Addition of collagen type I in agarose created a dose-dependent effect on matrix production in engineered cartilage

Abstract

Extracellular-matrix composition impacts mechanical performance in native and engineered tissues. Previous studies showed collagen type I-agarose blends increased cell-matrix interactions and extra-cellular matrix production. However, long-term impacts on protein production and mechanical properties of engineered cartilage are unknown. Our objective was to characterize the effect of collagen type I on matrix production of chondrocytes embedded in agarose hydrogels. We hypothesized that the addition of collagen would improve long-term mechanical properties and matrix production (e.g., collagen and glycosaminoglycans) through increased bioactivity. Agarose hydrogels (2% w/v) were mixed with varying concentrations of collagen type I (0, 2, 5 mg/mL). Juvenile bovine chondrocytes were added to the hydrogels to assess matrix production over 4 weeks through biochemical assays, and mechanical properties were assessed through unconfined compression. We observed a dose-dependent effect on cell bioactivity, where 2 mg/mL of collagen improved bioactivity, but 5 mg/mL had a negative impact on bioactivity. This resulted in higher modulus for scaffolds supplemented with lower collagen concentration as compared to the higher collagen concentration, but not when compared to the control. In conclusion, the addition of collagen to agarose constructs provided a dose-dependent impact on improving glycosaminoglycan production but did not improve collagen production or compressive mechanics.

Characterization of Composite Agarose-Collagen Hydrogels for Chondrocyte Culture

“…A lack of consensus exists regarding sGAG content in composite hydrogels. While some reports show higher collagen content associated with higher sGAG content 28 , others report the opposite effect, in which a low collagen content led to higher sGAG content 31 . However, as previously referred to, these differences could also be attributable to discrepancies among collagen sources and associated influences on cell behavior.…”

“…Composite hydrogels combine the favorable properties of each individual polymer, enabling tunable mechanical and structural properties and leading to more ECM-like interactions that promote cues for proliferation, differentiation, and matrix production. Few groups have studied the interactions between agarose and collagen biomaterials and their influence on cells [28][29][30][31][32][33]et. al.,assessed the impact of low concentration agarose blended with collagen on nucleus pulposus cells, finding composite hydrogels to outperform agarose-only hydrogels in terms of cell adhesion and proliferation, likely attributable to the binding motifs that exist within the collagen component 28 .…”

Degradation-Influenced/Induced Self-Assembly of Copolymers with the Combinatory Effects of Changed Molecular Weight and Dispersity

“…The self-assembly of amphiphilic block copolymers in a selective solvent has been extensively investigated both experimentally and theoretically over the years and exhibited wide applications such as in biomedicine. − Most of the pertinent fundamental research focuses on the preparation of multiple self-assembled structures and the factors of morphology control. − While degradation is an inherent character of some synthetic and natural polymers and much progress has been made in studies of degradable polymers, − the effect of degradation on self-assembly has not yet been fully investigated. Although the micelle morphology transformation during the degradation of amphiphilic block copolymers has been reported in some literature, − it is rare to treat degradation as a “construction” factor to change a material both mesoscopically and macroscopically.…”