Beneficial effects of activated macrophages on sulfur mustard-induced cutaneous burns, an in vivo experience

Objective: Macrophages are known to have key functions in almost every stage of wound healing and there is evidence for their beneficial effects in treating decubital ulcers and deep sternal wound infections in human. This study aimed to investigate the efficacy of a treatment with activated macrophages on ameliorating acute and long-term sulfur mustard (SM) induced skin injuries in the hairless guinea pig (HGP) model. Methods: HGP were exposed to SM vapor and treated with either a single or multiple intradermal injections of human activated macrophages in suspension (hAMS) into the wound bed. Clinical and histological evaluations were conducted up to 4 weeks post-exposure. Results: A single treatment with hAMS early after exposure (15 min and 6 h) resulted in a reduction in the number of damaged cells and vesications in the epidermis at 24 h. A substantial increase in cellular infiltration, mostly polymorphonuclears, was taking place in the hAMS-treated animals starting as early as 1 h after exposure. This flow of inflammatory cells continued, in the treated group, for at least 4 weeks, long after the injected macrophages were not detected. Repeated injections of hAMS (15 min, 48 h and 7 d post-exposure) decreased significantly the area of the wounds and improved the integrity of the barrier function as expressed by measuring trans-epidermal water loss up to 10 d. Conclusions: Our results indicate that the role of macrophages in wound healing is complex; their efficacy may depend on the timing of administration. Further investigation is required to determine whether they are required during the early phase of wound development and/or during the late phase of scar formation and remodeling.