From membrane differential filtration to lipidfiltration: technological progress in low-density lipoprotein apheresis

Comparison of double-filtration plasmapheresis (DFPP) versus heparin-mediated extracorporeal LDL-precipitation (HELP)-apheresis in early-onset preeclampsia

OBJECTIVES

Preeclampsia (PE) is a major cause of maternal and fetal mortality, and preterm birth. Previous studies indicate that lipid-apheresis may prolong pregnancy, namely heparin-mediated extracorporeal LDL-precipitation (HELP)- and dextran sulfate cellulose (DSC)-apheresis. We now report on double membrane plasmapheresis (DFPP) in early-onset preeclampsia (eoPE).

STUDY DESIGN

Open pilot study assessing the prolongation of pregnancy in PE by lipoprotein-apheresis (DRKS00004527). Two women with eoPE were treated by DFPP and compared to a historical cohort of 6 patients with eoPE treated by HELP-apheresis (NCT01967355).

MAIN OUTCOME MEASURES

Clinical outcome of mothers and babies and prolongation of pregnancies (time of admission to birth).

RESULTS

Patient 1 (33y; 22 + 5/7GW) received 4 DFPP. Delivery day 19; birthweight 270 g; weight at discharge 2134 g on day 132. Patient 2 (35y; 21 + 4/7GW) received 2 DFPP. Delivery day 19; birthweight 465 g; weight at discharge 2540 g on day 104. DFPP was well tolerated by both patients.

CONCLUSIONS

DFPP proved to be save and pregnancies remained stable as long as 19 days. Although babies were born very preterm both babies could finally be dismissed from hospital. No relevant clinical differences between DFPP and HELP-apheresis could be observed. Therefore, DFPP may extend the range of available apheresis techniques to prolong pregnancies in early-onset preeclampsia. However, further studies are necessary to gain more information. REGISTER: (DRKS00004527).

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolaemia: An expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is used for decades, lowering serum LDL-C levels by more than 70% directly after the treatment. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment goals and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

Clinical practice recommendations on lipoprotein apheresis for children with homozygous familial hypercholesterolemia: an expert consensus statement from ERKNet and ESPN

Homozygous familial hypercholesterolaemia is a life-threatening genetic condition, which causes extremely elevated LDL-C levels and atherosclerotic cardiovascular disease very early in life. It is vital to start effective lipid-lowering treatment from diagnosis onwards. Even with dietary and current multimodal pharmaceutical lipid-lowering therapies, LDL-C treatment goals cannot be achieved in many children. Lipoprotein apheresis is an extracorporeal lipid-lowering treatment, which is well established since three decades, lowering serum LDL-C levels by more than 70% per session. Data on the use of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia mainly consists of case-reports and case-series, precluding strong evidence-based guidelines. We present a consensus statement on lipoprotein apheresis in children based on the current available evidence and opinions from experts in lipoprotein apheresis from over the world. It comprises practical statements regarding the indication, methods, treatment targets and follow-up of lipoprotein apheresis in children with homozygous familial hypercholesterolaemia and on the role of lipoprotein(a) and liver transplantation.

Comparison of plasma separation using centrifugation or filtration for MONET lipoprotein apheresis in patients with cardiovascular disease and severe dyslipidemia

INTRODUCTION

Homozygous or severe heterozygous familial hypercholesterolemia and elevated lipoprotein(a) levels may be treated with membrane filtration. The MONET system (Fresenius Medical Care, Bad Homburg, Germany) involves plasma separation by centrifugation or filtration.

METHODS

Whether the method of plasma separation affects lipoprotein lowering and treatment safety was investigated in a single-center retrospective study.

RESULTS

The centrifugation-based plasma separation achieved a higher plasma flow and shorter time to treat 1 L of plasma (46.2 ± 8.6 min), than the filtration-based system (71.5 ± 40.0 min; p = 0.001). The mean reduction of LDL-cholesterol was 69% and 67% with centrifugation and filtration and was 75% for lipoprotein(a) with both plasma separation methods. A reduction of IgM by more than 60%, of albumin and total protein by approximately 20% and low frequency of side effects was observed.

CONCLUSIONS

The efficacy of lowering atherogenic lipoproteins was comparable with both plasma separation methods. Centrifugation was more time-efficient compared to filtration.

Long-term lipoprotein apheresis in the treatment of severe familial hypercholesterolemia refractory to high intensity statin therapy: Three year experience at a lipoprotein apheresis centre

BACKGROUND

Severe familial hypercholesterolemia (FH) individuals, refractory to conventional lipidlowering medications are at exceptionally high risk of cardiovascular events. The established therapeutic option of last choice is lipoprotein apheresis (LA). Herein, it was sought to investigate the clinical usefulness of LA in a highly selected group of severe heterozygous FH (HeFH), as recently described by the International Atherosclerosis Society (IAS), for their efficacy in lipid reduction and safety.

METHODS

Efficacy and safety of LA were investigated in 318 sessions of 7 severe HeFH females with cardiovascular disease, over a mean period of 26.9 ± 6.5 months. Relative reduction of low density lipoprotein cholesterol (LDL-C) ≥ 60%, clinical complications and vascular access problems were evaluated and compared between the direct adsorption of lipoproteins (DALI) and lipoprotein filtration (Membrane Filtration Optimized Novel Extracorporeal Treatment [MONET]). Additionally, lipoprotein (a) [Lp(a)], total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), triglycerides (TG) and fibrinogen concentrations were investigated.

RESULTS

The relative reduction of LDL-C, TC, TG and Lp(a) were 69.4 ± 12.9%, 59.7 ± 9.1, 51.5 ± ± 14.2% and 71.3 ± 14.4%, respectively. A similar efficacy was found in both systems in LDL-C removal. DALI system led to larger depletions of Lp(a) (80.0 [76-83]% vs. 73.0 [64.7-78.8]%; p < 0.001). The frequency of clinical side effects and vascular access problems were low (8.5%).

CONCLUSIONS

Long-term LA in severe HeFH individuals is safe and efficiently reduces LDL-C and Lp(a). Higher efficacy of the DALI system than MONET in Lp(a) removal may indicate the need for individualized application of the LA system in severe HeFH individuals.

Antioxidant defense system in familial hypercholesterolemia and the effects of lipoprotein apheresis

Oxidative stress is thought to play an important role in the pathogenesis of disorders associated with atherosclerosis. Alpha-tocopherol is considered to be an effective lipophilic antioxidant, which protects lipid membranes against peroxidation and thus prevents cell damage by reaction with free radicals. However, measurement of alpha-tocopherol concentration in serum does not reflect the content of α-tocopherol in membranes whereas erythrocyte alpha-tocopherol may be good indicator of antioxidative status. Therefore a simple isocratic reversed phase HPLC method has been developed and validated for the determination of alpha-tocopherol in human erythrocytes in a clinical setting. The content of alpha-tocopherol in human erythrocyte membrane and lipoperoxidation were studied in patients with severe hypercholesterolemia treated by lipoprotein apheresis. The group of hypercholesterolemic patients (n = 14) treated by lipoprotein apheresis was compared to healthy adult normolipidemic controls. After lipoprotein apheresis, the content of in membrane alpha-tocopherol did not change significantly despite decreased tocopherol in serum and lipoprotein fractions. We observed significantly decreased lipoperoxidation as revealed by serum TBARS, representing end products of lipid peroxidation, which increased from third day afterwards and remained significantly higher in comparison to controls until the next LDL-apheresis. We conclude that aggressive lipid lowering procedure with lipoprotein apheresis was associated with favorable transient decrease of lipoperoxidation. Simultaneously the cell membrane bound antioxidative defense mechanisms as reflected by the content of alpha-tocopherol in human erythrocyte membrane where not depressed in spite of its decreased plasma lipid carrier. Another variables involved remain to be investigated.

Effects of different lipoprotein apheresis methods on serum protein levels

BACKGROUND

A total plasma exchange was the first extracorporeal method to treat patients with severe hypercholesterolemia. But in the long run it has several disadvantages. The newer lipoprotein apheresis (LA) methods claim to be more selective with respect to the removal of atherogenic lipoproteins and thus are supposed to avoid an additional protein loss.

METHODS

We wanted to compare the effect of these methods on serum protein concentrations (total serum protein, albumin, proteins measured with electrophoresis, immunoglobulins, fibrinogen, transferrin, and ferritin) which were checked before and after a single LA session in 75 patients. All patients underwent active LA treatment using 6 different LA methods (HELP, TheraSorb(®) LDL, DALI, Lipidfiltration, Liposorber D, MONET). Post-apheresis concentrations were corrected for changes in hematocrit.

RESULTS

The slightest impact on total serum protein was observed with the whole-blood methods. Liposorber D showed the least reduction of albumin levels. All LA methods had a small effect on alpha1-globulins and beta-globulins, but alpha2-and gamma-globulins were reduced to a different extent. A major effect was seen on the immunoglobulins when filtration methods were applied. In the patients treated with MONET, both pre- and post-apheresis Immunoglobulin M concentrations were below the normal range. HELP and the filtration methods significantly reduced the fibrinogen concentrations. The filtration methods also decreased ferritin levels but the post-apheresis ferritin levels were still in the normal range.

CONCLUSION

All LA methods had an influence on protein concentrations. At present, these findings will not yield an individualized treatment approach for any selective LA method due to the lack of prospective comparative studies. At minimum, special attention should be paid to protein concentrations in patients suffering from protein deficit.

Extracorporeal Elimination of Circulating Pegylated Liposomal Doxorubicin (PLD) to Enhance the Benefit of Cytostatic Therapy in Platinum-Resistant Ovarian Cancer Patients

Ovarian cancer is the fifth most common malignancy in the world's female population and with the highest lethality index among gynecological tumors. The prognosis of metastatic disease is usually poor, especially in platinum-resistant cases. There are several options for the treatment of metastatic disease resistant to platinum derivates (e.g. paclitaxel, topotecan and pegylated liposomal doxorubicin), all of which are considered equipotent. Pegylated liposomal doxorubicin (PLD) is a liposomal form of the anthracycline antibiotic doxorubicin. It is characterized by more convenient pharmacokinetics and a different toxicity profile. Cardiotoxicity, the major adverse effect of conventional doxorubicin, is reduced in PLD as well as hematotoxicity, alopecia, nausea and vomiting. Skin toxicity and mucositis, however, emerge as serious issues since they represent dose and schedule-limiting toxicities. The pharmacokinetics of PLD (prolonged biological half-life and preferential distribution into tumor tissue) provide new possibilities to address these toxicity issues. The extracorporeal elimination of circulating liposomes after PLD saturation in the tumor tissue represents a novel and potent strategy to diminish drug toxicity. This article intends to review PLD characteristics and the importance of extracorporeal elimination to enhance treatment tolerance and benefits.

Double filtration plasmapheresis in the treatment of pancreatitis due to severe hypertriglyceridemia

BACKGROUND

Severe hypertriglyceridemia (HTG) leads to major complications such as acute pancreatitis. Lipoprotein apheresis has been proposed as a therapeutic tool for decreasing triglyceride levels, although experience is limited.

OBJECTIVE

To describe our experience with double filtration plasmapheresis (DFPP) in patients with severe HTG and pancreatitis in the plasmapheresis unit of a tertiary hospital in Spain.

METHODS

We recruited 4 patients with severe HTG (triglycerides [TGs] >1000 mg/dL) and acute pancreatitis. All the patients underwent DFPP as part of their treatment. Epidemiologic and laboratory data were collected before and after each plasmapheresis session.

RESULTS

The average TG level before plasmapheresis was 3136 mg/dL (35.44 mmol/L; range, 1306-6693 mg/dL, 14.76-75.63 mmol/L), and the average Acute Physiology And Chronic Health Evaluation (APACHE) II level before the first session was 6 (range, 3-8). All patients made a full recovery, with a significant improvement in TG levels after plasmapheresis. The mean number of sessions was 2.1 (range, 1-3), and mean TG level after plasmapheresis was 428 mg/dL (4.84 mmol/L; range, 169-515 mg/dL; 1.91-5.82 mmol/L). After the first session, the mean decrease in TG levels was 69.16% (2169 mg/dL, range, 945-5925 mg/dL; 24.51 mmol/L, range, 10.78-66.95 mmol/L), and after the last session, TG levels fell by 89.09% (2794 mg/dL, range, 945-6198 mg/dL; 31.57 mmol/L, range, 10.68-70.04 mmol/L). None of the patients developed complications related to plasmapheresis.

CONCLUSIONS

According to available evidence and our own experience, DFPP can be an effective and rapid treatment option in patients with severe HTG and complications. However, further research, including randomized controlled studies, is necessary.

Proteomic analysis of proteins eliminated by low-density lipoprotein apheresis

Low-density lipoprotein apheresis (LDL-A) treatment has been shown to decrease serum LDL cholesterol levels and prevent cardiovascular events in homozygous patients with familial hypercholesterolemia. Recently, LDL-A treatment has been suggested to have beneficial effects beyond the removal of LDL particles. In this study, to clarify the preventive effects of LDL-A treatment on atherosclerosis, the waste fluid from the adsorption columns was analyzed. The waste fluid of LDL adsorption columns was analyzed by two-dimensional electrophoresis followed by mass spectrometry. Serum concentrations of the newly identified proteins before and after LDL-A treatment were measured by enzyme-linked immunosorbent assay. We identified 48 kinds of proteins in the waste fluid of LDL adsorption columns, including coagulation factors, thrombogenic factors, complement factors, inflammatory factors and adhesion molecules. In addition to the proteins that were reported to be removed by LDL-A treatment, we newly identified several proteins that have some significant roles in the development of atherosclerosis, including vitronectin and apolipoprotein C-III (Apo C-III). The serum levels of vitronectin and Apo C-III decreased by 82.4% and 54.8%, respectively, after a single LDL-A treatment. While Apo C-III was removed with very low-density lipoprotein (VLDL) and LDL, vitronectin was removed without association with lipoproteins. The removal of proteins observed in the waste fluid has a certain impact on their serum levels, and this may be related to the efficacy of LDL-A treatment. Proteomic analysis of the waste fluid of LDL adsorption columns may provide a rational means of assessing the effects of LDL-A treatment.

Lipid apheresis techniques: current status in Germany

For long-term lipid apheresis therapy, several different technical systems have been developed which enable effective reduction of LDL cholesterol and other atherogenic lipoproteins, such as Lp(a), with sufficient selectivity and good clinical tolerance. Suitable techniques include whole blood adsorption with polyacrylamide and dextran sulfate cellulose, while primary plasma separation is used for cascade filtration, heparin-induced precipitation, immunoadsorption, silicate gel adsorption, and dextran sulfate cellulose (both techniques).

The technical features are described. Only intensive training and experience of the medical personnel guarantees reliable treatment safety of all systems at a very low rate of minor side effects.

LDL-apheresis: technical and clinical aspects

The prognosis of patients suffering from severe hyperlipidemia, sometimes combined with elevated lipoprotein (a) levels, and coronary heart disease refractory to diet and lipid-lowering drugs is poor. For such patients, regular treatment with low-density lipoprotein (LDL) apheresis is the therapeutic option. Today, there are five different LDL-apheresis systems available: cascade filtration or lipid filtration, immunoadsorption, heparin-induced LDL precipitation, dextran sulfate LDL adsorption, and the LDL hemoperfusion. There is a strong correlation between hyperlipidemia and atherosclerosis. Besides the elimination of other risk factors, in severe hyperlipidemia therapeutic strategies should focus on a drastic reduction of serum lipoproteins. Despite maximum conventional therapy with a combination of different kinds of lipid-lowering drugs, sometimes the goal of therapy cannot be reached. Hence, in such patients, treatment with LDL-apheresis is indicated. Technical and clinical aspects of these five different LDL-apheresis methods are shown here. There were no significant differences with respect to or concerning all cholesterols, or triglycerides observed. With respect to elevated lipoprotein (a) levels, however, the immunoadsorption method seems to be most effective. The different published data clearly demonstrate that treatment with LDL-apheresis in patients suffering from severe hyperlipidemia refractory to maximum conservative therapy is effective and safe in long-term application.

Kinetic targeting of pegylated liposomal doxorubicin: a new approach to reduce toxicity during chemotherapy (CARL-trial)

BACKGROUND

The therapeutic success of chemotherapeutic agents is often limited by severe adverse effects. To reduce toxicity of these drugs, nanoscale particle-based drug delivery systems (DDS) are used. DDS accumulate to some extent in tumor tissues, but only a very small portion of a given dose reaches this target. Accumulation of DDS in tumor tissues is supposed to be much faster than in certain other tissues in which side effects occur ("Kinetic Targeting"). Once saturation in tumor tissue is achieved, most of the administered DDS still circulate in the plasma. The extracorporeal elimination of these circulating nanoparticles would probably reduce toxicity.

METHODS

For the CARL-trial (Controlled Application and Removal of Liposomal chemotherapeutics), pegylated liposomal doxorubicin (PLD) was used as chemotherapeutic agent and double filtration plasmapheresis (DFPP) was performed for extracorporeal elimination of liposomes. PLD was given as 40 mg/m2 every 3 weeks in combination with vinorelbine 2 × 25 mg/m2 (neoadjuvant treatment of breast cancer, 12 patients), or as 40 mg/m2 every 4 weeks (recurrent ovarian cancer, 3 patients). Primary endpoints were the efficiency and safety profile of DFPP, and secondary endpoints were side effects and tumor response.

RESULTS

DFPP eliminated ~62% of circulating PLD, corresponding to ~45% of the total dose (n = 57 cycles). AUC of doxorubicin was reduced by 50%. No leakage of doxorubicin was detected during elimination, and no relevant DFPP-related side effects occurred. Reduction in tumor size > 30% occurred in 10/12 (neoadjuvant) and in 1/3 patients (recurrent). Only five grade 2 events and one grade 3 event (mucositis, neutropenia or leucopenia) and a single palmar-plantar erythrodysesthesia grade 2 were reported.

CONCLUSION

Extracorporeal elimination of PLD by DFPP is safe and efficient. CARL can diminish the main dose-limiting side effects of PLD, and probably many different DDS alike.

TRIAL REGISTRATION

DRKS00000163.

Pilot study of extracorporeal removal of soluble fms-like tyrosine kinase 1 in preeclampsia

BACKGROUND

Targeted therapies to stabilize the clinical manifestations and prolong pregnancy in preeclampsia do not exist. Soluble fms-like tyrosine kinase 1 (sFlt-1), an alternatively spliced variant of the vascular endothelial growth factor receptor 1, induces a preeclampsia-like phenotype in experimental models and circulates at elevated levels in human preeclampsia. Removing sFlt-1 may benefit women with very preterm (<32 weeks) preeclampsia.

METHODS AND RESULTS

We first show that negatively charged dextran sulfate cellulose columns adsorb sFlt-1 in vitro. In 5 women with very preterm preeclampsia and elevated circulating sFlt-1 levels, we next demonstrate that a single dextran sulfate cellulose apheresis treatment reduces circulating sFlt-1 levels in a dose-dependent fashion. Finally, we performed multiple apheresis treatments in 3 additional women with very preterm (gestational age at admission 28, 30, and 27+4 weeks) preeclampsia and elevated circulating sFlt-1 levels. Dextran sulfate apheresis lowered circulating sFlt-1, reduced proteinuria, and stabilized blood pressure without apparent adverse events to mother and fetus. Pregnancy lasted for 15 and 19 days in women treated twice and 23 days in a woman treated 4 times. In each, there was evidence of fetal growth.

CONCLUSIONS

This pilot study supports the hypothesis that extracorporeal apheresis can lower circulating sFlt-1 in very preterm preeclampsia. Further studies are warranted to determine whether this intervention safely and effectively prolongs pregnancy and improves maternal and fetal outcomes in this setting.

Use of ultra high performance liquid chromatography-tandem mass spectrometry to demonstrate decreased serum statin levels after extracorporeal LDL-cholesterol elimination

Background. Using our statin analysis method, it was possible to uncover a significant drop in statin levels (atorvastatin, simvastatin, and metabolites) after extracorporeal LDL-cholesterol elimination (EE) in severe familial hypercholesterolemia (FH). The purpose of this work was to identify the mechanism underlying this drop and its clinical significance as well as to propose measures to optimize a pharmacotherapeutical regimen that can prevent the loss of statins. Methods. Ultra High Performance Liquid Chromatography (UHPLC) connected to the triple quadrupole MS/MS system was used. Patients. A group of long-term treated patients (3–12 years of treatment) with severe FH (12 patients) and treated regularly by LDL-apheresis (immunoadsorption) or haemorheopheresis (cascade filtration) were included in this study. Results. After EE, the level of statins and their metabolites decreased (atorvastatin before/after LDL-apheresis: 8.83/3.46 nmol/l; before/after haemorheopheresis: 37.02/18.94 nmol/l). A specific loss was found (concentration of atorvastatin for LDL-apheresis/haemorheopheresis: 0.28/3.04 nmol/l in washing fluids; 11.07 nmol/l in filters). To prevent substantial loss of statin concentrations, a pharmacotherapeutic regimen with a longer time interval between the dose of statins and EE is recommended (15 hours). Conclusions. A specific loss of statins was found in adsorbent columns and filters. The decrease can be prevented by the suggested dosage scheme.

Comparison of different low density lipoprotein apheresis machines on brain natriuretic Peptide levels in patients with familial hypercholesterolemia

B-type natriuretic peptide (BNP) is a hormone released from cardiac ventricles during episodes of hemodynamic overload. Low density lipoprotein (LDL) apheresis, a procedure for patients with familial hypercholesterolemia (FH) and coronary artery disease (CAD), lowers plasma cholesterol and immediately reduces blood viscosity and coronary vascular resistance while improving myocardial blood flow and microvascular perfusion. Previous studies have demonstrated the ability of LDL apheresis to reduce BNP chronically. We undertook this study to evaluate the difference in reduction of BNP levels following a single treatment with two dissimilar LDL apheresis devices. We conducted a prospective trial involving 27 patients (19 F; age = 59 +/- 9 years) with FH who received at least 6 months of bi-weekly LDL apheresis therapy with either the Secura heparin extracorporeal LDL precipitation (HELP) system (N = 17 patients, B. Braun, Inc., Melsungen, Germany) or the Liposorber LA-15 dextran sulfate absorber (DSA) system (N = 10 patients, Kaneka, Inc., Osaka, Japan). We measured BNP levels immediately before and after one treatment of LDL apheresis. Following LDL apheresis, BNP levels were reduced by an average of 40 +/- 17% (P < 0.001). Despite treating equal amounts of plasma, the HELP system reduced BNP (45 +/- 18%) significantly more than the DSA system (31 +/- 11%, P = 0.031). In conclusion, LDL apheresis therapy, possibly through its immediate improvement of vascular flow and/or removal of the peptide from plasma, results in a significant reduction of BNP levels. The increased reduction of BNP by HELP may result from its superior acute alterations of rheological markers.

Elimination of liposomes by different separation principles used in low-density lipoprotein apheresis

Clinical success of many therapies is impaired by dose limiting toxicities. Nanoscale particle-based drug delivery systems such as liposomes show unique pharmacokinetic properties and improved toxicity profiles. Liposomes accumulate in tumor tissue, but only a small fraction of a total dose reaches the target site. The overwhelming amount of a given dose is needed only to build up a diffusion gradient for effective accumulation at the target site. In order to find a way to detoxify this predominant fraction after accumulation is completed, the different separation principles used for the apheresis of lipoproteins were evaluated for the extracorporeal elimination of liposomes. Appropriate radiolabeled model liposomes were prepared by extrusion. Separation efficacy, leakage of liposomal content and influence of plasma contact were measured. Membranes with pore sizes between 25 and 400 nm were used to investigate filtration properties of liposomes. Liposomes were precipitated by adding heparin and Ca(2+). Adsorption chromatography was investigated using dextran sulfate, heparin sepharose and functionalized polyacrylamide beads. Membrane filtration allowed the elimination of various liposomes, while precipitation and adsorption were only useful for positively charged liposomes. Leakage of liposomal content was not induced by adsorption, but precipitation induced leakage. Leakage during filtration was dependent on liposomal membrane lipids. Plasma contact reduced precipitation and adsorption efficacy of positively charged liposomes, while filtration properties of liposomes remained unchanged. For extracorporeal elimination of liposomal drug delivery systems, filtration-based techniques are presumably more convenient and versatile than precipitation- or adsorption-based apheresis technologies.

Protein adsorption during LDL-apheresis: proteomic analysis

BACKGROUND

The aim of our study was to investigate the clearance of functional proteins by different low-density lipoprotein-apheresis (LDL-A) methods with the help of proteomic analyses.

METHODS

Proteins were eluated from the different LDL-A columns and investigated with 2D electrophoresis combined with mass spectrometry methods. In parallel, we quantified the plasma protein loss from patients treated with double-filtration plasmapheresis (DFPP; n = 9), direct adsorption of lipoproteins (DALI; n = 5) or heparin-induced extracorporeal LDL precipitation (HELP; n = 7) with routine laboratory methods and western blots.

RESULTS

Proteomic analyses of the column-bound proteins revealed a column-type-dependent loss with the highest number of protein spots in DALI-treated patients (1001 +/- 36), followed by HELP (881 +/- 25) and DFPP (535 +/- 20). More than 70 functional proteins were identified. These proteins are involved in the coagulation pathway (e.g. kininogen1) and have adhesive (e.g. fibronectin), rheological (e.g. fibrinogen) and immunological/inflammatory properties (e.g. complement components). Quantification with western blot analyses demonstrated a significant depletion (P < 0.01) of these proteins comparing serum samples before and after the column with a systemic lowering in patients' serum.

CONCLUSIONS

These data reveal strong interaction between column and serum proteins during LDL-A. The clearance of proteins with adhesive, rheological, and inflammatory characteristics may have beneficial effects on microcirculation and reduce chronic inflammation but may also concomitantly induce side effects such as an increased bleeding risk.

Dextran-sulfate-adsorption of atherosclerotic lipoproteins from whole blood or separated plasma for lipid-apheresis—Comparison of performance characteristics with DALI and lipidfiltration

For many years dextran sulfate adsorption (DSA) treatment of separated plasma has been an established technology for low-density lipoprotein (LDL)-elimination. Recently a system for the treatment of whole blood based on DSA was introduced into clinical practice. To further characterize DSA treatment of whole blood, the performance characteristics of both DSA modalities were compared at two investigational sites with two alternative LDL apheresis systems being already in routine clinical use. In prospective cross-over design, DSA whole blood treatment was compared with a whole blood polyacrylate LDL adsorption system (DALI) in one study group. DSA for plasma treatment was compared with Lipidfiltration in cross-over design in a second study group. In total, 12 patients on chronic LDL apheresis received 169 treatments. Six patients were treated twice with whole blood polyacrylate adsorption and twice with whole blood DSA. LDL-cholesterol (74.9-78.0%) and lipoprotein (a) (72.1-73.3%) were reduced by both with equal efficacy. DSA achieved a significantly higher reduction rate of fibrinogen. Another six patients were treated eight times with DSA plasma adsorption followed by 16 Lipidfiltration treatments. LDL-cholesterol (67.0-70.2%) and lipoprotein (a) (69.2-73.7%) were reduced by both with equal efficacy. Fibrinogen was eliminated more efficiently by Lipidfiltration (50.2 vs. 38.5%). DSA proved to be a safe and effective in both treatment modes, for plasma as well as for whole blood. At the discretion of the apheresis specialist, depending upon the status of national approval, DSA of whole blood complements the armamentarium of powerful modalities for extracorporeal elimination of atherosclerotic lipoproteins to meet specific individual, medical, or logistic needs.

Hypercholesterolemia and LDL apheresis

Several trials have assessed the link between low-density lipoprotein cholesterol (LDL) and the development of coronary heart disease (CHD). LDL apheresis provides an effective role in treating patients with familial hypercholesterolemia (FH) and in preventing the progression of coronary artery disease (CAD). Five different techniques of LDL apheresis are in current use: immunoadsorption (IMA), dextran sulphate-cellulose adsorption (DSA), heparin extracorporeal LDL precipitation system (HELP), double filtration plasmapheresis (DFPP) or lipidfiltration and direct adsorption of lipoprotein using hemoperfusion (DALI). All methods are efficient,but their cost restricts LDL apheresis to the treatment of FH. Indications could include other diseases, but controlled trials are still lacking.

Therapeutic Apheresis-State of the Art in the Year 2005

Therapeutic apheresis is an extracorporeal blood purification method for the treatment of diseases in which pathological proteins or cells have to be eliminated. Selective plasma processing is more efficient in pathogen removal than unselective plasma exchange and does not require a substitution fluid like albumin. This overview presents the various selective devices for the treatment of plasma (plasmapheresis) and blood cells (leukocyte apheresis). Prospective randomized trials were performed for the treatment of age-related macular degeneration (Rheopheresis), sudden hearing loss (heparin-induced lipoprotein precipitation [HELP]), rheumatoid arthritis (Prosorba), dilative cardiomyopathy (Ig-Therasorb, Immunosorba), acute-on-chronic liver failure (molecular adsorbent recirculating system [MARS]), and ulcerative colitis (Cellsorba). Prospective non-randomized controlled trials were carried out treating hypercholesterolemia (Liposorber) and crossmatch-positive recipients before kidney transplantation (Immunosorba). Uncontrolled studies were done for ABO-incompatibility in living donor kidney transplantation (KT) (Glycosorb), acute humoral rejection after KT (Immunosorba) and acute liver failure (Prometheus). According to the 2002 International Apheresis Registry covering 11428 sessions in 811 patients, 79% of the patients showed an improvement of their condition by apheresis and only a few sessions were fraught with adverse effects (AE). The major AE were blood access difficulties (3.1%) and hypotension (1.6%). In summary, therapeutic apheresis is a safe and effective procedure for the treatment of diseases refractory to drug therapy.

Effect of Lipoprotein Apheresis on Oxidative Stress and Antioxidant Status in Familial Hypercholesterolemic Patients

Extracorporeal low-density lipoprotein (LDL) apheresis is an established and highly effective therapy for the patients with familial hypercholesterolemia (FH) not adequately responding to diet and drug therapy alone. This study was designed to measure the effect of lipid apheresis on oxidant and antioxidant status in a patient with FH. The levels of plasma lipid peroxidation were determined as thiobarbituric acid-reactive substances. The activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were established in one subject with FH before and after lipid apheresis.

The pre- and post lipid apheresis procedures witness a significant decrease in oxidative stress (p<0.05) but the erythrocyte levels of CAT, SOD and GPx were unchanged.

State of the Art of Low-density Lipoprotein Apheresis in the Year 2003

Low-density lipoprotein (LDL) apheresis is a last-resort treatment for hypercholesterolemic patients resistant to conservative lipid-lowering therapy. In the extracorporeal circuit, LDL, Lp(a) and coagulation factors are selectively eliminated, while the beneficial proteins like high-density lipoprotein, albumin and immunoglobulins are returned to the patient. Clinical effects of LDL apheresis comprise improvement of symptoms like angina and exercise tolerance, reduction of clinical coronary events like unstable angina, need for angioplasty or bypass operation, myocardial infarction and ultimately coronary mortality. The reduction of atherogenic lipoproteins and of coagulation factors by LDL apheresis (LA) positively influences hemorheology, endothelial function and coronary reserve. In the controlled LAARS, LA significantly improved the electrocardiographic signs of myocardial ischemia in the treadmill test. In angiographically controlled trials such as LARS and L-CAPS, a reduction of progression of coronary lesions was observed; in favorable cases, regression of the stenoses could be documented. In addition, in the LDL apheresis coronary morphology trial, LA decreased the coronary plaque area. The Hokuriku trial documented a 72% decrease of coronary events (MACE) in the LA group vs. controls treated only by statins. In longitudinal studies, the incidence of MACE after regular LA decreased compared with the preapheresis period in the same patients. Apart from coronary heart disease, recent studies indicate a positive effect of LA also on carotid artery stenoses and peripheral vascular disease. Prospective randomized studies showed the beneficial effects of cascade filtration on age-related macular degeneration and of heparin-induced LDL precipitation apheresis on acute inner ear deafness.