Personne : Castilloux, G.
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Département de chirurgie, Faculté de médecine, Université Laval
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- PublicationRestreintModulated response to cytokines of human wound healing myofibroblasts compared to dermal fibroblasts.(ScienceDirect, 1998-01-10) Germain, Lucie; Castilloux, G.; Auger, François A.; Garrel, Dominique; Moulin, Véronique; O'Connor-McCourt, MaureenMyofibroblasts play an important role in normal wound healing. They are present transiently during tissue repair. Their differentiation from fibroblasts and their role in granulation tissues are most likely to be modulated by cytokines. As these cells are derived from normal fibroblasts, their responses to cytokines are assumed to be similar. Until now, however, the difficulties in obtaining and maintaining normal human wound healing myofibroblastsin vitrohave hampered comparison. The present study was designed to determine the effect of TGF-β1 and IFN-γ, two cytokines known to modulate fibroblast morphology, on wound healing myofibroblasts and to compare it to fibroblasts. Morphological and phenotypic changes were followed by light and electron microscopy (stress fibers) and immunofluorescence cytochemistry (α-SM actin). Functional parameters such as the capacity to synthesize collagen and collagen gel contraction were studied. Both cytokines induced a strong modification of growth rate and phenotypic and morphological parameters in fibroblasts whereas collagen synthesis was slightly changed. Furthermore, TGF-β1 increased contractile capacity of fibroblasts whereas IFN-γ greatly decreased it. In myofibroblasts, TGF-β1 and IFN-γ did not induce any variation of morphology or growth rate. Interestingly, a strong modulation of functional parameters was observed: collagen synthesis was highly modified and, as for fibroblasts, the contractile capacity was altered. However, inhibition of contraction by IFN-γ was irreversible in myofibroblasts but not in fibroblasts. These results suggest that fibroblastic cells show modulated responses to cytokines according to their stage of differentiation during wound healing.
- PublicationAccès libreWhat's New in Human Wound-Healing Myofibroblasts?(springerLink, 1999-01-01) Germain, Lucie; Garrel, Dominique A.; Castilloux, G.; Auger, François A.; O'Connor-McCourt, Maureen; Moulin, VéroniqueDuring wound healing and fibrocontractive diseases, clinical and experimental investigations have shown that fibroblastic cells acquire some morphological and biochemical features similar to those of smooth muscle cells . These modified fibroblasts, called myofibroblasts, express de novo α-SM actin temporarily during wound healing and permanently in fibrotic situations, such as hypertrophic scars or fibromatosis. Myofibroblasts are thought to be involved in contraction and have been observed in practically all fibrotic conditions involving retraction and reorganization of connective tissues
- PublicationRestreintIn vitro models to study wound healing fibroblasts(Elsevier, 1996-08-06) Germain, Lucie; Jean, Andréa; Castilloux, G.; Garrel, Dominique A.; Auger, François A.; Moulin, VéroniquePhenotypic and contractile properties of human fibroblasts from dermis and from an experimental wound model were studied in vitro. When cultured in monolayer, dermal fibroblasts had an elongated spindle shape, were small in diameter and grew at a high rate. Wound fibroblasts grew slowly and were large, star shaped and had cytoplasmic stress fibres. Smooth muscle alpha actin was detected in 10 percent of dermal cells, whereas 20-80 per cent of wound fibroblasts contained this protein in their cytoplasm. The contractile property of cells was evaluated using a three-dimensional cell culture model. Our results show that wound fibroblasts contract collagen gels during the first days more strongly than dermal fibroblasts. These results show that, in vitro, wound fibroblasts have greater contractile capacity than dermal cells. The significant proportion of wound fibroblasts containing alpha-smooth muscle actin suggests that alpha-smooth muscle actin ratio may be related to wound contraction.
- PublicationRestreintFetal and adult human skin fibroblasts display intrinsic differences in contractile capacity(Alan R. Liss, 2001-06-05) Germain, Lucie; Tam, Betty Y. Y.; Castilloux, G.; Auger, François A.; Moulin, Véronique; O'Connor-McCourt, Maureen; Philip, AnieOne of the differences between fetal and adult skin healing is the unique ability of fetal wounds to heal without contracture and scar formation. Studies have shown that the ratio between the three isoforms of TGFβ is different in adult and fetal wounds. Thus, we analyzed the capacity of adult and fetal human skin fibroblasts to contract collagen gels after stimulation with TGFβ isoforms. In control medium, fetal fibroblasts had a contractile capacity similar to that of adult fibroblasts. However, the growth capacity of fetal fibroblasts was completely inhibited, in contrast to adult fibroblasts. When cells were treated with TGFβ, fetal fibroblasts showed an inhibition of their contractile capacity whereas adult fibroblasts further contracted gels. The contractile response was similar for all isoforms of TGFβ although TGFβ3 always had the strongest effect. We considered that the regulation of cell contractile capacity by TGFβ may be dependent on receptor expression for this cytokine, on myofibroblast differentiation of the cells, or in cell links with matrix. Since TGFβ receptor analysis did not show differences in receptor affinity, we studied the expression of α-smooth muscle (SM) actin, a fibroblast contractile marker and of three integrins, the cell surface receptors specific of the attachment of the fibroblasts with collagen matrix. We observed that the expression of α-SM actin and α3 and β1 integrin subunits was increased when TGFβ was added to the medium of adult fibroblasts whereas the levels of the α1 and α2 subunits were unchanged. In contrast, fetal fibroblasts treated with TGFβ showed a decrease of α1, α2, and β1 integrin expression but no change in α3 integrin and in α-SM actin expression. These results indicate that intrinsic differences between fetal and adult fibroblasts might explain their opposite responses to TGFβ stimuli. The variations in their α-SM actin and integrin expression patterns represent potentially important mechanisms used by fetal fibroblasts to regulate their response to cytokines, and likely contribute to the resultant differences in the quality of wound repair.