Ferdinand Muehlbacher

Current situation of donation after circulatory death in European countries

The aim of the present study was to describe the current situation of donation after circulatory death (DCD) in the Council of Europe, through a dedicated survey. Of 27 participating countries, only 10 confirmed any DCD activity, the highest one being described in Belgium, the Netherlands and the United Kingdom (mainly controlled) and France and Spain (mainly uncontrolled). During 2000–2009, as DCD increased, donation after brain death (DBD) decreased about 20% in the three countries with a predominant controlled DCD activity, while DBD had increased in the majority of European countries. The number of organs recovered and transplanted per DCD increased along time, although it remained substantially lower compared with DBD. During 2000–2008, 5004 organs were transplanted from DCD (4261 kidneys, 505 livers, 157 lungs and 81 pancreas). Short‐term outcomes of 2343 kidney recipients from controlled versus 649 from uncontrolled DCD were analyzed: primary non function occurred in 5% vs. 6.4% (P = NS) and delayed graft function in 50.2% vs. 75.7% (P < 0.001). In spite of this, 1 year graft survival was 85.9% vs. 88.9% (P = 0.04), respectively. DCD is increasingly accepted in Europe but still limited to a few countries. Controlled DCD might negatively impact DBD activity. The degree of utilization of DCD is lower compared with DBD. Short‐term results of DCD are promising with differences between kidney recipients transplanted from controlled versus uncontrolled DCD, an observation to be further analyzed.

A Randomized, Controlled Study to Assess the Conversion From Calcineurin-Inhibitors to Everolimus After Liver Transplantation—PROTECT

Posttransplant immunosuppression with calcineurin inhibitors (CNIs) is associated with impaired renal function, while mTor inhibitors such as everolimus may provide a renal‐sparing alternative. In this randomized 1‐year study in patients with liver transplantation (LTx), we sought to assess the effects of everolimus on glomerular filtration rate (GFR) after conversion from CNIs compared to continued CNI treatment. Eligible study patients received basiliximab induction, CNI with/without corticosteroids for 4 weeks post‐LTx, and were then randomized (if GFR > 50 mL/min) to continued CNIs (N = 102) or subsequent conversion to EVR (N = 101). Mean calculated GFR 11 months postrandomization (ITT population) revealed no significant difference between treatments using the Cockcroft‐Gault formula (−2.9 mL/min in favor of EVR, 95%‐CI: [−10.659; 4.814], p = 0.46), whereas use of the MDRD formula showed superiority for EVR (−7.8 mL/min, 95%‐CI: [−14.366; −1.191], p = 0.021). Rates of mortality (EVR: 4.2% vs. CNI: 4.1%), biopsy‐proven acute rejection (17.7% vs. 15.3%), and efficacy failure (20.8% vs. 20.4%) were similar. Infections, leukocytopenia, hyperlipidemia and treatment discontinuations occurred more frequently in the EVR group. No hepatic artery thrombosis and no excess of wound healing impairment were noted. Conversion from CNI‐based to EVR‐based immunosuppression proved to be a safe alternative post‐LTx that deserves further investigation in terms of nephroprotection.

Treg‐Therapy Allows Mixed Chimerism and Transplantation Tolerance Without Cytoreductive Conditioning

Establishment of mixed chimerism through transplantation of allogeneic donor bone marrow (BM) into sufficiently conditioned recipients is an effective experimental approach for the induction of transplantation tolerance. Clinical translation, however, is impeded by the lack of feasible protocols devoid of cytoreductive conditioning (i.e. irradiation and cytotoxic drugs/mAbs). The therapeutic application of regulatory T cells (Tregs) prolongs allograft survival in experimental models, but appears insufficient to induce robust tolerance on its own. We thus investigated whether mixed chimerism and tolerance could be realized without the need for cytoreductive treatment by combining Treg therapy with BM transplantation (BMT). Polyclonal recipient Tregs were cotransplanted with a moderate dose of fully mismatched allogeneic donor BM into recipients conditioned solely with short‐course costimulation blockade and rapamycin. This combination treatment led to long‐term multilineage chimerism and donor‐specific skin graft tolerance. Chimeras also developed humoral and in vitro tolerance. Both deletional and nondeletional mechanisms contributed to maintenance of tolerance. All tested populations of polyclonal Tregs (FoxP3‐transduced Tregs, natural Tregs and TGF‐β induced Tregs) were effective in this setting. Thus, Treg therapy achieves mixed chimerism and tolerance without cytoreductive recipient treatment, thereby eliminating a major toxic element impeding clinical translation of this approach.

Alemtuzumab (Campath-1H) and tacrolimus monotherapy after renal transplantation: results of a prospective randomized trial.

The lymphocyte‐depleting antibody alemtuzumab was evaluated in a prospective randomized multicenter trial in deceased donor kidney transplantation.

The Role of Non‐Deletional Tolerance Mechanisms in a Murine Model of Mixed Chimerism with Costimulation Blockade

Peripheral and central clonal deletion are important tolerance mechanisms in models using bone marrow transplantation (BMT) with costimulation blockade (CB). However, since tolerance can be found before peripheral deletion is complete and since elimination of recipient CD4+ cells at the time of BMT prevents tolerance induction, we investigated the potential roles of regulation and anergy in such a murine model. We found that transient elimination of CD25+ cells or neutralization of IL2 immediately after BMT and CB prevented the induction of skin graft tolerance. Cotransfer into SCID mice of CD4+ cells taken from chimeras early after BMT, together with naïve recipient‐type CD4+ cells significantly prolonged donor skin graft survival. In contrast, cotransfer of CD4+ cells harvested from chimeras late after BMT did not prolong donor skin graft survival. Besides, depletion of CD25+ cells in established chimeras several months post‐BMT did not break tolerance. In vivo administration of recombinant IL2 inhibited chimerism and tolerance neither early nor late post‐BMT, arguing against a decisive role for classical anergy. Thus, CD4 cell‐mediated regulation contributes significantly to tolerance induction early after BMT, but appears to have no critical role in the maintenance of tolerance.

Combination of extended donor criteria and changes in the Model for End-Stage Liver Disease score predict patient survival and primary dysfunction in liver transplantation: a retrospective analysis.

Background. The purpose of this study was to analyze the impact of extended donor criteria (EDC) and of changes in the Model for End-Stage Liver Disease (MELD) score while waiting for liver-transplantation (&Dgr;-MELD) on patient survival and initial graft function. Methods. We included 386 consecutive patients with end-stage liver disease who underwent orthotopic liver transplantation at the Medical University Vienna between 1997 and 2003. Primary outcome was patient survival and secondary outcome was initial graft function. EDC included: age >60 years, >4 days intensive medical care, cold ischemia time >10 hr, need for noradrenalin >0.2 &mgr;g/kg/min or doputamin >6 &mgr;g/kg/min, a donor peak serum sodium >155 mEq/L, a donor serum creatinine >1.2 mg/100 mL, and a body mass index >30. Results. &Dgr;-MELD was significantly higher in the nonsurvivor population (P=0.01) and EDC showed a significant influence on initial graft function (P=0.01). Worsening in either &Dgr;-MELD or the presence of at least two EDC was not associated with an increased risk of primary graft dysfunction and death. Worsening in &Dgr;-MELD and the presence of at least two EDC was significantly associated with primary graft dysfunction (P=0.01) and death (P=0.008). Conclusion. The combination of a liver recipient with worsening &Dgr;-MELD and a potential donor with at least two EDC should be avoided.

Influence of cumulative number of marginal donor criteria on primary organ dysfunction in liver recipients.

Abstract:  Background:  The aim of this cohort study was to assess the cumulative effect of marginal donor criteria on initial graft function and patient survival after liver transplantation.

Is MELD score sufficient to predict not only death on waiting list, but also post-transplant survival?

Model for end‐stage liver disease (MELD) score has emerged as a useful tool in predicting mortality in patients awaiting liver transplantation. There is still, however, discussion as to whether further parameters could improve the sensitivity and specificity of the MELD score. From 1997 to 2003, 621 adult patients with end‐stage liver disease were listed for orthotopic liver transplantation (OLT). Patients suffering from hepatoma were excluded from analysis (113 patients). The MELD score was investigated at the time of listing (MELD ON) and of coming off the list (MELD OFF). Patients who died while on the waiting list showed a significant increase in their MELD score during the waiting time (MELD ON: 21 ± 7 vs. MELD OFF: 28 ± 9) as well as a significantly higher MELD ON compared with patients who were transplanted (MELD ON: 16 ± 5 vs. MELD OFF: 17 ± 7) or removed from the waiting list (MELD ON: 16 ± 6 vs. MELD OFF: 12 ± 3). Multivariate analysis identified MELD ON, ascites and recurrent infection as independent risk factors for death on the waiting list (P < 0.01). MELD score was not identified as a predictor for the post‐transplant survival rate. MELD score is a strong predictor for death on the waiting list, but refractory ascites and recurrent infection are independent risk factors, too.

Short-term immunosuppression facilitates induction of mixed chimerism and tolerance after bone marrow transplantation without cytoreductive conditioning.

Background. Induction of mixed chimerism and tolerance usually requires cytoreduction or transplantation of high numbers of bone marrow cells (BMC). However, such protocols have only a suboptimal success rate and, more importantly, equivalent numbers of BMC cannot be routinely obtained in the clinical setting. The authors therefore evaluated whether a short-course of immunosuppression (IS) given in addition to co-stimulation blockade would facilitate chimerism induction and allow reduction of the minimally required number of BMC without cytoreduction. Methods. B6 mice received 200, 100, or 50×106 unseparated BMC from Balb/c donors plus an anti-CD40L monoclonal antibody (mAb) and CTLA4Ig (without irradiation or cytotoxic drugs). Some groups were treated additionally with IS (rapamycin, methylprednisolone, and mycophenolate mofetil for 4 weeks after bone marrow transplantation), donor-specific transfusion (DST), or anti-OX40L mAb, as indicated. Results. IS led to long-term multilineage chimerism in 9 of 10 mice receiving 200×106 BMC (without IS, 1 of 4; P<0.05), in all mice (n=10) receiving 100×106 (without IS, 6 of 9; P<0.05), and notably in 9 of 10 mice treated with 50×106 BMC (without IS, 4 of 10; P<0.05). With transient IS, donor skin grafts were accepted longer than 170 days in 9 of 10 mice receiving 200×106 (without IS, 0 of 5 mice; P<0.05), all mice receiving 100×106 (without IS, 6 of 9; P<0.05), and 6 of 11 mice receiving 50×106 BMC (without IS, 4 of 10). The use of DST or anti-OX40L mAb had no beneficial effect. Conclusions. Transient IS significantly improves rates of chimerism and donor skin graft survival, and allows lasting mixed chimerism after transplantation of only 50×106 BMC. Thus, IS might help in the further development of noncytoreductive chimerism protocols.

Tolerization of a Type I Allergic Immune Response through Transplantation of Genetically Modified Hematopoietic Stem Cells

Allergy represents a hypersensitivity disease that affects >25% of the population in industrialized countries. The underlying type I allergic immune reaction occurs in predisposed atopic individuals in response to otherwise harmless Ags (i.e., allergens) and is characterized by the production of allergen-specific IgE, an allergen-specific T cell response, and the release of biologically active mediators such as histamine from mast cells and basophils. Regimens permanently tolerizing an allergic immune response still need to be developed. We therefore retrovirally transduced murine hematopoietic stem cells to express the major grass pollen allergen Phl p 5 on their cell membrane. Transplantation of these genetically modified hematopoietic stem cells led to durable multilineage molecular chimerism and permanent immunological tolerance toward the introduced allergen at the B cell, T cell, and effector cell levels. Notably, Phl p 5-specific serum IgE and IgG remained undetectable, and T cell nonresponsiveness persisted throughout follow-up (40 wk). Besides, mediator release was specifically absent in in vitro and in vivo assays. B cell, T cell, and effector cell responses to an unrelated control allergen (Bet v 1) were unperturbed, demonstrating specificity of this tolerance protocol. We thus describe a novel cell-based strategy for the prevention of allergy.