Figure 3.

Single cell force spectroscopy of hMSCs detaching from the hydrogel surface. (a) Representative force–distance retraction curve when the hMSC-functionalized AFM tip is retracted from the surface of 100% RGD hydrogel. Typically, there is a large initial nonspecific adhesion of the hMSC to the hydrogel, followed by smaller force events after the bulk of the hMSC has detached as it moves away from the surface. The integrated area under the curve (blue) represents the total adhesion energy binding the single hMSC to the hydrogel surface. Inset illustrates ramp-like change in force (dotted line) preceding a force step event (between solid lines). (b) Total adhesion energy for hMSCs bound to 100%, 10%, and 0% RGD hydrogels. n = 7–13 per condition. Parametric one-way ANOVA with Tukey multiple comparison test. Box plots represent median ± IQR, whiskers represent minimum and maximum. ns = not significant. (c) Histogram of total registered force events during unbinding of hMSCs from 100% and 10% RGD hydrogels. N = 3 cells measured at n = 5 locations per n = 3 hydrogel replicates per condition. (d) Average total and RGD specific rupture events occurring on 100% and 10% RGD hydrogels, as defined through controlled interaction experiments (see Figure S5). N = 3 cells measured at n = 5 locations per n = 3 hydrogel replicates per condition. (e) Percentage of RGD rupture events per force displacement curve occurring on 100% and 10% RGD hydrogels.