Effects of Extracorporeal Blood Flow Rates on Patient Tolerance for LIXELLE® Treatment during Outpatient Hemodialysis

INTRODUCTION

Accumulation of β2-microglobulin (B2M) in dialysis patients contributes to several comorbidities of end-stage kidney disease (ESKD). The LIXELLE® device adsorbs B2M from blood using sorbent bead technology. Studies in Japan showed that LIXELLE treatment during hemodialysis (HD) at blood flow rates up to 250 mL/min removes B2M above HD alone and is well tolerated. We investigated tolerance for LIXELLE treatment during HD at higher HD blood flow rates standard in the USA.

METHODS

A prospective, open-label, non-randomized, single-arm, early-feasibility study (EFS) assessed tolerance and safety of LIXELLE treatment during HD at blood flow rates up to 450 mL/min. ESKD patients (40-75 years old) on thrice weekly outpatient HD were eligible. After a 1-week HD run-in, patients received LIXELLE plus HD at a blood flow rate of 250 mL/min (1 week), followed by LIXELLE plus HD at a blood flow rate up to 450 mL/min (1 week). These blood flow rates were tested with three LIXELLE column sizes in sequence (treatment = 6 weeks). B2M removal was assessed for each combination.

RESULTS

Ten patients with a historic intradialytic hypotension (IDH) rate of 0.42 events/HD session/patient were enrolled. Nine patients completed all combinations without IDH events (treatment IDH rate: 0.56 events/HD session/patient). No treatment-emergent serious adverse events or significant changes in red blood cell, platelet, or complement indices except haptoglobin were reported. B2M reduction ratios and removal of select proteins (<40 kDa) increased with escalating column size and blood flow rate.

CONCLUSION

LIXELLE plus HD across all column sizes was safe and well tolerated at blood flow rates up to 450 mL/min. Extent of B2M removal corresponded to column size-blood flow rate combinations. This EFS provides a risk profile to guide further studies of LIXELLE in ESKD patients at US-standard blood flow rates.

Uremic Toxicity: Present State of the Art

The uremic syndrome is a complex mixture of organ dysfunctions, which is attributed to the retention of a myriad of compounds that under normal condition are excreted by the healthy kidneys (uremic toxins). In the area of identification and characterization of uremic toxins and in the knowledge of their pathophysiologic importance, major steps forward have been made during recent years. The present article is a review of several of these steps, especially in the area of information about the compounds that could play a role in the development of cardiovascular complications. It is written by those members of the Uremic Toxins Group, which has been created by the European Society for Artificial Organs (ESAO). Each of the 16 authors has written a state of the art in his/her major area of interest.

Beta2-microglobulin removal and plasma albumin levels with high cut-off hemodialysis

PURPOSE

beta2-microglobulin (beta2MG) is pivotal to the pathogenesis of dialysis-related amyloidosis. We compared the effects of high cut-off hemodialysis (HCO-HD) with those of standard high-flux hemodialysis (HF-HD) regarding the concentration and clearance of beta2MG and albumin.

DESIGN

We enrolled ten patients with acute renal failure in a double-blind, cross-over, randomized controlled trial.

PROCEDURES

Each patient received four hours of HCO-HD (estimated in vivo cutoff 50-60 kDa) and four hours of HF-HD (estimated in vivo cutoff 15-20 kDa) in random order. Statistical methods and outcome measures: As data lacked normal distribution, we used nonparametric statistical analysis. Plasma and dialysate concentrations of beta2MG and albumin were measured at baseline and after four hours of each study treatment.

MAIN FINDINGS

We found significantly greater diffusive beta2MG clearances for HCO-HD compared to HF-HD (at the start: 71.8 ml/min vs. 5.1 ml/min; P=0.008 and at the end: 68.8 ml/min vs. 5.7 ml/min; P=0.008). We found a reduction in plasma beta2MG concentrations of -31.6% during HCO-HD compared to an increase by 25.7% during HF-HD; P=0.008. At baseline (HCO-HD: 26.0 g/L vs. HF-HD: 26.5 g/L), and at the end of both treatments, plasma albumin concentrations were comparable (HCO-HD: 25.5 g/L vs. HF-HD: 26.5 g/L; P=0.25). During HCO-HD, albumin clearance was 1.9 ml/min at the start and decreased significantly to 0.8 ml/min at the end; P=0.008. HF-HD had an albumin clearance of 0.01 ml/min.

CONCLUSIONS

HCO-HD was more effective in decreasing plasma beta2MG concentrations than standard HF-HD and did not reduce plasma albumin levels. Further studies of HCO-HD in the treatment of dialysis-related beta2MG accumulation appear warranted.

Blood purification for critical illness: cytokines adsorption therapy

Blood purification therapies have been clinically applied to treat cytokine-induced pathological effects. The effects of broad-spectrum adsorption using Lixelle (beta2-microglobulin adsorption column; Kaneka Corporation, Osaka, Japan) for the condition of hypercytokinemia in vitro, in an animal model and in humans with sepsis were investigated. We found that Lixelle could selectively adsorb not only beta2-microglobulin but also cytokines composed of glycoproteins in vitro. In addition, Lixelle beads could adsorb not only endotoxin (ET) but also microbial fragments such as peptidoglycan (PG) which is a component of Gram-positive bacteria. Hypercytokinemic rats were connected to a direct hemoperfusion (DHP) system using a mini Lixelle column and time-course changes in plasma levels of inflammatory cytokines were examined. In addition, a Lixelle column was used in direct hemoperfusion in patients with systemic inflammatory response syndrome (SIRS), and the relationship between a decrease in cytokines and clinical course was examined. The increases in plasma levels of IL-6 and tumor necrosis factor-alpha (TNF-alpha) were significantly inhibited in the group treated with the Lixelle column in an animal model. In humans with sepsis, for IL-1beta, IL-1Ra, IL-6, IL-8, and TNF-alpha, the adsorbing rates in vivo before and after the use of the Lixelle column tended to decrease with time. However, the reduction rates at 5 min after the start were 31.4, 39.3, 36.4, 76.2 and 71.6%, respectively, and at 3 h after the start, the rates were 18.0, 17.7, 12.9, 31.8, and 32.9%, respectively. Clinically, their blood pressure increased and they recovered from shock status. These results suggest that SIRS and sepsis with hypercytokinemia can be treated with the DHP using the Lixelle column.

A novel adsorbent of circulating bacterial toxins and cytokines: the effect of direct hemoperfusion with CTR column for the treatment of experimental endotoxemia

OBJECTIVES

The current study examined the ability of a new adsorbent, CTR, to remove enterotoxins, toxic shock syndrome toxin-1 (TSST-1), and cytokines from blood and/or serum in vitro and the effects of the extracorporeal treatment with CTR column on mortality rate and inflammatory responses to endotoxic shock in vivo.

DESIGN

Laboratory investigation.

SETTING

University and company experimental laboratory.

MATERIALS

CTR is composed of porous cellulose beads to which a hydrophobic organic compound with a hexadecyl alkyl chain has been covalently bound to the surface as a ligand. Human/bovine serum and human blood samples in vitro and Male Wistar rats were used.

INTERVENTIONS

CTR's ability to adsorb bacterial toxins and cytokines related to sepsis in serum and/or blood was examined with an in vitro batch adsorption protocol. In vivo, male Wistar rats were anesthetized and assigned to one of three groups (n=14 per group): Escherichia coli endotoxin (15 mg/kg intravenously) alone (endotoxemic), apheresis with control column without CTR for 120 mins (control column), or extracorporeal treatment with CTR column for 120 mins (CTR treatment).

MEASUREMENTS AND MAIN RESULTS

With use of the CTR adsorbent, the adsorption rates were 50% to 90% for enterotoxins, TSST-1, and cytokines such as TNF-alpha and interleukin (IL)-6 in the batch tests. In vivo, the mortality rates at 8 hrs after endotoxin injection were 92%, 92%, and 14% for the endotoxemic, control column, and CTR treatment groups, respectively. Hypotension and elevated plasma cytokine concentrations and the infiltration of neutrophils of the lungs were less conspicuous in the CTR treatment group than in the other two groups.

CONCLUSIONS

CTR, a novel adsorbent, effectively adsorbed small- to middle-sized proteins, such as cytokines, enterotoxins, and TSST-1 in vitro. Direct hemoperfusion apheresis with CTR column reduced mortality and had inhibitory effects on the inflammatory responses during endotoxemia in vivo. These findings suggest that extracorporeal blood purification with CTR column may be available to use for patients with sepsis and/or endotoxemia.

β2-Microglobulin-selective direct hemoperfusion column for the treatment of dialysis-related amyloidosis

Lixelle is a direct hemoperfusion-type adsorption column that was developed to selectively eliminate beta2-microglobulin (beta2-m) from the circulating blood of patients with dialysis-related amyloidosis (DRA). The adsorbent in Lixelle comprises porous cellulose beads to which hydrophobic hexadecyl alkyl chain is covalently bound. One milliliter of wet Lixelle beads eliminates more than 1 mg of beta2-m in vitro. In hemodialysis patients who were treated with Lixelle, Lixelle improved joint pain, nocturnal awakening, pinch strength, motor terminal latency, and their activity of daily living. The adsorbent adsorbs beta2-m selectively but not specifically, as well as inflammatory cytokines such as interleukin-1beta and IL-6 which are considered to be involved in the development of DRA. Lixelle treatments reduce the circulating levels of beta2-m and inflammatory cytokines, thereby improving the symptoms of patients with DRA.

Dialysis-related amyloidosis of the temporomandibular joint

Dialysis-related amyloidosis (DRA) is a serious complication occurring most commonly in patients undergoing long-term hemodialysis. We describe a case of amyloidosis of the bilateral temporomandibular joint (TMJ) that developed after long-term hemodialysis therapy.

Beta2-microglobulin adsorption column reduces digoxin trough level during hemodialysis: three case reports

We have previously reported that a beta2-microglobulin adsorption column for the treatment of dialysis-related amyloidosis decreased serum digoxin concentration in renal failure patients. Because the distribution volume of digoxin is high, it is uncertain whether the repetitive use of this column influences the pharmacokinetics of digoxin in renal failure patients. We have observed 3 renal failure patients whose trough serum digoxin concentrations were significantly reduced by the repetitive use of tandem beta2-microglobulin adsorption columns for treatment of dialysis-related amyloidosis. These patients experienced symptomatic elevation of their heart rates in parallel with a significant reduction in serum digoxin concentrations. Termination of the use of the adsorption column improved the symptoms in 1 patient; however, severe arthritic pain caused by amyloidosis relapsed. Dosage of digoxin was increased in 2 other patients with continuous treatment by the column. Their digoxin concentrations increased, and their heart rates decreased without any deterioration of joint pain. We have demonstrated that the repetitive use of the beta2-microglobulin adsorption column in tandem with standard hemodialysis actually decreases trough digoxin concentration in renal failure patients. Careful monitoring and alteration of digoxin dosage regimens are needed under these circumstances.

Arresting Dialysis-Related Amyloidosis: A Prospective Multicenter Controlled Trial of Direct Hemoperfusion with a beta2-Microglobulin Adsorption Column

We investigated the clinical efficacy of direct hemoperfusion with a beta2-microglobulin (beta2-m) adsorption column for the treatment of patients with dialysis-related amyloidosis. A 2-year prospective controlled study was performed to compare the effects of passaging blood through a (beta2-m) adsorption column (Lixelle) before it is passaged through the dialysis polysulfone membrane on the severity of amyloidosis in these individuals. Patients (n = 22) whose blood went through the Lixelle column prior to dialysis had a higher beta2-m removal rate compared to an equal number of controls, and they showed earlier improvement in their symptoms which included impaired daily activities, joint stiffness, and pain. The appearance of additional bone cysts was prevented in pre-adsorbed patients but not in the controls. Thus, the Lixelle column is useful in preventing the progression of dialysis-related amyloidosis and in ameliorating or arresting the progression of the symptoms of this disorder.

Beta2-microglobulin clearance with super high flux hemodialysis: an ex vivo study

BACKGROUND

Beta2m accumulation induces disease in patients with end-stage renal failure (ESRF). Thus, its removal from patients with ESRF appears desirable. Current dialysis technology, however, has limited effectiveness.

AIMS

To measure beta2m clearance with a novel super high flux membrane.

DESIGN

Ex vivo experimental study.

SETTING

Intensive Care Laboratory of Tertiary institution.

SUBJECTS

Six volunteers.

MEASUREMENTS AND RESULTS

At a blood flow of 300 ml/min, the clearance of beta2-MG increased from 113.5 +/- 38.5 ml/min with a dialysate flow rate of 200 ml/min to 184.8 +/- 61.1 ml/min with a flow rate of 300 ml/min and 195.0 +/- 60.0 ml/min with a 500 ml/min flow rate. The clearance of albumin was 4.5 ml/min with a dialysate flow rate of 200 ml/min, 5.2 ml/min for a flow rate of 300 ml/min and 5.8 ml/min for a flow rate of 500 ml/min.

CONCLUSIONS

High levels of beta2m clearance can be achieved with a super high flux membrane while albumin losses remain limited.

Beta-2 microglobulin in ESRD: an in-depth review

Beta-2 microglobulin is the most widely studied low-molecular-weight protein in end-stage renal disease. It is known to cause dialysis-related amyloidosis (DRA), by virtue of its retention when renal function fails, its deposition in tissues, its aggregation into fibrils, and its ability to become glycosylated. The onset of DRA may be protracted by the use of noncellulosic membranes, especially when high-volume hemodiafiltration is used in the treatment of renal failure. Adsorptive methods have been developed to improve the removal of beta-2 microglobulin. There seems to be a relative risk reduction in mortality when patients are treated with dialysis membranes that have a higher clearance of beta-2 microglobulin.

Effect of beta(2)-microglobulin adsorption column on dialysis-related amyloidosis

BACKGROUND

beta2-microglobulin (beta2-m) is considered a major pathogenic factor in dialysis-related amyloidosis (DRA), often seen in long-term dialysis patients. No effective therapy for this severely debilitating disease is currently available. Lixelle, an adsorption column, has been developed for the elimination of beta2-m; the efficacy of this column has been evaluated in this study.

METHODS

Seventeen hemodialysis patients with DRA were first treated with high-flux dialysis for a minimum of 1 year. This was followed by 1-year treatment with Lixelle column connected in series to the high-flux dialyzer. Treatments were used three times a week for both phases of this study. During the study period, beta2-m, pinch strength, motor terminal latency, and activities of daily living were evaluated.

RESULTS

After 1-year treatment with high-flux dialysis the beta2-m level remained unchanged; however, after 1-year treatment with the addition of the Lixelle column, beta2-m level decreased significantly from 34.5 +/- 8.4 mg/L to 28.8 +/- 7.3 mg/L (P < 0.05). After 1 year of Lixelle column use, the pinch strength increased from 6.8 +/- 4.7 pounds to 9.1 +/- 5.5 pounds (P < 0.01), and the median motor terminal latency was significantly reduced from 5.1 +/- 1.0 mseconds to 4.5 +/- 1.1 mseconds. A significant improvement was also observed in the activities of daily living score of the upper extremities.

CONCLUSION

These results suggest that the addition of Lixelle to the high-flux dialyzer is associated with a significant clinical improvement in DRA patients.

Beta2-microglobulin-selective adsorbent column (Lixelle) for the treatment of dialysis-related amyloidosis

Lixelle is a direct hemoperfusion-type adsorbent column developed for selective elimination of beta2-microglobulin (beta2-m) from the circulating blood of patients with dialysis-related amyloidosis (DRA). Lixelle S-35, that has a column volume of 350 mL, efficiently eliminates beta2-m and improves symptoms of DRA such as joint pain and nocturnal awakening. The performance of Lixelle S-15, that has a column volume of 150 mL, is dependent on the dialysis membrane used in combination with the adsorbent column in a hemodialysis circuit. The combination of S-15 and a dialysis membrane with a high beta2-m clearance eliminates an amount of beta2-m that is nearly equal to the amount removed by using S-35. Treatment with S-15 for 6 months improved joint pain with an efficacy similar to that observed when using S-35. The major adverse effects were hypotension and decrease in hematocrit, and these incidences were much less in S-15 compared to S-35.

Adsorption of endotoxin by beta2-microglobulin adsorbent column (Lixelle): the new approach for endotoxinemia

We previously reported that Lixelle, which was used for beta2-microglobulin (BMG) adsorption columns, could adsorb not only BMG but also inflammatory cytokines. We became interested in the application of Lixelle for patients with endotoxinemia and researched its ability to adsorb microorganism components in vitro using lipopolysaccharide (LPS) (Escherichia coli B8), endotoxin (ET) contaminated water. The initial concentrations of each water solution were LPS (ET 29,135 EU/L) and contaminated water (ET 3,523 EU/L) whole blood solution was LPS (ET 1,197.6 EU/L). Each 2.5 ml of the stock solution and adjusted diluted solutions contained 0.5 ml of Lixelle beads. After shaking at 37 degrees C for 2 h, ET in the solutions was determined using the endotoxin specific-limulus amebocyte lysate method. The results revealed that even though ET concentrations in LPS and contaminated water incubated in water solution and in whole blood were high, the samples containing Lixelle beads showed significant decreases. Thus, Lixelle beads can adsorb not only BMG but also microorganism components such as LPS and ET. These findings together with the ability of Lixelle to adsorb ET show the possibility of the application for treatment of endotoxinemia.

Plasmapheresis in the dysproteinemias

The dysproteinemias consist of a broad range of serious disease states with the common thread of excessive production of an abnormal, or para-protein. Various clinical syndromes may arise, either from the underlying disease process, the excess paraprotein, or both. Clinical presentation depends upon the organ system(s) affected by the abnormal protein. Diseases included under the classification of dysproteinemias include cryoprotein-related diseases, Waldenström's macroglobulinemia, hyperviscosity syndrome, monoclonal gammopathy, multiple myeloma, light chain disease, and amyloidosis. Plasmapheresis, often in conjunction with other therapies, has been widely used to treat the dysproteinemias and their resulting clinical syndromes. Automated plasmapheresis, which separates plasma from the cellular blood elements by centrifugation, is used most commonly in the United States. Membrane separation and immunoadsorption techniques are more commonly used in Europe and Japan. In automated plasmapheresis, the plasma is removed from the patient's circulation and replaced with a protein-based fluid such as 5% human albumin solution or plasma protein fraction or with fresh frozen plasma. Membrane separation and immunoadsorption allow the offending proteins to be removed more selectively from the patient's plasma prior to the plasma being returned to the patient. This review article presents a description of each disease, the rationale for plasmapheresis therapy, recommended schedules of plasmapheresis, and the use of adjunctive therapies. Results of published studies, case reports, and the author's experience in treating these diseases will serve as the foundation for discussion.

Nontransplant therapy for dialysis-related amyloidosis

There is no specific treatment for dialysis-related amyloidosis (DRA). Available therapy is directed at removal of large quantities of beta(2)-microglobulin (beta(2)M) and palliation of symptoms. Plasma concentrations of beta(2)M in end-stage renal disease (ESRD) depend on the degree of residual renal function, the type of blood purification therapy, and properties of the dialysis filtration membrane. Retention of beta(2)M appears to be a necessary, although not sufficient, condition for DRA. While preserving residual renal function is important, dialysis modality largely determines beta(2)M removal. Convective dialysis treatments (hemofiltration and hemodiafiltration) remove beta(2)M more efficiently than diffusive treatments (conventional dialysis). In addition, column adsorption of beta(2)M can extensively remove the molecule, as can nocturnal hemodialysis. Hemodialysis membrane properties that are particularly important with regard to beta(2)M removal include permeability, adsorptive capacity, and biocompatibility. As such, beta(2)M removal with highly permeable biocompatible membranes such as polysulfone and polyacrylonitrile is relatively large. Several studies have suggested that use of such membranes can significantly delay DRA development and may be useful in ameliorating DRA-associated symptoms. Non-dialysis-related therapy for DRA is palliative and includes both medical and surgical therapies. Medical therapy includes low-dose corticosteroids and nonsteroidal anti-inflammatory drugs (NSAIDs). Surgical therapy consists of relief of carpal tunnel syndrome, or palliation of shoulder pain, destroyed weight-bearing joints, or spinal cord compression. DRA is a serious complication of long-term dialysis. It is important for nephrologists to recognize the condition and attempt to slow its progression.

Modalities for the removal of beta 2-microglobulin from blood

The long-term accumulation of beta(2)-microglobulin (beta(2)M) in patients with kidney failure results in a debilitating condition referred to as dialysis-related amyloidosis (DRA). There have been few methods specifically designed to remove the large quantities of beta(2)M that are produced by the body. This article briefly reviews current modalities and concepts for the removal of beta(2)M from blood. The various approaches are classified according to the mechanism of beta(2)M clearance. The potential application of immunoadsorption, a biologically specific approach to remove macromolecules, in the treatment and understanding of DRA is discussed.

Effect of hemodialysis membranes on beta 2-microglobulin amyloidosis

Early after the identification of beta(2)-microglobulin amyloidosis (A beta(2)M) as the cause of carpal tunnel syndrome, it was thought that hemodialysis was a major cause in the development of the disease. It was subsequently shown that hemodialysis was not necessary for the development of dialysis-related amyloidosis; however, it was believed that the different dialysis membranes did modulate the progression of the disease. Current data demonstrate that hemodialysis fails to prevent or reverse the disease, but there is substantial evidence that high-flux, high-efficiency dialyzers slow its progression. Many factors related to hemodialysis have been evaluated in relation to A beta(2)M, including the effect of the bioincompatibility of the membrane, the capacity of the different membranes to remove beta(2)M, and the effect of reuse on beta(2)M levels. Moreover, there have been intensive efforts to evaluate, explore, and improve the different mechanisms in beta(2)M removal, with adsorption as a promising prospect. With the available evidence, it seems that the removal of beta(2)M by the membrane plays the most important role in modulating the disease outcome and rate of progression, although a large, long-term, multicentered and randomized study is still lacking to prove this relationship. However, it is possible that with the continuing advances in optimizing the beta(2)M removal efficiency of the different membranes, the frequency and severity of the disease can be substantially decreased.

Adsorption of microorganism components by lixelle beads

We reported previously that Lixelle, which was used for beta-2 microglobulin (BMG) adsorption columns, could adsorb not only BMG but also inflammatory cytokines. We then were interested in the application of Lixelle to patients with systemic inflammatory response syndrome (SIRS) and tried to find out its ability to adsorb microorganism components in vitro using lipopolysaccharide (LPS) (E. coli: B8), endotoxin (ET) containing water, and peptidoglycan (PG: Micrococcus luteus). The initial concentrations of each solution were LPS (ET: 29,135 EU/L), contaminated water (ET: 3,523 EU/L), and PG (67.1 ng/ml) and 2.5 ml of each of the stock solutions and adjusted diluted solutions contained 0.5 ml of Lixelle beads. After shaking at 37 degrees C for 2 h, ET in the solutions was determined by the ET specific-limulus amebocyte lysate (ES-LAL) method and PG by the silkworm larbae plasma (SLP) method. The results revealed that even when ET concentrations in LPS and contaminated water were high, the samples containing Lixelle beads showed significant decreases. There was some adsorption of PG but no significant differences. Thus, Lixelle beads can adsorb not only BMG but also microorganism components such as ET and PG. These findings, together with the ability to adsorb inflammatory cytokines by Lixelle, show the possibility of application for the treatment of infectious SIRS.

Osteoarticular disorders of renal origin: disease-related and iatrogenic

Osteoarticular disorders significantly limit the quality of long-term survival with chronic renal failure. beta 2M amyloidosis is a complication of chronic renal failure that has been recognized mostly in patients receiving long-term haemodialysis. Patients with beta 2M amyloidosis typically present with the triad of shoulder periarthritis, carpal tunnel syndrome, and flexor tenosynovitis of the hands. Other musculoskeletal manifestations of beta 2M amyloidosis include destructive spondyloarthropathy, cervico-occipital pseudotumours, bone cysts, and pathological fractures. At present, only renal transplantation may slow or halt the progession of beta 2M amyloidosis. Crystal-induced arthropathy, most commonly caused by basic calcium phosphate crystals, is an important cause of acute joint inflammation in the patient with renal failure. The incidence of bone and joint infection is increased in patients undergoing dialysis. Haemodialysis and peritoneal dialysis are also associated with an erosive or destructive arthropathy of finger joints, which is not explained by local amyloid deposition.

Polymeric adsorbent for removing toxic proteins from blood of patients with kidney failure

A hypercrosslinked styrenic polymer with an enhanced proportion of mesopores in the range 2-20 nm has been developed. The principle of the synthesis consists of the suspension polymerization of divinylbenzene (or copolymerization of styrene with divinylbenzene) in the presence of a porogen that is a theta-solvent for polystyrene. On the scale of thermodynamic affinity, theta-solvents occupy a border position between good solvents and precipitating media for the growing polymer chains. In this case, microphase separation takes place during the final stages of the polymerization process. The polymer was shown to adsorb 93-98% of beta2-microglobulin from the blood or plasma of patients with chronic kidney failure. At the same time, large essential proteins, like albumin, are not removed to a significant extent, obviously, due to the size-exclusion effect and the difference in the hydrophobicity of the proteins. By replacing surface exposed pendant vinyl groups of the polymer with hydrophilic functional groups, the material was made hemocompatible, according to the standard battery of biocompatibility tests required by ISO 10993 guidelines. No adverse effects such as fever or hypotension were noted in dogs in direct hemoperfusion experiments with the polymer.

Plasmapheresis and paraproteinemia: cryoprotein-induced diseases, monoclonal gammopathy, Waldenström's macroglobulinemia, hyperviscosity syndrome, multiple myeloma, light chain disease, and amyloidosis

Therapeutic plasmapheresis has been in widespread use as either a primary or adjunctive therapy in the United States since the 1960s. There are several types of plasmapheresis procedures used to treat various diseases. Plasma exchange with a centrifugal plasma separator using replacement fluid such as human albumin solution is the most widely used method in the United States. Other forms of plasmapheresis include membrane plasma separation, membrane fractionation, cryofiltration apheresis, immunoadsorption, and chemical affinity column pheresis. Therapeutic plasmapheresis has been used for the treatment of paraproteinemia to remove harmful paraproteins. Paraproteinemia is a disease classification in which abnormal or large amounts of plasma proteins such as cryoproteins or immunoglobulins are produced. In most cases, plasmapheresis is used in combination with corticosteroids and immunosuppressive drugs to prevent production of abnormal proteins or to treat the underlying disease. Cryoprotein-induced diseases, which include cryoglobulinemia, cryofibrinogenemia, and cold IgM antibody agglutinin with cryoglobulin properties, are a subclass of paraproteinemia. Other categories of paraproteinemia include monoclonal gammopathy, Waldenström's macroglobulinemia, hyperviscosity syndrome, multiple myeloma, light chain disease, and amyloidosis. Some of these diseases may be interrelated, and they may be associated with one another. In this review paper, we discuss the role of plasmapheresis in the specific classes of paraproteinemia in the United States, including our own experience.

The removal of beta-2-microglobulin by an immunoadsorption wall

The accumulation of beta-2-microglobulin (beta2M) in collagen-rich tissues has been proven to be the main cause of dialysis related amyloidosis. However, it remains uncertain which technique for the removal of beta2M can be used without compromising the advantages of other dialysis strategies. A new concept, an immunoadsorption wall, which combines the principles of immunoisolation and immunoadsorption is proposed to remove beta2M. The present investigations suggested that the application of the concept to clinical use is feasible and worthwhile. The concept, if validated, will help shape a novel multitask type of artificial kidney based on the combination of different separation technologies.

Lixelle adsorbent to remove inflammatory cytokines

A beta2-microglobulin (beta2M) selective adsorbent (Lixelle) for direct hemoperfusion has been used for the treatment of hemodialysis patients with the long-term complication of dialysis related amyloidosis (DRA), but there is no significant correlation between the serum level of beta2M and the occurrence of DRA. Inflammatory cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor alpha (TNFalpha) are related to the development of DRA. We studied the adsorptive rates of cytokines in vitro using the Lixelle adsorbent. The adsorptive rates were 98.5% for IL-1beta 98.0% for interleukin-1 receptor antagonist (IL-1RA), 82.9% for IL-6, 99.9% for IL-8, 31.2% for TNFalpha, and 46.1% for soluble TNF receptor (sTNFr), respectively. As the molecular weights of cytokines increase, the adsorptive rates decrease. The Lixelle column adsorbed beta2M and various inflammatory cytokines as well. Therefore, the removal of both beta2M and inflammatory cytokines may play an important role in the treatment of DRA.

New adsorption column (Lixelle) to eliminate beta2-microglobulin for direct hemoperfusion

The Lixelle column is an adsorbent column used to eliminate beta2-microglobulin (beta2M) selectively from circulating blood of dialysis related amyloidosis (DRA) patients, which is used in combination with a dialyzer in series. The column has such a high capacity for adsorbing beta2M that the most intensive removal of beta2M has been possible. In clinical trials of the column, the obvious improvement of subjective symptoms such as decreases in the frequency of nocturnal awakening, the joint pain severity index, and the joint mobility index were observed. Hypotension has been the most frequent adverse event observed during treatment since the column was put on the market. It is very important to clarify the causes of both the efficacy and the side effects. A controlled prospective study is now in progress to clarify the efficacy more scientifically. The results will be published soon elsewhere.

Long-term clinical evaluation of an adsorbent column (BM-01) of direct hemoperfusion type for beta 2-microglobulin on the treatment of dialysis-related amyloidosis

The clinical efficacy and safety of a beta 2-microglobulin (beta 2M) adsorbent column, BM-01, on the treatment of dialysis-related amyloidosis were investigated in 7 hemodialysis patients for more than 6 months. The percent reduction of serum beta 2M was more than 60-70%, and the level at the end of each session was less than 10 mg/L in almost all patients. The amount of beta 2M removed was calculated as more than 200-300 mg/session. The results demonstrated that BM-01 performed very well for removing beta 2M, was capable of maintaining less than 25 mg/L of time average concentration (TAC) for beta 2M, and improved the clinical symptoms. Clinically severe side effects were not observed. We recommend that BM-01 should undergo further evaluation for its usefulness in the long-term treatment of dialysis-related amyloidosis, though treatment with the column may not be successful in preventing the onset of the disease.