Asymmetric membrane filters for the removal of leukocytes from blood

Abstract

As part of a study on the mechanisms of leukocyte filtration, the influence of pore size distribution on filter efficiency was investigated. Conventional leukocyte filters are not suitable for model studies, as these filters are composed of tightly packed synthetic fibers, with a poorly defined porous structure. Therefore, open cellular polyurethane membranes with pore size distributions varying from approximately 15 to 65 microns were prepared. Filtration experiments with stacked packages of these membranes showed that leukocytes are best removed (greater than 99%) by filters with a pore size distribution of 11-19 microns. These pore sizes approach the size of leukocytes (6-12 microns). However, due to fast clogging, blood flow through these filters is rapidly reduced, which results in a low filter capacity. With an asymmetric membrane filter, in which the pore size decreases from about 65 to 15 microns in the direction of blood flow, both moderate removal of leukocytes (greater than 80%) and maintenance of flow (approximately 0.2 mL/s) are obtained. This results in efficient leukocyte removal. From cell analysis of both filtrate and filter, it is concluded that adhesion rather than sieving is the major filtration mechanism. Thus, further optimization of the filter may be achieved by surface modification.

Preparation of surface‐modified poly(butylene terephthalate) nonwovens and their application as leukocyte removal filters

“…Blood components were obtained from the Korea Red Cross Blood Center under the condition that they be used only for research purposes. Among the commercially available filters for leukocyte removal, two products, Pall RCXL2 (Pall Biomedical, Fajardo, PR) and Sepacell R‐500A (Asahi Medical Co, Tokyo, Japan),24–26 were included in the RBCs filtering experiments for comparison to PBT‐HA. Pall PXL8 (Pall Biomedical) and Sepacell PLS‐5A‐1 (Asahi Medical.)…”

On-chip sample preparations for Point-of-Care cellular analysis of blood

“…Mechanical filtration is an effective approach for the separation of cells based on distinctive size. A well-established application is the separation of WBCs and RBCs in whole blood [6][7][8][9]. Bench-top filtration concepts using fibrous membranes (nitrocellulose [7], polycarbonate [8,10], polyacrylamide [11]) can be simply down-scaled and implemented into microdevices.…”

Microfluidic Devices for Blood Fractionation

“…Red blood cells (RBCs) on the other hand have a biconcave disc-like structure with an average diameter of 7-8 µm and 2-3 µm thickness. Due to the high deformability of RBCs aided by the absence of nucleus, membrane-based filters are also commonly employed to filter leukocytes from blood [41,42]. The inherent differences in size and deformability between the RBCs and leukocytes have led to the development of several microfluidics techniques based on the principles of cell retention and retarded cell movement [40,[43][44][45].…”