Extracellular matrix-mimetic composite hydrogels of cross-linked hyaluronan and fibrillar collagen with tunable properties and ultrastructure.

A platform of enzymatically-crosslinked Collagen/Tyramine hyaluronan derivative (Col/HA-Tyr) hydrogels with tunable compositions and gelation conditions was developed to evaluate the impact of the preparation conditions on their physical, chemical and biological properties. At low HA-Tyr content, hydrogels exhibited a fibrillar structure, with lower mechanical properties compared to pure Col hydrogels. At high HA-Tyr and Horse Radish Peroxydase (HRP) content, a microfibrillar network was formed beside the banded Col fibrils and a synergistic effect of the hybrid structure on mechanical properties was observed. These hydrogels were highly resistant against enzymatic degradation while keeping a high degree of hydration. Unlike HA-Tyr hydrogels, encapsulation of human dermal fibroblasts within Col/HA-Tyr hydrogels allowed for high cell viability. These results showed that high HA-Tyr and HRP concentrations are required to positively impact the physical properties of hydrogels while preserving collagen fibrils. Those Col/HA-Tyr hydrogels appear promising for novel tissue engineering applications following a biomimetic approach.