Clinical Kidney Transplantation Research Articles

Lifestyle, Inflammation, and Vascular Calcification in Kidney Transplant Recipients: Perspectives on Long-Term Outcomes.

After decades of pioneering and improvement, kidney transplantation is now the renal replacement therapy of choice for most patients with end-stage kidney disease (ESKD). Where focus has traditionally been on surgical techniques and immunosuppressive treatment with prevention of rejection and infection in relation to short-term outcomes, nowadays, so many people are long-living with a transplanted kidney that lifestyle, including diet and exposure to toxic contaminants, also becomes of importance for the kidney transplantation field. Beyond hazards of immunological nature, a systematic assessment of potentially modifiable—yet rather overlooked—risk factors for late graft failure and excess cardiovascular risk may reveal novel targets for clinical intervention to optimize long-term health and downturn current rates of premature death of kidney transplant recipients (KTR). It should also be realized that while kidney transplantation aims to restore kidney function, it incompletely mitigates mechanisms of disease such as chronic low-grade inflammation with persistent redox imbalance and deregulated mineral and bone metabolism. While the vicious circle between inflammation and oxidative stress as common final pathway of a multitude of insults plays an established pathological role in native chronic kidney disease, its characterization post-kidney transplant remains less than satisfactory. Next to chronic inflammatory status, markedly accelerated vascular calcification persists after kidney transplantation and is likewise suggested a major independent mechanism, whose mitigation may counterbalance the excess risk of cardiovascular disease post-kidney transplant. Hereby, we first discuss modifiable dietary elements and toxic environmental contaminants that may explain increased risk of cardiovascular mortality and late graft failure in KTR. Next, we specify laboratory and clinical readouts, with a postulated role within persisting mechanisms of disease post-kidney transplantation (i.e., inflammation and redox imbalance and vascular calcification), as potential non-traditional risk factors for adverse long-term outcomes in KTR. Reflection on these current research opportunities is warranted among the research and clinical kidney transplantation community.

P130 Enhancing the clinical management kidney transplant patients presenting with unknown donor hla typing by a modified urine typing technology

P130 Enhancing the clinical management kidney transplant patients presenting with unknown donor hla typing by a modified urine typing technology

Graft Neutrophil Sequestration and Concomitant Tissue Plasminogen Activator Release During Reperfusion in Clinical Kidney Transplantation

BackgroundInflammation, coagulation, and fibrinolysis are tightly linked together. Reperfusion after transient ischemia activates both neutrophils, coagulation, and fibrinolysis. Experimental data suggest that tissue plasminogen activator (tPA) regulates renal neutrophil influx in kidney ischemia and reperfusion injury. MethodsIn 30 patients undergoing kidney transplantation, we measured renal neutrophil sequestration and tPA release from blood samples drawn from the supplying artery and renal vein early after reperfusion. tPA antigen levels were measured using a commercial enzyme-linked immunosorbent assay kit. For each parameter, transrenal difference (Δ) was calculated by subtracting the value of the arterial sample (ingoing blood) from the value of the venous sample (outgoing blood). ResultsPositive transrenal gradients of tPA antigen occurred at 1 minute [Δ = 14 (3–46) ng/mL, P < .01] and 5 minutes [Δ = 5 (-3 to 27) ng/mL, P < .01] after reperfusion. At 5 minutes after reperfusion, a negative transrenal gradient of neutrophils was observed [Δ = -0.17 (-1.45 to 0.24) x 10E9 cells/L, P < .001]. At 1 minute after reperfusion, neutrophil sequestration into the kidney (ie, negative transrenal neutrophil count) correlated significantly with tPA release from the kidney (ie, positive transrenal tPA concentration), (R = -0.513 and P = .006). ConclusionsThe findings suggest a proinflammatory role for tPA in ischemia and reperfusion injury in human kidney transplantation.

Experimental Rat Model for Brain Death Induction and Kidney Transplantation

Background: Experimental animal research has been pivotal in developing clinical kidney transplantation (KTx). One donor-associated risk factor with negative affect of transplantation outcome is brain death (BD). Many rat models for BD and KTx have been developed in the last decade, but no surgical guidelines have been developed for these models. Here, we describe a surgical technique for BD induction and the cuff technique for experimental KTx in rats.Methods: After intubation and mechanically ventilation of sixteen healthy adult male Sprague–Dawley rats were induction of BD performed. Animals were kept hemodynamically stable for eight hours. Then, the kidney was prepared and perfused with standard histidine–tryptophan–ketoglutarate solution. After explantation, grafts were immediately implanted in recipients using the cuff technique and reperfused. After 2 h of observation, animals were sacrificed by intravenous administration of potassium chloride.Results: In the early phase of BD, heart rate increased and mean arterial pressure decreased. Partial variations were observed in O2 partial pressure, O2 saturation, and HCO3. During the 2-h observation phase, all transplanted kidneys were sufficiently perfused macroscopically. There was no hyperacute rejection.Conclusions: It is feasible to observe BD for 8 h with maintained circulation in small experimental settings. The cuff technique for KTx is simple, the complication rate is low, and the warm ischemia time is short, therefore, this could be a suitable technique for KTx in the rat model.

Post‐transplant immunoglobulin A deposition and nephropathy in allografts

Post-transplant immunoglobulin A (IgA) nephropathy (IgAN) in the allograft is the major cause of allograft loss. Using a protocol biopsy, latent mesangial IgA deposition (IgAD) can be detected in the allograft. Latent IgAD is distinguished from IgAN by the absence of urinary abnormalities, although IgA is observed in the mesangium. However, the pathophysiology and most appropriate treatment strategy for latent mesangial IgAD in the allograft remain to be fully determined. Importantly, it is unknown whether all cases of post-transplant asymptomatic IgAD progress to symptomatic IgAN; indeed, IgA deposits disappear in some cases. The differences in allograft prognosis between asymptomatic IgAD and IgAN have also not been determined. Non-invasive methods of diagnosis of IgAD in the allograft using serological and pathological biomarkers are being developed. Possible serum biomarkers include serum galactose-deficient IgA1 (Gd-IgA1), Gd-IgA1-specific IgG and Gd-IgA1-specific IgA, and its immune complexes. Immunofluorescence analysis using Gd-IgA1 monoclonal antibody may provide a pathological biomarker. These serological and pathological biomarkers may be suitable for the characterization of the stage of IgAD. However, there is insufficient information regarding whether serological and pathological biomarkers can predict the progression of asymptomatic IgAD to symptomatic IgAN. We propose that the pathogenesis of IgAN can be defined through the clinical study of IgAD in the allograft using protocol biopsies conducted by nephrologists involved in clinical kidney transplantation.

Integration of a Massive Open Online Course on Clinical Kidney, Pancreas and Islet Transplantation into a Regular Medical Science Curriculum

Integration of a Massive Open Online Course on Clinical Kidney, Pancreas and Islet Transplantation into a Regular Medical Science Curriculum

Application of Ileobladder for Clinical Kidney Transplantation

Application of Ileobladder for Clinical Kidney Transplantation

Refinement of humoral immune monitoring in kidney transplantation: the role of "hidden" alloreactive memory B cells.

The advent of novel sensitive assays assessing circulating anti-human leukocyte antigen (HLA) antibodies has allowed recognizing humoral alloimmunity as the main immune-mediated mechanism responsible for allograft rejection and graft loss in kidney transplantation. However, current immune-monitoring techniques, exclusively focusing on circulating anti-HLA antibodies, may underestimate the magnitude of humoral immune response as they exclude the memory B-cell (mBC) pool. Different biological compartments are involved in the intricate mechanisms triggering humoral alloimmune responses even in absence of detectable circulating alloantibodies. Recent studies in animal models as well as in clinical kidney transplantation have shown the key role of this B-cell subset triggering allograft rejection, thus emphasizing the value of recognizing antidonor mBC both as a biomarker of allosensitization and as therapeutic targets. Therefore, considerable efforts are being made among the transplant research community to better understand the role, hierarchy, and impact of mBC in the context of organ transplantation. In this review article, we provide a deep insight into the biology of mBC as well as main evidence of their role orchestrating allograft rejection. Also, we provide a thorough description of main immune-monitoring tools aiming at tracking mBC and a rational for their potential use to refine current humoral immune-risk assessment in kidney transplantation.

The modern strategies for working out of transplant tolerance by using blood and bone marrow cells

This review presents analysis of the modern state of transplant tolerance forming problem in recipient organism by using stem/ progenitory cells of bone marrow (BM) and differentiated immunoregulatory (tolerogenic) subsets of blood cells-regulatory B- and T-lymphocytes (Treg), and regulatory dendritic cells (DCreg). It is pointed out that protocols based on the using BM cells, permit to work out the tolerance state and now they are estimate at clinical kidney transplantation, during multicentre investigations. Protocols, based on the using of Treg and DCreg, do note gain the impression of reliable, although at the application of their cells the tolerogenic effect can be obtain. It was given supposition that at using BM cells the forming of steady transplant tolerance state is a result of successive entering of central (thymical induction of temporary mixed chimer-ism) and peripheral tolerance mechanisms. Treg and DCreg induce mechanisms only peripheral tolerance. Combined application of BM cells and Treg permits to increase the terms for maintaining of donor chimerism into all cell lines (incuding Tcells) and transplant tolerance in recipient organism.

Complement Alternative Pathway Deficiency in Recipients Protects Kidney Allograft From Ischemia/Reperfusion Injury and Alloreactive T Cell Response.

Despite the introduction of novel and more targeted immunosuppressive drugs, the long-term survival of kidney transplants has not improved satisfactorily. Early antigen-independent intragraft inflammation plays a critical role in the initiation of the alloimmune response and impacts long-term graft function. Complement activation is a key player both in ischemia/reperfusion injury (IRI) as well as in adaptive antigraft immune response after kidney transplantation. Since the alternative pathway (AP) amplifies complement activation regardless of the initiation pathways and renal IR injured cells undergo uncontrolled complement activation, we speculated whether selective blockade of AP could be a strategy for prolonging kidney graft survival. Here we showed that Balb/c kidneys transplanted in factor b deficient C57 mice underwent reduced IRI and diminished T cell-mediated rejection. In in vitro studies, we found that fb deficiency in T cells and dendritic cells conferred intrinsic impaired alloreactive/allostimulatory functions, respectively, both in direct and indirect pathways of alloantigen presentation. By administering anti-fB antibody to C57 wt recipients in the early post Balb/c kidney transplant phases, we documented that inhibition of AP during both ischemia/reperfusion and early adaptive immune response is necessary for prolonging graft survival. These findings may have implication for the use of AP inhibitors in clinical kidney transplantation.

Cell therapeutic approaches to immunosuppression after clinical kidney transplantation.

Refinement of immunosuppressive strategies has led to further improvement of kidney graft survival in recent years. Currently, the main limitations to long-term graft survival are life-threatening side effects of immunosuppression and chronic allograft injury, emphasizing the need for innovative immunosuppressive regimens that resolve this therapeutic dilemma. Several cell therapeutic approaches to immunosuppression and donor-specific unresponsiveness have been tested in early phase I and phase II clinical trials in kidney transplantation. The aim of this overview is to summarize current cell therapeutic approaches to immunosuppression in clinical kidney transplantation with a focus on myeloid suppressor cell therapy by mitomycin C-induced cells (MICs). MICs show great promise as a therapeutic agent to achieve the rapid and durable establishment of donor-unresponsiveness in living-donor kidney transplantation. Cell-based therapeutic approaches may eventually revolutionize immunosuppression in kidney transplantation in the near future.

A Clinical Trial Aiming at Tolerance Induction by Adoptive Transfer of Ex Vivo-Induced, Donor-Specific Treg-Like Cells in Clinical Kidney Transplantation

A Clinical Trial Aiming at Tolerance Induction by Adoptive Transfer of Ex Vivo-Induced, Donor-Specific Treg-Like Cells in Clinical Kidney Transplantation

Mesenchymal stromal cells in clinical kidney transplantation

Progress in the improvement of short-term and long-term outcomes of kidney transplantation seems to have reached a plateau, partially due to consequences of very efficient, but nonspecific immunosuppressive drugs. In recent years, various forms of cell therapy, including the use of mesenchymal stromal cells, have been put forward as an alternative strategy for more defined therapy. It is thought that these therapies will not only allow controlled tapering of immunosuppressive medication, but might bring us also closer to the ambition of generating donor-specific immune regulation and tolerance. Different forms of alloimmunity, including direct, indirect and semi-direct alloantigen presentation have to be controlled before donor-specific immune regulation can be reached. Several mechanisms have been described how mesenchymal stromal cells can affect alloimmunity. Especially, the interaction with professional antigen presenting cells, like dendritic cells, is of critical importance. This review will discuss the current status of ongoing clinical trials with mesenchymal stromal cells in kidney transplantation and specifically concentrate on the possibilities and impossibilities of how these therapeutic strategies can contribute to control of the different forms of alloreactivity operation in organ transplantation.

Pathophysiological Trends During Withdrawal of Life Support: Implications for Organ Donation After Circulatory Death.

Donation after circulatory death (DCD) provides an alternative pathway to deceased organ transplantation. Although clinical DCD lung, liver, and kidney transplantation are well established, transplantation of hearts retrieved from DCD donors has reached clinical translation only recently. Progress has been limited by concern regarding the viability of DCD hearts. The aim of this study was to document the pathophysiological changes that occur in the heart and circulation during withdrawal of life (WLS) support. In a porcine asphyxia model, we characterized the hemodynamic, volumetric, metabolic, biochemical, and endocrine changes after WLS for up to 40 minutes. Times to circulatory arrest and electrical asystole were recorded. After WLS, there was rapid onset of profound hypoxemia resulting in acute pulmonary hypertension and right ventricular distension. Concurrently, progressive systemic hypotension occurred with a fall in left atrial pressure and little change in left ventricular volume. Mean times to circulatory arrest and electrical asystole were 8 ± 1 and 16 ± 2 minutes, respectively. Hemodynamic changes were accompanied by a rapid fall in pH, and rise in blood lactate, troponin-T, and potassium. Plasma noradrenaline and adrenaline levels rose rapidly with dramatic increases in coronary sinus levels indicative of myocardial release. These findings provide insight into the nature and tempo of the damaging events that occur in the heart and in particular the right ventricle during WLS, and give an indication of the limited timeframe for the implementation of potential postmortem interventions that could be applied to improve organ viability.

Innovations in Clinical Kidney Transplant Education by a Massive Open Online Course

Innovations in Clinical Kidney Transplant Education by a Massive Open Online Course

Innovating clinical kidney transplant education by a massive open online course

Innovating clinical kidney transplant education by a massive open online course

Dynamic changes of B-cell compartments in kidney transplantation: lack of transitional B cells is associated with allograft rejection.

B cells play an important role in the immune responses which affect the outcomes of kidney allografts. Dynamic changes of B-cell compartments in clinical kidney transplantation are still poorly understood. B-cell subsets were prospectively monitored using flow cytometry for 1 year in 98 kidney transplant recipients. Data were correlated with immunosuppression and clinical outcomes. An increase in the total population of B lymphocytes was observed during the first week after transplantation. The level of IgM(high) CD38(high) CD24(high) transitional B cells reduced significantly up until the third month, with partial repopulation in the first year. Lower numbers of transitional B cells in the third month were associated with higher risk of graft rejection. IgM(+) IgD(+) CD27(-) naive B cells did not change within follow-up. IgM(+) CD27(+) nonswitched memory B cells and IgM(-) CD27(+) switched memory B cells increased on post-operative day 7. IgM(-) CD38(high) CD27(high) plasmablasts showed similar kinetics during the first post-transplant year, similar to transitional B cells. In conclusion, sensitized kidney transplant recipients as well as those with either acute or chronic rejection within the first post-transplant year exhibited lower levels of transitional B cells. Therefore, these data further support the hypothesis that transitional B cells have a protective role in kidney transplantation.

Oral Platelet-Derived Growth Factor and Vascular Endothelial Growth Factor Inhibitor Sunitinib Prevents Chronic Allograft Injury in Experimental Kidney Transplantation Model.

Expression of both platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) is increased during the development of chronic rejection which remains the major reason for late allograft loss in clinical kidney transplantation. Sunitinib is a tyrosine kinase inhibitor which inhibits both VEGF and PDGF receptors. Here we investigated its effect on the development of chronic rejection. Rat aortic denudation model was used to define sunitinib dose. In vitro studies were done to investigate the effect of sunitinib on smooth muscle cell proliferation and migration. Kidney transplantations were performed from dark agouti rat strain (DA) to Wistar furth rat strain rats and syngenic DA-DA grafts were used as controls. Allografts were immunosuppressed either with cyclosporine or with cyclosporine and sunitinib. Grafts were harvested at 5 and 90 days for histology and immunohistochemistry. Serum creatinine levels were measured weekly to monitor graft function. Sunitinib decreased neointimal formation and smooth muscle cell proliferation and migration in a dose-dependent manner. Sunitinib was well tolerated and almost completely prevented chronic rejection changes and preserved significantly better renal graft function after transplantation. Sunitinib also inhibited chronic PDGF-A and -B and VEGF-A and -B expressions. These results demonstrate that combined inhibition of PGDF and VEGF with sunitinib prevents chronic rejection changes in experimental kidney transplantation which indicates that sunitinib could be a potential intervention also in clinical kidney transplantation.

Clinical trials for induction of renal allograft tolerance.

This review summarizes the current state of clinical trials for tolerance induction of human leukocyte antigen-matched or mismatched renal allografts via peritransplant infusion of donor bone marrow-derived products. Recent efforts to apply infusion of expanded regulatory T-cell preparations to minimize immunosuppressive dosages are also reviewed. Three centers in the United States have reported clinical trials for tolerance induction in recipients of living donor kidney transplants via donor hematopoietic stem cell transplantation. They have observed varying degrees of successful renal allograft tolerance induction following the establishment of either transient or persistent donor chimerism.A more recent clinical trial planned to evaluate administration of regulatory T cells to harness the immune response has recently been initiated in eight centers in Europe and the United States. Tolerance induction in clinical kidney transplantation from live donors has been achieved by donor hematopoietic stem cell transplantation. Improving the consistency and safety of tolerance induction and extending successful protocols to other organs, as well as to organs from deceased donors, are critical next steps to bringing tolerance to a wider range of clinical applications.

Organ-specific differences in achieving tolerance.

When it comes to tolerance induction, kidney allografts behave differently from heart allografts that behave differently from lung allografts. Here, we examine how and why different organ allografts respond differently to the same tolerance induction protocol. Allograft tolerance has been achieved in experimental and clinical kidney transplantation. Inducing tolerance in experimental recipients of heart and lung allografts has, however, proven to be more challenging. New protocols being developed in nonhuman primates based on mixed chimerism and cotransplantation of tolerogenic organs may provide mechanistic insights to help overcome these challenges. Tolerance induction protocols that are successful in patients transplanted with 'tolerance-prone' organs such as kidneys and livers will most likely not succeed in recipients of 'tolerance-resistant' organs such as hearts and lungs. Separate clinical trials using more robust tolerance protocols will be required to achieve tolerance in heart and lung recipients.