Engineering 3D Collagen Tunable Platforms for Mechanobiology Studies

Abstract

Construction of scaffolds is crucial for tissue engineering applications. Three dimensional (3D) scaffolds provide extracellular matrix analogs that function as suitable platforms for cell infiltration and physical supports to guide their differentiation and proliferation into the targeted functional tissue or organ. An ideal scaffold used for tissue engineering should possess excellent biocompatibility, microstructure and porosity adapted to cell invasion, controllable biodegradability, and suitable mechanical properties. Collagen is among the most promising biological materials for scaffold fabrication. It has numerous applications in tissue engineering such as nerve, bone, cartilage, tendon, ligament, blood vessel, and skin repair. In this study, we report the design, synthesis, and characterization of porous and bioactive type I collagen scaffolds via an ice-templating method, and we detail how mechanics, morphology, and protein contents of the scaffolds were tuned to make them suitable for mechanobiology studies. Scaffolds were generated by varying collagen concentration, freezing temperature, and mold material/shape. Their morphological and mechanical properties were assessed via Scanning Electron Microscopy, Hg Porosimetry, and Dynamic Mechanical Thermal Analysis. Our data indicate that the best control over scaffolds properties was achieved when using the Teflon rectangular molds and freezing temperatures of -10℃ while varying collagen concentration: Average pore size decreased from 214 µm to 35 µm and compressive modulus increased from 154 Pa to 1720 Pa when collagen concentration was increased from 0.5 wt.% to 1.25 wt.%. This trend tended to less pronounced when lower freezing temperatures were tested. Additionally, the scaffolds were coated with fibronectin (a protein from the extracellular matrix that promotes cell adhesion) to investigate the additional effect of molecular conformation on cell behavior. Collectively these data suggest that cell adhesion and proliferation can be coarsely controlled by scaffold morphology and mechanics and then finely tuned by protein conformation. Our research lays the groundwork for future investigation of the different methods to fabricate tunable collagen scaffolds and control the synergistic effects of collagen with other proteins present in the cellular/tissue micro-environment, which are crucial to govern cell-matrix interactions in mechanobiology studies.