Extended Data Fig. 3: Influence of RGD ligand on PDAC organoid chemoresistance.
a, Schematic of recombinant elastin-like protein (ELP) component of HELP, which can be engineered to display a non-interactive, scrambled RDG sequence, resulting in a HELP matrix without RGD, but with identical mechanical properties and HA concentration. b, Stiffness measurements of HELP RDG matrices stiffness-matched to HELP Low and HELP High (N = 3 independent experimental replicate hydrogels, mean ± s.d., unpaired two-tailed t-test, ****P < 0.0001). c, Representative bright-field images of PDAC organoids expanded within HELP RDG Low (top) or HELP RDG High (bottom) for four passages. Scale bar, 250 μm. d, qPCR quantification of mRNA-level ABCG2 expression in PDAC organoids expanded within HELP RDG Low or High for four passages (N = 4 independent experimental replicate hydrogels, mean ± 95% confidence interval). Statistical analysis comparing marker expression in Low vs. High matrices was performed using an unpaired two-tailed t-test (**P < 0.01). All data are normalized to GAPDH gene expression and respective marker expression in the PDAC organoid parent population cultured within Cultrex prior to expansion in HELP RDG (that is, Cultrex P0). e, Single-cell-level (left) and organoid-level (right) gemcitabine dose-response curves for PDAC organoids expanded within HELP RDG Low or High for four passages. Each data point represents the mean ± s.e.m. (N = 4 independent experimental replicate hydrogels, solid center line is nonlinear least squares regression of data; shaded region represents 95% confidence bands of nonlinear fit; data are normalized to positive controls (DMSO for single cells, 3,333 nM gemcitabine for organoids). f, Gemcitabine IC50 values calculated from nonlinear fit of dose-response curves shown in e for single-cell (left) and organoid (right) drug treatment in HELP RDG compared to HELP containing RGD. Each bar represents the mean ± s.e.m. (N = 4 independent experimental replicate hydrogels, unpaired two-tailed t-test between Low and High for each matrix variation, **P < 0.01, ***P < 0.001, ****P < 0.0001).
