The alignment and fusion assembly of adipose-derived stem cells on mechanically patterned matrices
ABSTRACT Cell patterning is typically accomplished by selectively depositing proteins for cell adhesion only on patterned regions; however in tissues, cells are also influenced by mechanical stimuli, which can also result in patterned arrangements of cells. We developed a mechanically-patterned hydrogel to observe and compare it to extracellular matrix (ECM) ligand patterns to determine how to best regulate and improve cell type-specific behaviors. Ligand-based patterning on hydrogels was not robust over prolonged culture, but cells on mechanically-patterned hydrogels differentially sorted based on stiffness preference: myocytes and adipose-derived stem cells (ASCs) underwent stiffness-mediated migration, i.e. durotaxis, and remained on myogenic hydrogel regions. Myocytes developed aligned striations and fused on myogenic stripes of the mechanically-patterned hydrogel. ASCs aligned and underwent myogenesis, but their fusion rate increased, as did the number of cells fusing into a myotube as a result of their alignment. Conversely, neuronal cells did not exhibit durotaxis and could be seen on soft regions of the hydrogel for prolonged culture time. These results suggest that mechanically-patterned hydrogels could provide a platform to create tissue engineered, innervated micro-muscles of neural and muscle phenotypes juxtaposed next to each other in order better recreate a muscle niche.
SourceAvailable from: Ludovic G Vincent[Show abstract] [Hide abstract]
ABSTRACT: Stem cells regulate their fate by binding to, and contracting against, the extracellular matrix. Recently, it has been proposed that in addition to matrix stiffness and ligand type, the degree of coupling of fibrous protein to the surface of the underlying substrate, that is, tethering and matrix porosity, also regulates stem cell differentiation. By modulating substrate porosity without altering stiffness in polyacrylamide gels, we show that varying substrate porosity did not significantly change protein tethering, substrate deformations, or the osteogenic and adipogenic differentiation of human adipose-derived stromal cells and marrow-derived mesenchymal stromal cells. Varying protein-substrate linker density up to 50-fold changed tethering, but did not affect osteogenesis, adipogenesis, surface-protein unfolding or underlying substrate deformations. Differentiation was also unaffected by the absence of protein tethering. Our findings imply that the stiffness of planar matrices regulates stem cell differentiation independently of protein tethering and porosity.Nature Material 08/2014; DOI:10.1038/nmat4051 · 36.43 Impact Factor
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ABSTRACT: Adipose-derived stem/stromal cells (ASCs) possess great potential as an autologous cell source for cell-based regenerative therapies. We have previously shown that mimicking the natural dynamic muscle loading patterns enhances differentiation capacity of ASCs into aligned myotubes. In particular, the application of uniaxial cyclic strain significantly increased ASC myogenesis in monolayer cultures. In this study, we demonstrate that the temporal expression of key myogenic markers Pax3/7, Desmin, MyoD and myosin heavy chain closely mimics patterns described for muscle satellite cells. Using these lineage markers, we propose that the progression from undifferentiated ASCs to myotubes can be described as transitions through discrete stages. Based on our experimental data, we developed a compartmental kinetic stage-transition model to provide a quantitative description of the differentiation of ASCs to terminally differentiated myotubes. The model describing ASCs’ myogenic differentiation in response to biophysical cues could help to obtain a deeper understanding of factors governing the biological responses and provide clues for experimental methods to increase the efficiency of ASC myogenesis for the development of improved muscle regenerative therapies.Cellular and Molecular Bioengineering 12/2014; 7(4). DOI:10.1007/s12195-014-0362-7 · 1.23 Impact Factor
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ABSTRACT: Cardiac fibrosis greatly impairs normal heart function post infarction and there is no effective anti-fibrotic drug developed at present. The current therapies for cardiac infarction mainly take effect by eliminating occlusion in coronary artery by thrombolysis drugs, vascular stent grafting or heart bypass operation, which are capable to provide sufficient blood flow for intact myocardium yet showed subtle efficacy in ameliorating fibrosis condition. The advances of in vitro cell/tissue models open new avenues for drug assessment due to the low cost, good controllability and availability as well as the convenience for operation as compared to the animal models. To our knowledge, no proper biomimetic in vitro cardiac fibrosis model has been reported yet. Here we engineered an in vitro cardiac fibrosis model using heart-derived fibroblasts, and the fibrogenesis was recapitulated by patterning the substrate rigidity which mimicked the mechanical heterogeneity of myocardium post-infarction. Various biomarkers for cardiac fibrosis were assayed to validate the biomimicry of the engineered platform. Subsequent addition of Rho-associated protein kinase (ROCK) pathway inhibitor reduced the ratio of myofibroblasts, indicating the feasibility of applying this platform in screening anti-fibrosis drugs.Biofabrication 12/2014; 6(4):045009. DOI:10.1088/1758-5082/6/4/045009 · 4.30 Impact Factor