In vivo Assessment of a Manual Single Lumen Alternating Micro-Batch Hemodiafiltration System.

INTRODUCTION: The manual single lumen alternating micro-batch hemodiafiltration (mSLAMB) system is a closed-loop dialysis system designed to provide kidney support in emergency situations (e.g., fluid overload, hyperkalemia, acidemia). If done repeatedly in small batches and at high flow rates, this system was found to achieve clearance levels comparable to traditional renal replacement therapy. METHODS: Using a porcine model, uremic toxins and exogenous fluorescent tracer concentrations were successfully lowered within just 1 h of treatment. RESULTS: With a maximal dialysate flow, mSLAMB can achieve decreases in serum potassium concentration of >0.5 mmol/L/h. With the mSLAMB hemodiafiltration system, micro-batch processing was also successful in removing up to 250 mL of ultrafiltrate in 8 cycles. CONCLUSION: This process could create a better fluid balance allowing for administering therapeutic fluids such as sodium bicarbonate in the clinic. Electrolyte imbalance and volume overload remain severe life-threatening emergencies in low resource settings; therefore, mSLAMB should be explored further due to its modest vascular access requirements, low cost, and ability to be performed without electricity or batteries.

Transdermal Detection of MB-102 and Correlation to Meropenem Pharmacokinetics During Continuous Renal Replacement Therapy: In Vivo Results.

Critically ill patients undergoing continuous renal replacement therapy (CRRT) have medical conditions requiring extensive pharmacotherapy. Continuous renal replacement therapy impacts drug disposition. Few data exist regarding drug dosing requirements with contemporary CRRT modalities and effluent rates. The practical limitations of pharmacokinetic studies requiring numerous plasma and effluent samples, and lack of generalizability of observations from specific CRRT prescriptions, highlight gaps in bedside assessment of CRRT drug elimination and individualized dosing needs. We employed a porcine model using transdermal fluorescence detection of the glomerular filtration rate fluorescent tracer agent MB-102, with the aim to assess the relationship between systemic exposure of MB-102 and meropenem during CRRT. Animals underwent bilateral nephrectomies and received intravenous bolus doses of MB-102 and meropenem. Once MB-102 equilibrated in the animal, CRRT was initiated. Continuous renal replacement therapy prescriptions comprised four combinations of blood pump (low versus high) and effluent (low versus high) flow rates. Changes in transdermal detected MB-102 clearance occurred immediately with a change in CRRT rates. Blood side meropenem clearance mirrored transdermal MB-102 clearance ( r2 : 0.95-0.97, p value all <0.001). We suggest transdermal MB-102 clearance provides real-time personalized assessment of drug elimination and could optimize prescription of drugs for critically ill patients requiring CRRT.

Estimating Changes in Glomerular Filtration Rate With Fluorescein Isothiocyanate-Sinistrin During Renal Replacement Therapy.

Excreted exclusively by the kidneys, fluorescein isothiocyanate (FITC)-sinistrin can be used to measure glomerular filtration rate (GFR) and is detectable transdermally. Determination of changes in native kidney GFR (NK-GFR) in patients with acute kidney injury, particularly during continuous renal replacement therapy, improves clinical decision-making capability. To test feasibility of measuring changes in NK-GFR during CRRT with FITC-sinistrin, in vitro circuits (n = 2) were utilized to simultaneously clear FITC-sinistrin by removal of ultrafiltrate at varying rates, simulating kidney function, and by dialysis at a constant rate. Clearance calculated by fluorescence-measuring devices on the circuit showed good agreement with clearance calculated from assay of fluid samples ( R2 = 0.949). In vivo feasibility was studied by dialyzing anesthetized pigs (n = 3) and measuring FITC-sinistrin clearance during progression from normal, to unilaterally, then bilaterally nephrectomized. FITC-sinistrin clearance was reduced in vitro , when ultrafiltrate was decreased or with successive nephrectomies in vivo . Transdermal readers showed 100% sensitivity in detecting a decrease in NK-GFR in pigs with a bias of 6.5 ± 13.4% between transdermal-derived GFR (tGFR) and plasma-measured methods determining proportional changes in clearance. Clearance of FITC-sinistrin by dialysis remained consistent. In patients receiving a constant dialysis prescription, transdermal measurement of FITC-sinistrin can detect relative changes in NK-GFR.

Immunomodulatory therapy using a pediatric dialysis system ameliorates septic shock in miniature pigs.

BACKGROUND: Application of the immunomodulatory selective cytopheretic device (SCD) to enhance renal replacement therapy and improve outcomes of acute kidney injury in pediatric patients is impeded by safety concerns. Therapy using a pediatric hemodialysis system could overcome these limitations. METHODS: Yucatan minipigs (8-15 kg) with induced septic shock underwent continuous hemodiafiltration with the CARPEDIEM™ pediatric hemodialysis system using regional citrate anticoagulation (RCA) with or without SCD (n = 5 per group). Circuit function plus hemodynamic and hematologic parameters were assessed for 6 h. RESULTS: SCD was readily integrated into the CARPEDIEM™ system and treatment delivered for 6 h without interference with pump operation. SCD-treated pigs maintained higher blood pressure (p = 0.009) commensurate with lesser degree of lactic acidosis (p = 0.008) compared to pigs only receiving hemodiafiltration. Renal failure occurred in untreated pigs while urine output was sustained with SCD therapy. Neutrophil activation levels and ss-SOFA scores at 6 h trended lower in the SCD-treated cohort. CONCLUSIONS: SCD therapy under RCA was safely administered using the CARPEDIEM™ pediatric hemodialysis system for up to 6 h and no circuit compatibility issues were identified. Sepsis progression and organ dysfunction was diminished with SCD treatment in this model supportive of therapeutic benefit of this immunomodulatory therapy. IMPACT: SCD therapy with regional citrate anticoagulation has the potential to be administered safely to patients weighing <20 kg using the Carpediem renal replacement therapy platform. Use of a renal replacement therapy platform designed specifically for neonates/infants overcomes safety concerns for delivery of SCD treatment in this population. SCD therapy using the Carpediem renal replacement therapy platform retained the suggestive efficacy seen in larger children and adults to reduce organ injury and dysfunction from sepsis.

Novel Leukocyte Modulator Device Reduces the Inflammatory Response to Cardiopulmonary Bypass.

Leukocyte (LE) activation during cardiopulmonary bypass (CPB) promotes a systemic inflammatory response that contributes to organ injury and postoperative organ dysfunction. A leukocyte modulatory device (L-MOD) for use during (and after) CPB to limit leukocyte-mediated organ injury was tested in a preclinical model. Twenty-two pigs underwent 180 minutes of CPB and 5 hours postoperative observation. Pigs received no intervention (group 1, n = 9), 3 hours of therapy by incorporation of L-MOD into the CPB circuit (group 2, n = 6), or 8 hours of therapy using a femoral venovenous L-MOD circuit during and after CPB (group 3, n = 7). Leukocyte activation was increased at the end of CPB and leukocyte counts, namely neutrophils, increased postoperatively in most animals. These indices trended much lower in group 3. Systemic vascular resistance was not as reduced post-CPB for the L-MOD-treated pigs, and urine output was significantly greater for group 3 (p < 0.01). At 5 hours post-CPB, group 3 had a lower troponin-I (1.59 ± 0.68 ng/ml) than group 1 or group 2 (3.97 ± 2.63 and 3.55 ± 2.04 ng/ml, respectively, p < 0.05) and a lower urine neutrophil gelatinase-associated lipocalin (7.57 ± 3.59 ng/ml) than the average of the other groups (50.71 ± 49.17, p < 0.05). These results demonstrate the therapeutic potential of L-MOD therapy to mitigate the inflammatory response to CPB. Eight hours of venovenous L-MOD resulted in less organ injury and post-op organ dysfunction in this model.

Regenerative Medicine and Immunomodulatory Therapy: Insights From the Kidney, Heart, Brain, and Lung.

Regenerative medicine was initially focused on tissue engineering to replace damaged tissues and organs with constructs derived from cells and biomaterials. More recently, this field of inquiry has expanded into exciting areas of translational medicine modulating the body's own endogenous processes, to prevent tissue damage in organs and to repair and regenerate these damaged tissues. This review will focus on recent insights derived from studies in which the manipulation of the innate immunologic system may diminish acute kidney injury and enhance renal repair and recovery without the progression to chronic kidney disease and renal failure. The manner in which these interventions may improve acute and chronic organ dysfunction, including the heart, brain, and lung, will also be reviewed.

A bio-artificial renal epithelial cell system conveys survival advantage in a porcine model of septic shock.

Renal cell therapy using the hollow fiber based renal assist device (RAD) improved survival time in an animal model of septic shock (SS) through the amelioration of cardiac and vascular dysfunction. Safety and ability of the RAD to improve clinical outcomes was demonstrated in a Phase II clinical trial, in which patients had high prevalence of sepsis. Even with these promising results, clinical delivery of cell therapy is hampered by manufacturing hurdles, including cell sourcing, large-scale device manufacture, storage and delivery. To address these limitations, the bioartificial renal epithelial cell system (BRECS) was developed. The BRECS contains human renal tubule epithelial cells derived from adult progenitor cells using enhanced propagation techniques. Cells were seeded onto trabeculated disks of niobium-coated carbon, held within cryopreservable, perfusable, injection-moulded polycarbonate housing. The study objective was to evaluate the BRECS in a porcine model of SS to establish conservation of efficacy after necessary cell sourcing and design modifications; a pre-clinical requirement to move back into clinical trials. SS was incited by peritoneal injection of E. coli simultaneous to insertion of BRECS (n=10) or control (n=15), into the ultrafiltrate biofeedback component of an extracorporeal circuit. Comparable to RAD, prolonged survival of the BRECS cohort was conveyed through stabilization of cardiac output and vascular leak. In conclusion, the demonstration of conserved efficacy with BRECS therapy in a porcine SS model represents a crucial step toward returning renal cell therapy to the clinical setting, initially targeting ICU patients with acute kidney injury requiring continuous renal replacement therapy. Copyright © 2014 John Wiley & Sons, Ltd.

Development of a wearable bioartificial kidney using the Bioartificial Renal Epithelial Cell System (BRECS).

Cell therapy for the treatment of renal failure in the acute setting has proved successful, with therapeutic impact, yet development of a sustainable, portable bioartificial kidney for treatment of chronic renal failure has yet to be realized. Challenges in maintaining an anticoagulated blood circuit, the typical platform for solute clearance and support of the biological components, have posed a major hurdle in advancement of this technology. This group has developed a Bioartificial Renal Epithelial Cell System (BRECS) capable of differentiated renal cell function while sustained by body fluids other than blood. To evaluate this device for potential use in end-stage renal disease, a large animal model was established that exploits peritoneal dialysis fluid for support of the biological device and delivery of cell therapy while providing uraemic control. Anephric sheep received a continuous flow peritoneal dialysis (CFPD) circuit that included a BRECS. Sheep were treated with BRECS containing 1 × 108 renal epithelial cells or acellular sham devices for up to 7 days. The BRECS cell viability and activity were maintained with extracorporeal peritoneal fluid circulation. A systemic immunological effect of BRECS therapy was observed as cell-treated sheep retained neutrophil oxidative activity better than sham-treated animals. This model demonstrates that use of the BRECS within a CFPD circuit embodies a feasible approach to a sustainable and effective wearable bioartificial kidney. Copyright © 2016 John Wiley & Sons, Ltd.

An Immunomodulatory Device Improves Insulin Resistance in Obese Porcine Model of Metabolic Syndrome.

Obesity is associated with tissue inflammation which is a crucial etiology of insulin resistance. This inflammation centers around circulating monocytes which form proinflammatory adipose tissue macrophages (ATM). Specific approaches targeting monocytes/ATM may improve insulin resistance without the adverse side effects of generalized immunosuppression. In this regard, a biomimetic membrane leukocyte processing device, called the selective cytopheretic device (SCD), was evaluated in an Ossabaw miniature swine model of insulin resistance with metabolic syndrome. Treatment with the SCD in this porcine model demonstrated a decline in circulating neutrophil activation parameters and monocyte counts. These changes were associated with improvements in insulin resistance as determined with intravenous glucose tolerance testing. These improvements were also reflected in lowering of homeostatic model assessment- (HOMA-) insulin resistant (IR) scores for up to 2 weeks after SCD therapy. These results allow for the planning of first-in-man studies in obese type 2 diabetic patients.

The bioartificial kidney.

Renal failure has an exceedingly high mortality rate despite advances in dialysis technology. Current renal replacement therapies (RRTs) restore only the filtration function of the kidney. Replacing the critical transport, metabolic, and endocrine functions of the kidney may provide more complete RRT, changing the natural history of these disease processes. Primary human renal epithelial cells (RECs) have been isolated and expanded under conditions that enhance propagation, resulting in maximum cell yield for use in bioengineered applications. These RECs demonstrate differentiated absorptive, metabolic, and endocrine functions of the kidney when tested under in vitro and preclinical ex vivo animal studies. When incorporated into bioengineered systems, RECs have proved to provide effective RRTs in both preclinical and clinical studies. These engineered "bioartificial kidneys" demonstrate metabolic activity with systemic effects and improvement of survival in patients with acute kidney injury and multiorgan failure. Results also indicate REC therapy influences systemic leukocyte activation and the balance of inflammatory cytokines, suggesting that this REC therapy may improve morbidity and mortality by altering the proinflammatory state of patients. This innovative approach for treating renal and inflammatory disease states may become a groundbreaking, transformative platform to current standard-of-care therapies, enabling the advancement of numerous lifesaving technologies.

Minimum inhibitory concentration and postantibiotic effect of amikacin for equine isolates of methicillin-resistant Staphylococcus aureus in vitro.

OBJECTIVE: To report the minimum inhibitory concentration (MIC) of amikacin sulfate for equine clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and characterize the initial kill and duration of the postantibiotic effect (PAE) for selected strains. STUDY DESIGN: Experimental study. METHODS: Isolates of MRSA (n=35) had their amikacin MIC determined using the E-test agar diffusion method. Two isolates with MICs>256 microg/mL limit were further characterized using broth macrodilution. Six distinct isolates with amikacin MICs of 32, 48, 128 (2 isolates) and 500 (2 isolates) microg/mL had PAE determinations made over a range of amikacin concentrations from 31.25-1000 microg/mL using standard culture-based techniques. RESULTS: Median MIC of the 35 isolates was 32 microg/mL (range 2 to >256 microg/mL). Mean PAE of selected MRSA strains had an overall mean (all amikacin doses) of 3.43 hours (range 0.10-9.57 hours). PAE for MRSA exposed to amikacin at 1000 microg/mL was 6.18 hours (range 3.30-9.57 hours), significantly longer than that for all other concentrations (P<.0001). There was no statistically significant effect of isolate MIC on PAE. CONCLUSIONS: Isolates had a wide range of MIC; however, growth of all 6 selected strains were inhibited within the range of concentrations tested, including 2 strains with MICs of 500 microg/mL. PAE duration was not influenced by the MIC of amikacin but was significantly longer with treatment at 1000 microg/mL than at lower concentrations. CLINICAL RELEVANCE: Clinical isolates of MRSA are susceptible to amikacin at concentrations achieved by regional perfusion: however, the modest duration of PAE observed suggest that further laboratory and in vivo evaluation be conducted before recommending the technique for clinical use.