The regulation of matrix stiffness on stem cell differentiation is one of milestones in the fields of biomaterials and cell biology in the latest decade. Very recently, this viewpoint found by American scientists was, however, argued by some European groups in, for instance, Nature Materials. Since a change of matrix stiffness is frequently accompanied by changes of other material parameters, a deterministic experiment is much desired to examine stem cell differentiation on materials with matrix stiffness and surface chemistry completely decoupled with each other.

Via the combination of hydrogel synthesis and nanopatterning techniques, Prof. Ding’s group prepared well-defined nanoarrays of cell-adhesive arginine-glycine-aspartate (RGD) peptides on persistently nonfouling poly(ethelyne glycol) (PEG) hydrogels to eliminate nonspecific protein adsorption and decouple matrix stiffness from surface chemistry. The careful combination of macromonomer chainlength and concentration led to different stiffnesses but the same swollen ratio under aqueous environment. This enabled the examination of matrix stiffness effect on stem cell differentiation at a constant RGD nanospacing, and the investigation of surface chemistry effect at a given hydrogel stiffness. The results confirm that both matrix stiffness and surface chemistry direct stem cell fate. This study deepens the understanding of cell-material interactions, and may be helpful for the design of new-generation biomaterials to direct stem cell fate.

This work was published on Nano Letters with a PhD student Kai Ye as the first author. See details：Kai Ye, Xuan Wang, Luping Cao, Shiyu Li, Zhenhua Li, Jiandong Ding*, Matrix stiffness and nanoscale spatial organization of cell-adhesive ligands direct stem cell fate, Nano Lett., 2015, 15(7): 4720-4729.

Article links: http://pubs.acs.org/doi/10.1021/acs.nanolett.5b01619