Case Study: Hydroxyapatite Based Microporous/Macroporous Scaffolds

Abstract

This chapter will present some of the unique processing approaches to develop porous scaffolds with porosity scaling in the range of either 1–50 μm or in the range of 100–300 μm. In the first part of this chapter, the results will be summarized to illustrate how hydroxyapatite scaffolds with micro/mesoscale porosity in the range of 1–50 μm can be produced using the polymer blend method using PMMA (poly methyl methacrylate) as porogenous template. The cytocompatibility assessment using human osteoblast cells (Saos2) confirm that the adopted processing approach to produce porous hydroxyapatite scaffolds can stimulate significant cell adhesion and osteoblast differentiation. In the second part of this chapter, the efficacy of polymer sponge replication method to prepare the macroporous hydroxyapatite scaffolds with interconnected oval shaped pores of 100–300 µm with pore wall thickness of ~50 µm will be demonstrated. The enhanced cellular functionality and the ability to support osteoblast differentiation for porous scaffolds in comparison to dense HA has been explained in terms of higher protein absorption on porous scaffold. The last part of the chapter will present the results on the protein adsorption and release kinetics as well as in vitro biodegradability of cryogenically cured hydroxyapatite-gelatin based micro/macroporous scaffolds (CHAMPS). The adsorption and release of bovine serum albumin (BSA) protein exhibits steady state behavior over the incubation period up to 10 days. The extensive micro-computed tomography (micro-CT) analysis establishes cancellous bone-like highly interconnected and complex porous architecture of CHAMPS scaffold. Importantly, excellent adsorption (up to 50 %) and release (up to 60 % of adsorbed protein) of BSA has been uniquely attributed to the inherent porous microstructure of the CHAMPS scaffold.