The alignment and fusion assembly of adipose-derived stem cells on mechanically patterned matrices

Departments of Bioengineering, University of California, San Diego, CA 92093, USA.
Biomaterials (Impact Factor: 8.56). 07/2012; 33(29):6943-51. DOI: 10.1016/j.biomaterials.2012.06.057
Source: PubMed


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.

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Available from: Yu Suk Choi,
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    • "the use of allogeneic ASCs not only for their conversion towards the myogenic lineage and thus contributing to counteract muscle loss , but also as providers of WT dystrophin and other potential beneficial factors that may be missing in dystrophic muscles . The use of coatings and hydrogels has shown to enhance myogenic differentiation from ASCs ( Choi et al . , 2012 ) . However , at present , a universal media composition for a robust myogenic differentiation of ASCs is missing . Table 1 summarizes the results showed in these works and indicates the composition of differentiation media used in each of them . In vivo Skeletal Muscle Differentiation Potential of ASCs All these in vitro works indicate"
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    • "In particular, ASCs have shown an enhanced rate of skeletal myogenic differentiation on substrates that mimic skeletal muscle stiffness, [25]. In addition, the fusion rate appears to be increased when the cells are guided to align on topographically patterned matrices [26]. While the adjustment of substrate properties such as topography and stiffness provides static mechanical cues, cyclic tensile strain (CTS) allows dynamic variation of the applied stimulus. "
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    • "By using substrates with high crosslinker content however [42], polymer chains are restricted from sliding across each other, dramatically reducing differential swelling between layers to less than 2 μm. Roughness changes between stripes on the hydrogel are also minimized to less than 200 nm [26]. A second challenge with bi-layer hydrogel fabrication is that polymer depletion effects in the soft stripes formed by the second layer's polymerization also confound the prediction of layer stiffness. "
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