(745c) Porous Cell-Laden Hydrogels for Tissue Engineering

Creation of functional 3-dimensional (3D) tissue engineered constructs has been limited by many challenges intrinsically associated with the 3D nature of the systems, such as insufficient mass transfer in the interior regions of large and avascular constructs, inhomogeneous cell seeding, and difficulties in regulating distinct behavior of different cell types in the same construct. We have developed a modular assembly approach to creating large, porous, and cell-laden 3D constructs that have the combined advantages of preformed porous scaffolds and in situ forming hydrogels to address the challenges in 3D tissue engineering. Microgels photolithographically fabricated from solutions of poly(ethylene glycol) diacrylate are assembled into large porous constructs in the presence of a polypeptide-based, physically bonded cross-linker through a physiologically permissive Michael-type addition reaction. The correlation between the properties of assembled constructs and the morphological features of microgels suggests the possibility for bottom-up modulation of the construct properties. The high pore interconnectivity revealed on the level of individual microgels suggests that these constructs are suitable for tissue engineering. Cells are uniformly distributed in assembled constructs and remain viable inside centimeter-sized constructs when perfusion-cultured for days. Sequential assembly of different microgels leads to stably maintained distinct layers within a single construct, indicating the potential application of this method to tailor extracellular microenvironments and control spatial locations for different cell types. This method will provide opportunities to create large 3D tissue engineered products.