Figure 7:

Mature collagen deposition was an ultrasensitive switch in response to initial infarct size. (A) Peak values of collagen deposition plotted against infarct size indicated an ultrasensitive switch, with a Hill coefficient of 9.56. (B) Roles of inflammatory cytokines IL-1β, GM-CSF, and TNFa in collagen deposition post MI for different initial infarct sizes. (C) Peak values of model components upstream of collagen indicated ultrasensitivity, amplified by fibroblasts. (D) Bifurcation analysis of a reduced model with TGFβ concentration, as the bifurcation parameter revealed a transcritical bifurcation. Filled circles: stable fixed points; open circles: unstable fixed points. Inset: bifurcation analysis with low concentrations of TGFβ. (E and F) Bifurcation analysis of the reduced model with either (E) fibroblasts or (F) crowding term removed from the proliferation term.