Substrate Elasticity Influences TRPV4 Mechanotransduction in Chondrocytes, Nicholas Trompeter

Osteoarthritis (OA) is the most common joint disorder in the United States, affecting over 54 million adults. During OA progression, the stiffness of cartilage decreases due to degradation of the extracellular matrix (ECM). The Transient Receptor Potential Vanilloid 4 (TRPV4) channel plays a crucial role in the development, function, and mechanosensation of cartilage through its conductance of calcium. While altering matrix stiffness changes the function and phenotype of chondrocytes, few studies have investigated the role ECM stiffness has on TRPV4-mediated calcium signaling and chondrocyte function. We postulated that ECM stiffness would modulate TRPV4 activity to alter chondrocyte phenotype and function. Here we highlight the influence of altering the ECM stiffness, modeled by poly(ethylene-glycol) (PEG) on chondrocyte function.
PEG hydrogels were made with substrate elasticities of 350kPa, 175kPa, and 35kPa to mimic normal, arthritic, and severely arthritic cartilage, respectively. Looking at intracellular calcium, we observed that Cells grown on the normal gels show significantly higher responses to 50% hypotonic swelling (HTS) when compared to cells grown on the other gels. Additionally, the cells grown on the arthritic gels show a significantly greater response to HTS when compared to cells grown on the 35kPA gels. Inhibition of TRPV4 with GSK219 significantly suppressed the response of cells to HTS when they were seeded on the normal and OA gels. We saw a few cells losing their cell membrane integrity when challenged with HTS. Thus, we sought to determine if ECM stiffness influences cell apoptosis. As the stiffness of the gels decreases, the number of apoptotic cells increases and TRVP4 stimulation can inhibit cell apoptosis on the severely OA gel. Our findings suggest substrate elasticity influences chondrocyte mechanotransduction and apoptosis in a TRPV4 dependent mechanism.

Department Name: Biomedical Engineering
Appears In: GSG presents 10th Annual Graduate Students’ Forum

Loading