Apheretic treatment of severe familial hypercholesterolemia: comparison of dextran sulfate cellulose and double membrane filtration methods for low density lipoprotein removal

Multifunctional Cellulose and Cellulose-Based (Nano) Composite Adsorbents

In recent years, faced with the improvement of environmental quality problems, cellulose and cellulose-based (nano) composites have attracted great attention as adsorbents. In this review article, we first report the recent progress of modification and functionalization of cellulose adsorbents. In addition, the adsorbents produced by the modification and functionalization of carboxymehyl cellulose are also introduced. Moreover, the cellulose-based (nano) composites as adsorbents are reviewed in detail. Finally, the development prospect of cellulose and cellulose-based (nano) composites is studied in the field of the environment. In this review article, a critical comment is given based on our knowledge. It is believed that these biomass adsorbents will play an increasingly important role in the field of the environment.

Comparison of Different Ldl-Apheresis Techniques

LDL-apheresis is an extracorporeal technique which removes all apo B100-containing lipoproteins (VLDL, LDL, Lp(a)) from plasma, in patients whith homozygous, and double heterozygous, familial hypercholesterolemia (FH). One of the most significant technical characteristics of LDL-apheresis is the selectivity in the removal of atherogenic lipoproteins, namely LDLs, which has been improved in the most recently developed techniques. The oldest system for therapeutic plasmapheresis in the treatment of severe hyperlipoproteinemias, is plasma-exchange, where all plasma components are unselectively removed. More recently, the systems (dextransulphate cellulose LDL-apheresis [DSC/LDL-A], heparin induced LDL precipitation-apheresis [HELP/LDL-A], immunoadsorption LDL-apheresis [IMA/LDL-A], direct adsorption of lipids [DALI]) have permitted a selective removal of LDL and of other apo B100-containing lipoproteins. The higher selectivity, thus the higher efficacy and safety, has also allowed the treatment of high risk patients with severe cardiovascular conditions, and pediatric patients. Therefore, it is currently possible to begin treatment with LDL-apheresis, even at a very early age. The most recent system for LDL-apheresis (DALI: Direct Adsorption of Lipids) even permits the removal of LDL from whole blood, without previous cell/plasma separation. This system is promising for further progress in the technology related to LDL-apheresis.

Hypocholesterolaemic effects of soya proteins: results of recent studies are predictable from the Anderson meta-analysis data

In 1995, Andersonet al.published a meta-analysis, derived from most of the clinical studies on soya proteins given to individuals with varying levels of cholesterolaemia that had been reported up to that time. The meta-analysis clearly indicated that cholesterolaemias were generally reduced by diets with soya given as a partial or total substitution of animal proteins, with final mean total and LDL-cholesterol reductions of 23·2 mg/dl and 21·7 mg/dl, respectively. These findings were recently strongly criticised, based on the evaluation of later studies, frequently involving individuals with normal or moderately elevated cholesterolaemias. In the present paper, these more recent studies were re-evaluated using a ‘nomogram’ prepared on the basis of the quartiles of initial cholesterol concentrations in the Anderson meta-analysis and their corresponding CI for net cholesterol change. The five studies belonging to the first quartile and thirteen out of the fourteen belonging to the second quartile gave results perfectly in line with the nomogram. Out of the fourteen studies belonging to the third quartile, ten agreed with the nomogram and two gave lower cholesterol reductions, whereas two gave higher reductions. Unfortunately, none of the recent studies belonged to the fourth quartile as treatment with statins or other lipid-lowering drugs is now mandatory in the presence of very high cholesterol levels. The re-evaluation thus shows that the thirty-three studies published in the past 10 years are in agreement with the Anderson meta-analysis and confirm its validity.

Lipidfiltration--safe and effective methodology to perform lipid-apheresis

Familial hypercholesterolemia (FH) not adequately responding to diet and drug therapy represents an indication for extracorporeal lipid-apheresis, which has become an highly effective and approved therapy for those patients in several countries. Based on different methodology, five treatment options of lipid-apheresis exist and are in widespread practical use covered by regular reimbursement in Germany. All methods are safe and demonstrate equivalent efficacy of reducing LDL cholesterol with respect to the single apheresis session as well as during long-term treatment. Therefore German reimbursement guidelines leave the choice of the method to the discretion of the apheresis center. Related to properties of the used technology all methods exhibit characteristic patterns of additional plasma protein elimination, which do not impair, but in part may increase the therapeutic benefit of lipid-apheresis. Fibrinogen reduction has to be mentioned as an example. The Lipidfiltration system is based on plasmafiltration previously referred to as membrane differential filtration (MDF), synonymous with double filtration plasmapheresis (DFPP). The new term Lipidfiltration was the result of technological progress in the manufacturing process of the plasmafilter resulting in enhanced sieving characteristics and capacity. The Lipidfiltration system is completed by a specifically designed therapy machine with optimised performance characteristics.

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

Extracorporeal low-density lipoprotein (LDL) apheresis is an established and highly effective therapy for patients with familial hypercholesterolemia (FH) not adequately responding to diet and drug therapy alone. Based on different methodology, five treatment options of LDL apheresis are available and in widespread practical use in Germany. All methods are safe and demonstrate equivalent efficacy of reducing LDL cholesterol with respect to the single apheresis session as well as during long-term treatment. Owing to methodological properties all methods also exhibit characteristics of additional plasma protein elimination, which do not impair, but in part, increase the beneficial therapeutic effect of LDL apheresis. Fibrinogen reduction has to be mentioned as an example. The lipidfiltration system is based on plasmafiltration previously named membrane differential filtration (MDF), synonymous with double filtration plasmapheresis (DFPP). The new term lipidfiltration was the result of technological progress leading to a significant improvement of the efficiency. The system consists of a novel lipid filter with enhanced sieving characteristics and capacity, and is completed by an enhanced therapy machine with an optimized heating unit.

Extracorporeal removal of lipids by dextran sulfate cellulose adsorption

Extracorporeal removal of low-density lipoprotein (LDL) cholesterol by dextran sulfate adsorption is indicated in patients with diet and drug resistant hyper-cholesterolemia to prevent or to regress coronary heart disease. Plasma separation is the first step in the process, followed by adsorption of LDL cholesterol and lipoprotein (a) (Lp[a]) to negatively charged dextran sulfate covalently bound to cellulose beads. The reduction per treatment in LDL cholesterol is 65-75% and in Lp(a) 40-60%. In most patients one treatment per week is sufficient to reduce mean LDL to 100-150 mg/dl. Minor side effects occur in 2-6% of treatments. Major side effects are rare. In uncontrolled studies long-term treatment was associated with inhibition of progression and induction of regression of coronary artery disease. LDL apheresis by dextran sulfate may increase blood perfusion of some tissues, and preliminary results indicate a beneficial effect on therapy resistant nephrotic syndrome with hypercholesterolemia.

Low-density lipoprotein apheresis as long-term treatment for children with homozygous familial hypercholesterolemia

OBJECTIVE

To determine the safety and efficacy of long-term dextran sulfate-affinity column low-density lipoprotein (LDL) apheresis for the treatment of children with receptor-negative homozygous familial hypercholesterolemia (HFH).

STUDY DESIGN

Two children with HFH (pretreatment cholesterol levels 22.1 to 24.7 mmol/L (ranges 850 to 950 mg/dl) began LDL apheresis treatments at ages 7 and 10 years, respectively. The LDL apheresis treatment interval was generally either 7 or 14 days; for the last 2 years of the study the treatment interval was 7 days. The patients had 167 and 188 LDL apheresis procedures during 64 and 70 months, respectively.

RESULTS

Individual procedures decreased total blood cholesterol levels by 63% to 68%. When the treatment interval was 7 days, the patients' time-averaged mean total cholesterol levels decreased to 7.3 +/- 0.65 mmol/L (280 +/- 25 mg/dl) and 6.4 +/- 0.55 mmol/L (247 +/- 22 mg/dl), respectively. Both children remained clinically well with normal growth and development. There was significant regression of xanthomas in both patients. The older patient required heart surgery for preexisting aortic stenosis and coronary ostial stenosis, but neither patient had progression of hypercholesterolemia-related cardiovascular disease. With the exception of iron (deficiency in patient 1), there was no evidence of depletion of serum components. Adverse reactions to LDL apheresis were rare and never severe.

CONCLUSIONS

Dextran sulfate-affinity column LDL apheresis is effective long-term treatment for children with receptor-negative HFH.

Selective removal of plasma low density lipoprotein with the HELP system: biweekly versus weekly therapy

PURPOSE

Biweekly (once every 2 weeks) heparin-induced extracorporeal low-density lipoprotein (LDL) precipitation (HELP) therapy was evaluated for safety and efficacy in selectively reducing LDL cholesterol levels compared with weekly HELP therapy.

PATIENTS AND METHODS

Biweekly treatments were given to high-risk, diet/drug resistant hypercholesterolemic patients (n = 23) after 6 months of weekly HELP therapy. Lipids, lipoprotein cholesterol, apolipoproteins A-I and B, and fibrinogen were measured on plasma samples before and after treatment.

RESULTS

Mean plasma volume treated was 2.8 l and mean treatment duration 1.7 h. Therapy complications were minimal. In 98% of 268 biweekly HELP treatments, LDL cholesterol levels were reduced by > 30%. For patients completing 6 months of biweekly therapy following 6 months' weekly therapy (n = 23), mean LDL cholesterol levels were reduced 138.5 mg/dl (111.2 mg/dl weekly) with a time-averaged decrease from mean pre-apheresis levels of 33% for biweekly therapy (39% weekly). Mean total cholesterol (161.2 mg/dl biweekly versus 132.9 weekly) and apolipoprotein B (104.6 mg/dl versus 92.6) levels were also reduced with each treatment. Mean HDL cholesterol was reduced only 6.1 mg/dl (6.3 mg/dl weekly).

CONCLUSIONS

Biweekly HELP treatments can safely reduce LDL cholesterol levels as consistently as weekly HELP treatments. However, the higher pre-treatment LDL cholesterol levels with biweekly treatments may produce less therapeutic benefit than with weekly therapy.

New targets for lipid lowering and atherosclerosis prevention

The effectiveness of plasma lipid lowering in the clinic is well supported by a growing number of contributions, indicating the significant improvement in cardiovascular risk in primary and particularly in secondary prevention. While these studies have clearly indicated that the more potent agents for cholesterol reduction can provide a very effective help, other pathways of lipid metabolism have gained interest. These should be evaluated, in the hope of providing a more complete answer to the question of regulating lipid absorption, distribution, and tissue deposition. In addition to newer more potent systemic lipid-lowering drugs (in particular hydroxymethylglutaryl coenzyme A reductase inhibitors), nonsystemic agents, including cholesterol sequestrants, are receiving attention. Some of these are effective at low concentrations, thus providing a potentially powerful tool for plasma cholesterol regulation. Another area of development is that of acyl coenzyme A cholesterol acyltransferase inhibitors, i.e., drugs interfering with cholesterol esterification in tissues, particularly in the arterial wall; the major problem with these seems to be that of poor tolerability and of lack of definitive proof of plasma cholesterol reduction in humans. At present, drugs for the treatment of elevated lipoprotein(a) levels are not available, with few exceptions; in this case, a better understanding of the regulation of lipoprotein(a) metabolism and of the potential benefit of treatment seems necessary. Elevation of congenitally low high density lipoprotein cholesterol levels may also be an important target: microsomal enzyme inducers have been tested, but have not provided a clinically significant response; drugs with a mixed endocrine-hypolipidemic activity possibly may prove effective. Other targets, e.g., the correction of the lipoprotein pattern characterized by "small low density lipoprotein," and the development of drugs specifically acting on the cholesteryl ester transfer protein and lipoprotein lipase systems, are being explored. Finally, new areas of development are in recombinant apolipoproteins (apo's) and in gene therapy. One case, i.e., that of apo A-I/HDL, is entering the clinical field; the mutant apo A-IMilano might provide help because of a combined cholesterol removing/fibrinolytic activity. In the case of gene therapy, at present, data on low density lipoprotein receptor replacement are encouraging. Further options, such as gene transfer in the arterial wall to induce vascular protection/disobliteration of occlusions, are also being tested.

Effectiveness of cascade filtration plasmapheresis in two patients affected by familial hypercholesterolemia

Hypercholesterolemia has been recognised as a primary risk factor for coronary heart disease. Reduction of plasma levels of total and LDL cholesterol has been shown to decrease coronary atherosclerosis. Plasmapheresis represents an useful non-pharmacological tool to treat severe hypercholesterolemias. We have evaluated the effectiveness of a system of plasmapheresis using a cascade filtration method in two young male subjects (aged 16 and 26 years) with homozygous familial hypercholesterolemia. Both showed severe coronary atherosclerosis as determined by angiography. Procedures were performed at intervals of 7 days in each case. We observed a mean reduction of plasma levels of total cholesterol of 59.5% (range 31.0-75.5%); LDL-cholesterol, 61.6% (range 32.6-77.1%); triglycerides, 48.1%; HDL-cholesterol, 31.1%; apo A-I, 30.8%; and apo B, 57.6%. We also noted a reduction of other parameters, such as fibrinogen (49.9%) and Lp(a) (59.9%). At the end of each procedure about 8 g of cholesterol was removed from the total body pool. A decrease of total proteins (26.9%) and albumin (19.6%) was also observed, but this was completely restored before the next apheresis (1 week). These data show the effectiveness of the removal of LDL in a cascade filtration system, which obtains results not very different from other more selective methods. The lack of selectivity is not much of a problem, since it also reduces other risk factors such as Lp(a) and fibrinogen.

Extracorporeal circuit heparinization in selective low density lipoprotein apheresis: changes in patient hemostasis and low molecular weight heparin benefit

Treatment by low density lipoprotein (LDL) apheresis using dextran sulfate columns (DSC) leads to hemostasis alterations with prolonged activated partial thromboplastin time (APTT) of more than 120 seconds. In order to explain this hypocoagulability, we studied hemostasis parameters both in patients and in the extracorporeal circulation (ECC). Hemostasis changes are first related to unfractionated heparin (UFH)--needed to avoid circuit coagulation--which leads to high residual heparinemia in the patient (more than 3 times the recommended level for therapeutic use). Second, the hypocoagulability is induced by a coagulation factor decrease (primarily factors V, VIII, and X) mainly due to an adsorption mechanism on dextran sulfate. Studies on samples from column inflow, outflow, and eluate confirm this mechanism. Low molecular weight heparin (LMWH) can be used in LDL apheresis on DSC without major changes in lipid removal or coagulation factors compared to UFH. The benefit of using LMWH is to reduce residual heparinemia into the therapeutic range.

Treatment of refractory familial hypercholesterolemia by low-density lipoprotein apheresis using an automated dextran sulfate cellulose adsorption system. The Liposorber Study Group

A subgroup of patients with familial hypercholesterolemia (FH) respond inadequately to standard diet and drug therapy, and are therefore at high risk for the premature development or progression of coronary artery disease. This study evaluated low-density lipoprotein (LDL) cholesterol and lipoprotein (a) removal in a multicenter, controlled trial with a new LDL apheresis procedure (Liposorber LA-15 System). The study comprised patients with FH who had not responded adequately to diet and maximal drug therapy. There were 54 patients with heterozygous FH (45 randomized to treatment and 9 control subjects) and 10 with homozygous FH (all of whom received LDL apheresis). The study included three 6-week treatment phases and a 4-week rebound phase. Treatments were administered at 7- to 14-day intervals. Mean acute reductions in LDL cholesterol were 76% in heterozygous FH patients and 81% in homozygous ones. Time-averaged levels of LDL cholesterol were reduced 41% (243 to 143 mg/dl) in heterozygous FH patients and 53% (447 to 210 mg/dl) in homozygous ones. The substantial acute reduction of lipoprotein (a) (means: 65%, heterozygous FH; 68%, homozygous FH) has not been reported with other therapies. The Liposorber LA-15 System represents an important therapeutic option in FH patients who respond inadequately to diet and drug therapy.

Treatment of children with homozygous familial hypercholesterolemia: safety and efficacy of low-density lipoprotein apheresis

We evaluated the safety and efficacy of dextran sulfate low-density lipoprotein (LDL) apheresis in the treatment of three children (aged 6, 7, and 10 years) with severe familial homozygous hypercholesterolemia and undetectable LDL receptor activity. A total of 35 double plasma volume procedures were performed. The ranges of the mean decreases of the three patients in plasma lipid concentrations after LDL apheresis (p less than 0.0001) were as follows: total cholesterol, 76% to 79%; LDL-cholesterol, 78% to 81%; very low density lipoprotein cholesterol, 69% to 75%; high-density lipoprotein cholesterol, 27% to 40%; and triglycerides, 34% to 68%. There were statistically significant but clinically and biologically irrelevant changes in hematologic indexes, serum chemistry values, immunoglobulin levels, complement activity, and plasma concentrations of fat-soluble vitamins. Simple correlation analysis of the variables affecting total cholesterol removal showed significant correlation coefficients (r values) for preapheresis total cholesterol values (r = 0.70; p less than 0.01) and preapheresis LDL-cholesterol values (r = 0.61; p less than 0.01). A multiple regression model explained 82% of the variance based on the preapheresis cholesterol concentration, volume of whole blood processed, and the serum albumin concentration. Side effects of the LDL-apheresis treatments were rare and included abdominal cramping and urticaria. Two procedures were aborted because of intravenous access problems in the younger children. This study confirms that LDL apheresis using a dextran sulfate affinity column is efficacious in rapidly lowering total and LDL-cholesterol concentrations. Furthermore, the procedure is safe and well tolerated by children as young as 6 years of age. This treatment may prevent the progression of atherosclerosis in children with homozygous familial hypercholesterolemia and may therefore avert early death.

Predictability of low-density lipoprotein levels during apheretic treatment of hypercholesterolaemia

The efficiency and efficacy of low-density lipoprotein (LDL) apheresis performed with a dextran sulphate cellulose (DSC) regenerating unit were tested in five familial hypercholesterolaemic patients. LDL apheresis was repeated four times at both bi-weekly and weekly intervals, processing one plasma volume each time. The efficiency of the procedure (i.e., the extent of lipoprotein removal) was nearly identical with both schedules. Efficacy parameters, i.e., decreases of plasma total and LDL cholesterol (TC and LDL-C) and apo B, were highly correlated (r greater than 0.96) with preapheresis levels, allowing an accurate prediction of the absolute lipid removal in the single individual. Plasma triglycerides, high-density lipoprotein cholesterol, apo A-I and apo A-II recovered rather rapidly, reaching 91-96% of the pre-apheresis values in 48 hours; the recovery of TC, LDL-C and apo B was much slower, with a relatively rapid early phase (80% recovery after about 7 days) followed by a successive slower rise. This pattern was highly reproducible in the single patient, allowing the definition of a simple mathematical model for an accurate (error less than 20%) prediction of the individual process. Based on this model one can design the treatment schedule necessary to maintain lipid levels within the desired range in the single individual. The hypolipidaemic efficacy of DSC apheresis appears, otherwise, not to be dependent upon the procedure per se, but on other individual factors, e.g. the amount of removable lipoproteins and the rate of lipid recovery; both can be predicted with sufficient accuracy.

Plasmapheresis: technique and complications

Plasmapheresis has been used in an increasing number of diverse conditions over the past 15 years, and patients on intensive care units are sometimes so treated. This article reviews the principles, different techniques and refinements available, including the more specific methods of antibody removal, such as immunoadsorption. The vascular access, anticoagulation, choice of fluid replacement and monitoring requirements are discussed. The reported possible complications of plasmapheresis, relating both to the practical aspects of the procedure and to the effects of plasma removal and the replacement fluids, are reviewed.