Research Interest

An important goal of the research related to liver diseases and liver transplantation (LT) is to prevent or delay the occurrence of end stage liver disease. For those who reach a status where LT is the only available, and life-saving, treatment, the goal is to optimize patient and graft survival following LT, as well as to minimize the risk of complications related to the surgical and medical treatment needed. The research also focuses on optimizing timing for LT as well as exploring new categories of patients who can be rescued or obtain improved life quality by the procedure. Moreover, improving donor graft quality by clinical and experimental liver preservation studies and actively taking part in the early development of new immunosuppressants to optimize graft survival and reduce patient morbidity is also essential. An important area of research has been related to different treatment strategies of hepatic cancers with or without the combination of LT. Combined treatment of LT and allogenic bone marrow transplantation was attempted, for the first time in the world, at the Karolinska Institutet, Huddinge, Sweden, and is presently being investigated. Novel indications for LT, such as delta-aminolevulinic acid dehydratase (ALAD)-deficiency porphyria and familial amyloidotic polyneuropathy (FAP), were likewise first treated by LT at our institution. The first FAP patient underwent LT at our institution in 1990. We now hold the world registry of LT for this indication.

In parallel with clinical research, active research has been performed in our experimental laboratory for small and large animals. Microdialysis in order to study liver preservation and monitor liver transplant recipients early after LT was first developed in our experimental laboratory and later introduced to the clinic. In 2000, a hepatocyte cell laboratory was founded at the division of Transplantation, Karolinska Institutet. At the laboratory, basic research on fetal and adult hepatocytes has been performed in order to understand different mechanisms of the hepatocyte, and its differentiation and maturation. Also, work has been done on preparation for hepatocyte transplantation as a clinical program. The first clinical hepatocyte transplantation in Scandinavia was performed at our institution at the beginning of 2008.

Aims

Aims of the research program are –

1. To create evaluation guidelines, monitor short-term and long-term outcome in order to reduce rejection episodes, and prolong graft and patient survival;
2. To increase the number of donor organs and improve preservation before transplantation surgery;
3. To increase access to transplantation treatment by means of hepatocyte transplantation and a living donor program; 
4. To study and treat liver disorders to prevent the need for LT.

Main projects

Familial amyloidotic polyneuropathy and related amyloidosis

The aim of the research is to develop and find the role for LT as treatment modality for different variants of genetic amyloidosis and following domino liver transplantation (DLT; see below). Familial amyloidotic polyneuropathy is an autosomal dominant disorder that is both debilitating and ultimately fatal and that is caused by a point mutation in the protein transthyretin (TTR), one of the prealbumins. The protein misevolves, leading to the formation of amyloid fibrils and deposits that interfere with nerve and muscle function. More than 80 amyloidogenic TTR variants have been described, of which FAP is the most common.

The only treatment that halts the progress of the disease is LT. This was performed to treat FAP for the first time in the world in 1990 at the Department of Transplantation Surgery, Karolinska University Hospital. Although endemic in some parts of the world, FAP is relatively uncommon in most countries. In order to better understand the effect of LT in the many different mutations of the disorder, a world register was initiated in 1995 at the Karolinska University Hospital. Today, more than 70 centers worldwide in 18 different countries report to the register and take part in the international research network. Presently in Sweden, several research projects are run in collaboration with Professor Ole Suhr and Professor Erik Lundgren at Norrlands University Hospital, Umeå. Doctor Arie Stangou, of Kings College, London, UK; Professor Teresa Coelho, from Porto, Portugal; Professor Yukio Ando, of Kumamoto, University of Japan; and Professor Joel Buxbaum, in San Diego, USA, are active collaborators in present international research projects related to FAP, other than registry data.

An important effect of LT for FAP is the possibility to use the FAP liver for transplantation into another patient with end stage liver disease, so-called “DLT”. We are presently investigating the risk of transfer of the FAP disease to the domino recipient in our own patient material of approximately 60 domino recipients, as well as in the domino liver transplant register, (part of FAPWTR), records most of the domino LTs performed in the world. We have been able to define better criteria for accepting patients for LT for FAP, as well as show prognostic factors, such as duration of disease before transplantation and the modified body mass index, to be important for the outcome. In spite of transplantation, some patients progress in their general disease or develop cardiac problems and part of the present research focuses on identification of specific mutations or comorbidity that hamper the effect of LT on the disease.

Clinical and experimental hepatocyte transplantation

The specific aim is to improve hepatocyte transplantation in small and large animal models using clinically relevant techniques, and to transfer this to clinical practice. The major problem with transplantation of hepatocytes in humans is that it is difficult to engraft a sufficient number of cells in the recipient. In small animal models, this has been achieved by several different modifications, often in combination, e.g., 70–90% hepatectomy to induce regeneration signals, precondition of host by treatment with toxins, e.g., retrosine, ß-galactosidase, carbon tetrachloride, and lethal radiation, or by genetically altered recipients to create a selective growth advantage for donor cells. However, these methods cannot be directly translated into the clinical situation and our aim is to try and increase engraftment after transplantation through clinically relevant approaches. These include (1) modification of the cell source, e.g., (a) hepatocytes alone vs. co-transplantation with non-parenchymal or progenitor cells; (b) identification and isolation of the clonogenic population in human hepatocytes; and (c) alternative cell sources/stem cells; as well as (2) pretreatment of the target organ by (a) evaluation of the route of delivery, and hydrodynamic injection; (b) partial liver ischemia–reperfusion injury; (c) local high dose injection of compounds that are toxic in high doses, but are harmless after dilution, such as certain bile acids; (d) treatment with collagenase to dissolve tissue, induce injury, facilitate access and release growth factors from the surrounding extracellular matrix; and (e) irradiation. It is of great importance to simultaneously, through experimental research, find safe ways to improve the technique and, ultimately, the clinical outcome.

Small animal models are used in many of our experiments, e.g., investigating the effect of cotransplantation of parenchymal and non-parenchymal or progenitor cells, and pretreatment of liver cells with collagenase. Small animal models also offer the possibility to evaluate the effect of hepatocyte transplantation in different metabolic disease models, such as acute intermittent porphyria and Niemann–Pick type C disease. A large animal model will give us opportunity to evaluate methods such as hydrodynamic infusion of cells, which is not technically possible in small animals.

We see a role for liver cell transplantation in several diseases currently treated with LT, and also in cases where LT is not yet possible, either due to the risk of the procedure or due to the lack of donor organs. This new technology would complement and extend the capabilities of the existing whole organ transplant program with innovative techniques that are considerably less invasive and less costly than existing treatment. We have been working on the isolation and characterization of fetal and adult hepatocytes in our laboratory. We are now moving to a more clinically oriented research program for hepatocyte transplantation. In January 2008, we performed the first hepatocyte transplantation in Scandinavia at our hospital, in collaboration with Pittsburgh, PA, USA (Stephen Strom and Ira Fox), and with the hepatocyte transplant laboratory in Brussels, Belgium (Etienne Sokal), where the cells were processed for transplantation. Our intention now is to expand this clinical hepatocyte transplant program with locally isolated hepatocytes.

Intrahepatic microdialysis monitoring during and after liver transplantation

Intrahepatic microdialysis monitoring of ischemia reperfusion injury in relation to LT was introduced for the first time in our experimental laboratory and later transferred to clinical service. By using this technique we have been able to demonstrate several unique metabolic changes that take place during the recovery from ischemia early after LT. In contrast to other organs, it was demonstrated that liver ischemia results in hyperglycemia. During the last 7-year period, two doctoral theses focused on microdialysis studies of the liver. Presently, clinical investigations to study rejection and vascular complications after LT using this technique are underway.

Microdialysis also gives us a unique opportunity for studying liver metabolism per se. We are organizing an international group of experts in the field of metabolism and we plan to start an international project on liver metabolomics. The research network involves our center and Professor Jens Jordan of the Clinical Pharmacology Institute in Hannover, Germany; Professor Sandor Batkai, from the Phenotyping Core Laboratory of Physiological Studies, NIH Bethesda, MD, USA; and Professor Vladimir Zagainov of the Privolzhsky District Medical Center and the Russian Academy of Science, in Nizhny Novgorod, Russia.

Liver transplantation in combination with allogenic stem cell transplantation in patients with advanced primary liver tumors

Due to a high recurrence rate, LT in patients with large hepatic malignancies has an inferior prognosis compared with patients with non-malignant indications. Allogeneic hematopoietic stem cell transplantation (HSCT) has previously been shown to induce a graft vs. tumor effect on various solid tumors. In this project, we explore the concept of treating patients with advanced primary liver tumors (aPLCs) with adjuvant HSCT following LT. The protocol is designed for 30 patients and is performed in close collaboration with the Center for Allogeneic Stem cell Transplantation (CAST) of our hospital. An interim evaluation was performed in June 2007. Inclusion criteria for the hepatocellular cancer (HCC) patients are a total tumor size >10 cm or a tumor that consists of more than three foci. For patients with cholangiocarcinoma (CC), the tumor must be unresectable and confined to the liver. The recipient should have access to a suitable stem cell donor, either a human leukocyte antigen (HLA)-identical sibling or an HLA-matched, unrelated donor. All LTs are performed with HLA-mismatched liver grafts. The HSCTs are performed, with a reduced intense conditioning regimen (fludarabine 30 mg/m2 x V and cyclophosphamide 60 mg/kg x II) 4–14 weeks after LT.

Conclusion and project continuation: Combined LT and HSCT is a feasible procedure but has some added transplant-related morbidity compared with LT alone. Consequently, a significant positive effect on survival cannot yet be shown in the LT+HSCT group. Further experience is needed to evaluate the potential anti-tumor effect of adjuvant HSCT, but a lower recurrence rate was demonstrated in the LT+HSCT group when compared to historical controls. Encouraged by these results, we aim for an increased recruitment rate during the next few years. Inclusion and exclusion criteria will remain unchanged.