In vitro bone engineering based on polycaprolactone and polycaprolactone-tricalcium phosphate composites

The filling of bone defects in load-bearing areas requires scaffolds possessing physical properties that are in the range of those of the host bone. In this report, composite scaffolds comprising medical-grade polycaprolactone and tricalcium phosphate (mPCL-TCP) (80:20), which have been designed for load-bearing applications, are characterized and compared with mPCL scaffolds, using in vitro studies. The composite scaffolds exhibited improved hydrophilicity, compressive modulus and strength. Human alveolar osteoblasts (AOs) grown on the composite achieved higher seeding efficiencies and more uniform distribution when compared with mPCL preparations alone. AOs demonstrated better proliferation, denser multilayered cell-sheets and showed earlier expression of bone matrix-related proteins on the composite than on mPCL during 28 days in vitro culture. The calcium content in the media decreased in both scaffold/cell constructs. Alkaline phosphatase activity increased significantly in mPCL matrices after osteogenic induction but no distinct change was observed in the composite. Osteocalcin expression was down-regulated by induction in the composite but was up-regulated in mPCL at both RNA and protein level. Immuno-reactive signals for osteopontin and collagen type 1, in combination with mineral nodules were found to be stronger in mPCL-TCP scaffolds. We conclude that the composite scaffolds were more hydrophilic and had improved mechanical properties over mPCL scaffolds. Moreover, the primary AOs achieved better cell proliferation, and showed earlier and different matrix protein expression patterns on the composite scaffolds than on the mPCL scaffolds. (c) 2006 Society of Chemical Industry.