Parathyroid hormone-related protein (107-111) improves the bone regeneration potential of gelatin-glutaraldehyde biopolymer-coated hydroxyapatite

Abstract

Biopolymer-coated nanocrystalline hydroxyapatite (HA) made as macroporous foams which are degradable and flexible are promising candidates as orthopaedic implants. The C-terminal (107-111) epitope of parathyroid hormone-related protein (PTHrP) exhibits osteogenic properties. The main aim of this study was to evaluate whether PTHrP (107-111) loading into gelatin-glutaraldehyde biopolymer-coated HA (HA(GIu)) scaffolds would produce an optimal biomaterial for tissue engineering applications. HA(GIu) scaffolds with and without PTHrP (107-111) were implanted into a cavitary defect performed in both distal tibial metaphysis of adult rats. Animals were sacrificed after 4 weeks for histological, microcomputerized tomography and gene expression analysis of the callus. At this time, bone healing occurred only in the presence of PTHrP (107-111)-containing HA(Giu) implant, related to an increase in bone volume/tissue volume and trabecular thickness, cortical thickness and gene expression of osteocalcin and vascular cell adhesion molecule I, but a decreased gene expression of Wnt inhibitors, SOST and dickkopf homolog 1. The autonomous osteogenic effect of the PTHrP (107-111)-loaded HA(Giu) scaffolds was confirmed in mouse and human osteoblastic cell cultures. Our findings demonstrate the advantage of loading PTHrP (107-111) into degradable HA(GIu) scaffolds for achieving an optimal biomaterial that is promising for low load bearing clinical applications. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.