Enhancement of bone regeneration through facile surface functionalization of solid freeform fabrication-based three-dimensional scaffolds using mussel adhesive proteins.

Solid freeform fabrication (SFF) is recognized as a promising tool for creating tissue engineering scaffolds due to advantages such as superior interconnectivity and highly porous structure. Despite structural support for SFF-based three-dimensional (3-D) scaffolds that can lead to tissue regeneration, lack of cell recognition motifs and/or biochemical factors has been considered a limitation. Previously, recombinant mussel adhesive proteins (MAPs) were successfully demonstrated to be functional cell adhesion materials on various surfaces due to their peculiar adhesive properties. Herein, MAPs were applied as surface functionalization materials to SFF-based 3-D polycaprolactone/poly(lactic-co-glycolic acid) scaffolds. We successfully coated MAPs onto scaffold surfaces by simply dipping the scaffolds into the MAP solution, which was confirmed through X-ray photoelectron spectroscopy and scanning electron microscopy analyses. Through in vitro study using human adipose tissue-derived stem cells (hADSCs), significant enhancement of cellular activities such as attachment, proliferation, and osteogenic differentiation was observed on MAP-coated 3-D scaffolds, especially on which fused arginine-glycine-aspartic acid peptides were efficiently exposed. In addition, we found that in vivo hADSC implantation with MAP-coated scaffolds enhanced bone regeneration in a rat calvarial defect model. These results collectively demonstrate that facile surface functionalization of 3-D scaffolds using MAP would be a promising strategy for successful tissue engineering applications.