Proliferation and function of MC3T3-E1 cells on freeze-cast hydroxyapatite scaffolds with oriented pore architectures.

Previous work by the authors showed that hydroxyapatite (HA) scaffolds with different types of oriented microstructures and a unique 'elastic-plastic' mechanical response could be prepared by unidirectional freezing of suspensions. The objective of the present work was to evaluate the in vitro cellular response to these freeze-cast HA scaffolds. Unidirectional scaffolds with approximately the same porosity (65-70%) but different pore architectures, described as 'lamellar' (pore width = 25 +/- 5 microm) and 'cellular' (pore diameter = 100 +/- 10 microm), were evaluated. Whereas both groups of scaffolds showed excellent ability to support the proliferation of MC3T3-E1 pre-osteoblastic cells on their surfaces, scaffolds with the cellular-type microstructure showed far better ability to support cell proliferation into the pores and cell function. These results indicate that freeze-cast HA scaffolds with the cellular-type microstructure have better potential for bone repair applications.