A Dexamethasone-Eluting Porous Scaffold for Bone Regeneration Fabricated by Selective Laser Sintering

Additive manufacture (AM) has been widely and rapidly applied in fabrication of 3D porous scaffolds for tissue engineering applications. For synthetic polymers of high melting temperature, the melting-extruding technique is the most applied AM method for such fabrication of polymer porous scaffolds. This results in a big challenge to directly process the scaffolds using the polymers and thermosensitive substances simultaneously because of deactivation under high temperature. In this article, the selective laser sintering (SLS) method was proposed to make a poly(l-lactic acid) (PLLA) porous scaffold containing dexamethasone (Dex) simultaneously. Dex was encapsulated in two groups of PLLA-bioactive glass (BG) composite microspheres with an average diameter of 115-120 μm and loading amounts of 0.68 ± 0.09 and 0.84 ± 0.10 μg/mg, respectively. The drug-loading composite microspheres were then fabricated into scaffolds under a laser fluence of 0.83-2.08 J/mm². The average pore size and compressive modulus for the porous scaffold were 450-500 μm and 18-25 MPa, respectively. Drug release experiments showed that Dex was released from the scaffold in a controlled manner until about a month. The eluting time of HPLC tests before or after SLS processing both presented at 4 min indicated no chemical structure changes for the drug. Ex vivo cell experiments also testified the comparable effect of released Dex with commercial products, showing that the bioactivities were not affected after SLS. Implantation of the composite scaffolds in rat cranium defects demonstrated that new bone and blood vessel formation was faster in the Dex-releasing scaffolds than in the groups without drug loading.