Figure 3.

Cell spreading as a function of gel thickness for HLFs on fibrin (red squares) and collagen (green triangles) gels, and for 3T3s on fibrin gels (blue circles). Reported as mean ± SE; HLFs on collagen, mean = 9 cells per data point, n = 4 gels; HLFs on fibrin, mean = 10 cells per data point, n = 5 gels; 3T3 on collagen, mean = 20 cells per data point, n = 2 gels. Open symbols indicate control cells on tissue culture plastic. Data from the literature for 3T3 fibroblasts (+ symbols) and hMSCs (x symbols) indicate that cells on PA gels are not affected by rigid boundaries more than ∼30 μm away. On nonlinear fibrin and collagen gels, fibroblasts sense the rigid boundary on much thicker gels (>100 μm), consistent with the spread area of hMSCs on collagen gels (star symbols), and the relationship between spread area and thickness is more gradual than on PA gels.