Biocompatible Peritoneal Dialysis Fluids Research Articles

Differential effects of biocompatible peritoneal dialysis fluids on human mesothelial and endothelial cells in 2D and 3D phenotypes.

Peritoneal dialysis (PD) is a life maintaining treatment in patients with end-stage renal disease. Its chronic application leads to peritoneal mesothelial layer denudation and fibrotic transformation along with vascular activation of inflammatory pathways. The impact of different PD fluids (PDF) on mesothelial and endothelial cell function and repair mechanisms are not comprehensively described. Mesothelial (MeT-5A) and endothelial cells (EA.hy926) were cultured in 1:1 ratio with cell medium and different PDF (icodextrin-based, amino acid-based, and glucose-based). Cell adhesion, cell migration, and cell proliferation in 2D and spheroid formation and collagen gel contraction assays in 3D cell cultures were performed. Cell proliferation and cell-mediated gel contraction were both significantly decreased in all conditions. 3D spheroid formation was significantly reduced with icodextrin and amino acid PDF, but unchanged with glucose PDF. Adhesion was significantly increased by amino acid PDF in mesothelial cells and decreased by icodextrin and amino acid PDF in endothelial cells. Migration capacity was significantly decreased in mesothelial cells by all three PDF, while endothelial cells remained unaffected. In 3D phenotypes the effects of PDF are more uniform in both mesothelial and endothelial cells, mitigating spheroid formation and gel contraction. On the contrary, effects on 2D phenotypes are more uniform in the icodextrin and amino acid PDF as opposed to glucose ones and affect mesothelial cells more variably. 2D and 3D comparative assessments of PDF effects on the main peritoneal membrane cell barriers, the mesothelial and endothelial, could provide useful translational information for PD studies.

#4387 LIQUID BIOPSY IN PATIENTS TREATED WITH BIOCOMPATIBLE PERITONEAL DIALYSIS FLUIDS – ITS RELATIONSHIP WITH CYTOLOGICAL AND HISTOLOGICAL FINDINGS

Abstract Background and Aims Peritoneal fibrosis can limit long term peritoneal membrane function in peritoneal dialysis (PD) patients. It has been related to bioincompatible PD fluids and peritoneal infections. There are no prospective studies regarding correlation between effluent biomarkers and peritoneal biopsy findings. Our aim was to study the possible relation of peritoneal effluent biomarkers and peritoneal morphology alterations. Method Multicenter prospective study in a cohort of stable PD patients treated with biocompatible PD fluids who received a kidney transplant. We collected in each patient peritoneal biopsy samples and peritoneal effluent fluid. We analyzed the relation between effluent biomarkers, phenotype of mesothelial cells (MC) cultured ex vivo, and peritoneal biopsy parameters (mesothelial integrity, fibrosis and hyalinizing vasculopathy). We compared them with patient characteristics, including peritoneal transport parameters. The biomarkers tested were Collagen-1 (COL-1), Fibronectin (FN), Collagen-13 (COL-13), Interleukin-6 (IL-6), Trombospondin-1, Cadherin 13 (CDH-13), CA-125, Gremlin-1 (GREM-1), Matrix metalloproteinase 2 (MMP-2), CC chemokine ligand 18 (CCL18), Plasminogen activator inhibitor 1 (PAI-1) and Vascular endothelial growth factor A (VEGF-A). Results Forty patients were included (mean age 54.5±15 years, 64% male, 24.1% diabetics). Mean time on PD was 25.5±27 months, 62.1% were on automated PD (APD) and 17.2% had prior peritonitis episodes. A normal MC culture phenotype was observed in 78% of patients. In peritoneal biopsies samples we found partial or total mesothelium preservation in 39%, submesothelial thickness in 42% and vasculopathy in 14% of cases. Effluent PAI-1 levels were significantly lower in patients with mesothelial cell loss than in those with mesothelial preservation (21.62 vs. 38.59 pg/ml respectively; p = 0.031). Patients with peritoneal fibrosis showed significantly higher effluent CDH-13 levels (3.51 vs. 2.32 pg/ml; p = 0.048) and supernatant PAI-1 levels (1183 vs. 72.73; p = 0.000) than those without fibrosis. No other statistical differences were found in other biomarkers analysed. Conclusion Most patients treated with biocompatible peritoneal dialysis fluids showed normal mesothelial cell phenotype in peritoneal effluent culture. Lower PAI-1 effluent levels were associated with mesothelial cell loss and higher effluent CDH-13 levels were related to peritoneal fibrosis.

Peritoneal dialysis fluids.

There have been significant advances in the understanding of peritoneal dialysis (PD) in the last 40years, and uptake of PD as a modality of kidney replacement therapy is increasing worldwide. PD fluids, therefore, remains the lifeline for patients on this treatment. Developing these fluids to be efficacious in solute clearance and ultrafiltration, with minimal adverse consequences to peritoneal membrane health and systemic effects is a key requirement. Since the first PD fluid produced in 1959, modifications to PD fluids have been made. Nonetheless, the search for that ideal PD fluid remains elusive. Understanding the components of PD fluids is a key aspect of optimizing the successful delivery of PD, allowing for individualized PD prescription. Glucose remains an integral component of PD fluids; however, its deleterious effects continue to be the impetus for the search of an alternative osmotic agent, and icodextrin remains the main alternative. More biocompatible PD fluids have been developed and have shown benefits in preserving residual kidney function. However, high cost and reduced accessibility remain deterrents to its widespread clinical use in many countries. Large-scale clinical trials are necessary and very much awaited to improve the narrow spectrum of PD fluids available for clinical use.

Effects of bicarbonate/lactate-buffered neutral peritoneal dialysis fluids on angiogenesis-related proteins in patients undergoing peritoneal dialysis

BackgroundIn order to facilitate the safe and long-term delivery of peritoneal dialysis (PD), it is necessary to improve the biocompatibility of peritoneal dialysis fluids (PDFs). The novel bicarbonate/lactate-buffered neutral PDFs (B/L-PDFs) are expected to be improved biocompatible. This study evaluated the biocompatibility of B/L-PDFs by analysis on the profile of angiogenesis-related proteins in drained dialysate of patients undergoing PD.MethodsConcentrations of 20 angiogenesis-related proteins in the dialysate were semi-quantitatively determined using a RayBio® Human Angiogenesis Antibody Array and were compared between B/L-PDFs and conventional lactate-buffered neutral PDFs (L-PDFs).ResultsThe expression of growth-related oncogene (GRO α/β/γ), which belongs to the CXC chemokine family, decreased significantly after use of the B/L-PDFs compared to the L-PDFs (P = 0.03). The number of the proteins with lower level in the B/L-PDFs compared with L-PDFs was significantly negatively correlated with the PD duration (Spearman ρ = − 0.81, P = 0.004).ConclusionThis study suggested that B/L-PDFs are more biocompatible than conventional PDFs.

Biocompatibility of a new PD solution for Japan, Reguneal\u2122, measured as in vitro proliferation of fibroblasts

BackgroundThe aim of this study was to investigate in vitro biocompatibility of Reguneal™, a new bicarbonate containing peritoneal dialysis fluid (PDF) for Japan, and compare it with other PDFs available in that country.MethodsWe assessed basal cytotoxicity using in vitro proliferation of cultured fibroblasts, L-929, determining the quantity of living cells by the uptake of Neutral Red. Levels of ten glucose degradation products (GDPs) were measured by a validated ultrahigh-performance liquid chromatography method in combination with an ultraviolet detector. We compared inhibition of fibroblast cell growth between brands of PDF, adjusting for dextrose and GDP concentrations using random-effects mixed models.ResultsThe results demonstrate that cytotoxicity of Reguneal™ is comparable to a sterile-filtered control and is less cytotoxic than most of the other PDFs, most of which significantly inhibited cell growth. As a “class effect”, increasing dextrose and GDP concentrations were non-significantly but positively associated with cytotoxicity. As a “brand effect”, these relationships varied widely between brands, and some PDFs had significant residual effects on basal cytotoxicity through mechanisms that were unassociated with either dextrose or GDP concentration.ConclusionOur study suggests that Reguneal™ is a biocompatible PDF. The results of our study also highlight that dextrose and GDPs are important for biocompatibility, but alone are not a complete surrogate. The results of our study need to be confirmed in other tissue culture models, and should lead to further research on determinants of biocompatibility and the effect of such PDFs on clinical outcomes.

Effects of Oral Paricalcitol and Calcitriol Treatment on Peritoneal Membrane Characteristics of Peritoneal Dialysis Patients - A Pilot Study.

Long-term peritoneal dialysis (PD) is frequently complicated by technique failure preceded by peritoneal remodeling. Vitamin D has potent immunomodulatory characteristics: anti-inflammatory, anti-angiogenic, anti-fibrotic properties, and influences on the macrophage phenotype. Little is known about the relation between pleiotropic effects attributed to vitamin D3 and the peritoneal membrane and what is the most appropriate vitamin D sterol in prevention of peritoneal remodeling in PD patients. Animal studies have suggested that paricalcitol has advantageous effects: decrease in plasma markers of inflammation, less peritoneal fibrosis, less pronounced PD-induced omental angiogenesis, and prevention of loss of ultrafiltration. We investigated whether paricalcitol is advantageous over calcitriol in PD patients. A multicenter open-label 1:1 randomized non-blinded clinical pilot study enrolled prevalent continous ambulatory PD (CAPD) patients for a period of 6 months comparing paricalcitol with calcitriol. All patients were treated with biocompatible PD fluids. The primary endpoint was peritoneal transport parameters, exploratory endpoints were biomarkers of peritoneal damage and cell analysis (including M1/M2 macrophages), and safety endpoints were metabolic parameters. Twenty-seven patients were included. Fourteen were randomized to treatment with paricalcitol. There was no difference in peritoneal transport parameters between the groups. We found similar Kt/V, D/P creatinine, D/D0 glucose, ultrafiltration, residual renal function and 24-h urine volume during the study. There was no difference in biomarker concentrations in peritoneal effluents, and no difference in leucocyte differentiation or mesothelial cells between the groups at any time point. Parathyroid hormone (PTH) levels decreased after administration of calcitriol after 12 and 24 weeks compared with baseline (p = 0.001; p = 0.025). Parathyroid hormone levels in the paricalcitol group did not change significantly. In this pilot study we investigated the effect of active vitamin D in PD patients. We found no specific benefit of active vitamin D3 in vitamin D3-sufficient PD patients. Additional studies in preferably incident patients, with an adequate PTH suppression in the intervention groups and during a longer period, are required to test the beneficial effects of active vitamin D3 over no treatment and to investigate whether in 25(OH)D3-deficient PD patients the type of active vitamin D3 matters.

Risk factors for encapsulating peritoneal sclerosis: Analysis of a 36‐year experience in a University Hospital

Encapsulating peritoneal sclerosis (EPS) is a rare but serious complication that occurs in peritoneal dialysis (PD) therapy. The present study aimed to identify the risk factors, especially peritonitis and biocompatible PD fluid. The study included 703 patients who received PD between January 1980 and March 2015 at two centres. The patients were divided into two groups: those who had developed EPS (EPS group: n = 44) and those who had no documentary evidence of EPS (non-EPS group: n = 659). The independent risks of EPS were determined by univariate and multivariate logistic models. Encapsulating peritoneal sclerosis occurred in 44/703 (6.3%) patients between January 1980 and March 2015. In multivariate logistic models of risk factors correlated with EPS, dialysate to plasma creatinine ratio (D/P Cr) by peritoneal equilibration test (PET) and history of peritonitis were risk factors for EPS development (P < 0.01, respectively) in addition to PD duration. Especially, total duration of peritonitis, defined by period between onset and resolution of peritonitis, was an important risk factor for EPS development in patients with a history of peritonitis. Receiver operating characteristic (ROC) curve analysis revealed that cut-off point for EPS development was 36 days. Moreover, biocompatible PD fluid contributed to decreased EPS development. Both the longer duration of peritonitis and higher D/P Cr, as well as the longer PD duration, were risk factors for EPS development. Furthermore, use of biocompatible PD fluid contributed to the decrease in EPS development.

The Potential Cardiovascular Benefits of Low-Glucose Degradation Product, Biocompatible Peritoneal Dialysis Fluids: A Review of the Literature.

Cardiovascular mortality in the end-stage renal disease (ESRD) population remains the leading cause of death. Targeting traditional cardiovascular risk factors has proven unsuccessful in this patient population, and therefore attention has turned to risk factors related to chronic kidney disease (CKD). The toxicity of high-glucose peritoneal dialysis (PD) solutions has been well documented. The breakdown of glucose into glucose degradation products (GDP) and advanced glycation end-products (AGE) has the ability to alter cell viability and cause premature apoptosis and is strongly correlated with interstitial fibrosis and microvascular sclerosis. Biocompatible solutions have been introduced to combat the hostile milieu to which PD patients are exposed.Given the considerable cardiovascular burden for PD patients, little is known about the cardiovascular impact the new biocompatible solutions may have. This review analyzes the existing literature regarding the mechanisms through which low-GDP solutions may modulate cardiovascular risk. Interventions using low-GDP solutions have provided encouraging changes in structural cardiovascular measures such as left ventricular mass (LVM), although metabolic changes from reduced GDP and AGE exposure yield inconclusive results on vascular remodelling. It is thought that the local effects of reduced glucose exposure may improve membrane integrity and therefore fluid status. Further research in the form of a robust randomized controlled trial should be carried out to assess the true extent of the cardiovascular benefits these biocompatible solutions may hold.

Risk factors for loss of residual renal function in children treated with chronic peritoneal dialysis

In dialyzed patients, preservation of residual renal function is associated with better survival, lower morbidity, and greater quality of life. To analyze the evolution of residual diuresis over time, we prospectively monitored urine output in 401 pediatric patients in the global IPPN registry who commenced peritoneal dialysis (PD) with significant residual renal function. Associations of patient characteristics and time-variant covariates with daily urine output and the risk of developing oligoanuria (under 100 ml/m2/day) were analyzed by mixed linear modeling and Cox regression analysis including time-varying covariates. With an average loss of daily urine volume of 130 ml/m2 per year, median time to oligoanuria was 48 months. Residual diuresis significantly subsided more rapidly in children with glomerulopathies, lower diuresis at start of PD, high ultrafiltration volume, and icodextrin use. Administration of diuretics significantly reduced oligoanuria risk, whereas the prescription of renin–angiotensin system antagonists significantly increased the risk oligoanuria. Urine output on PD was significantly associated in a negative manner with glomerulopathies (−584 ml/m2) and marginally with the use of icodextrin (−179 ml/m2) but positively associated with the use of biocompatible PD fluid (+111 ml/m2). Children in both Asia and North America had consistently lower urine output compared with those in Europe perhaps due to regional variances in therapy. Thus, in children undergoing PD, residual renal function depends strongly on the cause of underlying kidney disease and may be modifiable by diuretic therapy, peritoneal ultrafiltration, and choice of PD fluid.

Increasing the use of biocompatible, glucose-free peritoneal dialysis solutions.

A major concern inhibiting some clinicians from embracing peritoneal dialysis (PD) as the preferred first modality of dialysis is the effects of PD solutions on the peritoneal membrane. These anatomical and functional changes predispose to complications like peritonitis, encapsulating peritoneal sclerosis and ultrafiltration failure. In recent years, "biocompatible" and glucose-sparing PD regimens have been developed to minimize damage to the peritoneal membrane. Can the use of these more expensive solutions be justified on current evidence? In this review of the literature, we explore how we may individualize the prescription of biocompatible PD fluid.

Peritoneal Dialysis—Moving from Current Status to the Future

Peritoneal dialysis (PD) has been widely used as one of the major renal replacement therapies (RRT) for end-stage renal disease (ESRD) patients. Although PD therapy has witnessed remarkable technical advances, and the patient's survival early after starting PD is comparable, or superior, to that of hemodialysis, it is currently faced with many challenges. Long-term PD is associated with progressive loss of UF capacity, resulting in increased cardiovascular morbidity or ultimate discontinuation of PD. This is related to inflammation, new vessel formation (angiogenesis), and fibrotic thickening of the peritoneal membrane (PM). Bioincompatible PD fluid, along with peritonitis, is the major contributor to the PM change. In order to establish PD as a more general and longstanding renal replacement therapy, clinicians and scientists need to investigate the pivotal issues such as adequate volume control and long-term preservation of the peritoneal membrane and the prevention from devastating conditions such as encapsulating peritoneal sclerosis. In this special issue, we have compiled elegant reviews and clinical studies with a special interest in the above-mentioned “Contemporary issues of PD therapy.” This special issue deals with many of the current issues such as PD catheter implantation by nephrologists, clinical benefits of the newer biocompatible PD fluid, peritonitis, and how to cope with low ultrafiltration volume with bimodal and twice-daily icodextrin use and several others. It is the hope of our editorial committee that this special issue will contribute to an improved patient care and serve as a stimulus to seek a new knowledge in renal replacement therapy. Kook-Hwan Oh Yong-Lim Kim Wai-Kei Lo Peter J. Margetts

Effect of the Dialysis Fluid Buffer on Peritoneal Membrane Function in Children

Double-chamber peritoneal dialysis fluids exert less toxicity by their neutral pH and reduced glucose degradation product content. The role of the buffer compound (lactate and bicarbonate) has not been defined in humans. A multicenter randomized controlled trial in 37 children on automated peritoneal dialysis was performed. After a 2-month run-in period with conventional peritoneal dialysis fluids, patients were randomized to neutral-pH, low-glucose degradation product peritoneal dialysis fluids with 35 mM lactate or 34 mM bicarbonate content. Clinical and biochemical monitoring was performed monthly, and peritoneal equilibration tests and 24-hour clearance studies were performed at 0, 3, 6, and 10 months. No statistically significant difference in capillary blood pH, serum bicarbonate, or oral buffer supplementation emerged during the study. At baseline, peritoneal solute equilibration and clearance rates were similar. During the study, 4-hour dialysis to plasma ratio of creatinine tended to increase, and 24-hour dialytic creatinine and phosphate clearance increased with lactate peritoneal dialysis fluid but not with bicarbonate peritoneal dialysis fluid. Daily net ultrafiltration, which was similar at baseline (lactate fluid=5.4±2.6 ml/g glucose exposure, bicarbonate fluid=4.9±1.9 ml/g glucose exposure), decreased to 4.6±1.0 ml/g glucose exposure in the lactate peritoneal dialysis fluid group, whereas it increased to 5.1±1.7 ml/g glucose exposure in the bicarbonate content peritoneal dialysis fluid group (P=0.006 for interaction). When using biocompatible peritoneal dialysis fluids, equally good acidosis control is achieved with lactate and bicarbonate buffers. Improved long-term preservation of peritoneal membrane function may, however, be achieved with bicarbonate-based peritoneal dialysis fluids.

The Effects of Biocompatible Compared with Standard Peritoneal Dialysis Solutions on Peritonitis Microbiology, Treatment, and Outcomes: The Balanz Trial

A multicenter, multi-country randomized controlled trial (the balANZ study) recently reported that peritonitis rates significantly improved with the use of neutral-pH peritoneal dialysis (PD) solutions low in glucose degradation products ("biocompatible") compared with standard solutions. The present paper reports a secondary outcome analysis of the balANZ trial with respect to peritonitis microbiology, treatment, and outcomes. Adult incident PD patients with residual renal function were randomized to receive either biocompatible or conventional (control) PD solutions for 2 years. The safety population analysis for peritonitis included 91 patients in each group. The unadjusted geometric mean peritonitis rates in those groups were 0.30 [95% confidence interval (CI): 0.22 to 0.41] episodes per patient-year for the biocompatible group and 0.49 (95% CI: 0.39 to 0.62) episodes per patient-year for the control group [incidence rate ratio (IRR): 0.61; 95% CI: 0.41 to 0.90; p = 0.01]. When specific causative organisms were examined, the rates of culture-negative, gram-positive, gram-negative, and polymicrobial peritonitis episodes were not significantly different between the biocompatible and control groups, although the biocompatible group did experience a significantly lower rate of non-pseudomonal gram-negative peritonitis (IRR: 0.41; 95% CI: 0.18 to 0.92; p = 0.03). Initial empiric antibiotic regimens were comparable between the groups. Biocompatible fluid use did not significantly reduce the risk of peritonitis-associated hospitalization (adjusted odds ratio: 0.80; 95% CI: 0.48 to 1.34), but did result in a shorter median duration of peritonitis-associated hospitalization (6 days vs 11 days, p = 0.05). Peritonitis severity was more likely to be rated as mild in the biocompatible group (37% vs 10%, p = 0.001). Overall peritonitis-associated technique failures and peritonitis-related deaths were comparable in the two groups. Biocompatible PD fluid use was associated with a broad reduction in gram-positive, gram-negative, and culture-negative peritonitis that reached statistical significance for non-pseudomonal gram-negative organisms. Peritonitis hospitalization duration was shorter, and peritonitis severity was more commonly rated as mild in patients receiving biocompatible PD fluids, although other peritonitis outcomes were comparable between the groups.

A Combination of Biocompatible Peritoneal Dialysis Solutions and Residual Renal Function, Peritoneal Transport, and Inflammation Markers: A Randomized Clinical Trial

The benefits of biocompatible peritoneal dialysis (PD) fluids, particularly for residual renal function (RRF), are controversial. Moreover, the clinical effects of a PD regimen consisting of different biocompatible PD fluids have not been fully established. Prospective, randomized, controlled, open-label study. Patients with end-stage kidney disease newly started on continuous ambulatory PD therapy (N = 150). A 12-month intervention with 3 biocompatible PD fluids (a neutral-pH, low glucose degradation product, 1.5% glucose solution; a solution with 1.1% amino acid; and a fluid with 7.5% icodextrin) or conventional PD fluid. The primary outcome was change in RRF and daily urine volume. Secondary outcomes were peritoneal transport and inflammation markers. RRF, daily urine volume, serum and dialysate cytokine levels. RRF(3.24 ± 1.98 vs 2.88 ± 2.43 mL/min/1.73 m(2); P = 0.9) and rate of decline in RRF (-0.76 ± 1.77 vs -0.91 ± 1.92 mL/min/1.73 m(2) per year; P = 0.6) did not differ between the biocompatible- and conventional-PD-fluid groups. However, patients using the biocompatible PD fluids had better preservation of daily urine volume (959 ± 515 vs 798 ± 615 mL/d in the conventional group, P = 0.02 by comparison of difference in overall change by repeated-measures analysis of variance). Their dialysate-plasma creatinine ratio at 4 hours was higher at 12 months (0.78 ± 0.13 vs 0.68 ± 0.12; P = 0.01 for comparison of the difference in overall change by repeated-measures analysis of variance). They also had significantly higher serum levels of adiponectin and overnight spent dialysate levels of cancer antigen 125, adiponectin, and interleukin 6 (IL-6). No differences between the 2 groups were observed for serum C-reactive protein and IL-6 levels. Unblinded, relatively short follow-up; no formal sample-size calculations. Use of a combination of 3 biocompatible PD fluids for 12 months compared with conventional PD fluid did not affect RRF, but was associated with better preservation of daily urine volume. The biocompatible PD fluids also lead to changes in small-solute transport and an increase in dialysate cancer antigen 125, IL-6, adiponectin, and systemic adiponectin levels, but have no effect on systemic inflammatory response. The clinical significance of these changes, while of great interest, remains to be determined by further studies.

Impact of Global Economic Disparities on Practices and Outcomes of Chronic Peritoneal Dialysis in Children: Insights from the International Pediatric Peritoneal Dialysis Network Registry

BACKGROUND, OBJECTIVES, AND METHODS: The number of patients on chronic peritoneal dialysis (CPD) is increasing rapidly on a global scale. We analyzed the International Pediatric Peritoneal Dialysis Network (IPPN) registry, a global database active in 33 countries spanning a wide range in gross national income (GNI), to identify the impact of economic conditions on CPD practices and outcomes in children and adolescents. We observed close associations of GNI with the fraction of very young patients on dialysis, the presence and number of comorbidities, the prevalence of patients with unexplained causes of end-stage kidney disease, and the rate of culture-negative peritonitis. The prevalence of automated PD increased with GNI, but was 46% even in the lowest GNI stratum. The GNI stratum also affected the use of biocompatible peritoneal dialysis fluids, enteral tube feeding, calcium-free phosphate binders, active vitamin D analogs, and erythropoiesis-stimulating agents (ESAs). Patient mortality was strongly affected by GNI (hazard ratio per $10 000: 3.3; 95% confidence interval: 2.0 to 5.5) independently of young patient age and the number of comorbidities present. Patients from low-income countries tended to die more often from infections unrelated to CPD (5 of 9 vs 15 of 61, p = 0.1). The GNI was also a strong independent predictor of standardized height (p < 0.0001), adding to the impact of congenital renal disease, anuria, age at PD start, and dialysis vintage. Patients from the lower economic strata (GNI < $18 000) had higher serum parathyroid hormone (PTH) and lower serum calcium, and achieved lower hemoglobin concentrations. No impact of GNI was observed with regard to CPD technique survival or peritonitis incidence. We conclude that CPD is practiced successfully, albeit with major regional variation related to economic differences, in children around the globe. The variations encompass the acceptance of very young patients and those with associated comorbidities to chronic dialysis programs, the use of automated PD and expensive drugs, and the diagnostic management of peritonitis. These variations in practice related to economic difference do not appear to affect PD technique survival; however, economic conditions seem to affect mortality on dialysis and standardized height, a marker of global child morbidity.

A Study of the Clinical and Biochemical Profile of Peritoneal Dialysis Fluid Low in Glucose Degradation Products

Although peritoneal dialysis (PD) is a widely accepted form of renal replacement therapy, concerns remain regarding the bioincompatible nature of standard PD fluid (PDF). Short-term studies of new biocompatible PDFs low in glucose degradation products (GDPs) reveal divergent results with respect to peritoneal integrity. We studied 125 patients on maintenance PD who were assigned, by simple randomization, to receive either conventional or low-GDP PDF at PD initiation. Parameters of dialysis adequacy and peritoneal transport of small solutes were determined at initiation and after a period of maintenance PD at the time when serum and overnight effluent dialysate were simultaneously collected and assayed for various cytokines, chemokines, adipokines, and cardiac biomarkers. All patients were further followed prospectively for an average of 15 months from the day of serum and effluent collection to determine patient survival and cardiovascular events. Patients treated with conventional or low-GDP PDF were matched for sex, age, duration of dialysis, dialysis adequacy, and incidence of cardiovascular disease or diabetes. After an average of 2.3 years of PD treatment, the weekly total and peritoneal creatinine clearance, and the total and peritoneal Kt/V were comparable in the groups. However, urine output was higher in patients using low-GDP PDF despite there having been no difference between the groups at PD initiation. Patients using low-GDP PDF also experienced a slower rate of decline of residual glomerular filtration and urine output than did patients on conventional PDF. Compared with serum concentrations, effluent concentrations of tumor necrosis factor α, hepatocyte growth factor, macrophage migration inhibitory factor, interleukins 8 and 6, C-reactive protein, and leptin were found to be higher in both groups of patients after long-term PD, suggesting that the peritoneal cavity was the major source of those mediators. Compared with patients on low-GDP PDF, patients on conventional fluid showed elevated leptin and reduced adiponectin levels in serum and effluent. The effluent concentration of interleukin 8 was significantly lower in patients using low-GDP PDF. The survival rate and incidence of cardiovascular complications did not differ between these groups after maintenance PD for an average of 3.6 years. It appears that low-GDP PDF results in an improvement of local peritoneal homeostasis through a reduction of chronic inflammatory status in the peritoneum.

Buffer-dependent regulation of aquaporin-1 expression and function in human peritoneal mesothelial cells

Biocompatible peritoneal dialysis fluids (PDF) are buffered with lactate and/or bicarbonate. We hypothesized that the reduced toxicity of the biocompatible solutions might unmask specific effects of the buffer type on mesothelial cell functions. Human peritoneal mesothelial cells (HPMC) were incubated with bicarbonate (B-)PDF or lactate-buffered (L-)PDF followed by messenger RNA (mRNA) and protein analysis. Gene silencing was achieved using small interfering RNA (siRNA), functional studies using Transwell culture systems, and monolayer wound-healing assays. Incubation with B-PDF increased HPMC migration in the Transwell and monolayer wound-healing assay to 245 ± 99 and 137 ± 11% compared with L-PDF. Gene silencing showed this effect to be entirely dependent on the expression of aquaporin-1 (AQP-1) and independent of AQP-3. Exposure of HPMC to B-PDF increased AQP-1 mRNA and protein abundance to 209 ± 80 and 197 ± 60% of medium control; the effect was pH dependent. L-PDF reduced AQP-1 mRNA. Addition of bicarbonate to L-PDF increased AQP-1 abundance by threefold; mRNA half-life remained unchanged. Immunocytochemistry confirmed opposite changes of AQP-1 cell-membrane abundance with B-PDF and L-PDF. Peritoneal mesothelial AQP-1 abundance and migration capacity is regulated by pH and buffer agents used in PD solutions. In vivo studies are required to delineate the impact with respect to long-term peritoneal membrane integrity and function.

Biocompatible peritoneal dialysis fluids: clinical outcomes.

Peritoneal dialysis (PD) is a preferred home dialysis modality and has a number of added advantages including improved initial patient survival and cost effectiveness over haemodialysis. Despite these benefits, uptake of PD remains relatively low, especially in developed countries. Wider implementation of PD is compromised by higher technique failure from infections (e.g., PD peritonitis) and ultrafiltration failure. These are inevitable consequences of peritoneal injury, which is thought to result primarily from continuous exposure to PD fluids that are characterised by their “unphysiologic” composition. In order to overcome these barriers, a number of more biocompatible PD fluids, with neutral pH, low glucose degradation product content, and bicarbonate buffer have been manufactured over the past two decades. Several preclinical studies have demonstrated their benefit in terms of improvement in host cell defence, peritoneal membrane integrity, and cytokine profile. This paper aims to review randomised controlled trials assessing the use of biocompatible PD fluids and their effect on clinical outcomes.

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Biocompatibility of peritoneal dialysis solutions determined by genomics of human leucocytes: a cross-over study.

Sir, Peritoneal dialysis (PD) is based on passive movement of water and soluble molecules across the peritoneum. In continuous ambulatory peritoneal dialysis (CAPD), the patient's abdomen is filled with a dialysate fluid introducing an osmotic gradient driven by electrolytes and glucose, or macromolecules such as icodextrin. Biocompatibility of PD fluids is the most important criterion to enable long-term dialysis without introducing clinically significant changes in the functional characteristics of the peritoneum and systemic inflammatory effects [1]. The effects of biocompatibility on clinical outcome include changes in the physiology of cell populations constituting the peritoneal cavity (leucocyte, mesothelial and endothelial cells, and fibroblasts) and the gene expression of peripheral blood mononuclear cells (PBMCs) triggering alterations in cytokine, chemokine and growth factor networks, upregulation of proinflammatory and profibrotic pathways, and induction of carbonyl and oxidative stress [2–4]. Our study objective was to compare the genome-wide gene expression signature of PBMCs of PD patients using glucose-based (GBF) and icodextrin-based peritoneal fluids (IBF) to allow a direct comparison of biocompatibility relevant intracellular processes with respect to the PD fluid used. This pilot study should give us first insights into the alterations in gene expression of leucocytes triggered by different PD fluids and should provide an informative basis for future research. Therefore, we conducted a random cross-over study in five stable ESRD patients being treated with CAPD between 4 and 18 months (demographic data are provided on our laboratory homepage in Table ​Table11 (http://www.meduniwien.ac.at/nephrogene/data/pd/)). Blood samples (10 ml) were collected immediately after a 4- to 6-h dwell of GBF (Physioneal® 40, Glucose 2.27% w/v, 395 mOsmol/l) and an overnight dwell of IBF (Extraneal®, icodextrin 7.5%, 284 mOsmol/l) [study approved by the local Institutional review board (Ethical Committee # EK-318/06, see http://ohrp.cit.nih.gov/search/asearch.asp)]. Oligoarrays were obtained from the Stanford University Functional Genomics core facility. All microarray experiment protocols can be found on the Stanford University webpage at http://cmgm.stanford.edu/pbrown/protocols/index.html. Stratagene Universal human reference RNA was used as a reference. Raw data files as well as the MIAME checklist are available at our laboratory webpage. Table 1 Biological processes separating IBF- and GBF-treated patient groups as derived on the level of PBMC differential gene expression A paired t-test (P < 0.05) of log-transformed expression values was used to evaluate differences between IBF and GBF treatment. Differentially expressed genes (DEGs) were hierarchically clustered and graphically represented using the MultiExperiment Viewer (MeV) (Pearson correlation, complete linkage) [5]. DEGs were furthermore analysed with respect to their molecular functions, biological processes and interaction partner using gene ontology terms (GO-Terms), PANTHER (Protein ANalysis THrough Evolutionary Relationships) ontologies and Online Predicted Human Interaction Database (OPHID). A total of 124 genes (fold change over two, 34 up-regulated and 90 down-regulated in the IBF group) were identified as being significantly differentially expressed in PBMCs comparing patients under IBF and GBF usage (Figure 1 online on our homepage). A total of 27 up-regulated genes assigned to IBF treatment and 81 up-regulated genes associated with GBF treatment could be classified according to PANTHER ontologies (Table ​(Table1).1). A number of the genes up-regulated in the course of IBF usage were found to be involved in immune response and inflammatory processes. Genes up-regulated by GBF usage in contrast are found to be assigned to development and signal transduction processes. Our study provides full genome differential gene expression profiles of PBMCs after peritoneal dialysis on a genome-wide scale comparing GBF and IBF peritoneal dialysis fluids confirming the differential involvement of inflammation. A limitation of our study is the small sample size of five CAPD patients. Therefore, we used a random cross-over design and computed a paired t-test. These pilot data suggest reduced inflammation and consequently an improved biocompatibility of GBF peritoneal fluids compared with IBF fluids. Certainly, further evaluation in larger studies is needed.