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Low-molecular-weight protein-permeable cuprammonium rayon haemofilter
M Menth1, A Röckel, S Abdelhamid
1Department of Nephrology, Deutsche Klinik für Diagnostik, Wiesbaden, Germany.
Abstract:
Searching for a dialyser membrane with a cut-off similar to that of the human glomerulus, a modified cuprammonium rayon (AM-75-UP) and a polyacrylonitrile (PAN-15-DX) haemofilter were tested in vivo for the ability to eliminate substances of a molecular weight (MW) of 10-65 kilodaltons (kDa). Endogenous marker substances of a defined MW (beta-2-microglobulin 11.8 kDa; retinol binding protein 21 kDa; alpha-1-microglobulin 26.7 kDa; alpha-1-glycoprotein 41 kDa; alpha-1-antitrypsin 54 kDa; albumin 66.3 kDa) were measured by laser nephelometry or immunosorbent assay; sieving coefficients (SC) and protein elimination (PE) per 20 l haemofiltration were calculated for each low-MW protein. The PAN haemofilter shows elimination characteristics comparable to those of earlier tested haemofilters (polysulphone, AN69, cellulose triacetate) with a sharp cut-off in the MW range of 10-15 kDa. The cuprammonium rayon haemofilter is permeable for proteins with a higher MW; especially for alpha-1-microglobulin a relevant removal (SC 0.2; PE 0.56 g/20 l) was established. This membrane has a cut-off more similar to that of the human glomerulus; but far from the demanded quality with a relevant removal of substances in the MW range up to 60 kDa. Calculated albumin loss (2.4 +/- 0.2 g/20 l) seems to be tolerable for stable haemodialysis patients.
Insights
Researchers evaluated two hemodialysis membranes, AM-75-UP and PAN-15-DX, for their ability to remove medium-sized proteins. The PAN-15-DX showed a sharp cut-off, while the AM-75-UP demonstrated better removal of larger proteins, mimicking the human glomerulus more closely.
Area of Science:
- Nephrology
- Biomaterials Science
- Medical Device Engineering
Background:
- Hemodialysis requires membranes that mimic the kidney's filtration capabilities.
- Existing hemodialysis membranes have varying efficiencies in removing medium-molecular-weight substances.
- There is a need for dialyzer membranes with a cut-off similar to the human glomerulus.
Purpose of the Study:
- To evaluate the in vivo performance of modified cuprammonium rayon (AM-75-UP) and polyacrylonitrile (PAN-15-DX) hemodialysis membranes.
- To assess their ability to eliminate substances with molecular weights ranging from 10 to 65 kilodaltons (kDa).
- To compare their sieving coefficients and protein elimination characteristics against established membranes and the human glomerular filtration barrier.
Main Methods:
- In vivo testing of AM-75-UP and PAN-15-DX hemodialyzers.
- Measurement of endogenous marker substances (beta-2-microglobulin, retinol binding protein, alpha-1-microglobulin, alpha-1-glycoprotein, alpha-1-antitrypsin, albumin) using laser nephelometry or immunosorbent assay.
- Calculation of sieving coefficients (SC) and protein elimination (PE) per 20 L of hemofiltration.
Main Results:
- The PAN-15-DX hemodialyzer exhibited elimination characteristics similar to previously tested membranes, with a sharp cut-off around 10-15 kDa.
- The AM-75-UP hemodialyzer demonstrated greater permeability for higher molecular weight proteins.
- Specifically, AM-75-UP showed relevant removal of alpha-1-microglobulin (SC 0.2; PE 0.56 g/20 L), indicating a cut-off closer to the human glomerulus but insufficient for removing substances up to 60 kDa.
- Calculated albumin loss with AM-75-UP was 2.4 +/- 0.2 g/20 L, deemed tolerable for stable hemodialysis patients.
Conclusions:
- The PAN-15-DX membrane offers a selective removal profile typical of many current hemodialyzers.
- The AM-75-UP membrane shows potential for enhanced removal of medium-molecular-weight uremic toxins, more closely resembling glomerular filtration.
- While AM-75-UP's albumin loss is acceptable, further development is needed to achieve the desired removal range up to 60 kDa.