Project Title: Development of Extended-Lifetime Organic-Inorganic Scaffolds for Orthopaedical Applications

Acronym: NEWEXTLIFESCAFF

Funding Entity: European Comission , Marie Curie Outgoing International Fellowship (MOIF-CT-2005-7325)

Participating Entities:  University of Extremadura, Lawrence Berkeley National Laboratory

Duration: 01/03/2005 – 31/08/2006

Budget: 127 594 €

UEX Principal Investigator (PI): Pedro Miranda

Number of researchers: 1

Abstract:

A new generation of biomaterials for orthopaedic applications was developed. A novel processing technique, called robocasting or direct-write assembly, was successfully applied to fabricate porous bioceramic (hydroxyapatite and b-tricalcium phosphate) scaffolds for bone tissue engineering. The scaffolds consist of a 3D network of perfectly joined calcium phosphate rods fabricated in a pre-determined geometry. This was achieved by the computer-controlled robotic deposition of dense water-based suspensions of calcium phosphate powders capable of supporting their own weight. The calcium phosphate scaffold encourages bone cells to proliferate into its designed pore structure, helping the body to regenerate a damaged tissue region after its implantation. The processing technique used has significant advantages over more conventional techniques for fabricating porous scaffolds that do not allow a precise control of their three-dimensional external shape and internal morphology, but also over other technologies capable of producing analogous controlled structures (stereolithography, 3D printing, etc) in terms of simplicity and cost, and of avoiding the use of potentially toxic binders.

Calcium phosphate scaffolds are inherently brittle and this study has allowed us to identify the damage modes occurring in the scaffold structures. Computer finite element models of the scaffolds have been developed to calculate and predict their mechanical behaviour as a function of the different geometrical variables that can be controlled in the fabrication procedure. These computer models will allow us to optimize in the near future the geometrical design of the scaffolds in order to improve their mechanical performance for load-bearing orthopaedic applications.

Finally, the mechanical performance of the scaffold could be greatly improved by infiltration of the porous structure with biodegradable polymers (polylactic acid, polyglycolic acid, polycaprolactone, etc.) to create a composite. The degradation of the polymer after implantation will create in situ the porosity necessary for bone in-growth into the composite scaffolds. This possibility opens up a most promising and as yet unexplored way to create damage tolerant scaffolds for load bearing applications in bone tissue engineering. The viability of this concept has been preliminarily explored in this project with very promising results, though additional work is still needed to bring this concept to reality.