The extracellular environment in mammalian tissue is a complex composite material, with many different organic and inorganic features, and dynamic modulation of biochemical and biophysical parameters. In order to accurately reflect this dynamicity, next generation tissue-mimetic materials require control over both spatial and temporal signaling. We are developing composite hydrogel materials where external stimuli can guide stem cell activity with reversibility. Magnetic carbonyl iron particles were modified to promote distal reactivity using silane chemistry for conjugation within matrix protein tethered polyacrylamide and polyethylene glycol hydrogels. We demonstrate over two orders of magnitude shift in matrix elasticity in response to magnetic fields. The mechanical properties of the composite hydrogel can be easily and reversibly switched using permanent magnets, obviating the need for complex instrumentation.   Using mesenchymal stem cells as a promising therapeutic cell type, we show how magnetic fields modulate actomyosin contractility, which impacts secretion of pro-angiogenic molecules and the degree of commitment to the osteogenic lineage. The simplicity in which hydrogel mechanical properties can be modulated in situ will make this tool useful for a wide variety of applications, where temporal control over the biophysical microenvironment is desired.

Dynamic control of stem cell activity in composite hydrogels using permanent magnets

251st National Meeting (2016)

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