Silvia Wognum
Research Summary
A Structural Constitutive Model for Insights in Key Remodeling Phenomena in Soft Tissues
S. Wognum and M.S. Sacks
Virtually all tissues continuously grow, remodel and adapt to changes in their physiological environment, resulting in changes in structure and composition. The driving mechanisms and the underlying processes for growth and remodeling are tissue-dependent, but general trends among tissues with similar compositions should be apparent. Towards this end, we will develop a structurally based constitutive (i.e., stress-strain) model of a remodeling multi-component soft tissue, with experimentally measurable model parameters describing individual components. The basic building block of the model is the fiber ensemble, and remodeling will be incorporated as time-evolving changes in volume fractions and structural properties of the fiber ensembles. The model will be specialized for a tissue consisting of smooth muscle (SM), collagen, and elastin fibers, i.e., the urinary bladder wall (UBW), which undergoes profound remodeling as a result of spinal cord injury (SCI). Traditionally, it is assumed that tissues remodel in response to changes in local stress conditions to restore homeostatic stress values. In contrast, we hypothesize that distinct mechanical stimuli, such as prolonged periods of high strain or stress, or frequent shortterm intermittent loading, induce different remodeling events to compensate for the change in mechanical environment and to restore organ-level function. Using a structurally based constitutive model to simulate remodeling will allow for separate investigation of the contribution of each individual tissue component to the remodeling process, and it will shed more light on the underlying mechanisms.