MSCs were individually encapsulated in Dex - TA microgels using DOCKING and differentiated into the adipogenic and osteogenic lineages , which was visualized using both conventional histological stains and label - free analyses ( Figure 2 m   Error bars indicate ± standard error , n ≥ 32 . i ) Besides staining nuclei of dead cells , EthD-1 also stained Dex - TA and its intensity linearly ( R 2 = 0.99 ) correlated to the microgel E - modulus . Coefficients of variation ( CV = standard deviation / average ) of various microgel populations including soft , medium , and stiff ones were determined as a relative measure for inter - microgel variation within populations . The error bars indicate ± standard error , n ≥ 32 , and ± standard deviation , n ≥ 97 . j - l ) The viable ( closed circles ) and metabolically active ( open circles ) cell fractions of in vitro cultured single - MSC - laden microgels were determined using live / dead ( k ) and MTT staining ( l ) . Datapoints indicate average , n ≳ 100 . m ) In soft Dex - TA microgels , adipogenic differentiation after 4 weeks of culture in adipogenic differentiation medium ( DM ) was confirmed using Oil - Red - O ( ORO ) staining and n ) label - free detection of lipids using hyperspectral coherent anti - Stokes Raman scattering ( CARS ; characteristic lipid peak at 2850 cm −1 ) . o ) In stiff Dex - TA microgels , osteogenic differentiation after 4 weeks of culture in osteogenic differentiation medium was confirmed using Alizarin Red ( AR ) staining and p ) label - free detection of calcium phosphates using hyperspectral spontaneous Raman ( characteristic phosphate peak at 960 cm −1 ) . q , r ) Quantification of the per - cell adipogenic ( q ) and osteogenic ( r ) differentiation as a function of microgel stiffness and culture medium . " GM " indicates growth medium , lines indicate means , n ≥ 27 ( q ) , n ≥ 55 ( r ) , significance is indicated ( * * * * p < 0.0001 , Kruskal - Wallis analysis of variance ( ANOVA ) , validated with Mann - Whitney individual sample comparison ) . The yellow scale bar indicates 1 cm , the white scale bars indicate 50 µm , the black scale bars indicate 10 µm , and the red scale bar indicates 1 µm . www.advmat.de www.advancedsciencenews.com Figure S16 , Supporting Information ) . Quantification of intracellular lipid and extracellular calcified matrix deposition as proxies for adipogenesis and osteogenesis of MSCs revealed that the stiffness of Dex - TA tethered to cells played an essential role in their lineage commitment . Specifically , single - cellresolution analysis of MSC differentiation revealed that the adipogenic population fraction inversely correlated with microgel stiffness ( Figure 2q ) , while the osteogenic population fraction was characterized by a positive correlation with microgel stiffness ( Figure 2r ) . It is of note , that the single - cell - microgel platform offered unique opportunities toward handling , manipulation , and analysis of cells . For example , single - cellmicrogel analysis revealed the heterogeneity in lineage commitment within a population of differentiating stem cells under controlled chemical and mechanical stimuli . Furthermore , the single - cell microgels were demonstrated to be compatible with label - free analyses , which offered the opportunity of time - lapse monitoring of cell behavior in 3D while minimizing methodology - induced biases by omitting destructive analyses techniques . Regardless , our data indicated that DOCKINGmediated tethering facilitated the transduction of biomechanical cues from non - cell - adhesive biomaterials to MSC , thereby steering cell fate .