Accurate segmentation of renal tissues is an essential step for renal perfusion estimation and postoperative assessment of the allograft. Images are usually manually labeled, which is tedious and prone to human error. We present an image analysis method for the automatic estimation of renal perfusion based on perfusion magnetic resonance imaging. Specifically, non-contrasted pseudo-continuous arterial spin labeling (PCASL) images are used for kidney transplant evaluation and perfusion estimation, as a biomarker of the status of the allograft. The proposed method uses machine/deep learning tools for the segmentation and classification of renal cortical and medullary tissues and automates the estimation of perfusion values. Data from 16 transplant patients has been used for the experiments. The automatic analysis of differentiated tissues within the kidney, such as cortex and medulla, is performed by employing the time-intensity-curves of non-contrasted T1-weighted MRI series. Specifically, using the Dice similarity coefficient as a figure of merit, results above 93%, 92% and 82% are obtained for whole kidney, cortex, and medulla, respectively. Besides, estimated cortical and medullary perfusion values are considered to be within the acceptable ranges within clinical practice.

Monitoring renal allograft function after transplantation is key for the early detection of allograft impairment, which in turn can contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising noninvasive technique to assess and characterize renal physiopathology; however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period). The purposes of the current study were to evaluate the reproducibility of mpMRI in transplant patients and to characterize normal values of the measured parameters, and to estimate the labeling efficiency of Pseudo-Continuous Arterial Spin Labeling (PCASL) in the infrarenal aorta using numerical simulations considering experimental measurements of aortic blood flow profiles. The subjects were 20 transplant patients with stable kidney function, maintained over 1 year. The MRI protocol consisted of PCASL, intravoxel incoherent motion, and T1 inversion recovery. Phase contrast was used to measure aortic blood flow. Renal blood flow (RBF), diffusion coefficient (D), pseudo-diffusion coefficient (D*), flowing fraction ( f$$ f $$), and T1 maps were calculated and mean values were measured in the cortex and medulla. The labeling efficiency of PCASL was estimated from simulation of Bloch equations. Reproducibility was assessed with the within-subject coefficient of variation, intraclass correlation coefficient, and Bland-Altman analysis. Correlations were evaluated using the Pearson correlation coefficient. The significance level was p less than 0.05. Cortical reproducibility was very good for T1, D, and RBF, moderate for f$$ f $$, and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f$$ f $$ (r = 0.66), RBF and eGFR (r = 0.64), and D* and eGFR (r = -0.57) were found. Normal values of the measured parameters employing the mpMRI protocol in kidney transplant patients with stable function were characterized and the results showed good reproducibility of the techniques.

Regulatory T cells are an important component of an immune response shaping the overall behavior to potential antigens including alloantigens. Multiple mechanisms have been shown to contribute towards developing and sustaining a immunological regulatory response. One of the described contact dependent suppressive mechanisms regulatory cells have been shown to utilize is through the production of adenosine from extracellular ATP mediated by CD39 and CD73. In this study we demonstrate that the adenosinergic pathway plays a major role in the suppressive/regulatory effects antigen specific regulatory T cell enriched lines (ASTRLs) that have been of expanded ex vivo from stable kidney transplant patients. We have previously shown that these ASTRL cells are capable of suppressing alloimmune responses in vitro and significantly prolonging allograft survival in an animal model of kidney transplantation. For this study nineteen ASTRLs were expanded from 17 kidney transplant patients by repeated stimulation of recipient peripheral blood mononuclear cells with donor specific HLA-DR peptides. All 19 ASTRLs showed upregulation of numerous markers associated with regulatory cells and were able to inhibit donor antigen specific T cell proliferation in a dose dependent fashion. ASTRLs suppressed indirect and direct alloimmune responses compatible with our previous animal study findings. Upregulation of both CD39 and CD73 was observed post expansion and ASTRLs demonstrated extracellular hydrolysis of ATP, indicating functionality of the upregulated proteins. We also showed that inhibition of the adenosinergic pathway using inhibitors of CD39 resulted in abrogation of suppression and increased antigen specific T cell proliferation. This demonstrates that the main mechanism of action of the suppressive activity donor peptide driven ASTRLs generated from kidney transplant patients is the adenosinergic pathway. Furthermore this suggests the possibility that combining infusion of Tregs with other treatments, such as adenosine receptor agonists or increasing CD39 expression in the grafts may further enhance a regulatory response to the allograft and possibly achieve transplantation tolerance.

Background. The clinical effectiveness of coronavirus disease 2019 (COVID-19) vaccination in kidney transplant (KT) recipients is lower than in the general population. Methods. From April to October 2021, 481 KT recipients with COVID-19, included in the Spanish Society of Nephrology COVID-19 Registry, were analyzed. Data regarding vaccination status and vaccine type were collected, and outcomes of unvaccinated or partially vaccinated patients (n = 130) were compared with fully vaccinated patients (n = 351). Results. Clinical picture was similar and survival analysis showed no differences between groups: 21.7% of fully vaccinated patients and 20.8% of unvaccinated or partially vaccinated died (P = 0.776). In multivariable analysis, age and pneumonia were independent risk factors for death, whereas vaccination status was not related to mortality. These results remained similar when we excluded patients with partial vaccination, as well as when we analyzed exclusively hospitalized patients. Patients vaccinated with mRNA-1273 (n = 213) showed a significantly lower mortality than those who received the BNT162b2 vaccine (n = 121) (hazard ratio: 0.52; 95% confidence interval, 0.31-0.85; P = 0.010). Conclusions. COVID-19 severity in KT patients has remained high and has not improved despite receiving 2 doses of the mRNA vaccine. The mRNA-1273 vaccine shows higher clinical effectiveness than BNT162b2 in KT recipients with breakthrough infections. Confirmation of these data will require further research taking into account the new variants and the administration of successive vaccine doses.

Coronavirus disease 2019 (COVID-19) in kidney transplant recipients has a high risk of complications and mortality, especially in older recipients diagnosed during the early period after transplantation. Management of immunosuppression has been challenging during the pandemic. We investigated the impact of induction immunosuppression, either basiliximab or thymoglobulin, on the clinical evolution of kidney transplant recipients developing COVID-19 during the early period after transplantation. We included kidney transplant recipients with <6 months with a functioning graft diagnosed with COVID-19 from the initial pandemic outbreak (March 2020) until 31 July 2021 from different Spanish centres participating in a nationwide registry. A total of 127 patients from 17 Spanish centres developed COVID-19 during the first 6 months after transplantation; 73 (57.5%) received basiliximab and 54 (42.5%) thymoglobulin. Demographics were not different between groups but patients receiving thymoglobulin were more sensitized [calculated panel reactive antibodies (cPRAs) 32.7 +/- 40.8% versus 5.6 +/- 18.5%] and were more frequently retransplants (30% versus 4%). Recipients >65 years of age treated with thymoglobulin showed the highest rate of acute respiratory distress syndrome [64.7% versus 37.1% for older recipients receiving thymoglobulin and basiliximab (P < .05), respectively, and 23.7% and 18.9% for young recipients receiving basiliximab and thymoglobulin (P > .05)], respectively, and the poorest survival [mortality rate 64.7% and 42.9% for older recipients treated with thymoglobulin and basiliximab, respectively (P < .05) and 8.1% and 10.5% for young recipients treated with thymoglobulin and basiliximab (P > .05), respectively]. Older recipients treated with thymoglobulin showed the poorest survival in the Cox regression model adjusted for comorbidities. Thus thymoglobulin should be used with caution in older recipients during the present pandemic era.

Cystinosis is a rare autosomal recessive disease leading to end-stage renal disease within the second or third decade of life. Since the era of specific treatment with cysteamine, prognosis has substantially improved and pregnancy becomes an increasing concern. Pregnancy data in patients with cystinosis were collected through an anonymized survey. We collected data for 19 pregnancies in 12 women. Seventeen patients were transplanted, 1 was on hemodialysis and 1 had chronic kidney disease (CKD) stage 4. These 19 pregnancies resulted in 13 live births (68.4%): 3 spontaneous early miscarriages, 1 ectopic pregnancy, 1 early pre-eclampsia (at 21 weeks), and 1 preterm birth with neonatal death at 24 weeks were reported. After exclusion of early miscarriage or termination, pregnancy success rate was 86.7%. In successful pregnancies, median gestational age at delivery was 34 weeks (24-37). Preeclampsia occurred in seven pregnancies (7/15, 46.7%). A cesarean section was performed in all pregnancies. Median baby weight at delivery was 2175 g (620-3374 g). After pregnancy, one patient reached end-stage renal disease, but she already had advanced CKD before pregnancy (creatinine 239 mu mol/L, eGFR 23 ml/min/1.73 m(2)). In three other patients, there was a decrease of eGFR of 8, 20, and 53 ml/min/1.73 m(2), respectively. The majority of pregnancies were successful, but severe antenatal and post-natal complications may occur, in particular preeclampsia that was noticed in nearly half of patients and fetal loss in one-third of them. These results may help pre-pregnancy counseling and pregnancy management.

Background and objective: We compared the efficacy and safety of standard vs. extended primary cytomegalovirus (CMV) prophylaxis in solid organ transplantation. Materials and methods: Retrospective cohort study of CMV seronegative recipients who received CMV prophylaxis after solid organ transplantation from seropositive donor (D+/R-) (2007-2017). CMV infection in the first two years after transplantation in recipients with prophylaxis longer or shorter than 100 days were compared. Results: CMV infection occurred in 29 of 66 patients (43.9%) with prophylaxis. Forty-five patients (68.2%) received extended prophylaxis. CMV infection and disease rates were not different between patients with extended and standard prophylaxis. However, extended prophylaxis was associated with a higher rate of myelotoxicity (68.9% vs. 42.9%, p<0.05). Conclusions: Extending primary CMV prophylaxis over 100 days did not prevent late-onset infection but it was associated with hematological toxicity.

El trasplante renal de donante vivo (TRDV) es la opción terapéutica con las mejores expectativas de supervivencia para el injerto y para el paciente con insuficiencia renal terminal; sin embargo, este tipo de trasplantes ha experimentado un descenso progresivo en los últimos años en España. Entre las posibles explicaciones del descenso de actividad se encuentra la coincidencia en el tiempo con un aumento en el número de donantes renales fallecidos, tanto por muerte encefálica como por asistolia controlada, que podría haber generado una falsa impresión de ausencia de necesidad del TRDV. Además, la disponibilidad de un mayor número de riñones para trasplante habría supuesto un incremento en la carga de trabajo de los profesionales que pudiera enlentecer los procesos de donación en vida. Otro posible argumento radica en un posible cambio de actitud hacia posturas más conservadoras a la hora de informar a pacientes y a familiares acerca de esta opción terapéutica, a raíz de los artículos publicados respecto al riesgo de la donación a largo plazo. Sin embargo, existe una importantísima variabilidad en la actividad entre centros y comunidades autónomas, no explicada por el volumen de trasplante procedente de otros tipos de donante. Este dato, unido a que la indicación de donación renal en vida se realiza de manera mayoritaria en situación de enfermedad renal crónica avanzada (ERCA) y que el tiempo en diálisis es un factor pronóstico negativo respecto a la supervivencia postrasplante, permite concluir que el descenso depende además de otros factores. Por este motivo, en la reunión anual de equipos de trasplante renal, celebrada en la sede de la Organización Nacional de Trasplantes (ONT) en 2018, se constituyó un grupo de trabajo formado por equipos de trasplante renal, el grupo de trasplantes de la Sociedad Española de Nefrología (SEN) (SENTRA), la Sociedad Española de Trasplantes (SET) y la ONT, con el objetivo de identificar otras causas que condicionaron el descenso de la actividad de este tipo de trasplantes en España y su posible relación con la gestión del proceso de donación de vivo. El grupo de trabajo diseñó un cuestionario de autoevaluación, que fue cumplimentado por las 33 unidades de trasplante renal de donante vivo activas en España. El cuestionario contiene preguntas sobre las diferentes fases del proceso de donación de vivo: información inicial, estudio del donante vivo e información de los riesgos, consentimiento, recursos humanos (RRHH), nefrectomía, trasplante y seguimiento posterior. El análisis de las respuestas ha dado como resultado la creación de un análisis de debilidades, amenazas, fortalezas y oportunidades (DAFO) del programa a nivel nacional y ha permitido elaborar recomendaciones específicas dirigidas a mejorar cada una de las fases del proceso de donación en vida. El documento, denominado Análisis de situación del trasplante renal de donante vivo y hoja de ruta ha sido también revisado por un panel de expertos en TRDV, representantes de varias sociedades científicas implicadas (Asociación Española de Urología [AEU], Sociedad Española de Enfermería Nefrológica [SEDEN], Sociedad Española de Inmunología [SEI/GETH]), el Grupo de Trabajo Enfermedad Renal Crónica Avanzada (ACERCA), la Asociación de Pacientes para la Lucha Contra la Enfermedad Renal (ALCER) y sometido posteriormente a consulta pública. Tras incluir las mejoras sugeridas, el documento final ha sido adoptado institucionalmente en el Consejo Interterritorial de Trasplantes (CIT) del Sistema Nacional de Salud. El trabajo realizado y las recomendaciones para optimizar el TRVD se describen a lo largo del presente artículo, organizados por los diferentes apartados del proceso de donación.

Background The use of mycophenolic acid (MPA) in women during pregnancy causes an increase in miscarriages and birth defects with a typical embryopathy profile. Although epidemiological data does not suggest a greater risk among the offspring of male kidney transplant recipients, the European Medicines Agency and The Spanish Agency of Medicines and Medical Devices introduced the recommendation of using contraceptive methods. Methods We conducted a national retrospective study in 15 Spanish Kidney Transplant Centers to evaluate the frequency of miscarriages and birth defects between the offspring from male kidney transplants recipients. We included 151 males who had fathered 239 offspring, 225 under MPA and 14 without MPA. Results The results of our study showed an incidence of miscarriages in the MPA group of 9.8%, and of birth defects of 4%. Conclusions We observed an incidence of miscarriages between the offspring fathered by kidney transplant males under MPA lower than the general population. The incidence of birth defects was similar to the incidence described in other studies and the fact that we did not find the typical embryopathy profile makes it difficult to associate them to the use of MPA. Because of that, we urge the European and Spanish Agencies to reconsider their recommendations for males.

Introduction: Remdesivir has demonstrated antiviral activity against coronavirus, shortening the time to recovery in adults hospitalized with moderate/severe COVID-19. Severe adverse events such as acute kidney injury have been reported. Scant data are available on the use and safety of remdesivir in kidney transplant recipients. Methods: We present a multicenter cohort study of 51 kidney transplant recipients with COVID-19 treated with remdesivir. Outcomes and safety were assessed. Results: Mean age at diagnosis was 60 years, with a median time since kidney transplant of 4.5 years. Mean time since admission to remdesivir was 2 days. Twenty-eight patients (54.9%) required mechanical ventilation (19 noninvasive). Mortality was 18.9% and markedly higher if aged >= 65 years (45% vs. 3.2% in younger patients). Acute kidney injury was present in 27.7% of patients, but was diagnosed in 50% before treatment. No patients required remdesivir discontinuation because of adverse events. We did not find significant hepatoxicity or systemic symptoms resulting from the drug. Conclusion: In our cohort of kidney transplant recipients, remdesivir was well tolerated and safe in renal and hepatic toxicity, but randomized trials are needed to assess its efficacy.