Cellular processes under mechanical stress

Abstract

Introduction. To prevent burns from scar formation and contraction, the use of splinting therapy in the early phase of wound healing is considered as an effective non-surgical method. Splinting entails the application of a mechanical load in the opposite direction of the contractile force within the wound, based on the assumption that wound- or scar contraction will be prevented or reduced. However, clinical research provides conflicting evidence on its effectiveness and optimal treatment method. Therefore, the aim of this study was to design an in vitro model to investigate the mechanoresponsive cellular effects of stress on specifically Human Eschar Fibroblasts and their extracellular matrix, in order to confirm or disprove effects of burn splinting. Methods. The two major players of the burn wound model include (1) the fibroblasts, and (2) the novel extracellular matrix they produce. Outcome measures were chosen that directly relate to matrix organization, fibroblast functioning and matrix functioning. Three chronological sub-goals were defined to achieve the goal of designing a burn wound splinting model: (1) Formulating a suitable mechanical stress protocol; (2) Select a system that enables the selected mechanical stress of extensible substrates that facilitate the growth of fibroblasts and their derived extracellular matrix; (3) Create and optimize conditions to culture fibroblasts on an extensible substrate. To successfully reach these goals, the current literature on this subject was evaluated and comparative experiments were executed. Feasibility of the model was tested in a pilot study. Results. The MCB1 stretching apparatus was provided by Association of Dutch Burn Centre as a suitable device, which was modified to fulfill all predefined requirements. Human Eschar fibroblasts and dermal fibroblasts were cultured on custom made silicone culture wells. Cross-linked gelatin-A coating and vitamin C-supplemented culture medium were selected for optimal cell culturing results. A clinically relevant stretching regimen was chosen, given the paucity of available evidence in literature. A pilot study to test the feasibility of the model indicated that both dynamic and static stretching of eschar fibroblasts show a trend towards thicker, denser collagen matrices compared to unstretched conditions. These collagen fibers also showed a greater degree of alignment. However, no definitive conclusions can be drawn since sample size is limited. Conclusion. The model presented in this work constitutes a practical framework to test mechanotransducive processes in burn scars on a cellular and molecular level. A pilot study using this model showed excellent feasibility