title: Matrix-driven formation of mesenchymal stem cell-extracellular matrix microtissues on soft alginate hydrogels.
abstract: Mesenchymal stem cells (MSCs) can be made to rearrange into microtissues in response to specific matrix cues, a process that depends on a balance between cell-matrix and cell-cell interactions. The effect of such cues, and especially their interplay, is still not fully understood, particularly in three-dimensional (3-D) systems. Here, the behaviour of human MSCs cultured within hydrogel matrices with tailored stiffness and composition was evaluated. MSC aggregation occurred only in more compliant matrices (G'≤ 120 Pa), when compared to stiffer ones, both in the presence and in the absence of matrix-bound arginine-glycine-aspartic acid cell-adhesion ligands (RGD; 0, 100 and 200 μM). Fibronectin assembly stabilized cell-cell contacts within aggregates, even in non-adhesive matrices. However, MSCs were able to substantially contract the artificial matrix only when RGD was present. Moreover, compliant matrices facilitated cell proliferation and provided an environment conducive for MSC osteogenic differentiation, even without RGD. Cell interactions with the original matrix became less important as time progressed, while the de novo-produced extracellular matrix became a more critical determinant of cell fate. These data provide further insights into the mechanisms by which MSCs sense their microenvironment to organize into tissues, and provide new clues to the design of cell-instructive 3-D matrices.
authors.affiliation: Instituto de Engenharia Biomédica (INEB), Rua do Campo Alegre, No. 823, 4150-180 Porto, Portugal; Faculdade de Engenharia, Universidade do Porto (FEUP), Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal.
authors.forename: F Raquel
authors.initials: FR
authors.lastname: Maia
authors.affiliation: Instituto de Engenharia Biomédica (INEB), Rua do Campo Alegre, No. 823, 4150-180 Porto, Portugal; Faculdade de Engenharia, Universidade do Porto (FEUP), Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal.
authors.forename: Keila B
authors.initials: KB
authors.lastname: Fonseca
authors.affiliation: Centro de Biologia Ambiental/Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa (FCUL), Campo Grande s/n, 1749-016 Lisboa, Portugal.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Rodrigues
authors.affiliation: Instituto de Engenharia Biomédica (INEB), Rua do Campo Alegre, No. 823, 4150-180 Porto, Portugal; Faculdade de Engenharia, Universidade do Porto (FEUP), Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal; Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Rua de Jorge Viterbo Ferreira No. 228, 4050-313 Porto, Portugal.
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Granja
authors.affiliation: Instituto de Engenharia Biomédica (INEB), Rua do Campo Alegre, No. 823, 4150-180 Porto, Portugal. Electronic address: ccbarrias@ineb.up.pt.
authors.forename: Cristina C
authors.initials: CC
authors.lastname: Barrias
mesh_terms: D000464:Alginates; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D005109:Extracellular Matrix; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006801:Humans; D020100:Hydrogels; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D008855:Microscopy, Electron, Scanning
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D020100:Hydrogels; D020723:Glucuronic Acid
keywords: Cell aggregation; Cell traction; Cell–matrix interactions; Hydrogels; Viscoelastic properties