Mechanical Optimization Of A Tendon Hydrogel
Jack E. Akerman, BS MS, Zhen Wang, Paige Fox, MD PhD, James Chang, MD.
Stanford University, Stanford, CA, USA.
Hydrogels have been shown to be an effective scaffold in different biomedical applications. From wound healing to tendon lesions, they accelerate the recovery process. Animal studies have demonstrated that a novel tendon-derived hydrogel (tHG) promotes tendon recovery. These findings are supported by in vitro experiments that show the tHG improves the viability of multiple cell types. However, migration into and out of tHG remains limited. Scaffolds have chemical and mechanical components at play. We hypothesize altering the mechanical properties of the hydrogel will enhance cell viability and migration.
By tuning the mechanical moduli of tHG while only minimally affecting the chemical composition of the gel, we determined the relationship between the rheological properties of tHG and cell viability. Different amounts of alginate and hyaluronic acid (HA) were used to increase the complex viscosity, storage modulus, and loss modulus of tHG to varying degrees. The effects on viscosity and storage modulus were measured with an Ares-G2 Rheometer. We used 1% human tendon tHG with alginate concentrations of 0.2% and 0.5%, and HA concentrations of 0.05% and 0.1%.
There was no significant change observed in cell viability observed amongst all groups. The addition of alginate and HA affected the rheological properties of the gel, but did not negatively affect cell viability. The reduction of ground human tendon as the base collagen from 2% to 1% reduced by half the need for this valuable material without changing cell viability. The addition of alginate led to more favorable storage and loss moduli. Alginate significantly increased the viscosity of the gel.
1% tHG with higher storage and loss moduli, through the addition of alginate was easier to handle than the standard 1% tHG, resulting in a more usable and less expensive hydrogel with the same resultant rates of cell survival. This promising optimized hydrogel can be applied to tendon and wound healing applications where collagen scaffold supplementation is valuable.
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