RESUMO
In vitro models of normal mammary epithelium have correlated increased extracellular matrix (ECM) stiffness with malignant phenotypes. However, the role of increased stiffness in this transformation remains unclear because of difficulties in controlling ECM stiffness, composition and architecture independently. Here we demonstrate that interpenetrating networks of reconstituted basement membrane matrix and alginate can be used to modulate ECM stiffness independently of composition and architecture. We find that, in normal mammary epithelial cells, increasing ECM stiffness alone induces malignant phenotypes but that the effect is completely abrogated when accompanied by an increase in basement-membrane ligands. We also find that the combination of stiffness and composition is sensed through ß4 integrin, Rac1, and the PI3K pathway, and suggest a mechanism in which an increase in ECM stiffness, without an increase in basement membrane ligands, prevents normal α6ß4 integrin clustering into hemidesmosomes.
Assuntos
Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Matriz Extracelular/fisiologia , Glândulas Mamárias Humanas/patologia , Glândulas Mamárias Humanas/fisiopatologia , Alginatos/metabolismo , Membrana Basal/fisiologia , Materiais Biocompatíveis , Fenômenos Biofísicos , Linhagem Celular , Epitélio/patologia , Epitélio/fisiopatologia , Feminino , Ácido Glucurônico/metabolismo , Hemidesmossomos/fisiologia , Ácidos Hexurônicos/metabolismo , Humanos , Integrina alfa6beta4/metabolismo , Ligantes , Mecanotransdução Celular/fisiologia , Modelos Biológicos , Fenótipo , Fosfatidilinositol 3-Quinases/metabolismo , Transdução de Sinais , Proteínas rac1 de Ligação ao GTP/metabolismoRESUMO
Wound dressing biomaterials are increasingly being designed to incorporate bioactive molecules to promote healing, but the impact of matrix mechanical properties on the biology of resident cells orchestrating skin repair and regeneration remains to be fully understood. This study investigated whether tuning the stiffness of a model wound dressing biomaterial could control the behavior of dermal fibroblasts. Fully interpenetrating networks (IPNs) of collagen-I and alginate were fabricated to enable gel stiffness to be tuned independently of gel architecture, polymer concentration or adhesion ligand density. Three-dimensional cultures of dermal fibroblasts encapsulated within matrices of different stiffness were shown to promote dramatically different cell morphologies, and enhanced stiffness resulted in upregulation of key-mediators of inflammation such as IL-10 and COX-2. These findings suggest that simply modulating the matrix mechanical properties of a given wound dressing biomaterial deposited at the wound site could regulate the progression of wound healing.