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Construction of a liposome dialyzer for the preparation of high-value, small-volume liposome formulations.

ABSTRACT: The liposome dialyzer is a small-volume equilibrium dialysis device, built from commercially available materials, that is designed for the rapid exchange of small volumes of an extraliposomal reagent pool against a liposome preparation. The dialyzer is prepared by modification of commercially available dialysis cartridges (Slide-A-Lyzer cassettes), and it consists of a reactor with two 300-μl chambers and a 1.56-cm(2) dialysis surface area. The dialyzer is prepared in three stages: (i) disassembling the dialysis cartridges to obtain the required parts, (ii) assembling the dialyzer and (iii) sealing the dialyzer with epoxy. Preparation of the dialyzer takes ∼1.5 h, not including overnight epoxy curing. Each round of dialysis takes 1-24 h, depending on the analyte and membrane used. We previously used the dialyzer for small-volume non-enzymatic RNA synthesis reactions inside fatty acid vesicles. In this protocol, we demonstrate other applications, including removal of unencapsulated calcein from vesicles, remote loading and vesicle microscopy.

SUBMITTER: Adamala K

PROVIDER: S-EPMC4982460 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

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Construction of a liposome dialyzer for the preparation of high-value, small-volume liposome formulations.

Adamala Katarzyna K Engelhart Aaron E AE Kamat Neha P NP Jin Lin L Szostak Jack W JW

Nature protocols 20150528 6

The liposome dialyzer is a small-volume equilibrium dialysis device, built from commercially available materials, that is designed for the rapid exchange of small volumes of an extraliposomal reagent pool against a liposome preparation. The dialyzer is prepared by modification of commercially available dialysis cartridges (Slide-A-Lyzer cassettes), and it consists of a reactor with two 300-μl chambers and a 1.56-cm(2) dialysis surface area. The dialyzer is prepared in three stages: (i) disassemb ...[more]

PMID: 26020615

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Project description:BackgroundThe bulk of randomized trial evidence for the expanding use of High Flux (HF) hemodialysis worldwide comes from two randomized controlled trials, one of which (HEMODIALYSIS, HEMO) allowed, while the other (Membrane Outcomes Permeability, MPO) excluded, the reuse of membranes. It is not known whether dialyzer reuse has a differential impact on outcomes with HF vs low flyx (LF) dialyzers.MethodsProportional Hazards Models and Joint Models for longitudinal measures and survival outcomes were used in HEMO to analyze the relationship between β2-microglobulin (β2M) concentration, flux, and reuse. Meta-analysis and regression techniques were used to synthesize the evidence for HF dialysis from HEMO and MPO.FindingsIn HEMO, minimally reused (< 6 times) HF dialyzers were associated with a hazard ratio (HR) of 0.67 (95% confidence interval, 95%CI: 0.48-0.92, p = 0.015), 0.64 (95%CI: 0.44 - 0.95, p = 0.03), 0.61 (95%CI: 0.41 - 0.90, p = 0.012), 0.53 (95%CI: 0.28 - 1.02, p = 0.057) relative to minimally reused LF ones for all cause, cardiovascular, cardiac and infectious mortality respectively. These relationships reversed for extensively reused membranes (p for interaction between reuse and flux < 0.001, p = 0.005) for death from all cause and cardiovascular causes, while similar trends were noted for cardiac and infectious mortality (p of interaction between reuse and flux of 0.10 and 0.08 respectively). Reduction of β2M explained only 1/3 of the effect of minimally reused HF dialyzers on all cause mortality, while non-β2M related factors explained the apparent attenuation of the benefit with more extensively reused dialyzers. Meta-regression of HEMO and MPO estimated an adjusted HR of 0.63 (95% CI: 0.51-0.78) for non-reused HF dialyzers compared with non-reused LF membranes.ConclusionsThis secondary analysis and synthesis of two large hemodialysis trials supports the widespread use of HF dialyzers in clinical hemodialysis over the last decade. A mechanistic understanding of the effects of HF dialysis and the reuse process on dialyzers may suggest novel biomarkers for uremic toxicity and may accelerate membrane technology innovations that will improve patient outcomes.

Project description:BackgroundMyoglobin clearance in acute kidney injury requiring renal replacement therapy is important because myoglobin has direct renal toxic effects. Clinical data comparing different modalities of renal replacement therapy addressing myoglobin clearance are limited. This study aimed to compare two renal replacement modalities regarding myoglobin clearance.MethodsIn this prospective, randomized, single-blinded, single-center trial, 70 critically ill patients requiring renal replacement therapy were randomized 1:1 into an intervention arm using continuous veno-venous hemodialysis with high cutoff dialyzer and a control arm using continuous veno-venous hemodiafiltration postdilution with high-flux dialyzer. Regional citrate anticoagulation was used in both groups to maintain the extracorporeal circuit. The concentrations of myoglobin, urea, creatinine, β2-microglobulin, interleukin-6 and albumin were measured before and after the dialyzer at 1 h, 6 h, 12 h, 24 h and 48 h after initiating continuous renal replacement therapy.ResultsThirty-three patients were allocated to the control arm (CVVHDF with high-flux dialyzer) and 35 patients to the intervention arm (CVVHD with high cutoff dialyzer). Myoglobin clearance, as a primary endpoint, was significantly better in the intervention arm than in the control arm throughout the whole study period. The clearance values for urea and creatinine were higher in the control arm. There was no measurable albumin clearance in both arms. The clearance data for β2-microglobulin and interleukin-6 were non-inferior in the intervention arm compared to those for the control arm. Dialyzer lifespan was 57.0 [38.0, 72.0] hours in the control arm and 70.0 [56.75, 72.0] hours in the intervention arm (p = 0.029).ConclusionsMyoglobin clearance using continuous veno-venous hemodialysis with high cutoff dialyzer and regional citrate anticoagulation is better than that with continuous veno-venous hemodiafiltration with regional citrate anticoagulation.Trial registrationGerman Clinical Trials Registry (DRKS00012407); date of registration 23/05/2017. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00012407 .

Project description:BackgroundRegional anticoagulation with citrate during renal replacement therapy (RRT) reduces the risk of bleeding, extends dialyzer lifespan and is cost-effective. Therefore, current guidelines recommend its use if patients are not anticoagulated for another reason and if there are no contraindications against citrate. RRT with regional citrate anticoagulation has been established in critically ill patients as continuous veno-venous hemodialysis (CVVHD) to reduce citrate load. However, CVVHD is inferior regarding middle molecule clearance compared to continuous veno-venous hemofiltration (CVVH). The use of a high cut-off dialyzer in CVVHD may thus present an option for middle molecule clearance similar to CVVH. This may allow combining the advantages of both techniques.MethodsIn this prospective, randomized, single-blinded single-center-trial, sixty patients with acute renal failure and established indication for renal replacement therapy were randomized 1:1 into two groups. The control group was put on CVVHD using regional citrate anticoagulation and a high-flux dialyzer, while the intervention group was on CVVHD using regional citrate anticoagulation and a high-cut-off dialyzer. The concentrations of urea, creatinine, β2-microglobulin, myoglobin, interleukin 6 and albumin were measured pre- and post-dialyzer 1, 6, 12, 24 and 48 hours after initiating CVVHD.ResultsMean plasma clearance for β2-microglobulin was 19.6±5.8 ml/min in the intervention group vs. 12.2±3.6 ml/min in the control group (p<0.001). For myoglobin (8.0±4.5 ml/min vs. 0.2±3.6 ml/min, p<0.001) and IL-6 (1.5±4.3 vs. -2.5±3.5 ml/min, p = 0.002) a higher mean plasma clearance using high-cut-off dialyzer could be detected too, but no difference for urea, creatinine and albumin could be observed concerning this parameter between the two groups.ConclusionCVVHD using a high cut-off dialyzer results in more effective middle molecule clearance than that with high-flux dialyzer.Trial registrationGerman Clinical Trials Register (DRKS00005254, registered 26th November 2013).

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Construction of a liposome dialyzer for the preparation of high-value, small-volume liposome formulations.

Publications

Construction of a liposome dialyzer for the preparation of high-value, small-volume liposome formulations.

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