Reduction of low-density lipoproteins with dextran sulfate in patients with familial hypercholesterolemia

Non-pharmacological lowering of low-density lipoprotein by apheresis and surgical techniques

In the past year, new data have appeared on the long-term benefits of low-density lipoprotein apheresis in severely hypercholesterolemic patients who are refractory to lipid-lowering drug therapy. Such data are critical for clinical decision-making, because they confirm the hypothesis that the dramatic reduction in low-density lipoprotein made possible by this technique produces clear-cut clinical benefits. Because of its efficacy and low incidence of side-effects, apheresis for severe drug-refractory hypercholesterolemia has superseded surgical approaches, such as liver transplantation or ileal bypass.

Low-density lipoprotein removal methods by membranes and future perspectives

Since the application by Thompson et al. in 1975 of plasma exchange for the treatment of 2 patients with familial hyperlipidemia, plasma purification techniques for selective low-density lipoprotein (LDL) removal (i.e., LDL apheresis) have been developed and adopted for the management of this disease. Thermofiltration is one of the LDL apheresis systems that utilizes membrane techniques developed by Nose and Malchesky's group in 1985. This article reviews its rationale, in vitro studies, animal studies, and clinical investigation. Thermofiltration effectively and selectively removes LDL cholesterol while retaining in the plasma physiologically important macromolecules such as albumin and high-density lipoprotein (HDL) cholesterol. Based on the global view of the treatment of atherosclerosis by LDL apheresis, membrane techniques are as effective, safe, and simpler to apply than other methods. Additionally, these methods are effective for the removal of lipoprotein (a) and fibrinogen; thus, they can address the needs in these application areas.

Adsorption treatment in hyperlipidemia

Clinical LDL- adsorption has made overwhelming progress in recent years. Thus, immunoadsorption with polyclonal anti-LDL-antibodies and chemoadsorption using the dextransulfate system have been applied successfully for selective LDL-removal in routine clinical plasma treatment of hypercholesterolemic patients suffering from coronary artery disease. Clinical pilot studies showed good results using immunoadsorption with anti-LDL-F(ab)-columns. Promising laboratory results have been achieved using immunoadsorption with monoclonal LDL-antibodies, polyacrylate/fractogel and macroporous cellulose. While these systems need a primary separation step for cells and plasma, the integrated plasma separation/adsorption device and the LDL-hemoperfusion module using E 280590 can even treat whole blood. Thus, these systems hold a great promise for the future.

Extracorporeal methods in lipid reduction pursuant to improvement in risk factors associated with atherosclerosis

Atherosclerosis is the leading cause of death in the United States. Elevated plasma levels of low-density lipoprotein and lipoprotein(a) [Lp(a)] and subnormal levels of high density lipoprotein are risk factors in atherosclerotic coronary heart disease. Extracorporeal methods of affecting these risk factors are reviewed. The limited information on the effects of apheresis procedures on Lp(a) is discussed and extended from a kinetic modeling approach. An estimate, made of the number of patients who could be expected to benefit from extracorporeal lipid lowering, is presented.

Thermofiltration in hypercholesterolemia treatment: analysis of removal and posttreatment cholesterol recovery

Thermofiltration, a system of membrane plasmapheresis for LDL apheresis, is used to treat patients with refractory hyperlipidemia. In this system, the separated plasma is warmed to or above physiologic temperature, filtered with a membrane filter, and returned to the patient on-line. Plasma infusion products are not required. In this study one calculated plasma volume was treated weekly, biweekly, or monthly in patients classified as type II hypercholesterolemic. Reduction and sieving of lipoproteins were evaluated. The reduction ratios of high-density lipoprotein cholesterol (HDLc) and low-density lipoprotein cholesterol (LDLc) were 0.30 +/- 0.06 and 0.58 +/- 0.05, respectively (mean +/- S.D.). Sieving coefficients of the plasma filter for HDLc and LDLc were 0.62 +/- 0.12 and 0.03 +/- 0.02, respectively (mean +/- S.D. of 31 treatments). To evaluate the posttreatment recovery the apparent fractional catabolic rates (FCRa) for total cholesterol and LDLc were calculated. FCRa was 0.151 +/- 0.06 and 0.148 +/- 0.06 day-1 for total cholesterol and LDLc, respectively. The ratio of the posttreatment concentration on the seventh day to the concentration immediately pretreatment was found to be significantly higher for HDLc than for LDLc, 0.92 +/- 0.8 vs. 0.77 +/- 0.1 (mean +/- S.D.), due to faster HDLc recovery. The ratio of LDLc/HDLc was lowered for up to 2 weeks after the treatments.

Immunosorbents for LDL-apheresis

Low density lipoprotein (LDL) (1,03-1,05 g/ml) was utilized as antigen to obtain polyclonal (PcAb) and monoclonal (McAb) antibodies. Immunosorbents capable of selective removing LDL from human plasma were developed on the basis of the antibodies preparation. The sorbents called "Immunoliposorber PcAb" and "Immunoliposorber McAb" are currently undergoing clinical trials in the USSR Cardiology Research Center, Acad. of Med. Sciences.

Treatment of hypercholesterolemia by precipitation of lipoproteins with dextran sulfate

An on-line continuous system for the selective precipitation of low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL) has been devised and tested. This system conserves high-density lipoproteins (HDL) and other plasma macromolecules. LDL and VLDL are precipitated from plasma using 10-35 mg/dl dextran sulfate (Mr 5,000) in the presence of 55 mM calcium with a reduced concentration of monovalent cations. The plasma is obtained by membrane filtration of whole blood using the COBE Centry TPE System (Cobe Laboratories Inc, Lakewood, Co.). The precipitated LDL plus VLDL is removed by filtration, and the electrolytes are restored by dialysis. The plasma minus LDL plus VLDL is then returned to the patient. Four patients with heterozygous familial hypercholesterolemia (type II) were treated 70 times. The mean pretreatment serum cholesterol was 383 mg/dl. The mean reductions in plasma components were: LDL plus VLDL 63%; HDL 27%; fibrinogen 19%; albumin 15%; IgG 20%; IgA 19%; IgM 25%; C3 30%; and C4 27%. The cholesterol returned to near normal values in approximately 2 weeks after each treatment. Four normal volunteers were each treated one time. These individuals had a mean pretreatment serum cholesterol of 201 mg/dl. The mean reduction in plasma components were: LDL plus VLDL 70%; HDL 27%; fibrinogen 24%; albumin 14%; IgG 18%; IgA 17%; IgM 20%; C3 27%; C4 22%; C3 proactivator 12%; alpha 1-antitrypsin 17%; ceruloplasma 17%; transferrin 18%; alpha 2-macroglobulin 17%; and orosomucoid 13%. It is our conclusion that dextran sulfate precipitation is an effective on-line means of selectively removing LDL plus VLDL from plasma while conserving HDL and other plasma macromolecules.(ABSTRACT TRUNCATED AT 250 WORDS)