Longitudinal mortality risks and kidney functional outcomes in Japanese living kidney donors.

OBJECTIVES: Previous studies suggested that living kidney donors do not have a higher risk of death or kidney failure than the general population. However, living kidney donor risk is controversial. Furthermore, only a few studies have evaluated long-term kidney function after kidney donation. METHODS: This study evaluated Japanese kidney donor' long-term outcomes, including mortality and kidney function. From 1965 to 2015, 230 donors (76 males, 154 females, and a median age of 54) were enrolled in this study. The median observation period was 11.0 (range, 0.3-41.0) years. RESULTS: In total, 215 donors were still alive, and 15 had died. Causes of death included malignancies, cardiovascular disease, pneumonia, suicide, gastrointestinal bleeding, and kidney failure. Actual donor survival rates at 10, 20, and 30 years were 95.3%, 90.7%, and 80.9%, respectively. These values were comparable to age- and gender-matched expected survival. Long-term kidney function after donation was evaluated in 211 donors with serum creatinine data. Two donors developed kidney failure 24 and 26 years post-donation, respectively. The percentage of donors whose estimated glomerular filtration rate (eGFR) remained ≥45 mL/min/1.73 m2 at 10, 20, and 30 years after donation were 84.2%, 73.0%, and 63.9%, respectively. Survival rates of donors with eGFR <45 mL/min/1.73 m2 were comparable to those in persons with eGFR >45 mL/min/1.73 m2. CONCLUSION: Our findings revealed that kidney donors did not have a higher long-term risk of death than the general population. Although some donors showed decreased kidney function after donation, kidney function did not impact their survival.

Kidney donor age of 50 years or above is a risk factor for calcineurin inhibitor-induced nephrotoxicity.

INTRODUCTION: Calcineurin inhibitor (CNI)-induced nephrotoxicity (CNI-T) is a post-transplantation complication that leads to graft dysfunction. Older-donor kidney grafts may be susceptible to chronic CNI exposure because of long-term arteriolar damage. The primary aim of this study was to examine the CNI-T incidence and time-course changes in the graft function according to donor age. METHODS: We included 334 kidney transplant recipients. CNI-T was defined by Banff arteriolar hyaline thickening scores of ≥2 based on allograft protocol biopsy. Depending on donor age, participants were divided into the D > 70 (≥70 years), D60 (60-69 years), D50 (50-59 years), and D < 49: (≤49 years) groups. We investigated the extent to which CNI-T affected the transplanted kidney function. Patients who did not develop CNI-T during the study period were included in the non-CNI-T group; the remaining were grouped into the CNI-T group. RESULTS: The CNI-T incidence was higher in donors aged >50 years. Compared to D < 49, the CNI-T risk was 1.86 times higher in D50 and 2.9 times higher in D > 70. Furthermore, the CNI-T group exhibited a significantly lower graft function 10 years after transplantation. CONCLUSION: CNI-T incidence increases in donors aged ≥50 years and affects renal function after 10 years.

Low dose tacrolimus exposure and early steroid withdrawal with strict body weight control can improve post kidney transplant glucose tolerance in Japanese patients.

The development of diabetes mellitus (DM) after living donor kidney transplantation (KT) is a risk factor for worsening transplant kidney function, cardiac disease, and cerebrovascular disease, which may affect prognosis after KT. At our institution, all patients' glucose tolerance is evaluated perioperatively by oral glucose tolerance tests (OGTTs) at pre-KT, and 3, 6, and 12 month (mo.) after KT. We analyzed the insulinogenic index (ISI) and homeostasis model assessment beta cell (HOMA-ß) based on the immunoreactive insulin (IRI) levels to determine how glucose tolerance changed after KT in 214 patients who had not been diagnosed with DM before KT. In addition, we analyzed the body mass index (BMI) which may also influence glucose tolerance after KT. The concentration of tacrolimus (TAC) in blood was also measured as the area under the curve (AUC) to examine its effects at each sampling point. The preoperative-OGTTs showed that DM was newly diagnosed in 22 of 214 patients (10.3%) who had not been given a diagnosis of DM by the pre-KT fasting blood sugar (FBS) tests. The glucose tolerance was improved in 15 of 22 DM patients at 12 mo. after KT. ISI and IRI deteriorated only at 3 mo. after KT but improved over time. There was a trend of an inverse correlation between HOMA-ß and TAC-AUC. We also found inverse correlations between IRI and an increase in BMI from 3 to 12 mo. after KT. Early corticosteroid withdrawal or the steroid minimization protocol with tacrolimus to maintain a low level of diabetogenic tacrolimus and BMI decrease after KT used by our hospital individualizes lifestyle interventions for each patient might contribute to an improvement in post-KT glucose tolerance.

Mechanism and treatment for chronic antibody-mediated rejection in kidney transplant recipients.

Chronic antibody-mediated rejection of kidney transplantation is a major cause of late-stage graft loss. Donor-specific antibodies are the main cause of antibody-mediated rejection; in particular, de novo donor-specific antibodies are a risk factor for chronic active antibody-mediated rejection. The level of de novo donor-specific antibodies tends to increase with time throughout long-term graft survival. Donor-specific antibodies induce humoral rejection through complement activation, which results in tissue injury and coagulation. Additionally, complement activation promotes the migration of inflammatory cells through the innate immune response, causing endothelial injury. This inflammatory response may cause persistent glomerulitis and peritubular capillaritis, leading to fixed pathological lesions that impair graft function. No treatment has been established for chronic antibody-mediated rejection, a condition in which antibody-mediated rejection becomes irreversible. Thus, antibody-mediated rejection must be detected and treated while it is still reversible. In this review, we discuss the development of de novo donor-specific antibodies and the mechanisms leading to chronic antibody-mediated rejection and summarize the current treatment options and the latest biomarkers for detecting chronic antibody-mediated rejection at an earlier stage.

Exacerbation of Intimal Fibrosis and Endarteritis in a Kidney Transplant Recipient with Chronic Active Antibody-Mediated Rejection and COVID-19: A Case Report.

Kidney transplant recipients are immunocompromised hosts at risk for comorbidity and mortality due to infection. Currently, there are no established guidelines for the management of immunosuppressed transplant recipients with coronavirus disease 2019 (COVID-19). The impact of COVID-19 and its therapeutic management on chronic active antibody-mediated rejection (CAAMR) are still unclear. Here, we report a case of CAAMR exacerbation with endarteritis and intimal fibrosis after COVID-19. A 41-year-old female kidney transplant recipient with CAAMR was admitted to a local hospital with moderately severe COVID-19. Her doses of tacrolimus and mycophenolate mofetil were reduced, and she was administered methylprednisolone pulse and antiviral drugs. This resulted in a good clinical course and she was discharged in 15 days. During and after hospitalization, the immunosuppressants were gradually returned to the baseline levels. However, about 1.5 months after discharge, the serum creatinine level became elevated. An indication kidney biopsy showed CAAMR with intimal fibrosis and endarteritis in all interlobular arteries. An increase of immunosuppressant led to a decrease of the serum creatinine level. Factors contributing to CAAMR with intimal fibrosis and endarteritis may include (1) insufficient immunosuppression due to changes in the levels of immunosuppressive; (2) overlap with endothelial cell injury caused by COVID-19, and (3) an immune-activated state associated with COVID-19. COVID-19 is a life-threatening disease that can result in unexpected changes in immunological status. Possible allograft rejection should be carefully managed in such patients.

Analysis of T-cell alloantigen response via a direct pathway in kidney transplant recipients with donor-specific antibodies.

Donor-specific antibodies (DSAs) are the main cause of graft loss over time. The direct pathway of alloantigen recognition is important in the pathogenesis of acute rejection. Recent studies have suggested that the direct pathway also contributes to the pathogenesis of chronic injury. Nevertheless, there are no reports on T-cell alloantigen response via the direct pathway in kidney recipients with DSAs. We analyzed the T-cell alloantigen response via the direct pathway in kidney recipients with DSAs (DSA+) or without DSAs (DSA-). A mixed lymphocyte reaction assay was implemented to assess the direct pathway response. DSA+ patients showed significantly higher CD8+ and CD4+ T cell responses to donor cells than DSA- patients. Furthermore, proliferating CD4+ T cells showed a marked increase in Th1 and Th17 responses in DSA+ patients than in DSA- patients. In a comparison between anti-donor and third-party responses, the anti-donor CD8+ and CD4+ T cell response was significantly lower than the anti-third-party response. In contrast, the donor-specific hyporesponsiveness was absent in DSA+ patients. Our study demonstrated that DSA+ recipients have a greater potential for developing immune responses against the donor tissues via the direct alloantigen recognition pathway. These data contribute to an understanding of DSAs pathogenicity during kidney transplantation.

Use of Mixed Lymphocyte Reaction Assay to Evaluate Immune Tolerance before Kidney Transplantation with an Immunosuppression-Free Protocol following Hematopoietic Stem Cell Transplantation from the Same Donor.

Several cases of kidney transplantation after hematopoietic stem cell transplantation (HSCT) from the same donor for end-stage renal disease have been reported. In those cases, immunosuppressive drugs were discontinued since immune tolerance was supposed to be induced. Theoretically, the recipient's immune system recognizes the kidney allograft as its own tissue with the same human leukocyte antigen (HLA) profile, and the kidney allograft will not be rejected, even without the use of immunosuppressive agents. However, almost all recipients receive immunosuppressants in the early stages after kidney transplantation owing to concerns of acute rejection. Here, we report a successful case of post-HSCT kidney transplantation without the use of immunosuppressive drugs, in which a mixed lymphocyte reaction (MLR) assay was used to evaluate immune tolerance before kidney transplantation. The patient was a 25-year-old woman. Five years prior, she developed acute myeloid leukemia and underwent HLA-half-matched peripheral blood stem cell transplantation. Thereafter, she was in remission of the acute myeloid leukemia, but 1 year later, she developed renal graft-versus-host disease. Subsequently, the patient's renal function gradually deteriorated to end-stage renal failure, and she underwent kidney transplantation with the previous stem cell donor: her mother. HLA typing of donor and recipient showed a complete chimerism in the peripheral blood. The pretransplantation complement-dependent cytotoxic crossmatch and flow cytometric T-cell crossmatch results were both negative, and HLA antibody measurements were all negative. The MLR assay revealed no T-lymphocyte reaction to the donor; therefore, immunosuppressants were not used. Two years after transplantation, the patient's serum creatinine concentration was around 0.8 mg/dL (down from 4 mg/dL before transplantation). No abnormalities were observed in a renal biopsy performed after 3 months. Our study, along with others, indicates that immune tolerance to a donor develops in post-HSCT kidney transplantation from the same donor.

Comparison of Humoral Response in Kidney Transplant Recipients and Donors and Healthy Volunteers Following Second Dose of SARS-CoV-2 mRNA Vaccine.

PURPOSE: To investigate the kinetics and durability of anti-spike glycoprotein (S) immunoglobulin G (IgG) after the second dose of mRNA-based SARS-CoV-2 vaccine in kidney transplant recipients (recipients) compared with those in kidney donors (donors) and healthy volunteers (HVs) and identify factors negatively associated with SARS-CoV-2 vaccine effectiveness in recipients. METHODS: We enrolled 378 recipients with no history of COVID-19 and no anti-S-IgG before the first vaccine and who received a second mRNA-based vaccine dose. Antibodies were detected using an immunoassay more than 4 weeks after the second vaccine dose. Anti-S-IgG <0.8, ≥0.8 to 15, and ≥15 U/mL were considered negative, weak positive, and strongly positive, respectively, whereas anti-nucleocapsid protein IgG was negative. Anti-S-IgG titer was determined in 990 HVs and 102 donors. RESULTS: Anti-S-IgG titers were 154, 2475, and 1181 U/mL in the recipient, HV, and donor groups, respectively, with values significantly lower in recipients. The anti-S-IgG-positivity rate of recipients gradually increased following the second vaccination, suggesting that recipients had a delayed response compared with the HV and donor groups, who had a 100% positivity rate at an earlier time point. Anti-S-IgG titers decreased in donors and HVs, whereas they remained stable in recipients, although at a significantly lower level. Independent negative factors associated with anti-S-IgG titers in recipients were age >60 years and lymphocytopenia (odds ratio: 2.35 and 2.44, respectively). CONCLUSIONS: Kidney transplant recipients demonstrate delayed and attenuated responses, with lower SARS-CoV-2 antibody titers after the second dose of the mRNA-based COVID-19 vaccine.

A Case of Kidney Transplantation from a Deceased Donor with Acute Kidney Injury due to Rhabdomyolysis.

Acute kidney injury (AKI) due to rhabdomyolysis occurs because of renal ischemia or acute tubular necrosis due to the deposition of myoglobin casts in the renal tubules. Donors with AKI due to rhabdomyolysis are not contraindication for transplantation. However, the dark red kidney raises concerns about renal hypofunction or primary nonfunction after transplantation. We report the case of a 34-year-old man with a 15-year history of hemodialysis for chronic renal failure due to congenital anomalies of the kidney and urinary tract. The patient received a renal allograft from a young woman who suffered cardiac death. The serum creatinine (sCre) level of the donor at the time of transport was 0.6 mg/dL, and renal ultrasonography revealed no abnormalities in renal morphology or blood flow. Her serum creatinine kinase level increased to 57,000 IU/L 58 h after femoral artery cannulation and sCre level worsened to 1.4 mg/dL, suggesting AKI due to rhabdomyolysis. However, since the urine output of the donor was maintained, the sCre elevation was thought to be nonproblematic. The allograft had a dark red appearance at the time of procurement. The perfusion of the isolated kidney was good, but the dark red color did not improve. A 0-h biopsy showed flattening of the renal tubular epithelium and absence of the brush border and myoglobin casts in 30% of the renal tubules. Rhabdomyolysis-related tubular damage was diagnosed. Hemodialysis was discontinued on postoperative day 14. Twenty-four days after the operation, the transplanted kidney function progressed favorably (sCre 1.18 mg/dL), and the patient was discharged. Protocol biopsy 1 month after transplantation showed disappearance of myoglobin casts and improvement in renal tubular epithelial damage. The patient's sCre level was approximately 1.0 mg/dL 24 months after transplantation, and he is doing well without complications.

Incidence of post-transplant hepatitis B virus reactivation with the use of kidneys from donors with resolved hepatitis B virus infection.

Donors with resolved hepatitis B virus (HBV) infection may be a solution for the organ shortage for kidney transplantation (KT). The purpose of this study was to clarify the current state of HBV markers after KT from donors with resolved HBV infection to HBV naïve recipients and the rate of HBV reactivation in recipients with resolved HBV infection. Furthermore, we investigated HBV covalently closed circular DNA (cccDNA) in transplanted organs from donors with resolved HBV infection and the capability of HBV replication in kidney cell lines. We retrospectively analysed the HBV status of 340 consecutive donors and recipients who underwent KT in a single centre. We prospectively measured cccDNA by real-time polymerase chain reaction in kidney biopsy specimens of 32 donors with resolved HBV infection. HBV reactivation was found in three recipients with resolved HBV infection (4.8%, 3/63) after KT. We analysed 45 cases of transplantation from donors with resolved HBV infection to HBV-naive recipients. One case (2.2%, 1/45) became seropositive for hepatitis B core antibody (anti-HBc) and in another case (2.2%, 1/45), HBV-DNA was detected qualitatively in an HBV naive recipient with a donor with resolved HBV infection. In the latter case, cccDNA was measured in the donor kidney during KT. HBV replication was observed in kidney cell lines with HBV plasmid transfection. In conclusion, the risk of reactivation in anti-HBc-positive donors is relatively low. However, post-transplant HBV monitoring should be conducted in all at-risk cases.

Vesicoureteral reflux treatment following kidney transplantation potentially prevents graft function deterioration and allows long-term graft survival.

OBJECTIVES: The impact of vesicoureteral reflux post-kidney transplantation on graft survival remains unclear, and guidelines on appropriate vesicoureteral reflux management post-kidney transplantation are lacking. For this reason, we conducted a retrospective study on the impact of vesicoureteral reflux and its treatment on graft survival. METHODS: We evaluated 347 consecutive kidney transplantation recipients, who also underwent a ureteroneocystostomy, between 1996 and 2012. RESULTS: Vesicoureteral reflux was diagnosed in 55 cases (15.9%), with a median post-kidney transplantation duration of 50 months (range 0-172 months). Among these, 22 were monitored, 17 underwent transurethral collagen injections, and 16 received a ureteroneocystostomy. The 10-year graft survival rate was significantly lower in recipients with vesicoureteral reflux (68.9%) than in those without vesicoureteral reflux (84.4%) (P = 0.0165). Moreover, among the vesicoureteral reflux recipients, the 10-year graft survival rate was significantly higher in those whose vesicoureteral reflux was cured (80.1%) than in those whose vesicoureteral reflux persisted (53.6%) (P = 0.0062). Multivariate analysis showed that vesicoureteral reflux was significantly associated with both overall and death-censored graft loss (odds ratio 3.737 and 3.685; P = 0.0015 and P = 0.0052, respectively). Lastly, the incidence of interstitial fibrosis and tubular atrophy was higher in recipients with vesicoureteral reflux than in those without vesicoureteral reflux (P = 0.0009). CONCLUSIONS: Post-kidney transplantation vesicoureteral reflux has a negative impact on long-term graft survival, and that treatment prevents graft deterioration. From the perspective of maintaining long-term graft function in kidney recipients, vesicoureteral reflux may be one of the most important complications to be addressed.

[TREATMENT OF BLADDER UROTHELIAL CARCINOMA WITH LUNG METASTASIS AFTER RENAL TRANSPLANTATION].

We report a case of bladder cancer in a 54-year-old woman who underwent renal transplantation for chronic renal failure. Six years after the transplantation, she was diagnosed with muscle-invasive bladder cancer with multiple lung metastases. She received gemcitabine/cisplatin therapy for Stage IV bladder cancer, and the dose of the immunosuppressants was reduced to prevent adverse effects. Since lung metastatic lesions disappeared after four courses of chemotherapy and no new lesions were found, we performed radical cystectomy and right nephroureterectomy with ileal conduit construction. Although she was followed closely without therapy, multiple lung metastases appeared 6 months after the radical cystectomy. Gemcitabine/carboplatin therapy was administered, and the lung metastasis improved slightly until the end of the 4th course, but aggressive growth was observed after the 5th course. She switched to palliative treatment without requesting additional treatment and died of cancer 1 year and 9 months after total cystectomy.There is no evidence-based treatment strategy for advanced bladder cancer after kidney transplantation. It is necessary to recognize that the patient had renal dysfunction and was in an immunosuppressed state. Thus, it is crucial to select appropriate drug and surgical treatments for each patient.

Long-Term Outcome of ABO-Incompatible Kidney Transplantation in Patients Treated With Low-Dose Rituximab Regimen.

BACKGROUND: Introduction of rituximab in the desensitization protocols for ABO-incompatible (ABOI) kidney transplantation (KTX) has afforded excellent results. However, the acceptability of minimal dosage of rituximab in these protocols remains to be defined. METHODS: Sixty-three patients who underwent ABOI KTX were included in this study. The desensitization protocol consisted of plasmapheresis, tacrolimus, mycophenolate mofetil, methylprednisolone, intravenous immunoglobulin, basiliximab, and low-dose rituximab (100 mg/body). We evaluated the efficacy, safety, and long-term outcome of this protocol (group R, n = 39) and compared them with those of patients who underwent splenectomy (group S, n = 24). RESULTS: Graft and patient survival at 10 years after KTX were comparable between the groups (94.4% [group R] vs 95.4% [group S] and 94.6% [group R] vs 95.8% [group S], respectively). The incidence of acute antibody-mediated rejection (AAMR) was similar in the 2 groups (10.2% vs 12.5%). There were no significant differences in the incidence of chronic active antibody-mediated rejection. Of the patients, 7 developed AAMR and 3 of these patients (1 in group R and 2 in group S) lost their grafts. There were no significant differences in the incidence of chronic active antibody-mediated rejection. The incidence of postoperative cytomegalovirus infection in group R was significantly lower than that in group S. Furthermore, the incidence of postoperative late-onset neutropenia was low in group R. CONCLUSIONS: A low-dose rituximab regimen for ABOI KTX is acceptable for preventing AAMR with a low incidence of delayed adverse events.

Femoral nerve palsy following kidney transplantation: A case report and review of the literature.

INTRODUCTION: Femoral nerve palsy is a rare but serious complication of kidney transplantation. We report a case of femoral nerve palsy following kidney transplantation and conduct a review of the literature on this complication. CASE PRESENTATION: A 35-year-old woman with end-stage kidney disease, underwent kidney transplantation in the right iliac fossa. The day after the transplantation, she could not straighten her right leg. Physical examination revealed a paresis of her right quadriceps muscle. The patient's sensation of her right thigh was also impaired. We diagnosed her with femoral nerve palsy caused by inappropriate compression from a self-retaining retractor. Rehabilitation was started immediately. The patient's motor weakness gradually improved, and the patient became able to walk independently 4 weeks later. However, the patient's neuropathic pain sustained 6 months after her kidney transplantation. CONCLUSION: The improper use of self-retaining retractors can lead to femoral nerve palsy in patients undergoing kidney transplantation.

Increased urinary exosomal SYT17 levels in chronic active antibody-mediated rejection after kidney transplantation via the IL-6 amplifier.

Chronic active antibody-mediated rejection (CAAMR) is a particular problem in kidney transplantation (KTx), and ~25% of grafts are lost by CAAMR. Further, the pathogenesis remains unclear, and there is no effective cure or marker. We previously found that a hyper NFκB-activating mechanism in non-immune cells, called the IL-6 amplifier, is induced by the co-activation of NFκB and STAT3, and that this activation can develop various chronic inflammatory diseases. Here, we show that synaptotagmin-17 (SYT17) is increased in an exosomal fraction of the urine from CAAMR patients, and that this increase is associated with activation of the IL-6 amplifier. Immunohistochemistry showed that SYT17 protein expression was increased in renal tubule cells of the CAAMR group. While SYT17 protein was not detectable in whole-urine samples by western blotting, urinary exosomal SYT17 levels were significantly elevated in the CAAMR group compared to three other histology groups (normal, interstitial fibrosis and tubular atrophy, and calcineurin inhibitors toxicity) after KTx. On the other hand, current clinical laboratory data could not differentiate the CAAMR group from these groups. These data suggest that urinary exosomal SYT17 is a potential diagnostic marker for CAAMR.

Safety and Efficacy of Retroperitoneoscopic Living Donor Nephrectomy: Comparison of Early Complication, Donor and Recipient Outcome with Hand-Assisted Laparoscopic Living Donor Nephrectomy.

INTRODUCTION: Laparoscopic surgery has been a standard procedure of living donor nephrectomy (LDN). Transperitoneal hand-assisted laparoscopic LDN (HALDN) has been commonly reported by many centers with excellent outcome. However, there are few studies reporting retroperitoneoscopic LDN (RPLDN). MATERIALS AND METHODS: Four hundred four consecutive kidney donors (124 men, 280 women) were enrolled in this study. Age of the donors was 55.0 ± 10.7 years. RPLDN was performed for 294 donors, and HALDN for 110 donors. We compared perioperative donor outcome and early complication rates between RPLDN and HALDN to evaluate the safety and efficacy of RPLDN. RESULTS: Intraoperative blood loss was significantly less in RPLDN than in HALDN (p < 0.05). The conversion rate to open surgery was similar between the two groups. The intraoperative complication rate was 1.0% (two vascular injuries and one bowel injury) in RPLDN and 0.9% (one vascular injury) in HALDN. The postoperative complication rate was 3.4% (six surgical site infections, two postoperative bleeding, one colon perforation, one ileus, one rhabdomyolysis) in RPLDN and 1.8% (two surgical site infections) in HALDN. Although warm ischemic time was significantly longer in RPLDN than in HALDN (p < 0.01), the incidence of delayed graft function was similar between the two groups. Furthermore, there was no difference in 1-year graft survival between the two groups. CONCLUSIONS: Both RPLDN and HALDN procedures were well tolerated with minimal complication rates, and both procedures showed similar impact on recipient graft function. These results suggest that RPLDN could be a feasible option for LDN as well as HALDN.

Upregulation of CD80 on glomerular podocytes plays an important role in development of proteinuria following pig-to-baboon xeno-renal transplantation - an experimental study.

We have previously reported that co-transplantation of the kidney with vascularized donor thymus from α-1,3-galactosyltransferase gene knockout pigs with an anti-CD154 with rituximab-based regimen led to improved xenograft survival in baboons with donor-specific unresponsiveness. However, nephrotic syndrome emerged as a complication in which the glomeruli showed mild mesangial expansion with similarities to minimal change disease (MCD) in humans. Since MCD is associated with CD80 expression in glomeruli and elevated urinary excretion, we evaluated a potential role for CD80 in xenograft nephropathy. Study 1 confirmed high urinary CD80 excretion in nephrotic animals with renal xenografts showing CD80 expression in glomeruli. In Study 2, baboons receiving xenografts received CTLA4-Ig once a week from the second postoperative week or no CTLA4-Ig. The non-CTLA4-Ig group developed severe proteinuria with modest mesangial expansion with high urinary excretion of CD80 and documented CD80 expression in glomerular podocytes. All of the recipients in non-CTLA4-Ig groups had to be euthanized before POD 60. In contrast, CTLA4-Ig group showed a marked reduction in proteinuria and survived significantly longer, up to 193 days. These results demonstrate that anti-CD80 targeted therapy represents a promising strategy for reduction of proteinuria following renal xeno-transplantation with improved survival.

Remaining Physiological Barriers in Porcine Kidney Xenotransplantation: Potential Pathways behind Proteinuria as well as Factors Related to Growth Discrepancies following Pig-to-Kidney Xenotransplantation.

Considerable shortages in the supply of available organs continue to plague the field of solid organ transplantation. Despite changes in allocation, as well as the utilization of extended criteria and living donors, the number of patients waiting for organs continues to grow at an alarming pace. Xenotransplantation, cross-species solid organ transplantation, offers one potential solution to this dilemma. Previous extensive research dedicated to this field has allowed for resolution of xenograft failure due to acute rejection, leaving new areas of unresolved challenges as barriers to success in large animal models. Specific to kidney xenotransplantation, recent data seems to indicate that graft compromise can occur due to discrepancies in growth between breeds of donors and significant proteinuria leading to nephrotic syndrome in the recipient. Given these potential limitations, herein, we review potential pathways behind proteinuria, as well as potential causative factors related to growth discrepancies. Control of both of these has the potential to allow xenotransplantation to become clinically applicable in an effort to resolve this organ shortage crisis.