Hans J. Schlitt

rAAV-mediated stable expression of heme oxygenase-1 in stellate cells: A new approach to attenuate liver fibrosis in rats†

Liver fibrosis is the consequence of activation of hepatic stellate cells mediated by persistent or recurrent liver injury, where oxidative stress or inflammatory response resulting from immune cells and cytokines are involved. Targeting of hepatic stellate cells could be an important strategy for the therapy of liver fibrosis. In this study, we showed a tropism of recombinant adeno‐associated virus (rAAV, serotype 2) with high efficiency in transduction of a homeostatic gene, heme oxygenase‐1 (HO‐1), to activated stellate cells. The binding of rAAVs to stellate cells increased significantly after serum‐stimulated activation compared with quiescent status. Portal injection of rAAVs to normal or carbon tetrachloride (CCl4)‐induced liver fibrosis showed a distinct distribution of rAAV binding. The majority of injected rAAVs bound to the cells in fibrotic areas that were associated with higher expression levels of fibroblast growth factor receptor‐1α at 2 hours after administration. Isolation of different types of cells from CCl4‐induced fibrotic livers showed predominant expression of transgene in stellate cells after rAAV/HO‐1 administration on day 3 and remained stable for 12 weeks. In addition, HO‐1–transduced stellate cells showed reduced transcript levels of type 1 collagen and impaired proliferative ability compared with controls. With this approach, the severity of established micronodular cirrhosis was markedly reduced. In conclusion, these findings suggest a new approach for the treatment of liver fibrosis using adeno‐associated virus‐mediated gene transfer. (HEPATOLOGY 2005;42:335–342.)

Right Portal Vein Ligation Combined With In Situ Splitting Induces Rapid Left Lateral Liver Lobe Hypertrophy Enabling 2-Staged Extended Right Hepatic Resection in Small-for-Size Settings

Objective:To evaluate a new 2-step technique for obtaining adequate but short-term parenchymal hypertrophy in oncologic patients requiring extended right hepatic resection with limited functional reserve. Background:Patients presenting with primary or metastatic liver tumors often face the dilemma that the remaining liver tissue may not be sufficient. Preoperative portal vein embolization has thus far been established as the standard procedure for achieving resectability. Methods:Two-staged hepatectomy was performed in patients who preoperatively appeared to be marginally resectable but had a tumor-free left lateral lobe. Marginal respectability was defined as a left lateral lobe to body weight ratio of less than 0.5. In the first step, surgical exploration, right portal vein ligation (PVL), and in situ splitting (ISS) of the liver parenchyma along the falciform ligament were performed. Computed tomographic volumetry was performed before ISS and before completion surgery. Results:The study included 25 patients with primary liver tumors (hepatocellular carcinoma: n = 3, intrahepatic cholangiocarcinoma: n = 2, extrahepatic cholangiocarcinoma: n = 2, malignant epithelioid hemangioendothelioma: n = 1, gallbladder cancer: n = 1 or metastatic disease [colorectal liver metastasis]: n = 14, ovarian cancer: n = 1, gastric cancer: n = 1). Preoperative CT volumetry of the left lateral lobe showed 310 mL in median (range = 197–444 mL). After a median waiting period of 9 days (range = 5–28 days), the volume of the left lateral lobe had increased to 536 mL (range = 273–881 mL), representing a median volume increase of 74% (range = 21%–192%) (P < 0.001). The median left lateral liver lobe to body weight ratio was increased from 0.38% (range = 0.25%–0.49%) to 0.61% (range = 0.35–0.95). Ten of 25 patients (40%) required biliary reconstruction with hepaticojejunostomy. Rapid perioperative recovery was reflected by normalization of International normalized ratio (INR) (80% of patients), creatinine (84% of patients), nearly normal bilirubin (56% of patients), and albumin (64% of patients) values by day 14 after completion surgery. Perioperative morbidity was classified according to the Dindo-Clavien classification of surgical complications: grade I (12 events), grade II (13 events), grade III (14 events, III a: 6 events, III b: 8 events), grade IV (8 events, IV a: 3 events, IV b: 5 events), and grade V (3 events). Sixteen patients (68%) experienced perioperative complications. Follow-up was 180 days in median (range: 60–776 days) with an estimated overall survival of 86% at 6 months after resection. Conclusions:Two-step hepatic resection performing surgical exploration, PVL, and ISS results in a marked and rapid hypertrophy of functional liver tissue and enables curative resection of marginally resectable liver tumors or metastases in patients that might otherwise be regarded as palliative.

A new pumpless extracorporeal interventional lung assist in critical hypoxemia/hypercapnia*

Objective:Pump-driven extracorporeal gas exchange systems have been advocated in patients suffering from severe acute respiratory distress syndrome who are at risk for life-threatening hypoxemia and/or hypercapnia. This requires extended technical and staff support. Design:We report retrospectively our experience with a new pumpless extracorporeal interventional lung assist (iLA) establishing an arteriovenous shunt as the driving pressure. Setting:University hospital. Patients:Ninety patients with acute respiratory distress syndrome. Interventions:Interventional lung assist was inserted in 90 patients with acute respiratory distress syndrome. Measurements and Main Results:Oxygenation improvement, carbon dioxide elimination, hemodynamic variables, and the amount of vasopressor substitution were reported before, 2 hrs after, and 24 hrs after implementation of the system. Interventional lung assist led to an acute and moderate increase in arterial oxygenation (Pao2/Fio2 ratio 2 hrs after initiation of iLA [median and interquartile range], 82 mm Hg [64–103]) compared with pre-iLA (58 mm Hg [47–78], p < .05). Oxygenation continued to improve for 24 hrs after implementation (101 mm Hg [74–142], p < .05). Hypercapnia was promptly and markedly reversed by iLA within 2 hrs (Paco2, 36 mm Hg [30–44]) in comparison with before (60 mm Hg [48–80], p < .05], which allowed a less aggressive ventilation. For hemodynamic stability, all patients received continuous norepinephrine infusion. The incidence of complications was 24.4%, mostly due to ischemia in a lower limb. Thirty-seven of 90 patients survived, creating a lower mortality rate than expected from the Sequential Organ Failure Assessment score. Conclusions:Interventional lung assist might provide a sufficient rescue measure with easy handling properties and low cost in patients with severe acute respiratory distress syndrome and persistent hypoxia/hypercapnia.

Immunomodulatory effects of mesenchymal stem cells in a rat organ transplant model

Background. Recent reports suggest that mesenchymal stem cells (MSCs) have immunomodulatory properties. Mesenchymal stem cells can suppress the immune response toward alloantigen in vitro by inhibiting T cell proliferation in mixed-lymphocyte reactions (MLRs). However, relatively little has been reported regarding the immunomodulative potential of MSCs in vivo. Herein the authors confirm the immunomodulatory effects of rat MSCs in vitro and tested for tolerogenic features in a model of allogeneic heart transplantation. Methods. Mesenchymal stem cells were obtained from bone marrow aspirates of male Lewis rats (major histocompatibility complex [MHC] haplotype RT1l) and ACI rats (RT1a). Lewis MSCs were cocultured with ACI spleen cells to reveal direct effects of MSCs on lymphocytes. In addition, MSCs were added to MLRs between ACI T cells as responders and irradiated Lewis spleen cells as stimulators. Finally, MSCs were administered in an allogeneic heart transplantation model at different doses (with and without cyclosporin A [CsA]). Results. Mesenchymal stem cells appeared with typical spindle-shaped morphology in culture and readily differentiated into adipocytes when exposed to differentiation media. Mesenchymal stem cells expressed MHC class I, but not class II or costimulatory molecules. In vitro, MSCs phagocytosed ACI spleen cells. When introduced into an MLR, donor MSCs suppressed the proliferation of stimulated T cells. However, in vivo, MSC injection did not prolong allograft survival. In addition, concurrent treatment with low-dose CsA and MSCs accelerated allograft rejection. Conclusions. The present data confirm previous reports suggesting that MSCs have immunomodulatory properties in vitro. However, their tolerogenic properties in vivo must be questioned, as MSC injections were not only ineffective at prolonging allograft survival, but tended to promote rejection.

Replacement of calcineurin inhibitors with mycophenolate mofetil in liver-transplant patients with renal dysfunction: a randomised controlled study

BACKGROUND Renal dysfunction is a major complication of long-term immunosuppressive therapy with calcineurin inhibitors (CNI) in liver-transplant recipients. We undertook a randomised study to assess the safety and efficacy of CNI withdrawal and replacement by mycophenolate mofetil. METHODS 28 people who had had renal dysfunction attributable to suspected CNI toxicity after liver transplantation participated in the study. We replaced CNI with mycophenolate mofetil in a stepwise pattern in half the group (study patients); the other half (controls) stayed on CNI immunosuppression. Renal function, blood pressure, uric acid, and blood lipids were measured before and 6 months after study entry. Side-effects of medication and graft function were recorded throughout the study. FINDINGS At the end of the study, mean (SD) serum creatinine had fallen by 44.4 (48.7) micromol/L in study patients compared with 3.1 (14.3) micromol/L in controls; a mean difference of 41.3 micromol/L (95% CI 12.4-70.2). Moreover, systolic and diastolic blood pressure, and serum uric acid decreased significantly in the study group but not in the control group (mean [95% CI] between group differences 10.8 mm Hg [3.0-18.6], 5.0 mm Hg [0.9-9.2], and 83.1 micromol/L [12.7-153.6], respectively). There were no changes in cholesterol or triglyceride concentrations in either group. Side-effects were reported by eight of the study patients. Three reversible episodes of acute graft rejection occurred in study patients during mycophenolate mofetil monotherapy, whereas none occurred in the control group. INTERPRETATION Substitution of CNI by mycophenolate mofetil can improve renal function, blood pressure, and uric acid concentration of liver-transplant patients, but there is an increased rejection risk with mycophenolate mofetil monotherapy.

Cytomegalovirus in transplantation – challenging the status quo

Abstract:  Background:  Cytomegalovirus (CMV) infection of solid organ transplant (SOT) recipients causes both ‘‘direct’’ and ‘‘indirect’’ effects including allograft rejection, decreased graft and patient survival, and predisposition to opportunistic infections and malignancies. Options for CMV prevention include pre‐emptive therapy, whereby anti‐CMV agents are administered based on sensitive viral assays, or universal prophylaxis of all at‐risk patients. Each approach has advantages and disadvantages in terms of efficacy, costs, and side effects. Standards of care for prophylaxis have not been established.

Rapamycin Protects Allografts From Rejection While Simultaneously Attacking Tumors In Immunosuppressed Mice

Cancer is an increasingly recognized problem associated with immunosuppression. Recent reports, however, suggest that the immunosuppressive agent rapamycin has anti-cancer properties that could address this problem. Thus far, rapamycin’s effects on immunity and cancer have been studied separately. Here we tested the effects of rapamycin, versus cyclosporine A (CsA), on established tumors in mice simultaneously bearing a heart allograft. In one tumor-transplant model, BALB/c mice received subcutaneous syngenic CT26 colon adenocarcinoma cells 7 days before C3H ear–heart transplantation. Rapamycin or CsA treatment was initiated with transplantation. In a second model system, a B16 melanoma was established in C57BL/6 mice that received a primary vascularized C3H heart allograft. In vitro angiogenic effects of rapamycin and CsA were tested in an aortic ring assay. Results show that CT26 tumors grew for 2 weeks before tumor complications occurred. However, rapamycin protected allografts, inhibited tumor growth, and permitted animal survival. In contrast, CsA-treated mice succumbed to advancing tumors, albeit with a functioning allograft. Rapamycin’s antitumor effect also functioned in severe combined immunodeficient BALB/c mice. Similar effects of the drugs occurred with B16 melanomas and primary vascularized C3H allografts in C57BL/6 mice. Furthermore, in this model, rapamycin inhibited the tumor growth-enhancing effects of CsA. Moreover, in vitro experiments showed that CsA promotes angiogenesis by a transforming growth factor-β–related mechanism, and that this effect is abrogated by rapamycin. This study demonstrates that rapamycin simultaneously protects allografts from rejection and attacks tumors in a complex transplant-tumor situation. Notably, CsA protects allografts from rejection, but cancer progression is promoted in transplant recipients.

Recurrence Patterns of Hepatocellular and Fibrolamellar Carcinoma After Liver Transplantation

PURPOSE Tumor recurrence is the major limitation of long-term survival after liver transplantation for hepatocellular carcinoma (HCC) or fibrolamellar carcinoma (FLC). Understanding tumor-biologic characteristics is important for selection of patients and for development of adjuvant therapeutic strategies. PATIENTS AND METHODS The study included 69 patients who underwent potentially curative liver transplantation for HCC/FLC and survived for more than 150 days; minimum follow-up was 33 months. Frequency, localization, and timing of recurrence were analyzed and compared with primary tumor and patient characteristics. RESULTS Tumor recurrence was observed in 39 patients at 67 locations. Hematogenous spread was the major route of tumor recurrence (87%), and the most frequent sites were the liver (62%), lung (56%), and bone (18%). Parameters associated with recurrence were absence of cirrhosis, tumor size greater than 5 cm, more than five nodules, vascular infiltration, and International Union Against Cancer (UICC) stage IVA. Selective intrahepatic recurrence was found in nine patients (23%); it was associated with highly differentiated tumors, lack of vascular infiltration, and male sex. Recurrence at multiple sites was found predominantly in young patients (< or = 40 years) and for multicentric (> 5) primary tumors. Recurrences were observed within a wide time range after transplantation (43 to 3,204 days; median, 441 days); late recurrences (> 1,000 days, n = 8) were associated with highly differentiated or fibrolamellar tumors and low UICC stages. Surgical treatment was the only therapeutic option associated with prolonged survival after recurrence. CONCLUSION In transplant recipients, hepatocellular carcinomas vary considerably in their pattern and kinetics of metastases. Tumor cells may persist in a dormant state for long time periods before giving rise to clinical metastases. Surgical treatment of recurrence should be considered whenever possible.

Mesenchymal stem cells can induce long-term acceptance of solid organ allografts in synergy with low-dose mycophenolate.

The induction of tolerance towards allogeneic solid organ grafts is one of the major goals in transplantation medicine. Mesenchymal stem cells (MSC) inhibit the immune response in vitro, and thus are promising candidate cells to promote acceptance of transplanted organs in vivo. Such novel approaches of tolerance induction are needed since, to date, graft acceptance can only be maintained through life-long treatment with unspecific immunosuppressants that are associated with toxic injury, opportunistic infections and malignancies. We demonstrate that donor-derived MSC induce long-term allograft acceptance in a rat heart transplantation model, when concurrently applied with a short course of low-dose mycophenolate. This tolerogenic effect of MSC is at least partially mediated by the expression of indoleamine 2,3-dioxygenase (IDO), demonstrated by the fact that blocking of IDO with 1-methyl tryptophan (1-MT) abrogates graft acceptance. Moreover we hypothesize that MSC interact with dendritic cells (DC) in vivo, because allogeneic MSC are rejected in the long-term but DC acquire a tolerogenic phenotype after applying MSC. In summary, we demonstrate that MSC constitute a promising tool for induction of non-responsiveness in solid organ transplantation that warrants further investigation in clinical trials.

Influence of arginine, omega-3 fatty acids and nucleotide-supplemented enteral support on systemic inflammatory response syndrome and multiple organ failure in patients after severe trauma

This study investigated the influence of an enteral diet supplemented with arginine, omega-3 fatty acids, and nucleotides (Impact, Sandoz Nutrition, Berne, Switzerland) on the incidence of systemic inflammatory response syndrome (SIRS) and multiple organ failure (MOF) in patients after severe trauma. Thirty-two patients with an injury-severity score > 20 were included in this prospective, randomized, double-blind, controlled study. Primary endpoints were the incidence of SIRS and MOF. Secondary endpoints were parameters of acute phase and immune response as well as infection rate, mortality, and hospital stay. For statistical analysis 29 patients (test group n = 16, control n = 13) were eligible. In the test group, significantly fewer SIRS days per patient were found during 28 d. The difference was highly significant between d 8-14 (P < 0.001). MOF score was significantly lower in the test group on d 3 and d 8-11 (P < 0.05). Acute phase parameters showed lower C-reactive protein serum levels (significant on D day 4) and fibrinogen plasma levels (significant on d 12 and 14; P < 0.05). HLA-DR expression on monocytes showed significantly higher fluorescence activity on d 7. No significant difference was found for T-lymphocyte CD4/CD8 ratio, interleukin-2 receptor expression, infection rate, mortality (2/16 vs. 4/13), and hospital stay. The results of the study provide further support for beneficial effects of arginine, omega-3-fatty acids and nucleotide-supplemented enteral diet in critically ill patients.