Kidney transplantation across HLA and ABO antibody barriers. Curr Opin Organ Transplant. 2013;18:445-454. [PMID: 23838650 DOI: 10.1097/mot.0b013e3283636c20]

Comparative Study of the Impact of Human Leukocyte Antigens on Renal Transplant Survival in Andalusia and the United States

Renal transplantation is the treatment of choice for patients suffering from chronic renal disease, one of the leading causes of death worldwide. Among the biological barriers that may increase the risk of acute renal graft rejection is the presence of human leukocyte antigen (HLA) incompatibilities between donor and recipient. This work presents a comparative study of the influence of HLA incompatibilities on renal transplantation survival in the Andalusian (South of Spain) and United States (US) population. The main objective is to analyse the extent to which results about the influence of different factors on renal graft survival can be generalised to different populations. The Kaplan-Meier estimator and the Cox model have been used to identify and quantify the impact on the survival probability of HLA incompatibilities, both in isolation and in conjunction with other factors associated with the donor and recipient. According to the results obtained, HLA incompatibilities considered in isolation have negligible impact on renal survival in the Andalusian population and a moderate impact in the US population. Grouping by HLA score presents some similarities for both populations, while the sum of all HLA scores (aHLA) only has an impact on the US population. Finally, the graft survival probability of the two populations differs when aHLA is considered in conjunction with blood type. The results suggest that the disparities in the renal graft survival probability between the two populations under study are due not only to biological and transplantation-associated factors, but also to social-health factors and ethnic heterogeneity between populations.

Therapeutic apheresis in kidney diseases: an updated review

Besides conventional medical therapies, therapeutic apheresis has become an important adjunctive or alternative therapeutic option to immunosuppressive agents for primary or secondary kidney diseases and kidney transplantation. The available therapeutic apheresis techniques used in kidney diseases, including plasma exchange, double-filtration plasmapheresis, immunoadsorption, and low-density lipoprotein apheresis. Plasma exchange is still the leading extracorporeal therapy. Recently, growing evidence supports the potential benefits of double-filtration plasmapheresis and immunoadsorption for more specific and effective clearance of pathogenic antibodies with fewer side effects. However, more randomized controlled trials are still needed. Low-density lipoprotein apheresis is also an important supplementary therapy used in patients with recurrent focal segmental glomerulosclerosis. This review collects the latest evidence from recent studies, focuses on the specific advantages and disadvantages of these techniques, and compares the discrepancy among them to determine the optimal therapeutic regimens for certain kidney diseases.

Rethinking incompatibility in kidney transplantation

Donor/recipient incompatibility in kidney transplantation classically refers to ABO/HLA-incompatibility. Kidney paired donation (KPD) was historically established to circumvent ABO/HLA-incompatibility, with the goal of identifying ABO/HLA-compatible matches. However, there is a broad range of donor factors known to impact recipient outcomes beyond ABO/HLA-incompatibility, such as age and weight, and quantitative tools are now available to empirically compare potential living donors across many of these factors, such as the living donor kidney donor profile index (LKDPI). Moreover, the detrimental impact of mismatch at other HLA antigens (such as DQ) and epitope mismatching on posttransplant outcomes has become increasingly recognized. Thus, it is time for a new paradigm of incompatibility that considers all of these risks factors together in assessing donor/recipient compatibility and the potential utility for KPD. Under this new paradigm of incompatibility, we show how the LKDPI and other tools can be used to identify donor/recipient incompatibilities that could be improved through KPD, even for those with a traditionally "compatible" living donor.

Efficient Kidney Exchange with Dichotomous Preferences

This paper studies a general kidney exchange model with compatible patient-donor pairs, incompatible patient-donor pairs, single donors, and patients on the waiting list. We derive an explicit formula of the maximal number of feasible kidney transplants under several sizes of cycles and chains of exchange, analyze the effect of different ways of exchange on efficiency, and provide substantial simulation results based on the USA data. Our results further show that kidney exchange can be decentralized for relatively large populations, and that allowing compatible pairs and single donors to exchange with incompatible pairs can significantly increase the number of feasible kidney transplants. A more general model of two-category type-compatible exchanges is also established.

Long-term outcome of kidney transplant by using restored kidney grafts after tumour ex vivo excision - a prospective study

The aim of this study is to report long-term outcomes of kidney transplantation by using the kidney graft after a small tumour ex vivo excision. A structured programme was established to use the restored kidney graft from urological referral after radical nephrectomy. The criteria were defined as tumour size ≤3 cm, margin clear on frozen section and recipients aged ≥60 years or those on the urgent list for transplantation as a result of imminent lack of dialysis access. The recipients were followed up regularly for surveillance of tumour recurrence. Between February 2007 and February 2018, 28 recipients had kidney transplantation by using the restored kidney grafts. The tumour size was 2.6 ± 0.7 cm. The follow-up was median 7 years without evidence of tumour recurrence. The patient and graft survival was satisfactory. Kidney transplantation by using restored kidneys after a small tumour excision is a novel source for selected recipients. The long-term patient and graft survival is satisfactory. Although there is a risk of tumour recurrence, it is rare event. Together with literature review, we would support use of kidney graft after a small tumour excision for selected recipients.

Effect of simultaneous presence of anti-blood group A/B and -HLA antibodies on clinical outcomes in kidney transplantation across positive crossmatch: a nationwide cohort study

ABO-incompatible (ABOi) and positive crossmatch (XM) kidney transplantation (KT) have been considered immunologically challenging. The present study analyzed the clinical outcomes in XM positive KT based on ABO incompatibility. We used data from the Korea Organ Transplantation Registry, a nationwide database, and a single-center registry. A total of 263 patients with positive XM were divided into an ABO compatible (ABOc) & XM positive (ABOc/XM+, n = 176) group and an ABOi & XM positive (ABOi/XM+, n = 87) group. The overall rejection rate one year after KT was significantly higher in the ABOi/XM+ group than in the ABOc/XM+ group (P < 0.01). A total of four mortalities occurred, all in the ABOi/XM+ patients (P < 0.01). There were no differences in surgical complications or the occurrence of infection-related complications, including BK virus nephropathy. Multivariate analysis indicated that female vs. male (odds ratio (OR), 2.27; P = 0.03), DSA class I (MFI/1000) (OR, 1.10; P = 0.03), DSA class II (MFI/1000) (OR, 1.10; P < 0.01), and ABOi & XM+ status (OR, 2.38; P < 0.01) were significant risk factors for acute rejection during the year after transplantation. Overall graft survival was inferior in ABOi/XM+ patients than in ABOc/XM+ patients (P = 0.02). ABO incompatibility in XM-positive KT patients was found to be a significant risk factor for the development of rejection within one year after transplantation as well as for long-term graft survival. The anti-blood group A, B and anti-HLA antibodies may show synergistic activity.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice - Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Eighth Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating and categorizing indications for the evidence-based use of therapeutic apheresis (TA) in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Eighth Edition of the JCA Special Issue continues to maintain this methodology and rigor in order to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Eighth Edition, like its predecessor, continues to apply the category and grading system definitions in fact sheets. The general layout and concept of a fact sheet that was introduced in the Fourth Edition, has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of TA in a specific disease entity or medical condition. The Eighth Edition comprises 84 fact sheets for relevant diseases and medical conditions, with 157 graded and categorized indications and/or TA modalities. The Eighth Edition of the JCA Special Issue seeks to continue to serve as a key resource that guides the utilization of TA in the treatment of human disease.

The degree of major histocompatibility complex matching between purebred Maltese and mongrel dogs using microsatellite markers

Long-term maintenance of transplanted organs is one of the major factors that increases survival time of recipients. Although obtaining a major histocompatibility complex (MHC)-matched donor with the recipient is essential for successful organ transplantation, there have been limited reports on MHC matching between dogs. In this study, we analyzed the canine MHC matching rates using Maltese, one of the most popular purebred dogs, and mongrel dogs in Korea. Genomic DNA was extracted from blood leukocytes and DNA was amplified by polymerase chain reaction with primers specific to MHC microsatellite markers. The MHC matching degree was confirmed by the microsatellite markers using polyacrylamide gel electrophoresis. The MHC matching rates of each donor-recipient groups including Maltese-Maltese, mongrel-mongrel and Maltese-mongrel were 4.76%, 5.13% and 6.67%, respectively. There were no significant differences in the MHC matching degree between each group. These results demonstrate that MHC-matched donors could be selected from other breeds as much as from the same breed for transplantation. Knowledge of the MHC matching degree of purebred and mongrel dogs would offer valuable information not only for improving the success rate of organ transplantation surgery in canine patients but also for transplantation research using experimental canine models.

Anti-HLA Donor-Specific IgG Subclasses and C1q-binding Evolution in Posttransplant Monitoring

Background

The identification of low-level antibodies by single-antigen bead methodology has brought advancements to risk evaluation of kidney transplant recipients. However, the use of mean fluorescence intensity (MFI) to quantify antibodies and to guide therapy is not enough. Notably, immunoglobulin G (IgG) subclass switching is hypothesized to follow a programmed sequence after an emergency signal from the germinal center. In transplantation this process is not clear yet. In the present study, we sequentially evaluate anti-HLA donor specific antibody (DSA) subclasses, their profile changes, and C1q-binding ability and the influence of those characteristics on antibody mediated rejection (AMR) occurrence and allograft function.

Methods

A total of 30 DSA-positive patients were tested for IgG subclass content and C1q-binding in sequential serum samples.

Results

Twenty-one patients were DSA-positive before transplant; patients sensitized only by transfusion or pregnancies had IgG1 and/or IgG3, and patients sensitized by both transfusion and pregnancies or previous transplant showed a broader range of IgG subclasses. C1q binding was detected in high MFI made up of IgG1 or multiple IgG subclasses. Only 4 patients were positive for C1q posttransplantation and 3 of these showed an increase in MFI, changes in subclasses patterns, AMR, and allograft dysfunction.

Conclusions

Posttransplant evaluation of DSA subclasses and the ability to bind C1q may be informative for both AMR occurrence and allograft dysfunction. Monitoring these events may help to better define risk and interventional time points.

Reflections on the usefulness of extracorporeal photopheresis in renal transplant rejection: A concise review of the involved mechanisms and therapeutic perspectives

Renal rejection clinically represents a major cause of graft dysfunction and sadly the loss of the renal transplant. This is despite the considerable progress in immunosuppressive therapy. It is strongly believed that the complex immunologic network underlying the response against major histocompatibility molecules (MHC) is responsible for rejection, an unresolved issue that is, in part, not inhibited by the current prophylactic and therapeutic strategies. Extracorporeal photopheresis (ECP) is an effective cell therapy approach that was successfully used in immunomodulating heart rejection, acute and chronic GvHD, lung rejection and some selected autoimmune diseases. In this concise report we provide a brief review on the mechanisms of action and the use of ECP in acute and chronic renal allograft rejection.

Guidelines on the Use of Therapeutic Apheresis in Clinical Practice-Evidence-Based Approach from the Writing Committee of the American Society for Apheresis: The Seventh Special Issue

The American Society for Apheresis (ASFA) Journal of Clinical Apheresis (JCA) Special Issue Writing Committee is charged with reviewing, updating, and categorizing indications for the evidence-based use of therapeutic apheresis in human disease. Since the 2007 JCA Special Issue (Fourth Edition), the Committee has incorporated systematic review and evidence-based approaches in the grading and categorization of apheresis indications. This Seventh Edition of the JCA Special Issue continues to maintain this methodology and rigor to make recommendations on the use of apheresis in a wide variety of diseases/conditions. The JCA Seventh Edition, like its predecessor, has consistently applied the category and grading system definitions in the fact sheets. The general layout and concept of a fact sheet that was used since the fourth edition has largely been maintained in this edition. Each fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis in a specific disease entity. The Seventh Edition discusses 87 fact sheets (14 new fact sheets since the Sixth Edition) for therapeutic apheresis diseases and medical conditions, with 179 indications, which are separately graded and categorized within the listed fact sheets. Several diseases that are Category IV which have been described in detail in previous editions and do not have significant new evidence since the last publication are summarized in a separate table. The Seventh Edition of the JCA Special Issue serves as a key resource that guides the utilization of therapeutic apheresis in the treatment of human disease. J. Clin. Apheresis 31:149-162, 2016. © 2016 Wiley Periodicals, Inc.

ABO-Incompatible Kidney Transplantation

ABO-incompatible (ABOi) kidney transplantation has long been considered a contraindication to successful kidney transplantation. During the last 25 years, increasing organ shortage enforced the development of strategies to overcome the ABO antibody barrier. In the meantime, ABOi kidney transplantation has become a routine procedure with death-censored graft survival rates comparable to the rates in compatible transplantations. Desensitization is usually achieved by apheresis and B cell-depleting therapies that are accompanied by powerful immunosuppression. Anti-A/B antibodies are aimed to be below a certain threshold at the time of ABOi kidney transplantation and during the first 2 weeks after surgery. Thereafter, even a rebound of anti-A/B antibodies does not appear to harm the kidney transplant, a phenomenon that is called accommodation, but is poorly understood. There is still concern, however, that infectious complications such as viral disease, Pneumocystis jirovecii pneumonia, and severe urinary tract infections are increased after ABOi transplantations. Recent data from the Collaborative Transplant Study show that during the first year after kidney transplantation, one additional patient death from an infectious complication occurs in 100 ABOi kidney transplant recipients. Herein, we review the recent evidence on ABOi kidney transplantation with a focus on desensitization strategies and respective outcomes.

Identification of patients at risk for renal impairment after living donor kidney transplantation

PURPOSE

Outcome after living donor kidney transplantation is highly relevant, since recipient and donor were exposed to notable harm. Reliable identification of risk factors is necessary.

METHODS

Three hundred sixty-six living donor kidney transplants were included in this observational retrospective study. Relevant risk factors for renal impairment 1 year after transplantation and delayed graft function were identified with univariable and multivariable binary logistic regression and ordinal regression analysis.

RESULTS

Eighty-four patients (26.6 %) suffered from renal impairment KDIGO stage ≥4 1 year post-transplant; median estimated glomerular filtration rate was 35.3 ml/min. In multivariable ordinal regression, male recipient sex (p < 0.001), recipient body mass index (p = 0.006), donor age (p = 0.002) and high percentages of panel reactive antibodies (p = 0.021) were revealed as independent risk factors for higher KDIGO stages. After adjustment for post-transplant data, recipient male sex (p < 0.001), donor age (p = 0.026) and decreased early renal function at the first post-transplant outpatient visit (p < 0.001) were identified as independent risk factors. Delayed graft function was independently associated with long stay on the waiting list (p = 0.011), high donor body mass index (p = 0.043), prolonged warm ischemic time (p = 0.016) and the presence of preformed donor-specific antibodies (p = 0.043).

CONCLUSIONS

Broadening the donor pool with non-blood related donors seems to be legitimate, although with respect to careful medical selection, since donor age in combination with male recipient sex were shown to be risk factors for decreased graft function. Warm ischemic time and waiting time need to be kept as short as possible to avoid delayed graft function. Transplantation across HLA and ABO borders did not affect outcome significantly.

Preconditioning Therapy in ABO-Incompatible Living Kidney Transplantation: A Systematic Review and Meta-Analysis

BACKGROUND

ABO-incompatible (ABOi) kidney transplantation is now an established form of renal replacement therapy, but the efficacy and safety of the different types of preconditioning therapies are unclear. We aimed to synthesize the totality of the published evidence about the effects of any form of preconditioning therapies in living donor ABOi kidney transplantation on graft and patient outcomes.

METHODS

We searched MEDLINE, Embase, and Clinicaltrial.gov databases (inception through June 2015) to identify all studies that described the outcomes of adult living donor ABOi kidney transplantations using any form of preconditioning therapies. Two independent reviewers identified studies, extracted data, and assessed the risk of bias. Data were summarized using the random effects model, and heterogeneity was explored using subgroup analyses. We assessed confidence in the evidence using the Grading of Recommendations Assessment, Development, and Evaluation framework.

RESULTS

Eighty-three studies (54 case reports and case series, 25 cohort, 2 case-control, and 2 registry studies) involving 4810 ABOi transplant recipients were identified. Overall, confidence in the available evidence was low. During a mean follow-up time of 28 (standard deviation [SD], 26.6) months, the overall graft survival for recipients who received immunoadsorption or apheresis was 94.1% (95% confidence interval [95%CI], 88.2%-97.1%) and 88.0% (95% CI, 82.6%-91.8%), respectively. For those who received rituximab or underwent splenectomy, the overall graft survival was 94.5% (95% CI, 91.6%-96.5%) and 79.7% (95% CI, 72.9%-85.1%), respectively. Data on other longer-term outcomes, including malignancy, were sparse.

CONCLUSIONS

Rituximab or immunoadsorption appeared to be promising preconditioning strategies before ABOi kidney transplantation. However, the overall quality of evidence and the confidence in the observed treatment effects are low. The increased use of ABOi kidney transplantation needs to be matched with randomized trials of different types, dosing, and frequency of preconditioning therapies so that this scarce resource can be used most effectively and efficiently.

Analysis of 4000 kidney transplantations in a single center: Across immunological barriers

Kidney transplant (KT) is the optimal renal replacement therapy for patients with end-stage renal disease (ESRD). The demand for kidneys, however, continues to exceed the supply. To overcome this problem, efforts to extend the donor pool by including human leukocyte antigen (HLA)- and ABO-incompatible (ABOi) KTs are increasing. The aim of this article was to retrospectively review data on recipients, donor profiles, and clinical outcomes in 4000 cases of KT. In addition, we analyzed clinical outcomes in ABOi and flow-cytometric crossmatch (FCXM) positive KT in a subgroup analysis.This was a retrospective, observational study using data extracted from medical records. A total of 4000 consecutive patients who underwent KT at our institution from January 1990 to February 2015 were included in this study. KTs across immunological barriers such as ABO incompatible (276 cases, 6.9%), FCXM positive (97 cases, 2.4%), and positive complement-dependent cytotoxicity (CDC) XM KT (16 cases, 0.4%) were included.From a Kaplan-Meier analysis, overall patient survival (PS) rates after KT at 1, 5, 10, and 20 years were 96.9%, 95.1%, 92.0%, and 88.9%, respectively. The overall graft survival (GS) rates after KT at 1, 5, 10, and 20 years were 96.3%, 88.9%, 81.2%, and 67.4%, respectively. Our subgroup analysis suggested that overall PS, GS, death-censored GS, and rejection-free GS in ABOi KT showed no significant differences in comparison with ABO-compatible KT if adequate immunosuppressive treatment was performed. The overall PS rate in patients who underwent FCXM positive KT did not differ significantly from that of the control group during the 3-year follow-up (P = 0.34). The overall GS, death-censored GS, and rejection-free GS also did not differ significantly between the FCXM KT and control groups (P = 0.99, 0.42, and 88).The outcomes of KTs continually improved during the study period, while the annual number of KTs increased. ABO or FCXM positive KTs can be performed safely with successful graft outcomes.

Excellent long term patient and renal allograft survival after ABO-incompatible kidney transplantation: Experience of one center

AIM: To investigate the long-term results of ABO-incompatible (ABOi) kidney transplantation in a single center in Greece.

METHODS: Thirty consecutive ABOi kidney transplantations were performed from June 2005 to December 2013. All patients received rituximab one month prior to transplantation. Immunoadsorption therapy was performed for the removal of anti-A/B IgG antibodies until the titer was ≤ 1:16. Additional apheresis sessions were performed post-operatively. Intravenous immunoglobulin and oral immunosuppression consisting of tacrolimus (TAC) in combination with either everolimus or mycophenolate acid was administered. We compared the long term results of our ABOi group to those of a matched group of 30 ABO compatible (ABOc) living kidney recipients with similar baseline characteristics. The ABOc recipients received an immunosuppressive regimen consisting of TAC and mycophenolate acid. All patients in both groups received induction therapy with Basiliximab or Daclizumab, whereas corticosteroids were instituted on the day of surgery. During the follow-up period, indication biopsies were performed and interpreted by an experienced nephropathologist. The parameters we analyzed included the following: Donor/recipient age, gender, blood type, human leukocyte antigen mismatches, panel reactive antibodies, primary cause of renal failure, mean time on dialysis, immunosuppressive regimen, patient survival, graft outcome, incidence of rejections, surgical and infectious complications.

RESULTS: The mean follow-up period was 6 years (range 1 to 9 years). A mean of 5.0 ± 3.0 (range 0-14) pre-transplant immunoadsorptions were required in order to reach the target titer. Patient survival in ABOi group in comparison to ABOc group at 1, 3, 5 and 8 years did not differ significantly (100% vs 100%, 96% vs 100%, 92% vs 100% and 92% vs 100%, P = ns). Additionally, graft survival was similar in the two groups at the same time points (100% vs 100%, 96% vs 96%, 92% vs 96% and 81% vs 92%, P = ns). The mean serum creatinine and the estimated glomerular filtration rate by the modification of diet in renal disease formula at 1, 3, 5 and 8 years did not differ significantly between ABOi and ABOc group. None of the patients in the ABOi group developed acute or chronic antibody-mediated rejection evidenced by histological signs. Four patients (13.3%) in the ABOi group and 3 (10%) in the ABOc group experienced acute cellular rejection, which was treated successfully in all cases. Bacterial and viral infections were also similar between the two groups.

CONCLUSION: ABOi kidney transplantation is a safe and effective alternative that enables kidney transplantation in countries with unacceptably long deceased-donor waiting lists.

Immunoadsorption and hemodialysis as a tandem procedure: a single-center experience of more than 60 procedures

PURPOSE

We have designed a desensitization program that gives good results and is cost effective for kidney-transplant patients who have a potential living donor, who are ABO incompatible (ABOi), and who may or may not have donor-specific alloantibodies (DSAs).

METHODS

Desensitization at pretransplant is based on immunosuppressants (such as rituximab, tacrolimus, and mycophenolic acid) and apheresis to retrieve potentially detrimental isoagglutinins and DSAs from blood. In 2011, we implemented immunoadsorption (IA) instead of plasmapheresis in our center as part of the desensitization protocol. Because IA is very tedious and time-consuming, we decided to perform IA and hemodialysis (HD) in tandem instead of performing these methods sequentially. Herein, we report on more than 100 of these tandem procedures and compare the results to those obtained when IA was performed before a HD session.

RESULTS

The tandem process resulted in nursing time being cut by half: from almost 10h30 min/patient to 6 h/patient. When IA was performed alone, body-weight gain was 1 kg (range 0 to 1.75) and the median volume of plasma treated per session was 6500 mL (range 4500 to 10 600). Conversely, during a tandem IA + HD session, the net median weight gain was -1.5 kg (range -4.1 to 0) and the median volume of plasma treated per session was 5000 mL (range 4000 to 8600). In addition, the tandem procedure was as well tolerated as that for IA followed by HD.

CONCLUSIONS

Tandem IA plus HD is a safe and cost-effective procedure.

Evaluation of renal transplantations performed in the Transplantation Center at Sanko University Medical School

INTRODUCTION

Renal transplantation is the optimum treatment to improve the quality and length of life in end-stage renal disease. The aim of this study is to evaluate patients who underwent renal transplantation in our transplantation center and to present our clinical experience.

METHODS

Living donor and cadaveric renal transplants performed in the Transplantation Center of Sanko University Medical School between 2011 and 2014 were evaluated retrospectively. In our study, important parameters, such as delayed graft function, early and late phase infections and urologic complications after the operation, results of renal transplants with marginal donors with high creatinine levels, and increase in posttransplant body mass index were evaluated regarding to the living donor and cadaveric renal transplants performed in our transplantation center.

RESULTS

We included 136 patients were (92 males [68%] and 44 females [32%]), with an average age of 38.9 ± 9.8 years (range, 17-67). There were 63 living donor renal transplantations (43%) and 73 cadaveric renal transplantations (57%). The youngest cadaveric donor was 3 years old, and the oldest was 86. Fifteen of the cadaveric donors had blood creatinine levels around 1.5 g/dL. The highest level of creatinine from cadaveric donors was 5.1 g/dL.

CONCLUSIONS

Living donor renal transplantations have higher success rate than cadaveric renal transplantations. Ureteroneocystostomy and native ureteropyelostomy seem to be safe and efficient treatment methods for ureteral complications. High creatinine levels in marginal donors do not affect graft function in early stages.

Toward Efficient Enzymes for the Generation of Universal Blood through Structure-Guided Directed Evolution

Blood transfusions are critically important in many medical procedures, but the presence of antigens on red blood cells (RBCs, erythrocytes) means that careful blood-typing must be carried out prior to transfusion to avoid adverse and sometimes fatal reactions following transfusion. Enzymatic removal of the terminal N-acetylgalactosamine or galactose of A- or B-antigens, respectively, yields universal O-type blood, but is inefficient. Starting with the family 98 glycoside hydrolase from Streptococcus pneumoniae SP3-BS71 (Sp3GH98), which cleaves the entire terminal trisaccharide antigenic determinants of both A- and B-antigens from some of the linkages on RBC surface glycans, through several rounds of evolution, we developed variants with vastly improved activity toward some of the linkages that are resistant to cleavage by the wild-type enzyme. The resulting enzyme effects more complete removal of blood group antigens from cell surfaces, demonstrating the potential for engineering enzymes to generate antigen-null blood from donors of various types.

Complement Interception Across Humoral Incompatibility in Solid Organ Transplantation: A Clinical Perspective

The humoral barrier in transplant biology is the result of preformed donor-specific antibodies (DSAs), directed either against human leukocyte antigens (HLA) or non-HLA antigens such as blood group (ABO) molecules. The term "sensitization" applies to patients carrying these antibodies. Transplantation is widely accepted as a life-saving opportunity for patients with terminal end-organ disease. However, in sensitized patients, transplant outcome is hampered by antibody-mediated rejection (AMR) as a consequence of DSA exposure. Furthermore, sensitized patients have limited access to "matched" organs from the both living and deceased donor pool.Considering the crucial role of the complement system in the pathophysiology of AMR and the availability of complement intervention therapeutics, there is a growing interest in complement-targeting strategies. This review highlights the emerging importance of monitoring and modulation of the complement system in the context of enabling transplantation across humoral incompatibility in sensitized recipients with preformed anti-HLA or natural anti-ABO antibodies. It also discusses the significance of the complement system in the induction of accommodation and further emphasizes current and future perspectives of novel complement therapeutics.

An update on ABO-incompatible kidney transplantation

ABO-incompatible kidney transplantation is nowadays a well-established procedure to expand living donor transplantation to blood group incompatible donor/recipient constellations. In the last two decades, transplantation protocols evolved to more specific isohaemagglutinin elimination techniques and established competent antirejection protection protocols without the need of splenectomy. ABOi kidney transplantation associated accommodation despite isohaemagglutinin reappearance, C4d positivity of peritubular capillaries as well as the increased incidence of bleeding complications is currently under intense investigation. However, most recent data show excellent graft survival rates equivalent to ABO-compatible kidney transplantation outcome.

Strategies to increase the donor pool and access to kidney transplantation: an international perspective

In this position article, DESCARTES (Developing Education Science and Care for Renal Transplantation in European States) board members describe the current strategies aimed at expanding living and deceased donor kidney pools. The article focuses on the recent progress in desensitization and kidney paired exchange programmes and on the expanded criteria for the use of donor kidneys and organs from donors after circulatory death. It also highlights differences in policies and practices across different regions with special regard to European Union countries. Living donor kidney paired exchange, the deceased donor Acceptable Mismatch Programme and kidneys from donors after circulatory death are probably the most promising innovations for expanding kidney transplantation in Europe over the coming decade. To maximize success, an effort is needed to standardize transplant strategies, policies and legislation across European countries.

Salvage of grafts with vascular thrombosis during live donor renal allotransplantation: a critical analysis of successful outcome

OBJECTIVES

To report a high-volume institution experience with salvage techniques for vascular accidents during live donor renal allotransplantation.

METHODS

Between March 1976 and January 2011, 2208 recipients underwent live donor renal allotransplantation. A retrospective review of recipients with vascular accidents - renal artery thrombosis and renal vein thrombosis - was carried out. Salvage procedures were recorded and their outcomes were assessed.

RESULTS

A total of 23 (1%) vascular accidents occurred, including renal artery thrombosis and renal vein thrombosis in 19 (0.8%) and four (0.18%) recipients, respectively. All renal artery thrombosis patients were treated by open revascularization and the graft was salvaged in 12 patients (63%). Two renal vein thrombosis events were resolved by percutaneous catheter-directed thrombolytic therapy. Of the other two allografts, one was salvaged by thrombectomy and revascularization, and the other was lost. On univariable analysis, older recipients (P = 0.003), pretransplant hypertension (P =  0.001), more human leukocyte antigen mismatches (≥3; P = 0.036), shorter ischemia time (≤45 min; P = 0.004) and longer time to diagnosis (>3.5 days; P = 0.013) were significantly associated with non-salvage of the graft after vascular accidents. Nevertheless, none of these variables were significant on the multivariable analysis. Over a median follow up of 35 months, the median (range) serum creatinine was 2 mg/dL (range 0.8-8.8 mg/dL), and 11 (79%) recipients were living with functioning grafts.

CONCLUSIONS

Despite the devastating complications, vascular accidents are salvageable and revascularization is crucial for graft salvage. Angiographic percutaneous techniques are viable alternatives for renal vein thrombosis.

Transplantation: rituximab induction only for sensitized kidney recipients?

In contrast to earlier studies that showed a beneficial influence of rituximab on HLA antibody production after kidney transplantation, a recent report by Ashimine et al. questions such an effect. That previous studies included presensitized patients who are more prone to antibody development, might explain this controversy.