Researcher(s)
- Alexandra Misikova, Biological Sciences, University of Delaware
Faculty Mentor(s)
- Elise Corbin, Biomedical Engineering, University of Delaware
Abstract
Tendonitis is a dynamic process characterized by complex interactions between various cellular and molecular mechanisms, tissue remodeling, inflammation, and structural changes over time. It can manifest in different forms but often results in the softening or stiffening of the tendon extracellular matrix (ECM). Current approaches to studying environmental effects on tendons usually employ substrates with fixed elastic moduli. The elastic modulus, which dictates tendon health and function as well as its capacity to withstand tensile loads under pathophysiological conditions, can influence tenocytes’ genotype. Building on previous genotypic studies, we developed an in vitro disease model using magnetorheological elastomer (MRE) technology to study how tendons respond to a stiffening or softening event starting from a physiological baseline. MREs are heterogeneous composites with varying viscoelastic properties in response to an external magnetic field. Here, we developed MRE formulations to achieve a range of elastic moduli from physiological (~300kPa) to pathophysiological (~200 and ~400kPa) under various magnetic field strengths. The first MRE formulation consisted of 7% (v/v) Sylgard 184 PDMS, 68% (v/v) Sylgard 527 PDMS, and 25% (v/v) Carbonyl Iron Particles (CIP) (low-range), and the second was 10%/65%/25% (high-range), for the softening and stiffening events, respectively. To manufacture these MREs without agglomeration, we mixed toluene with the PDMS pre-polymer at a 1:5 ratio to ensure uniform CIP distribution during curing. The low- and high-range MREs exhibit dynamic ranges of 183.70 ± 16.13kPa to 288.61 ± 14.81kPa and 297.36 ± 10.23kPa to 425.05 ± 7.81kPa, respectively, from 0mT to 350mT flux densities. Importantly, the low-range formulation with 350mT is statistically similar to that of the high-range formulation without a magnet, representing the physiological condition. Using these MREs, we can investigate the effects of genotypic transitions on tendons in response to stiffening or softening under pathological conditions through RT-PCR analysis. This approach provides insights into the biological state of the tendon, including its development, structural integrity, ECM remodeling, and repair processes.