Exploring the interplay between hydrogel mechanics and growth factor signal transduction in hMSCs

The cellular microenvironment greatly impacts cell communication, development, and signaling. These characteristics include growth factors which are critical regulators of numerous cellular processes and play an important role in development and regeneration. Hydrogels can be used to mimic this microenvironment to provide a more natural environment for the cells. This project looks at the interplay between hydrogel mechanics and growth factor presentation, specifically in transforming growth factor (TGF)-beta signal transduction. This is done by growing human mesenchymal stem cells on NorHA hydrogels of varying stiffnesses (1-2 kPa, 8-10 kPa, and 20-25 kPa) with varying concentrations of TGF-1 and bone morphogenetic protein (BMP)-2 and analyzing the differences in Smad protein expression via western blots. Smad proteins are important mediators of canonical TGF-and BMP signaling. Thus far, I have optimized the western blot protocol, formed hydrogels with varying stiffnesses, and observed the presence of phosphorylated Smad in cells grown with growth factors versus cells grown without growth factors. By attempting to mimic the microenvironmental characteristics of muscle tissue, we hope to maximize growth factor signal transduction in hMSCs to help understand hMSC myogenic differentiation. Current work focuses on developing NorHA hydrogels with varying growth factor concentrations and seeding hMSCs on these gels. It will also inform the design of clinically translational tissue engineering scaffolds to repair various musculoskeletal tissues. The use of these hydrogels with growth factors can help increase efficiency of tissue regeneration.