17. Investigating the Interplay between Hydrogel Mechanics and TGF-β Signal Transduction on Human Mesenchymal Stromal Cell Differentiation

Tissue regeneration provides a method by which cell behavior can be guided toward functional tissue regeneration. Tissue regeneration scaffolds currently lack the ability to accurately represent and mimic the innate extracellular matrix (ECM). The ECM greatly influences cell development, processes, and signaling. Properties such as mechanical stiffness and signals such as growth factors interact to modulate cell behaviors; however, little is known about the interaction and the integrated impact they have on signal transduction. This project looks at the interplay between stiffness and growth factor presentation, specifically transforming growth factor (TGF)-√ü signaling, using ECM- mimicking hydrogels. Analyzing the differential expression of Smad and phosphorylated Smad proteins (canonical mediators of TGF-Œ≤ signaling) between human mesenchymal stem cells grown on hydrogels of varying stiffnesses (1, 5, 20 kPa) with either TGF-Œ≤1 or bone morphogenetic protein (BMP)-2 via western blots can help understand the relationship between mechanical stiffness and growth factor signaling transduction. Thus far, I have optimized the western blot protocol, carried out material characterization, seeded hMSCs on hydrogels, and observed the ratio of Smad signaling to a housekeeping protein. I hypothesize that cells grown in the presence of growth factors will have a significantly higher quantity of phosphorylated Smad protein than those grown without the presence of growth factors. This study will contribute to the knowledge of the scientific community in order to help increase the efficacy of growth factor-mediated tissue regeneration.