Pilotstudie 08.07

Background
Hypertrophic scar formation subsequent to trauma of burn injury is still complicating wound healing. It is responsible for serious functional and cosmetic problems. Increasing evidence exists that immunological responses early following wounding play an important role. Macrophages can initiate hypertrophic scar formation by production of different cytokines that stimulate fibroblasts to produce excess extracellular matrix. In response to exposure to microenvironmental signals, the function of macrophages is highly affected. This leads to different activation pathways with different outcomes. Within our group we have ample experience with both different macrophage pathways as also with wound healing, which we now combine in the present multidisciplinary application.

Objective(s)
We will investigate the relation between hypertrophic scar tissue formation and macrophage cytokine repertoire and the so called M1/M2 macrophage ratio in humans relevant for the clinical situation. In this approach we will also study the effect of these M1/M2 macrophage supernatants on fibroblast differentiation.  

Methods
In this pilot study, macrophage activation in early burn wounds will be studied. In this model, monocytes are added to supernatant of resected tissue from burn patients and control patients. Eschar from burn wounds, resected scars, and normal skin will be provided by the departments of Plastic Surgery and Burn Center of the Red Cross Hospital in Beverwijk and the department of Plastic surgery of the VU University medical center. Directly after sampling, a small part of the tissues will be processed for histology/immunohistochemistry. The rest of the tissue specimens will be incubated in culture medium at 37ºC for 24 hours. Subsequently, supernatant of this mixture will be added to monocytes for 48 hours and the effect on cytokine production and other parameters (defining the M1/M2 macrophage phenotype) will be studied. Moreover we will also subsequently study the effect of macrophage secreted factors on fibroblast differentiation.

Anticipated results
In this pilot study we want to prove an association between M2 activated macrophages/M2 associated cytokine repertoire and hypertrophic scar formation. If so, our results will enable us to influence the evolution of hypertrophic scars towards normal scars in the future. Therefore we anticipate that our pilot study may result in a complete patient folluw-up study.