Dextran Sulfate Adsorption Research Articles

Lipoprotein Apheresis Alleviates Treatment-Resistant Peripheral Artery Disease Despite the Normal Range of Atherogenic Lipoproteins: The LETS-PAD Study.

Peripheral artery disease (PAD) severely impairs patient prognosis and quality of life (QOL). Although lipoprotein apheresis (LA) has been applied to patients with PAD and elevated serum atherogenic lipoproteins, we hypothesized that LA can be effective for treating PAD even in patients with controlled serum lipoproteins through pleiotropic anti-atherosclerotic effects beyond lipoprotein removal. This study aimed to evaluate the efficacy of LA in patients with treatment-resistant PAD and controlled serum lipoproteins focusing on QOL. In a single-arm prospective study, 30 patients with refractory PAD who had controlled serum lipoproteins underwent sequential LA sessions using dextran sulfate adsorption columns, aiming to complete 10 sessions. The ankle-brachial pressure index (ABI) and vascular QOL (VascuQOL) score were evaluated as the primary outcomes. Secondary outcomes included reactive hyperemia index (RHI) and biological antioxidant potential (BAP) as an endothelial function test and serum antioxidative-capacity evaluation, respectively. ABI significantly increased after LA sessions (pre-treatment 0.60±0.09 vs. post-treatment 0.65±0.13, p=0.023). Total VascuQOL score (3.7±1.1 vs 4.6±1.1, p＜0.001) and RHI (1.70±0.74 vs 2.34±1.76, p=0.023) significantly improved after the LA sessions. BAP tended to increase after the LA sessions, and the change reached statistical significance 3 months after treatment. ABI and QOL improved after a series of LA sessions in conventional treatment-resistant PAD patients with controlled serum lipoprotein levels. Increased antioxidative capacity and ameliorated endothelial function were observed after the LA treatment.

Intima-media Thickness Measured at the Common-carotid Artery in Patients Treated with Lipoprotein Apheresis

<h3>Lead Author's Financial Disclosures</h3> Nothing to disclose. <h3>Study Funding</h3> None. <h3>Background/Synopsis</h3> Common carotid intima-thickness (CIMT) is as a marker of arterial wall injury and arteriosclerosis. Healthy asymptomatic young and middle-aged individuals of the European-ancestry show mean CIMT of 610 + /-110μmmicrometers with a strong linear relation between age and CIMT. In the general population, an annual rate of change in mean common CIMT is estimated at 15μm (95% CI, 12 to 17), with a median standard deviation of 53. <h3>Objective/Purpose</h3> We sought to compare annual CIMT progression rates in 10 patients with severe hypercholesterolemia treated with lipoprotein apheresis with published annual CIMT progression estimates in age-comparable 1) healthy individuals based on the nomograms, 2) patients with elevated lipoprotein(a), and 3) familial hypercholesterolemia (FH). <h3>Methods</h3> Patients (mean age 60+/-9 years, 70% female, 80% statin intolerant) were treated with the dextran sulfate adsorption apheresis system for primary and secondary atherosclerotic cardiovascular disease (ASCVD) prevention every two weeks between 2005 and 2020 (mean duration, 10+/-4 years). To minimize intra-individual and inter-individual variability in CIMT assessment we used computerized algorithms with measurements performed by the same sonographer. <h3>Results</h3> The baseline mean CIMT was 850+/-170μm and maximum CIMT was 1040+/-220um across the age range of 46 to 70 years. The baseline median levels of total cholesterol were 317 (interquartile range (IQR), 262 to 361); LDL-C, 214 (133 to 253); HDL-C, 56 (44 to 68); triglycerides, 170 (121 to 215), lipoprotein(a), 26 (9 to 120), all in mg/dL. Acute effects of lipoprotein apheresis determined as a difference before and immediately after the procedure were estimated as a median of 72+/-8% and 75+/-7% reduction in the LDL-C and lipoprotein(a) levels, respectively. Regular treatment with lipoprotein apheresis resulted in average reduction in the mean CIMT of −40μm (IQR, −50 to 20). An annual CIMT progression rate was associated with the combined percentage reduction in the lipoprotein(a) (P=0.032) and LDL-C levels (P=0.029). Using the Bayesian Estimation Supersedes the t -Test (BEST) method, the annual rate of CIMT progression was compared to those reported in the literature (Table 1). <h3>Conclusions</h3> Composite CIMT progression rates were slowed with lipoprotein apheresis. In this cohort of high-risk patients with poor statin tolerance, the use of CIMT surveillance was noted to increase compliance with long-term lipid-modifying therapies in the clinical setting.

Complexation of pea protein isolate with dextran sulphate and interfacial adsorption behaviour and O/W emulsion stability at acidic conditions

SummaryThis study was aimed at improving the emulsifying property and physical stability of pea protein isolate (PPI) stabilised emulsions at acidic conditions by complexation with dextran sulphate (DS). Soluble and insoluble complexes with different charge and particle size were formed depending on the phase separation behaviour. The surface adsorption of PPI became slower after complexation with DS, but the percentage of adsorbed proteins at the oil–water interface was not affected. The formation of PPI–DS soluble complexes at high content of DS (≥0.4%) significantly improved the negative net charges of PPI, prevented the aggregation of protein, which further improved the emulsifying property of PPI at acidic conditions through the strong electrostatic repulsion and steric hindrance effects. Insoluble complexes with relatively weak net charge and large particles were formed at low DS content (≤0.2%), resulting in the bridging flocculation of oil droplets at pH 5 and 4. Thus, the emulsifying ability of PPI under acidic conditions could be significantly improved by formation of soluble complexes with DS.

Non-coating method for non-adherent cell culture using high molecular weight dextran sulfate and bovine serum albumin

Non-adherent cell culture surface has been widely used for producing cell spheroids and cell aggregates. The purpose of this study was to formulate a new method for non-adherent cell culture without coating or surface-modification that has been needed. We found that high-molecular-weight dextran sulfate (DS) and bovine serum albumin (BSA) synergistically prevented cell adhesion in media supplemented with no or low serum. This method worked on tissue culture-treated polystyrene surfaces as well as on commercially available low-attachment- and untreated polystyrene surfaces. Further investigation revealed that BSA may mediate the adsorption of DS to the surface. In addition, as the adsorption of fluorescently labeled fibronectin was inhibited by BSA alone, it appears that protein adsorption and cell adhesion do not always correlate. Finally, we demonstrated the successful formation of HepG2 spheroids and cardiomyocyte aggregates using this method. In conclusion, cell adhesion can be effectively suppressed by simply adding DS and BSA to the culture medium without coating or surface modification, and it may be useful for generating cell spheroids and aggregates.

Establishing low-density lipoprotein apheresis tolerability in patients with prior anaphylactoid reactions to lipoprotein apheresis using magnesium sulfate.

Lipoprotein apheresis (LA) tolerability is a key factor for the utilization of this therapy. Common reactions to LA are hypotension and nausea. Serious reactions include severe hypotension and anaphylactoid reactions (0.13%-1.3% and 0.2%-0.4%, respectively). The bradykinin response drives these reactions and can worsen with the use of angiotensin-converting-enzyme inhibitors. Efforts to mitigate these reactions are necessary for the tolerability of LA with a dextran sulfate-adsorption (DSA) system. In an effort to increase apheresis tolerability, seven patients at The University of Kansas, Department of Clinical Pharmacology, who had prior anaphylactoid reactions (defined as general cutaneous flushing, nausea/vomiting, tongue swelling, lightheadedness, and hypotension) to the DSA despite pharmacologic intervention, were treated with pre-LA intravenous magnesium adapted from a protocol developed by co-author Eliaz. This protocol consists of 1.5g of magnesium sulfate administered over 45 minutes. All seven patients were treated with intravenous magnesium sulfate immediately before LA. No episodes of anaphylactoid reactions during LA have been reported to date. Magnesium infusion before DSA can be utilized to establish tolerability in patients with prior anaphylactoid reactions to LA. Proposed mechanisms include temporary stabilization of the negative-positive interactions of the dextran sulfate filter leading to a reduction of circulating bradykinin, reduction of nitric oxide, and reduction of the sympathetic response to LA.

Short- and long-term effects of lipoprotein apheresis on plasma hormones in patients with therapy-resistant dyslipidemia

Background and aimsLipoprotein apheresis (LA) is a highly effective method to improve the clinical and metabolic situation in patients with therapy-resistant disorders of lipid metabolism. Cholesterol is the substrate for the synthesis of all steroid hormones. If repeated massive reduction of LDL-cholesterol may interfere with human adrenal steroidogenesis, and could become clinically relevant is unknown, so far. Thus, the aim of this study was to determine possible short- and long-term effects of LA on blood plasma levels of ACTH, cortisol, aldosterone, DHEAS, renin and testosterone. MethodsIn total, 39 patients, treated with one of four LA techniques were studied: 1. Lipid Filtration (LF; n = 7), 2. Dextran Sulfate Adsorption (DSA; n = 7), 3. Membrane Filtration Optimised Novel Extracorporeal Treatment (MONET; n = 8), and 4. Direct Absorption of Lipoproteins (DALI; n = 15). Hormone levels were analyzed before and after five LA sessions with an interval of 20 weeks covering a total observation time of two years. In addition patients were comprehensively characterized by clinical and laboratory data. ResultsPatients treated with LA revealed an acute reduction of steroid hormones and ACTH, independent of apheresis technology but no long-term insufficiency in steroidogenesis was observed. Plasma renin levels were stable in LF patients and were highly elevated in patients under DSA, MONET and DALI apheresis throughout the observation period. ConclusionsIn summary, these data suggest that although different LA techniques considerably differ in their acute effects on hormone levels during LA, they did not alter long-term hormone levels sustainably.

High serum triglyceride concentrations in patients with homozygous familial hypercholesterolemia attenuate the efficacy of lipoprotein apheresis by dextran sulfate adsorption

Background and aimsMaximizing the acute reduction of LDL-cholesterol (C) and lipoprotein (a) (Lp(a)) concentrations in patients with homozygous familial hypercholesterolemia (HoFH) is the main goal of lipoprotein apheresis (LA). The objective of this study was to examine how the pre-LA serum TG concentrations influence the efficacy of LA to acutely reduce LDL-C and Lp(a) concentrations in HoFH patients. MethodsData from 1761 LA treatments of HoFH patients (n = 10) and compound heterozygous patients (n = 5) collected between 2008 and 2016 were analyzed. These data included the pre- and post-LA concentrations of LDL-C, TGs and Lp(a); volume of filtered plasma; type of LA system used (dextran sulfate adsorption (DSA) or heparin-induced extracorporeal LDL precipitation (HELP)); and interval between treatments. ResultsA significant association between the pre-LA TG concentrations and acute LA-induced reduction in LDL-C, modified by the type of LA system used, was observed (ppre-LA TG quartile*LA system = .04). Using the DSA system, the acute reduction of the LDL-C concentrations was attenuated by 3.9% when the pre-LA TG concentrations were >2.09 mmol/L vs. ≤0.93 mmol/L (highest vs. lowest quartiles: −59.4% vs. −63.3%, p = .007). Using the HELP system, no significant difference was observed in the reduction of LDL-C between the highest and the lowest quartiles of serum TGs (−65.8% vs. −66.4%, p = .9). No association was observed between pre-LA TG concentrations and acute LA-induced decrease in Lp(a) (p = .2). ConclusionsThe efficacy of LA is inversely associated with pre-LA TG concentrations in HoFH patients who used the DSA system instead of the HELP system.

Impact of lipoprotein apheresis with dextran‐sulfate adsorption on the expression of genes involved in cardiovascular health in the blood of patients with homozygous familial hypercholesterolemia

Lipoprotein apheresis (LA) with dextran sulfate adsorption (DSA) is a reliable method to decrease LDL-cholesterol (C) concentrations in patients with homozygous familial hypercholesterolemia (HoFH). The objective of the present study was to investigate the impact of LA with DSA on the mRNA expression of genes associated with cardiovascular health in the whole blood of HoFH patients. Blood samples were collected before and after LA treatment with DSA in 9 HoFH patients. Microarray analyses were performed to measure the whole blood expression of >30000 annotated genes pre- and post-LA. Concomitant reductions in LDL-C (median -73.8%, range: -55.9 to -82.0, P = .0001) and lipoprotein (a) concentrations (median -74.1%, range -65.6 to -84.1, P = .003) were induced with LA treatment. LA with DSA did not impact the whole blood mRNA expression of most key genes involved in cardiovascular health, including those associated with cholesterol, fatty acid and lipoprotein metabolism. However, LA with DSA significantly upregulated the whole blood expression of early growth response protein (EGR)1 (1.94-fold, P = .02), EGR3 (1.56-fold, P = .0008) and B-cell lymphoma 3-encoded protein (BCL3; 1.25-fold, P = .03). In conclusion, this study demonstrated that a single LA treatment with DSA has very limited impact on the whole blood expression of a broad spectrum of genes associated with cardiovascular health. Our results suggest that contact between blood cells and the primary membrane or extracorporeal circulation could upregulate the expression of EGR1, EGR3, BCL3, and MMP9 in blood cells.

KL 14 Targeted therapies in preeclampsia

Preeclampsia is a devastating hypertensive complication of pregnancy for which there is no suitable treatment other than premature delivery of the fetus. Approximately 5% of pregnancies are affected, producing substantial maternal and fetal morbidity and mortality, including an increased risk of cardiovascular consequences later in life. Levine and colleagues ( NEJM , 2004) demonstrated over a decade ago that the presence of excess soluble FMS-like tyrosine kinase (sFlt-1), a splice variant of vascular endothelial growth factor, is predictive of preeclampsia in at-risk women. We subsequently hypothesized that antagonizing or removing excess circulating sFlt-1 will help prolong gestational duration and, in turn, markedly improve fetal outcomes. To avoid the risks of administering investigational pharmacologic agents to pregnant women, we devised a novel approach using extracorporeal apheresis to remove sFlt-1 (a positively-charged protein) from the maternal circulation in women with frank preeclampsia. Our multidisciplinary team designed and conducted two single-arm, proof-of-concept clinical studies to determine the feasibility of apheresis using dextran-sulfate adsorption (DSA) columns to remove sFlt-1 from maternal blood of women with very pre-term preeclampsia (defined as ⩾ 140 mmHg or ⩾ 90 mmHg, respectively, on 2 occasions at least 4 h apart; proteinuria (24-h total protein excretion of ⩾ 300 mg or ⩾ 2+ on dipstick testing), or ⩾ 0.35 g protein/gram creatinine). In both studies, delivery decisions were made by the treating Obstetrician/MFM based on maternal and fetal clinical parameters. Maternal blood sFlt-1 levels, BP, and proteinuria were monitored at study entry and during and after pheresis at frequent, pre-specified time points. Clinical parameters of maternal and fetal well-being were monitored throughout the pheresis intervention and following therapy. Gestational age at delivery and birth weight, fetal APGAR scores, and fetal outcomes including NICU admission and complications (e.g., ventilatory support) were documented. Eight women completed the first pilot study (Thadhani et al., Circulation , 2011) which utilized DL-75 DSA columns (without separating whole blood into red cells and plasma); 5 received single apheresis treatments; 3 received apheresis up to twice per week for 3 ( n = 2, one of whom gave birth to twins) or 4 ( n = 1) total treatments. The pheresis interventions stabilized maternal parameters without leaving any residual adverse effects. Maternal blood pressure was only transiently and not markedly decreased, sFlt-1 levels were lowered by 17–34%, and protein-to-creatinine levels rose and fell in conjunction with sFlt-1. The two patients with singleton fetuses who underwent more than one apheresis treatment had pregnancies prolonged by 15 days (2 treatments) and 23 days (4 treatments). The patient with twins had her pregnancy prolonged by 19 days (2 treatments), remarkable given that most twin pregnancies are not prolonged more than a few days with expectant management. In our second study (Thadhani, JASN , 2016), 11 women received a total of 17 apheresis treatments using a modified apheresis apparatus that first separated plasma from whole blood before passing through a plasma-specific DSA column, improving the efficiency of sFlt-1 removal, minimizing the need for therapeutic anticoagulation, and reducing potential immune cell activation. Six women were treated once, 4 were treated twice and 1 was treated 3 times). All experienced a reduction of sFlt-1 from 17,394 (range 7916–35,301) pg/mL to 14,265 (6446–26,259) pg/mL post-apheresis. The safety of this approach was again verified and, among women treated multiple times, pregnancy continued on average for 15 days (range 11–21). We are now planning additional studies aiming to ultimately conduct a randomized clinical trial that will compare this promising therapy with the currently flawed standard-of-care. Follow up approaches in developing therapies for preeclampsia include a specific antibody column that only removes sFlt-1 and administration of ligands that neutralize circulating sFlt-1.

Pleiotropic effects of regular lipoprotein-apheresis

BackgroundLipoprotein(LP)-apheresis is the treatment of choice in patients suffering from severe familial hypercholesterolemia. A wide range of mechanisms has been claimed to be responsible for the known clinical benefit. MethodsPatients suffering from heterozygous familial hypercholesterolemia undergoing LP-apheresis either with direct adsorption of lipoproteins (DALI) or dextran sulfate (DS) were examined. A total volume of 10 l blood was exchanged. Non-lipid effects, mainly concerning endothelial function (circulating endothelial cells, circulating endothelial progenitor cells, flow-mediated vasodilation, microalbuminuria) as well as left ventricular ejection fraction and homocysteine were assessed. ResultsA single LP-apheresis session improves paradox contractile response in statin intolerant patients, but not in those on regular statin therapy. In contrast, over a 6-months follow-up after treatment initiation, all the examined parameters (circulating endothelial cells, circulating endothelial progenitor cells, flow mediated vasodilatation, homocysteine, microalbuminuria and left ventricular ejection fraction) improved. When available, a comparison between DS vs. DALI was performed. In none of the subgroups a significant difference was noted. DiscussionThese findings indicate that beyond the well known lipid/lipoprotein lowering action the broad spectrum of functional tests examined reflecting mainly endothelial function is significantly improved by LP-apheresis treatment on the long-term and seems to be a key underlying reason for the clinical improvement seen in these patients.

Polyelectrolyte micro- and nanoparticles with doxorubicin

Doxorubicin-containing micro- and nanoparticles obtained by layer-by-layer adsorption of dextran sulfate and chitosan on an insoluble antibiotic–polyanion complex with subsequent sonication were studied. The effects of the molecular mass of biopolymers, the number of polyelectrolyte layers, and the pH of the reaction medium on the composition, physicochemical properties, and the efficiency of doxorubicin incorporation have been examined. The release of doxorubicin and the mucoadhesive properties of the polyelectrolyte particles have been analyzed to determine the possibilities of their potential applications.

Increasing plasma lysophosphatidylcholine levels in patients with regular dextran sulfate lipoprotein apheresis

ObjectivesPreviously we found a highly significant increase of phosphatidylethanolamines (PE) in response to acute lipoprotein apheresis (LA) with whole blood dextran sulfate adsorption (DSA) in contrast to the overall tendency of reduction of lipid metabolites of all lipid classes in post-apheresis plasma. Therefore, the aim of the present study was to analyze long-term modifications of the plasma lipidomic profile in patients with repeated DSA apheresis. MethodsNine patients weekly treated with DSA were followed for 40 weeks. Pre- and post-apheresis levels of routine lipid parameters and lipidomic profiles of five apheresis sessions were assessed. ResultsThe main finding of the present study was a progressive increase of pre- and post-apheresis plasma lysophosphatidylcholine (LPC) levels, which doubled in concentration at the end of the 40 week observation period. LPC metabolites which mainly contributed to this increase were LPC 20:4 > 18:0 > 18:1 > 16:0 > 20:3 > 18:2. ConclusionThese data indicate that long-term application of DSA technology may be associated with a continuous increase in LPC levels. Possible pro- or anti-atherogenic consequences should be elucidated in further studies.

Long-term therapeutic efficacy of lipoprotein apheresis on circulating oxidative stress parameters – A comparison of two different apheresis techniques

BackgroundA chronic lipoprotein apheresis therapy leads to an expressed reduction in the incidence of cardiovascular events in high-risk patients. In addition to the elimination of atherogenic lipoproteins such as LDL and lipoprotein(a), an antioxidative effect of lipoprotein apheresis has been suspected. Objectives and methodsWe investigated long-term biochemical effects in sixteen patients undergoing lipoprotein apheresis – lipid filtration (LF, n = 7) or dextran sulfate adsorption (DSA, n = 9). Systemic oxidative stress markers (blood phagocyte chemiluminescence, levels of oxidized LDL and antioxLDL antibodies) were examined at the 1st, 40th and 80th apheresis sessions. ResultsIn DSA patients, the 80th apheresis session was associated with significantly higher LDL cholesterol removal and lower HDL cholesterol deprivation as compared to LF patients. In contrast to LF patients, DSA patients showed a long-term progressive decrease in circulating oxidant generating activity as evaluated by whole blood chemiluminescence (p < 0.05). Moreover, a single LF apheresis session was associated with higher systemic generation of reactive oxygen species over time. ConclusionCompared to LF, long-term DSA apheresis is associated with a gradual reduction of circulating oxidative burden and may be considered a beneficial molecular mechanism of this technique.

Layer-by-layer adsorption of biopolyelectrolytes as a universal approach to fabrication of protein-loaded microparticles

This study was aimed at examination of microparticles formed via the layer-by-layer adsorption of dextran sulfate and chitosan onto the insoluble complexes of various proteins with polyanions. Microparticles with all tested proteins were stable at pH values of 1–5. At pH > 6 the mucoadhesivity of the microparticles changed and the encapsulated proteins were released. Microparticles were able to protect the proteins from proteases. Proteinous protease inhibitors encapsulated as well (2–3%) completely prevented protein proteolysis. The pharmacological effect of microencapsulated insulin was studied in vivo using the model of chronic diabetes in rats, which were treated by oral administration.

Single whole blood dextran sulfate adsorption favorably affects systemic oxidative balance in lipoprotein apheresis patients

Objective and methodsThe acute changes of circulating oxidative stress parameters were compared in 16 patients undergoing two different apheresis techniques: plasma lipidfiltration (LF) or whole blood dextran sulfate adsorption (DSA). ResultsImmediately after apheresis LF was associated with an increase in systemic phagocyte count, enhanced formation of reactive oxygen species and decreased activity of the antioxidant enzyme paraoxonase. After DSA, circulating phagocyte oxidant generating activity was significantly lower. Compared to LF, the systemic level of oxidized LDL and antioxLDL antibodies showed a larger decrease in DSA. All measured oxidative stress parameters returned to nearly pre-apheresis level at day three after apheresis, ConclusionThe data show a more pronounced leukocyte activation immediately after LF in contrast to DSA, possibly as a consequence of necessity of prior separation of blood plasma. The pathophysiological importance of the short-term oxidative burden after a single apheresis session remains to be determined.

Differential effects of lipoprotein apheresis by lipidfiltration or dextran sulfate adsorption on lipidomic profile

Objective and methodsAcute modification of plasma lipidomic profile was assessed by top-down shotgun profiling on a LTQ Orbitrap hybrid mass spectrometer in 14 patients treated with two different apheresis techniques: plasma lipidfiltration (LF) and whole blood dextran sulfate adsorption (DSA). ResultsPatients treated with DSA revealed a significantly more pronounced reduction of LDL-cholesterol (LDL-C), a diminished decrease of HDL-cholesterol (HDL-C) and triglycerides (TG), and a similar reduction in lipoprotein (a) (Lp(a)) level. Against the overall tendency of reduction of lipid metabolites of all lipid classes in post-apheresis plasma, independent of apheresis technology applied, a highly significant increase of phosphatidylethanolamines (PE) in response to DSA was observed. ConclusionThese data indicate that DSA technology may be associated with an activation or damage of blood cells at contact surface which subsequently leads to a massive liberation of cellular and membrane PE's. Pathophysiological consequences, especially with respect to coagulation system and oxidative stress, have to be further elucidated.

Defining the Role of Lipoprotein Apheresis in the Management of Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal co-dominant disorder characterized by a marked elevation of serum low-density lipoprotein (LDL) cholesterol (LDL-C) concentration, which in turn is associated with a greatly increased risk of premature cardiovascular disease. International consensus recommends the use of statins as the first line of treatment for patients with this condition. However, homozygote FH patients with persistently elevated LDL-C levels are usually resistant to multiple-drug therapy. Fortunately, LDL apheresis (or simply 'lipoprotein apheresis') provides a treatment option for patients who are refractory or intolerant to lipid-lowering medications, or if there is progressive cardiovascular disease despite maximal drug therapy. Lipoprotein apheresis is an extracorporeal LDL-C-lowering treatment similar in concept to renal dialysis. There are now five main methods for extracorporeal lipoprotein apheresis in use, namely dextran sulfate adsorption (DSA), heparin extracorporeal LDL precipitation (HELP), polyacrylate full blood adsorption (PFBA or DALI® system) using hemoperfusion, immunoadsorption, and filtration plasmapheresis. Lipoprotein apheresis has been shown to be successful in reducing LDL-C levels, as well as levels of lipoprotein(a) [Lp(a)], a prothrombotic proatherogenic lipoprotein. In contrast, however, lipoprotein apheresis seems to have a smaller effect in preventing atherosclerosis progression, thus suggesting that a major component of the reduction in cardiovascular events may be mediated by mitigating Lp(a) levels. Side effects are infrequent and mild, and have mainly consisted of lightheadedness, nausea, vomiting, and hypotension. As these are often bradykinin-mediated and associated with concomitant ACE inhibitor use, angiotensin type 2 receptor antagonists should be used instead of ACE inhibitors with DALI and PFBA. Nevertheless, there is scope for wider application of lipoprotein apheresis. The high cost and invasive nature of lipoprotein apheresis limits uptake; however, it is an important treatment modality that should be considered in carefully selected patients. National and international registries compiling outcome data for lipoprotein apheresis need to be established to help expand the evidence base regarding its effectiveness.

Mucoadhesive polyelectrolyte microparticles containing recombinant human insulin and its analogs aspart and lispro

Microparticles containing recombinant human insulin and its analogs aspart and lispro were prepared using an alternate adsorption of chitosan and dextran sulfate from solutions onto microaggregates of protein-dextran sulfate insoluble complex. The following properties of polyelectrolyte hormone-containing microparticles were studied: pH stability, surface charge, mucoadhesive properties, Ca(2+) binding, degradation under the influence of proteases (trypsin, chymotrypsin). The influence of the self-association ability of encapsulated insulins on the form of protein releasing from microparticles was studied. Insulins aspart and lispro released from the microparticles as monomers were more liable to proteolysis than human insulin released as a hexamer. The combined effect of properties of polyelectrolyte microparticles and of encapsulated recombinant proteins on the bioavailability of insulin under peroral administration is discussed.

Low Density Lipoprotein Apheresis Reduces PF4 on the Surface of Platelets: a Possible Protective Mechanism Against HIT

AbstractAbstract 2530Heparin is the anticoagulant used when performing low density lipoprotein (LDL)-apheresis using the Liposorber® system for patients with hypercholesterolemia. This system removes LDL particles via adsorption to a dextran sulfate cellulose bead column (LA-15 column). Despite the exposure to large amounts of heparin and the predisposition of patients with vascular diseases such as atherosclerosis to heparin induced thrombocytopenia (HIT), HIT in patients undergoing LDL-apheresis is very rare. We, therefore, investigated the possibility that the LDL apheresis procedure decreases platelet factor 4 (PF4) adsorbed to cell surfaces and/or plasma HIT antibody levels, either of which would disfavor HIT. We enrolled 25 patients undergoing LDL apheresis (Liposorber®) in the Apheresis and Infusion Clinic at the Hospital of the University of Pennsylvania. Patients were 28–77 years old with high levels of LDL-cholesterol or Lp(a). Whole blood samples were drawn before (pre-treatment), immediately after (post-treatment), and 30 minutes after treatment (30‘ post-treatment). Plasma samples were also drawn proximal (pre-column) and distal (post-column) to the LA-15 column after ∼350-500ml (∼15-30 minutes) of plasma volume had been processed. PF4, anti-PF4-heparin complex (HIT) antibodies and soluble CD40 ligand (sCD40L; as a marker of platelet activation) were measured using ELISA. Serotonin release assay was performed on samples that were positive for HIT antibodies. Platelet surface PF4 and P-selectin were measured by flow cytometry. Heparin levels were measured using the heparin anti-Xa chromogenic assay. The Student's t test, ANOVA and Wald tests were used to compare results. There were more males than females. None of the patients had any clinical symptoms of HIT. The LA-15 column was found to efficiently remove PF4 (pre-column mean ± SD=133.8 ± 88.26 IU/ml, post-column mean ± SD=0 IU/ml; P<0.0001, 2-tailed). The PF4 level in peripheral blood plasma did not change significantly after LDL apheresis (pre-treatment mean ± SD=116.5 ± 79.14 IU/ml, post-treatment mean ± SD=110.8 ± 67.28 IU/ml; P=NS). However, the amount of PF4 on the platelet surface was significantly decreased by LDL apheresis (pre-treatment mean fluorescence intensity (MFI) mean ± SD=46.32 ± 20.98, post-treatment MFI mean ± SD=31.37 ± 10.11, 30‘ post-treatment MFI mean ± SD=29.83 ± 10.35; P<0.001 for pre-treatment vs post-treatment and pre-treatment vs 30'post-treatment, 2-tailed). Heparin concentration in the plasma sample increased during treatment and remained elevated 30 minutes after treatment ended (pre-treatment mean ± SD=0.05 ± 0.10 U/ml, post-treatment mean ± SD=0.89 ± 0.09 U/ml, 30'post-treatment mean ± SD=0.79 ± 0.17 U/ml, P<0.0001 for pre-treatment vs post-treatment and pre-treatment vs 30'post-treatment, 2-tailed). HIT antibodies were found in only 2 patients and these antibodies were nonfunctional as assessed by the serotonin release assay. Platelet surface P-selectin, a marker of platelet activation, did not change during treatment (pre-treatment MFI mean ± SD=49.07 ± 27.24, post-treatment MFI mean ± SD=45.14 ± 25.77; P=NS) nor did sCD40L levels which were low before and after treatment. These data provide a potential explanation for the near lack of HIT in hypercholesterolemic patients undergoing LDL apheresis. They also suggest the possibility that the Liposorber® system (or the dextran sulfate adsorption column) may be useful for lowering PF4 in patients with HIT and may have therapeutic potential in its treatment as surface-bound PF4 is the pathologic target of HIT antibodies. Disclosures:No relevant conflicts of interest to declare.

Low‐density lipoprotein apheresis reduces platelet factor 4 on the surface of platelets: a possible protective mechanism against heparin‐induced thrombocytopenia and thrombosis

Heparin-induced thrombocytopenia and thrombosis (HITT) is characterized by thrombocytopenia due to the formation of antibodies against heparin : platelet factor 4 (PF4) complexes. Despite the exposure to heparin during treatment and predisposition of patients with atherosclerosis to HITT, HITT in patients undergoing low-density lipoprotein (LDL) apheresis is rare. We investigated the possibility that LDL apheresis decreases PF4 on platelet (PLT) surfaces and/or plasma HITT antibody levels, either of which would disfavor HITT. We enrolled 25 patients undergoing LDL apheresis at the Hospital of the University of Pennsylvania. Blood samples were drawn before and after treatment. Plasma samples were drawn proximal and distal to the LA-15 treatment column. PF4, HITT antibodies, heparin levels, and P-selectin were measured. No patient had clinical symptoms of HITT. The LA-15 column was found to efficiently remove PF4. PF4 levels in peripheral blood plasma did not change significantly after LDL apheresis. However, PLT surface PF4 significantly decreased after treatment. HITT antibodies were found in only two patients and were nonfunctional. PLT surface P-selectin did not change during treatment. We have demonstrated that LDL apheresis via dextran sulfate absorption removes plasma PF4 and reduces the amount of PF4 on the surface of circulating PLTs. Reduced surface PF4 may decrease antibody formation and/or recognition by HITT antibodies. These data provide a potential explanation for the near lack of HITT in hypercholesterolemic patients undergoing LDL apheresis. They also suggest the possibility that LDL apheresis using dextran sulfate adsorption may have therapeutic value in the treatment of HITT.