Bone response to 3D periodic hydroxyapatite scaffolds with and without tailored microporosity to deliver bone morphogenetic protein 2

Abstract

Three types of model hydroxyapatite (HA) scaffolds were implanted in the metacarpal and metatarsal bones of goats. Scaffolds, consisting of a latticed pattern of rods, were fabricated with a solid freeform fabrication (SFF) technique. All scaffolds contained macropores; some were also fabricated with micropores (5.2 +/- 2.0 microm). Recombinant human bone morphogenetic protein-2 (rhBMP-2) was added to some microporous scaffolds. rhBMP-2 caused increased percent filled with bone tissue compared to microporous scaffolds without rhBMP-2. Lamellar bone in the scaffolds was aligned perpendicular to the long axis of the bone near the junctions of the rods that make up the scaffold but was more random away from the junctions of rods. Microporous scaffolds stained beneath areas of contact with new bone. This staining might indicate either extracellular matrix (ECM) in the rods, byproducts of ECM production, or reaction of cellular products with the scaffold.

Bone regeneration with BMP-2 and hydroxyapatite in critical-size calvarial defects in rats

“…BMP: Bone Morphogenetic Protein, HAP: Hydroxyapatite, BMP/HAP: Combined Group, SD: Standard Deviation, *p <0.05/CI 95%, **p <0.01/CI 99%. osteogenesis is affected by the interconnecting channels, porosity, and, most importantly the pore size, determining the capacity of bone ingrowth into the porous scaffold (Dellinger et al, 2006). The construction of HAP pores has disadvantages as the unfilled pores are ideal for the proliferation of bacteria, which can lead to deep infections and, also, HAP is not sufficiently stable in a large defect (Rupprecht et al, 2003).…”

A review of the mechanical behavior of CaP and CaP/polymer composites for applications in bone replacement and repair

“…Microporosity has been shown by multiple research groups to be important for osteointegration [128,103]. The four studies included here all incorporated microporosity, or micropores within the rods, in one or more of the samples tested.…”

Medical Application of Calcium Orthophosphate Bioceramics

“…The alternatives include use hierarchical bioactive scaffolds to engineer in vitro living cellular constructs for transplantation or use bioresorbable bioactive particulates or porous networks to activate in vivo the mechanisms of tissue regeneration [692,693]. Thus, the aim of calcium orthophosphate bioceramics is to prepare artificial porous scaffolds able to provide the physical and chemical cues to guide cell seeding, differentiation and assembly into 3D tissues of a newly formed bone [648,[694][695][696][697][698][699][700]. Particle sizes, shape and surface roughness of the scaffolds are known to affect cellular adhesion, proliferation and phenotype.…”