Three-dimensional micropatterning of bioactive hydrogels via two-photon laser scanning photolithography for guided 3D cell migration.

Micropatterning techniques that control three-dimensional (3D) arrangement of biomolecules and cells at the microscale will allow development of clinically relevant tissues composed of multiple cell types in complex architecture. Although there have been significant developments to regulate spatial and temporal distribution of biomolecules in various materials, most micropatterning techniques are applicable only to two-dimensional patterning. We report here the use of two-photon laser scanning (TPLS) photolithographic technique to micropattern cell adhesive ligand (RGDS) in hydrogels to guide cell migration along pre-defined 3D pathways. The TPLS photolithographic technique regulates photo-reactive processes in microscale focal volumes to generate complex, free from microscale patterns with control over spatial presentation and concentration of biomolecules within hydrogel scaffolds. The TPLS photolithographic technique was used to dictate the precise location of RGDS in collagenase-sensitive poly(ethylene glycol-co-peptide) diacrylate hydrogels, and the amount of immobilized RGDS was evaluated using fluorescein-tagged RGDS. When human dermal fibroblasts cultured in fibrin clusters were encapsulated within the micropatterned collagenase-sensitive hydrogels, the cells underwent guided 3D migration only into the RGDS-patterned regions of the hydrogels. These results demonstrate the prospect of guiding tissue regeneration at the microscale in 3D scaffolds by providing appropriate bioactive cues in highly defined geometries.