PHEMA cryogel for in-vitro removal of anti-dsDNA antibodies from SLE plasma Erdoğan Özgür a , Nilay Bereli a , Deniz Türkmen a , Serhat Ünal b , Adil Denizli a, ⁎ a Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara, Turkey b Faculty of medicine, Hacettepe University, Ankara, Turkey abstract article info Article history: Received 25 January 2010 Received in revised form 6 December 2010 Accepted 17 February 2011 Available online 24 February 2011 Keywords: Antibody removal Anti-dsDNA PHEMA Cryogels DNA SLE Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA) cryogel carrying DNA was used in the removal of anti-dsDNA antibodies from systemic lupus erythematosus (SLE) patient plasma. The PHEMA cryogel was prepared by bulk polymerization which proceeds in an aqueous solution of monomer frozen inside a plastic syringe. After thawing, the PHEMA cryogel contains a continuous matrix having interconnected macropores of 10–200 μm size. Pore volume in the PHEMA cryogel was 67.5%. Ester groups in the PHEMA structure were converted to imine groups by reacting with poly(ethyleneimine) (PEI) in the presence of NaHCO 3 . Amino (-NH 2 ) content of PEI-modified PHEMA cryogel was determined as 82 mg PEI/g. Then, DNA was attached onto the PHEMA cryogel via amino groups (53.4 mg DNA/g cryogel). Anti-dsDNA-antibody concentration declined significantly from 780 IU/ml to 80 IU/ml with the time. The maximum anti-dsDNA-antibody adsorption amount was 70 × 10 3 IU/g. Anti-dsDNA-antibodies could be repeatedly adsorbed and eluted without noticeable loss in the anti-dsDNA-antibody adsorption amount. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Circulating immune complexes, autoantibodies such as anti- double-stranded DNA antibodies have been implicated in the pathogenesis of systemic lupus erythematosus (SLE) [1]. Anti- dsDNA antibodies serve as markers of diagnostic and prognostic significance in SLE, and there is compelling evidence for an association between anti-dsDNA antibodies and tissue damage [2]. Since many of the clinical manifestations of this disease can be attributed to immune complex deposition, the concept has arisen that antibodies against DNA mediate tissue damage by the formation of DNA-anti-dsDNA antibody immune complexes which localize throughout the body, most prominently in the kidneys [3]. However, this model, while consistent with many clinical and serologic findings, has been difficult to verify. For example, although there is suggestive evidence for DNA- anti-dsDNA antibody complexes in patient sera, such complexes have not been demonstrated either consistently or conclusively [4]. The level of anti-dsDNA antibodies correlates well with the disease activity and organ involvements, such as nephritis and cerabritis. In such cases the removal of anti-dsDNA antibodies from plasma may lead to a clinical improvement. Analysis of plasmapheresis has shown that plasma exchange acts by removing autoantibodies [5]. But, risks of plasmapheresis therapy stem from the nonspecific elimination of all plasma components according to their plasma content. Necessary substitutions may induce allergic reactions and plasma replacement can convey infective diseases. Because of the disadvantages of plasmapheresis, efforts were made to develop a more specific extracorporeal technique to remove the pathogenic substances from plasma. Immunoadsorption with affinity adsorbents has become increasingly utilized as a therapeutic modality to remove pathogenic antibodies contained in the plasma of patients. Immuno-adsorption was first applied to the treatment of SLE in 1979 when Terman et al. tried to remove anti-DNA antibodies from a patient by plasma perfusion over a charcoal device [6]. Nicolaev et al. applied DNA-immobilized activated carbon hemoperfusion column to the treatment of patients with psoriasis [7]. Ventura et al. utilized poly(ethylene vinyl alcohol) hollow fiber carrying histidine for the removal of anti-dsDNA antibodies in in-vitro system [8]. Zhu et al. used DNA-immobilized non-woven poly (ethylene terephthalate) fabric fibers for treatment of SLE [9]. Recently, Yu and He prepared DNA-immobilized hydroxyethyl crosslinked chitosan beads as immunoadsorbents for specific removal of anti-dsDNA anti- bodies in SLE serum [10]. Kato and Ikada reported anti-dsDNA antibody adsorption using DNA-carrying poly(ethylene terephthalate) microfibers [11]. We report herein our studies on the use of selective anti-dsDNA antibody adsorption using DNA-attached poly(hydroxyethyl methac- rylate) cryogel. Traditional columns have a major limitation: incapability of processing whole blood. Blood cells are trapped between the beads of the column resulting in increased flow resistance and complete blockage of the flow. Expanded-bed chromatographic set-up overcomes the problem of handling particulate-containing fluids. Materials Science and Engineering C 31 (2011) 915–920 ⁎ Corresponding author. E-mail address: denizli@hacettepe.edu.tr (A. Denizli). 0928-4931/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.msec.2011.02.012 Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec