroads into the previously intrinsic frontiers. As long as the current circumstances do not change, a shift in the intrinsic frontiers of that which is surgically feasible will not be possible. The current situation forces the transplant surgeon to apply a more restrictive indications and organ acceptance policy. With this approach we can try to regain the previously excellent short- and long-term results of a 1­year survival of 90% and a 20-year survival of 50%.

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.

[Vascular reconstruction in visceral transplantation surgery]. / Gefäßrekonstruktionen in der viszeralen Transplantationschirurgie.

Vascular reconstruction is obligatory in transplantation surgery. A differentiation is made between routine vascular reconstructions, which are required for all solid organ transplantations and special cases. Because of the shortage of organs it is often necessary to use organs with complex anatomical vascular prerequisites, which requires high vascular surgical expertise for individualized reconstruction. Non-routine reconstructions are often also necessary on the side of the recipient. This review article presents both the routine and exceptional types of reconstruction.

The liver graft as Trojan horse-multilineage donor-derived hematopoiesis after liver transplantation: case report.

Hematopoietic macrochimerism, which is rarely seen after orthotopic liver transplantation (OLT), has been linked to the development of graft versus host disease (GvHD). We report on a patient with GvHD after OLT in whom full engraftment of donor-derived, multilineage hematopoiesis occurred, indicating that the liver contains pluripotent hematopoietic progenitor cells (HPC) capable to restore hematopoiesis in recipients. Although preventing graft rejection, standard immunosuppressive therapy may be under certain immunological conditions not sufficient to prevent GvHD. Age-, disease-, and treatment-related variables might be critical determinants for the development of an effective alloreactive T-cell response leading to the establishment of full hematopoietic chimerism.

Pancreatic graft survival despite partial vascular graft thrombosis due to splenocephalic anastomoses.

Thrombotic complications following pancreas transplantation are still the most common cause of nonimmunologic graft loss. The aim of this study was to analyze pancreatic graft function after partial arterial graft thrombosis and the investigation of the pancreatic arterial anatomy with regard to intraparenchymal anastomoses. We retrospectively analyzed the data for 175 consecutive pancreas transplants performed between January 2002 and October 2007. Selective Y-graft angiography was performed in 10 and rubber-milk injection in 5 fresh pancreas specimens. Thrombosis of one leg of the Y-graft was diagnosed in 18 (10.3%) patients. Only one of these patients with thrombosis of the splenic artery required exogenous insulin. Sufficient graft perfusion was demonstrated in all of the remaining grafts. One graft was lost due to acute rejection. In all specimens angiography showed an excellent perfusion of the pancreaticoduodenal arcade, even after selective cannulation of the splenic artery. Arterial collaterals between the gastroduodenal, splenic artery and the superior mesenteric artery were demonstrated. Our results demonstrate that global perfusion of the pancreatic graft and sufficient graft function is sustained after the thrombotic occlusion of one branch of the Y-graft by a complex system of intraparenchymal anastomoses. These anatomical findings may have consequences for resection strategies in pancreas surgery.

Excellent results with calcineurin inhibitor-free initial immunosuppression in old recipients of old kidneys.

The ever increasing demand for donor organs has forced transplant surgeons to liberalize selection criteria. To avoid initial nephrotoxicity to kidneys from donors over 65 years of age, immunosuppression was begun with an IL-2 receptor antibody, mycophenolate mofetil, and steroids in a total of 38 recipients over 65 years. Calcineurin inhibitors (CI) were added after sufficient graft function was reached. After a mean cold ischemia time of 14:01 hours and a delayed function rate of 31%, patient survival, graft survival, and serum creatinine were 97.4%, 94.7%, and 1.5 mg/dL at 1 and 92.1%, 92.1%, and 1.7 mg/dL at 2 years, respectively. Thus, excellent results can be achieved in old recipients of old donor kidneys with CI-free initial immunosuppression.