Analysis of the transforming growth factor-/spl beta//sub 1/ pathway and extracellular matrix formation as a hybrid system

It is generally accepted that aging of the vascular system plays an important role in cardiovascular disease (CVD). Recent experimental findings have indicated the involvement of the cytokine transforming growth factor-/spl beta//sub 1/ (TGF-/spl beta//sub 1/) in these vascular aging processes. This cytokine is, after binding to a cell receptor, associated with numerous cellular processes, including formation of the extracellular matrix (ECM, the biomolecular network that surrounds the cell). We implemented TGF-/spl beta//sub 1/ signaling and its effect on ECM formation with piecewise-linear differential equations (PLDEs), which have several advantageous properties over traditional continuous modeling. Aging of the system was simulated as a reduction in cell sensitivity for TGF-/spl beta//sub 1/. The model predicted a disturbed ECM balance during aging, which corresponds well to findings from the literature. The outcome of this hybrid approach was satisfactory and, therefore, we will continue modeling of various aging-related pathways with PLDEs in future research.