Versatile design of hydrogel-based scaffolds with manipulated pore structure for hard-tissue regeneration.

In recent years, a variety of biomimetic hydrogel scaffolds have been used in tissue engineering because hydrogels can provide reasonable soft-tissue-like environmental conditions for various cell responses. However, although hydrogels can provide an outstanding biofunctional platform, their poor mechanical stability and low processability have been obstacles for their usage as biomedical scaffolds. To overcome this limitation, we propose a simple and versatile method using 3D printing supplemented with a low-temperature working plate and coating process to reinforce the mechanical properties and various cellular activities by accommodating the poly(ε-caprolactone) (PCL). To determine the efficiency of the method, we used two typical hydrogels (alginate and collagen), which were deposited in a multi-layer configuration, and PCL as a coating agent. The scaffolds were evaluated in terms of various physical and cellular activities (metabolic activity and osteogenic activity). Throughout the experiments, significant increases in the tensile modulus (>6-fold), cell proliferation (>1.2-fold), and calcium deposition (>1.3-fold) were observed for the hydrogel/PCL scaffolds compared to those for pure hydrogel. Based on the experimental results, we can confirm that the proposed hydrogel scaffold can be a highly promising biomedical scaffold for application in tissue regeneration.