Biomaterials 23 (2002) 1213–1219 Studies on new polymeric biomaterials with tunable hydrophilicity, and their possible utility in corneal repair surgery Monique J. Bruining a , A. Paul Pijpers b , Peter Kingshott c , Leo H. Koole a, * a Center for Biomaterials Research, University of Maastricht, P.O. Box 616, 6200 MD Maastricht, The Netherlands b DSM Research, Geleen, The Netherlands c Aachen Centre of Competence: Biomaterials, Department of Textile Chemistry and Macromolecular Chemistry, Aachen, Germany Received 26 January 2001; accepted 22 June 2001 Abstract A well-known complication in corneal repair surgery is (recurrent) rejection of donor corneal tissue, particularly in patients suffering from an auto-immune disease such as rheumatoid arthritis. Down-regulation of their immune system, by means of drugs, is necessary in order to perform an allograft implantation afterwards. The patient may need a temporary prosthetic cornea while the immune system is inactivated. Recently, NeuroPatch s , a mesh-type polyurethane, was used for this purpose. The material exhibits excellent biocompatibility and allows ingrowth of stromal fibroblasts which deposit matrix material into the pores. A serious drawback of NeuroPatch s is its non-transparency, which impairs vision. In this work we attempted to develop an improved biomaterial that combines the advantages of NeuroPatch s with optical transparency. Based on previous findings that copolymers of hexaethyleneglycolmethacrylate (HEGMA) and butylmethacrylate (BMA), are transparent and well accepted by human corneal epithelial cells, we studied these materials further in detail. (Bruining et al., Bio-Macromolecules 1 (2000) 418) Copolymerizations were studied by means of 1 H NMR. The influence of the HEGMA content on hydrophilicity, flexibility and resistance to protein adsorption was studied. The results indicate that materials with a HEGMA content of approximately 20 mol% are potentially useful in corneal repair surgery. These biomaterials meet most of the stringent physical and biological requirements. r 2001 Elsevier Science Ltd. All rights reserved. Keywords: Polymeric biomaterials; Tunable hydrophilicity; Corneal repair surgery 1. Introduction Treatment of corneal perforations, resulting from trauma or from pathological thinning, is mainly based on the use of allografts [1–3]. Allograft implantation has become a well-established procedure. A well-known complicating effect is immunological rejection of donor corneal tissue. Particularly, patients suffering from rheumatoid arthritis are at high risk. A strategy to prevent rejection is to down-regulate the patient’s immune system prior to implantation. This approach may require a method for temporary closure of the corneal perforation [4–6]. Recently, Nuijts et al. re- ported that NeuroPatch s is a suitable polymeric biomaterial for this purpose [7]. NeuroPatch s is a polyurethane mesh with excellent biocompatibility; the material allows ingrowth of stromal fibroblast cells which deposit matrix material into the NeuroPatch s pores and cavities. In this way, the implant integrates with the (healthy) surrounding corneal tissue. The major drawback of NeuroPatch s is its non-transparency. Consequently, vision of the patient can be severely impaired, at least until the allograft is implanted. In an attempt to develop a biomaterial that combines the advantages of NeuroPatch s with optical transpar- ency, we recently developed new biomaterials in an attempt to combine the advantages of NeuroPatch s with optical transparency [8]. These are copolymers of butylmethacrylate (BMA) and hexaethyleneglycol- methacrylate (HEGMA). The materials possess ade- quate transparency, and it was found that cultured human epithelial cells readily proliferate and migrate at their surface. These observations led us to believe that the copolymers of BMA and HEGMA are potentially *Corresponding author. Tel.:+31-4-3388-1674; fax: +31-4-3367- 0988. E-mail address: l.koole@bioch.unimaas.nl (L.H. Koole). 0142-9612/02/$-see front matter r 2001 Elsevier Science Ltd. All rights reserved. PII:S0142-9612(01)00237-X