Cardiac Mechanics

Tissue engineering (TE) is a rapidly growing field with the goal of developing fully biocompatible tissue replacements. One approach to producing functional replacements is to seed human mesenchymal stem cells (hMSCs) onto electrospun scaffolds and induce the hMSCs to differentiate into functional tissue. In order to induce hMSC differentiation into various tissue types, chemical signals are frequently used. Mechanical strain is also a potent instigator of hMSC differentiation. However, the relationship between mechanical strain within electrospun scaffolds and hMSC behavior is poorly understood. The primary hindrance to a better understanding of the link between mechanical forces and cell behavior is the complex loading conditions that cells on electrospun fibers experience.

The intricate geometry of electrospun scaffolds makes it difficult to quantify the forces generated within the matrix and even more difficult to quantify cellular strains. Knowledge of the strain generated within an electrospun matrix and the concurrent cellular strains may lay the groundwork for the design of TE structures with predictable cellular response. The long term goal of this research is develop an in vitro model to evaluate the response of hMSCs seeded onto electrospun fibers with highly defined geometry and mechanical loading.

The first step in investigating the response of hMSCs on electrospun fibers to cyclic tensile forces is to fully characterize the mechanical properties of electrospun fibers; to that end, the following research is proposed. A method of applying a precise strain to parallel and evenly spaced electrospun fibers will be developed. Using perfectly parallel fibers will eliminate any component of non-axial loading. Next, the tensile, viscoelastic, and cyclic mechanical properties of a collection of parallel electrospun fibers will be determined. Characterizing the electrospun fibers prior to any studies with seeded cells will provide a baseline for future work that will seek to determine if seeded hMSCs produce any measurable force on the fibers and will accurately quantify the levels of force that the cells will experience. Finally, a constitutive model which describes the response of parallel electrospun fibers to various applied loads and strain rates will be developed. The results gained from this research could have implications in the fields of tissue engineering, bioreactor design, and mechanobiology.