Interaction of cell culture with composition effects on the mechanical properties of polycaprolactone-hydroxyapatite scaffolds fabricated via selective laser sintering (SLS)

In the current study PCL/HA composites were fabricated using SLS as two- and three-dimensional lattice structures and exposed to a cellular component (MC 313 osteoblast-like cells). The main aims were to determine the mechanical differences due to powder composition and to observe the physical and mechanical changes pertaining to cell presence. These structures were characterized by compressive mechanical testing, and the effects of cell culturing and degradation on mechanical properties of the scaffolds with different PCL/HA compositions were determined. Moreover, changes in the scaffold morphology due to the cell culture conditions were determined by mu-CF analysis. Cells steadily grew on the scaffolds for 21 days with preferential distribution around the macropores and initially PCL/HA(15%) composites had higher cell numbers. Removal of loosely sintered parts was observable during the culturing period. Cell culture conditions did not change the compressive moduli significantly but had a distinct effect on compressive strength. For PCL/HA(15%) composites, an initial loss in strength caused by cell culture was reversed by longer cell exposure, with compressive strength of the structures restored to the initial properties (p <= 0.05). mu-CT measurements showed widespread morphological changes in the scaffolds, such as a decrease in the roughness of the struts. In general, in the initial period composites with lower HA content (15 wt.%) showed better metabolic activity compared to the higher HA content, however by day 14 the performance of the two compositions was equal. These results suggest that changes in sintering due to the differences in powder composition can have profound effects on the short and long term mechanical properties of the scaffold particularly:under cell culture conditions, and this should be closely considered for SLS processing of scaffolds. (C) 2012 Elsevier B.V. All rights reserved.