Celecoxib does not delay cutaneous wound healing in haemophilia B mice

It can be difficult to provide analgesia in haemophilic patients because non-steroidal anti-inflammatory drugs (NSAIDs) can impair platelet function by inhibition of cyclo-oxygenase 1 (COX-1) and, thereby, increase the risk of bleeding. Therefore, selective COX-2 inhibitors have been used in haemophiliacs to reduce the risk of bleeding imposed by most conventional NSAIDs. Celecoxib and rofecoxib have been reported to be useful in managing the pain of joint bleeds and synovitis [1,2]. The use of rofecoxib has also been reported to reduce factor use in haemophiliacs suffering a joint bleed [3], presumably by reducing the pain associated with bleeding. Another drug of the same class, etoricoxib, also showed good efficacy in haemophilic arthropathy, with no evidence of increased joint bleeding compared to placebo [4]. Thus, COX-2 inhibitors have a role to play in pain management in haemophiliacs. We have recently reported that wound healing is abnormal in a haemophilia B (HB) mouse model [5]. Specifically, epithelial closure was delayed in HB mice, as was macrophage influx into the wound site. Haemophilic animals also developed subcutaneous haematomas. Angiogenesis was enhanced in the HB mice and probably contributed to delayed bleeding. We have routinely used acetominophen (Tylenol, McNeil) for post-biopsy analgesia in our mice, as it is thought to not increase the risk of bleeding in haemophilia. When required by our institutional animal care and use committee (IACUC) to change analgesic agents to meloxicam, we found that healing times were significantly prolonged in both the HB and corresponding wild type mice. Meloxicam is a preferential COX-2 inhibitor (ratio of COX-1 to COX-2 inhibition of 0.2). Our interpretation of this finding was that even modest inhibition of COX-1 led to impaired platelet function and that this effect led to delayed healing. Accordingly, we hypothesized that a pure COX-2 inhibitor would not impair wound healing in HB. Therefore, we examined the effects of celecoxib, a nearly pure COX-2 inhibitor at clinically relevant levels, in our model. A total of 56 HB mice (28 treated and 28 controls) were used for these experiments under a protocol approved by the University of North Carolina IACUC. A single 3 mm punch biopsy wound was placed on the dorsal skin of each mouse as we have previously described [5]. One dose of celecoxib (20 mg kg) was administered daily by oral gavage to each treated mouse, with the first dose given 30 min prior to placement of a single 3 mm punch biopsy wound on the dorsal skin. The mice were anaesthetized using isoflurane delivered by nose cone during biopsy placement and each gavage procedure. Control mice were handled identically, but were given only the safflower oil vehicle at each gavage. The size of each wound in two dimensions was measured daily. According to the experimental plan, four treated and four control mice were to be sacrificed on days 2, 4, 6, 8, 10, 12 and 15. At the time of sacrifice, tissue was collected and fixed in 10% neutral buffered formalin for histological examination. The area of the skin wound was processed into paraffin and sections cut for routine staining with haematoxylin and eosin as well as immunohistochemical staining for CD34 to aid in counting blood vessel profiles as previously described [5]. Two mice in the control group and four in the treated group died during the course of the experiment. This mortality rate of 3–7% was well within the range we have historically experienced for studies of HB mice that require repeated handling, as for gavage. The time course of epithelial closure was not significantly different in celecoxib-treated and Correspondence: Maureane Hoffman, MD, PhD, Laboratory Service (113), Durham VAMC, Durham, NC 27705, USA. Tel. : +1 919 286 6925; fax: +1 919 286 6818; e-mail: maureane@med.unc. edu