More than four decades of graft survival in pediatric kidney transplant recipients.

BACKGROUND: Early in the history of kidney transplantation, short-term graft survival was low. Yet some have had excellent long-term survival. Herein, we describe characteristics of pediatric recipients with > 40 years of graft survival currently alive with a functioning first graft. METHODS: We reviewed all pediatric (age < 18 years) kidney transplants performed at the University of Minnesota between January 1, 1970, and December 31, 1979 (n = 148), to identify all recipients currently alive with a functioning first graft. Data are presented as medians with interquartile ranges (IQR) and proportions. RESULTS: We identified 10 recipients with > 40-year graft survival (median follow-up: 45.0 years (IQR: 43.1, 48.1)). The median age at transplant was 13.8 years (IQR: 5.1, 16.3). All recipients were white; half were male. Of the 10, 4 had glomerulonephritis, 2 had congenital anomalies of the kidney and the urinary tract, 2 had congenital nephrotic syndrome, 1 had Alport syndrome, and 1 had cystic kidney disease as kidney failure cause. Nine patients received a living-related donor transplant, and 1 patient received a deceased-donor transplant. The median estimated glomerular filtration rate at 20 years post-transplant was 79.9 (IQR: 72.3, 98.4); at 30 years, 67.7 (IQR: 63.2, 91.8); and at 40 years, 80.3 ml/min/1.73 m2 (IQR: 73.7, 86.0). None developed rejection, 5 developed hypertension, 2 developed dyslipidemia, 1 developed diabetes, and 7 patients developed malignancy (4 skin cancer, 2 breast cancer, and 1 post-transplant lymphoproliferative disease). CONCLUSION: Pediatric kidney transplant recipients may achieve > 4 decades of graft survival. Cancer is a common complication warranting vigilant screening.

Depression, Quantified Medication Adherence, and Quality of Life in Renal Transplant Candidates and Recipients.

Like patients with many chronic illnesses, ESRD patients experience psychological challenges with greater incidence of depression and reduced quality of life (QoL). A series of 139 transplant candidates' depression and QoL, and a subset of 82 candidates' medication adherence were monitored, revealing heterogenous patterns of depression and adherence and reduced QoL. Twenty-eight patients who received kidney transplants were re-evaluated 6 months post-transplant revealing mixed patterns. Mean depression and quantitated adherence decreased and QoL increased. Some patients improved whereas others declined in depression and adherence. Pre-transplant depression was negatively correlated with post-transplant adherence but positively correlated with post-transplant depression. Nevertheless, the ability to predict individuals' post-transplant adherence and depression, principal objectives of pre-transplant psychological evaluations, is limited. Consequently, it is important to provide periodic screening of ESRD patients for depression and adherence pre- and post-transplant as they reflect changing states, rather than static traits, with variable patterns across patients.

Medication adherence is associated with an increased risk of cancer in kidney transplant recipients: a cohort study.

Background: Nonadherence to posttransplant immunosuppressive medication is associated with increased rates of rejection and graft loss, yet it is unknown to what degree ideal adherence is associated with the sequelae of overimmunosuppression. Specifically, we questioned whether excellent adherence increased the posttransplant cancer risk. Methods: Between August 1998 and August 2006, 195 consenting kidney transplant recipients had electronic monitoring of theirimmunosuppressive medication adherence. Results: Based on their average quantitative adherence to a single immunosuppressant drug over the first 6 months posttransplant, recipients were grouped into adherence tertiles (highest, >97.9% adherence; middle, 91-97.8%; lowest, <91%). The cumulative incidence of cancer was calculated for patients in each tertile, treating death as a competing risk. The association between adherence and cancer rate was calculated after adjusting for recipient risk factors, using a competing risk proportional hazards model. The median duration of follow-up was 10.1 years. The 10-year estimated cumulative cancer incidence was 59.4% in the most adherent, 36.1% in the middle group and 38.1% in the least adherent group (P = 0.006). Excluding nonmelanocytic skin cancers, cancer incidence remained significantly higher in the highest adherence group (P = 0.002). Conclusions: These data provide additional support for the need to individualize immunosuppression to minimize both rejection and immunosuppressive drug-related complications including cancer.

Transcranial optical imaging reveals a pathway for optimizing the delivery of immunotherapeutics to the brain.

Despite the initial promise of immunotherapy for CNS disease, multiple recent clinical trials have failed. This may be due in part to characteristically low penetration of antibodies to cerebrospinal fluid (CSF) and brain parenchyma, resulting in poor target engagement. We here utilized transcranial macroscopic imaging to noninvasively evaluate in vivo delivery pathways of CSF fluorescent tracers. Tracers in CSF proved to be distributed through a brain-wide network of periarterial spaces, previously denoted as the glymphatic system. CSF tracer entry was enhanced approximately 3-fold by increasing plasma osmolality without disruption of the blood-brain barrier. Further, plasma hyperosmolality overrode the inhibition of glymphatic transport that characterizes the awake state and reversed glymphatic suppression in a mouse model of Alzheimer's disease. Plasma hyperosmolality enhanced the delivery of an amyloid-ß (Aß) antibody, obtaining a 5-fold increase in antibody binding to Aß plaques. Thus, manipulation of glymphatic activity may represent a novel strategy for improving penetration of therapeutic antibodies to the CNS.

Single-Cell Transcriptome Analyses Reveal Endothelial Cell Heterogeneity in Tumors and Changes following Antiangiogenic Treatment.

Angiogenesis involves dynamic interactions between specialized endothelial tip and stalk cells that are believed to be regulated in part by VEGF and Dll4-Notch signaling. However, our understanding of this process is hampered by limited knowledge of the heterogeneity of endothelial cells and the role of different signaling pathways in specifying endothelial phenotypes. Here, we characterized by single-cell transcriptomics the heterogeneity of mouse endothelial cells and other stromal cells during active angiogenesis in xenograft tumors as well as from adult normal heart, following pharmacologic inhibition of VEGF and Dll4-Notch signaling. We classified tumor endothelial cells into three subpopulations that appeared to correspond with tip-like, transition, and stalk-like cells. Previously identified markers for tip and stalk cells were confirmed and several novel ones discovered. Blockade of VEGF rapidly inhibited cell-cycle genes and strongly reduced the proportion of endothelial tip cells in tumors. In contrast, blockade of Dll4 promoted endothelial proliferation as well as tip cell markers; blockade of both pathways inhibited endothelial proliferation but preserved some tip cells. We also phenotypically classified other tumor stromal cells and found that tumor-associated fibroblasts responded to antiangiogenic drug treatments by upregulating hypoxia-associated genes and producing secreted factors involved in angiogenesis. Overall, our findings better define the heterogeneity of tumor endothelial and other stromal cells and reveal the roles of VEGF and Dll4-Notch in specifying tumor endothelial phenotype, highlighting the response of stromal cells to antiangiogenic therapies.Significance: These findings provide a framework for defining subpopulations of endothelial cells and tumor-associated fibroblasts and their rapid changes in gene expression following antiangiogenic treatment. Cancer Res; 78(9); 2370-82. ©2018 AACR.

Improved Outcomes of Kidney Transplantation in Infants (Age < 2 years): A Single-Center Experience.

BACKGROUND: Infants (age, < 2 years) with end-stage renal disease (ESRD) have increased morbidity and mortality. We evaluated our long-term outcomes of kidney transplants (KTx) in infants. METHODS: Between 1984 and 2014, 136 infants underwent KTx. We examined trends in survival rates and complications by era (1984-1993 [era 1], 1994-2003 [era 2], 2004-2014 [era 3]). RESULTS: Patients were 92.6% white and 70.6% males. Posttransplant (Tx) initial length of hospital stay declined 37% over the 30-year period (P <0.01). Ten-year death-censored graft survival improved from 60% (era 1) to 80% (era 2) (P = 0.04). The incidence of acute rejection, graft thrombosis, cytomegalovirus, and urine leaks did not significantly change across eras. Frequency of Epstein-Barr virus diagnosis (era 2 vs era 3, P < 0.01) increased. Post-Tx lymphoproliferative disorder incidence was increased in era 2 compared with eras 1 and 3 (P = 0.03). CONCLUSIONS: Infants deserve earlier consideration for KTx. Length of initial hospital stay and patient and graft survival rates after KTx have improved in infants since 1984.

Front tracking velocimetry in advection-reaction-diffusion systems.

In advection-reaction-diffusion systems, the spreading of a reactive scalar can be significantly influenced by the flow field in which it grows. In systems with sharp boundaries between reacted and unreacted regions, motion of the reaction fronts that lie at those boundaries can quantify spreading. Here, we present an algorithm for measuring the velocity of reaction fronts in the presence of flow, expanding previous work on tracking reaction fronts without flow. The algorithm provides localized measurements of front speed and can distinguish its two components: one from chemical dynamics and another from the underlying flow. We validate that the algorithm returns the expected front velocity components in two simulations and then show that in complex experimental flows, the measured front velocity maps fronts from one time step to the next self-consistently. Finally, we observe a variation of the chemical speed with flow speed in a variety of experiments with different time scales and length scales.

Class II Eplet Mismatch Modulates Tacrolimus Trough Levels Required to Prevent Donor-Specific Antibody Development.

Despite more than two decades of use, the optimal maintenance dose of tacrolimus for kidney transplant recipients is unknown. We hypothesized that HLA class II de novo donor-specific antibody (dnDSA) development correlates with tacrolimus trough levels and the recipient's individualized alloimmune risk determined by HLA-DR/DQ epitope mismatch. A cohort of 596 renal transplant recipients with 50,011 serial tacrolimus trough levels had HLA-DR/DQ eplet mismatch determined using HLAMatchmaker software. We analyzed the frequency of tacrolimus trough levels below a series of thresholds <6 ng/ml and the mean tacrolimus levels before dnDSA development in the context of HLA-DR/DQ eplet mismatch. HLA-DR/DQ eplet mismatch was a significant multivariate predictor of dnDSA development. Recipients treated with a cyclosporin regimen had a 2.7-fold higher incidence of dnDSA development than recipients on a tacrolimus regimen. Recipients treated with tacrolimus who developed HLA-DR/DQ dnDSA had a higher proportion of tacrolimus trough levels <5 ng/ml, which continued to be significant after adjustment for HLA-DR/DQ eplet mismatch. Mean tacrolimus trough levels in the 6 months before dnDSA development were significantly lower than the levels >6 months before dnDSA development in the same patients. Recipients with a high-risk HLA eplet mismatch score were less likely to tolerate low tacrolimus levels without developing dnDSA. We conclude that HLA-DR/DQ eplet mismatch and tacrolimus trough levels are independent predictors of dnDSA development. Recipients with high HLA alloimmune risk should not target tacrolimus levels <5 ng/ml unless essential, and monitoring for dnDSA may be advisable in this setting.

Understanding Medication Nonadherence after Kidney Transplant.

Alloimmunity remains a barrier to long-term graft survival that necessitates lifelong immunosuppressive therapy after renal transplant. Medication nonadherence has been increasingly recognized as a major impediment to achieving effective immunosuppression. Electronic medication monitoring further reveals that nonadherence manifests early after transplant, although the effect is delayed. The etiology of nonadherence is multifactorial, with the strongest risk factors including past nonadherence and being an adolescent or young adult. Other risk factors with smaller but consistently important effects include minority race/ethnicity, poor social supports, and poor perceived health. In children, risk factors related to parental and child psychologic and behavioral functioning and parental distress and burden are also important. Qualitative systematic reviews highlight the need to tailor interventions to each transplant recipient's unique needs, motivations, and barriers rather than offer a one size fits all approach. To date, relatively few interventions have been studied, and most studies conducted were underpowered to allow definitive conclusions. If the kidney transplant community's goal of "one transplant for life" is to become a reality, then solutions for medication nonadherence must be found and implemented.

Front tracking for quantifying advection-reaction-diffusion.

We present an algorithm for measuring the speed and thickness of reaction fronts, and from those quantities, the diffusivity and the reaction rate of the active chemical species. This front-tracking algorithm provides local measurements suitable for statistics and requires only a sequence of concentration fields. Though our eventual goal is front tracking in advection-reaction-diffusion, here we demonstrate the algorithm in reaction-diffusion. We test the algorithm with validation data in which front speed and thickness are prescribed, as well as simulation results in which diffusivity and reaction rate are prescribed. In all tests, measurements closely match true values. We apply the algorithm to laboratory experiments using the Belousov-Zhabotinsky reaction, producing speed, diffusivity, and reaction rate measurements that are statistically more robust than in prior studies. Finally, we use thickness measurements to quantify the concentration profile of chemical waves in the reaction.

Outcomes and Risk Factors for Graft Loss: Lessons Learned from 1,056 Pediatric Kidney Transplants at the University of Minnesota.

BACKGROUND: Advances in immunosuppression, surgical techniques, and management of infections in children receiving kidney transplants have affected outcomes. STUDY DESIGN: We analyzed a prospectively maintained database of pediatric kidney transplantations. RESULTS: From June 1963 through October 2016, we performed 1,056 pediatric kidney transplantations. Of these, 129 were in children less than 2 years old. The most common indications for transplant were congenital anomalies (dysplastic kidneys), obstructive uropathy, and congenital nephrotic syndrome. Living donors constituted 721 (68%) of all donors. The graft and patient survival rates remarkably improved for both deceased and living donor recipients (p = 0.001). Currently, graft survival rates for deceased donor recipients are 92% at 1 year, 76% at 5 years, and 57% at 10 years post-transplant; for living donor recipients, 96% at 1 year, 85% at 5 years, and 78% at 10 years. The graft half-life was 19 years in deceased donor recipients, compared with 25 years in living donor recipients (p ≤ 0.001). Acute rejection was the most common cause of graft loss in the first year post-transplant. The following risk factors were associated with an increased risk of graft loss: deceased donor grafts (p = 0.0001), retransplant (p = 0.02), ages 11 to 18 years (p = 0.001) and pre-transplant urologic issues (p = 0.04). Living donor grafts (p ≤ 0.0001) and pre-emptive transplants (p = 0.02) were associated with decreased risks of graft loss. CONCLUSIONS: The success rates of pediatric kidney transplants have significantly improved. Pre-emptive kidney transplantation with a living donor graft continues to be superior and should be the choice in children with end-stage renal disease.

Optimal stretching in the reacting wake of a bluff body.

We experimentally study spreading of the Belousov-Zhabotinsky reaction behind a bluff body in a laminar flow. Locations of reacted regions (i.e., regions with high product concentration) correlate with a moderate range of Lagrangian stretching and that range is close to the range of optimal stretching previously observed in topologically different flows [T. D. Nevins and D. H. Kelley, Phys. Rev. Lett. 117, 164502 (2016)]. The previous work found optimal stretching in a closed, vortex dominated flow, but this article uses an open flow and only a small area of appreciable vorticity. We hypothesize that optimal stretching is common in advection-reaction-diffusion systems with an excitation threshold, including excitable and bistable systems, and that the optimal range depends on reaction chemistry and not on flow shape or characteristic speed. Our results may also give insight into plankton blooms behind islands in ocean currents.

Hemoglobin of 12 g/dl and above is not associated with increased cardiovascular morbidity in children on hemodialysis.

In adults on chronic hemodialysis, achieving a hemoglobin concentration of 12g/dl and above with erythropoiesis stimulating agents leads to increased cardiovascular events and mortality, but this may not be true in children. Therefore, we conducted a retrospective cohort study of pediatric patients (under 18) from the Centers for Medicare and Medicaid Services End Stage Renal Disease (ESRD) Clinical Performance Measures (CPM) project (2000 to 2008) merged with the United States Renal Data System. Hemoglobin was determined from the Clinical Performance Measures data, and beginning annually on January 1st of the next year, patients were followed for up to 1 year. We determined the outcomes (mortality, hospitalization, and cardiovascular events) during follow-up by hemoglobin group at baseline. Models were adjusted for demographic and clinical characteristics of 1569 children studied. The hemoglobin 12 g/dl and above group was older, had fewer years of ESRD, and was more often transplanted. Inpatient and outpatient visits for congestive heart failure, cardiomyopathy, and valvular heart disease were most common in the hemoglobin under 10g/dl group and the frequency of these diagnoses decreased with increasing hemoglobin. The hazard ratio of all-cause mortality (0.33, 95% confidence interval 0.14-0.81) and the adjusted relative rate of all-cause hospitalizations (0.81, 0.74-0.89) were significantly lower in the hemoglobin 12 g/dl and above group. Cardiovascular hospitalizations were significantly higher in the hemoglobin under 10g/dl group (1.31, 1.05-1.64). Thus, in children on hemodialysis, hemoglobin 12g/dl and above is not associated with increased cardiovascular visits, mortality, or all-cause and cardiovascular-related hospitalizations.

Optimal Stretching in Advection-Reaction-Diffusion Systems.

We investigate growth of the excitable Belousov-Zhabotinsky reaction in chaotic, time-varying flows. In slow flows, reacted regions tend to lie near vortex edges, whereas fast flows restrict reacted regions to vortex cores. We show that reacted regions travel toward vortex centers faster as flow speed increases, but nonreactive scalars do not. For either slow or fast flows, reaction is promoted by the same optimal range of the local advective stretching, but stronger stretching causes reaction blowout and can hinder reaction from spreading. We hypothesize that optimal stretching and blowout occur in many advection-diffusion-reaction systems, perhaps creating ecological niches for phytoplankton in the ocean.

Desirability and feasibility of wireless electronic monitoring of medications in clinical trials.

Medication nonadherence is a vexing problem in health care necessitating patients and health professionals' efforts to prevent, minimize, or reverse it. Research participants' inconsistent medication taking obscures treatment efficacy and adds costs to biomedical research. Electronic monitoring devices (EMDs), like the Medication Event Monitoring System (MEMS), have grown in sophistication, providing precise, timely insights into individuals' medication-taking patterns across clinical populations. This article reports on the desirability and feasibility study of using a wireless EMD in clinical research to promote adherence to clinical regimens and research protocols. Nonadherence in transplant patients has been linked to late acute rejection and graft loss. High levels of adherence (97.7 %) were documented for six renal transplant recipients for a mean of 6 months (M = 196.1 ± 71.2 days) who indicated acceptance of the technology. MEMS data confirmed the feasibility of using wireless EMDs to monitor medication use. Monitoring provides greater assurance that research studies reflect the biological impact of medications and provide a basis for targeting adherence enhancement efforts within research investigations.

Predictive patterns of early medication adherence in renal transplantation.

BACKGROUND: Patients' adherence with posttransplant immunosuppression is known to affect renal transplant outcomes. METHODS: Prospectively, individual medication adherence patterns in 195 kidney transplant recipients were quantified with electronic medication monitors. Monitored drugs were mycophenolate mofetil, sirolimus, or azathioprine. Monitoring began at hospital discharge and continued an average of 15±8 months. Patient follow-up for clinical outcomes averaged 8±3 years. Each month's adherence percentage was calculated as the sum of daily adherence percents, divided by the number of evaluable days. RESULTS: During the first 3 months after transplantation, patients (n=44) with declining medication adherence, defined as dropping by 7% or higher (equal to missing 2 days) between months 1 and 2, later experienced lower mean medication adherence for months 6 to 12, 73% versus 92% respectively (P<0.0001). Compared to patients with stable adherence, they also had more frequent (P=0.034) and earlier (P=0.065) acute rejection episodes. This was additionally associated with more frequent (P=0.017) and earlier (P=0.046) death-censored graft loss.In addition, daily medication adherence, expressed as the percentage of doses taken, decreased as the number of prescribed daily doses increased. During the first 3 months after transplantation, adherence with four doses per day averaged 84%, compared to 91% for patients on twice-daily dosing (P=0.024) and 93.5% for patients on once-daily dosing (P=0.008). CONCLUSIONS: Early declining medication nonadherence is associated with adverse clinical outcomes. This pattern is detectable during the first 2 months after transplantation. Early detection of nonadherence provides opportunities to target interventions toward patients at the highest risk for adverse behaviors and events.

Discovery of siRNA lipid nanoparticles to transfect suspension leukemia cells and provide in vivo delivery capability.

As a powerful research tool, siRNA's therapeutic and target validation utility with leukemia cells and long-term gene knockdown is severely restricted by the lack of omnipotent, safe, stable, and convenient delivery. Here, we detail our discovery of siRNA-containing lipid nanoparticles (LNPs) able to effectively transfect several leukemia and difficult-to-transfect adherent cell lines also providing in vivo delivery to mouse spleen and bone marrow tissues through tail-vein administration. We disclose a series of novel structurally related lipids accounting for the superior transfection ability, and reveal a correlation between expression of Caveolins and successful transfection. These LNPs, bearing low toxicity and long stability of >6 months, are ideal for continuous long-term dosing. Our discovery represents the first effective siRNA-containing LNPs for leukemia cells, which not only enables high-throughput siRNA screening with leukemia cells and difficult-to-transfect adherent cells but also paves the way for the development of therapeutic siRNA for leukemia treatment.

Preclinical evaluation of the novel multi-targeted agent R1530.

PURPOSE: This study describes the antiproliferative activity of the multikinase inhibitor R1530 in vitro and its antitumor and anti-angiogenic activity, pharmacokinetics, and tolerability in vivo. METHODS: The antiproliferative activity of R1530 was investigated in a range of human tumor, endothelial and fibroblast cell lines. Tolerability and antitumor activity were assessed in mice bearing a range of human tumor xenografts, and anti-angiogenic properties were established in the murine corneal pocket assay. R1530 pharmacokinetics in mice were established. RESULTS: R1530 strongly inhibited human tumor cell proliferation. Growth factor-driven proliferation of endothelial and fibroblast cells was also inhibited. Significant tumor growth inhibition was demonstrated in a lung cancer xenograft model with a range of once daily, weekly and twice-weekly doses of R1530 (3.125-50 mg/kg qd, 100 mg/kg qw, 100 mg/kg biw). Daily doses were most effective in the lung cancer model and also had significant growth inhibitory effects in models of colorectal, prostate, and breast tumors. Tumor regression occurred in all models treated with the maximum tolerated daily dose (50 mg/kg). The doses of 25 and 50 mg/kg qd resulted in biologically significant increased survival in all tested models. After oral administration in nude mice, R1530 showed good tissue penetration. Exposure was dose dependent up to 100 mg/kg with oral administration. CONCLUSIONS: R1530 has demonstrated activity against a range of tumor models in vitro and in vivo and is an effective inhibitor of angiogenesis. These findings support the approach of targeting multiple pathways in the search for potential agents with improved anticancer properties.

The pharmacokinetics of valganciclovir prophylaxis in pediatric solid organ transplant patients at risk for Epstein-Barr virus disease.

Antiviral prophylaxis with valganciclovir is used frequently in pediatric solid organ transplant patients to prevent Epstein-Barr virus (EBV)-induced infections and tissue-invasive disease including post-transplant lymphoproliferative disorder (PTLD). This approach is untested in clinical trials and valganciclovir dosing strategies in children are highly variable. Our objective was to characterize the pharmacokinetics of ganciclovir in the plasma of pediatric kidney and liver transplant patients taking valganciclovir for EBV prophylaxis. Virologic response was also evaluated. Ganciclovir was measured by liquid chromatography/ultraviolet detection. EBV DNA was quantified by TaqMan(®) polymerase chain reaction. NONMEM(®) VI was used for data analysis. Ganciclovir plasma profiles were consistent with a one-compartment model. Final model estimates of apparent oral clearance (L/h), apparent volume of distribution (L), and absorption rate constant were 7.33, 35.1, and 0.85, respectively. There was evidence of lower bioavailability in children younger than three years. All eight subjects achieved ganciclovir plasma concentrations above reported in vitro concentrations needed to inhibit EBV replication by 50%. However, four subjects had detectable EBV DNA with a median (range) of 18,300 (4,400 to 54,900) copies/mL of whole blood. These findings support the need for further studies of the clinical pharmacology and efficacy of valganciclovir for EBV prophylaxis.