An evaluation of the capacity of differently prepared demineralised bone matrices (DBM) and toxic residuals of ethylene oxide (EtOx) to provoke an inflammatory response in vitro

Demineralised bone matrix (DBM) is a form of allogeneic tissue graft widely used in oral and maxillofacial procedures. There is a long history of cont roversy relating to the suitability of ethylene oxide gas (EtOx) as a termi nal sterilisation agent for this graft, relating to its effects on the clin ical performance of the grafts. Furthermore, the generation of a toxic resi dual chemical (ethylene chlorohydrin, ECl) during the ethylene oxide steril isation of patellar tendon allografts has been implicated in the failure of these grafts owing to the induction of a localised inflammatory response. In this study we have investigated the capacity of a range of different DBM preparations, and ECl dilutions, to induce the production of three pro-inf lammatory cytokines, interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta), and tumour necrosis factor alpha (TNF-alpha) from human peripheral blood mo nonuclear cells (PBMNCs). The levels of EtOx and ECl in EtOx terminally ste rilised DBM and mineralised bone grafts were measured by gas chromatography . It was found that the only factor capable of rendering DBM pro-inflammato ry was the presence of small (<20 micrometre diameter) DBM particles. No ot her processing or sterilisation technique resulted in the DBM becoming pro- inflammatory. Although it was also found that DBM, when EtOx-sterilised, re tained more ECl than mineralised bone grafts following a standard EtOx ster ilisation protocol, ECl did not provoke an inflammatory response in vitro a t levels up to and including those which are cytotoxic to PBMNCs. <(c)> 200 1 Elsevier Science Ltd. All rights reserved.