Three-dimensional gradients in isotropic and anisotropic mimetic scaffolds for regenerative medicine applications

Gradients of 3-D complex functional patterns at micro-scale are common in nature, and used in several fields such as drug delivery, micro-fabrication, drug development and tissue engineering1. While diverse fabrication techniques based on material science, micro-scale engineering, and microfluidics have been used to synthesize biomimetic and tailored microenvironments2,3, a need is still present for improved methods of gradient shape control and stability4. Here, we describe customized crosslinking and freeze-drying techniques to guide 3-D structures gradients and porosity, programmed by composition and shape into isotropy and anisotropy. Using control over crosslinking and temperature as a driving mechanism, hydrogel-like structures were built in 3-D porous gradients. We demonstrate unique capabilities such as 3-D soft systems with controlled porous architecture fabricated without compromising the produced gradients. Finally, we developed a 3-D osteochondral in vitro model by culturing fat pad adipose-derived stem cells in the gradient structures under dynamic conditions using a custom dual-chamber bioreactor. The developed technique allows the control of 3-D gradients anisotropy with broad applications in interfaced tissue engineering and drug delivery with special focus on regenerative medicine.