Effect of sinusoidal stretching and c48/80 on the morphology of dermal fibroblasts and the mechanical response of skin

• Main Author: Martel, Hélène
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/9107

Dermal fibroblasts are connected to each other and to elements of the extracellular matrix (ECM). In vitro studies using fibroblasts grown in collagen gels have demonstrated that fibroblasts are able to deform the gel via cell adhesions. The purpose of this project was to investigate qualitatively the effect of sinusoidal stretching of fresh strips of skin on both the mechanical response of the tissue and the morphology of the fibroblasts. These investigations were carried out for skin soaked in a physiological solution (Kreb's buffer) with and without addition of a mast cell degranulating material, compound 48/80 (C48/80). Two by 10 millimeters strips of skin were removed from the back of 3 male rats. Skin samples were either only soaked in Kreb's buffer in the presence or absence of C48/80, or simultaneously soaked and intermittently sinusoidally stretched in Kreb's buffer in the presence or absence of C48/80. Controls consisted of skin samples fixed immediately after excision from the rats or samples only soaked in buffer. All tissues were fixed and processed for transmission electron microscopy. Morphometric analysis of the relative surface area of fibroblast cytoplasmic extensions and cell bodies showed that sinusoidal stretching of rat skin results in the retraction of fibroblast cytoplasmic extensions and "rounding up" of the cells. Incubation with C48/80 alone had no apparent effect on fibroblast cytoplasmic extensions and morphology. The measurement of tension during sinusoidal stretching in Kreb's buffer with or without addition of C48/80 demonstrated that the tension has a tendency to decrease as the number of sine wave cycles and stretching sequences increased. In addition, during the 14.33 minute interval between two successive stretching sequences the tissue demonstrated recovery of tension. The decrease in tension observed as a result of biomechanical experiments along with the "rounding up" of fibroblasts demonstrated in the morphological study are consistent with the hypothesis that cell adhesions play a role in the mechanical response of the tissue. The biomechanical and morphological results, however, did not support the hypothesis that C48/80 alone induces lost of fibroblast adhesions.