Fabrication of Collagen-Hyaluronic Acid Cryogels by Directional Freezing Mimicking Cartilage Arcade-like Structure.

The internal architecture of tissue-like constructs is fundamental to their structural and biological functions. Here, we introduce a simple and robust method to fabricate cryogels based on derivatized extracellular matrix (ECM) macromolecules with porosity arranged according to the typical Benninghoff zonal architecture of articular cartilage. To obtain this arcade-like structure, the technique used the growth of ice crystals from copper pins at cryogenic temperatures. The directional cryogel formation enabled the organized growth of ice crystals over a large distance (>4 mm). The compositional properties were achieved by forming double networks (DNs) of hyaluronic acid and collagen derivatives (MeHA and CollGTA, respectively), which also served to improve the mechanical properties of the otherwise weak collagen scaffolds. Compositionally biomimetic and more resilient MeHA-CollGTA DNs (Young's modulus ≈ 200 kilopascals) were therefore produced. The technique presented expands the fabrication methods available for providing ECM macromolecules with architectural elements mimicking cartilage complexity.