In vitro assessment of three-dimensionally plotted nagelschmidtite bioceramic scaffolds with varied macropore morphologies

Abstract

It is known that porous scaffolds play an important role in bone/periodontal tissue engineering. A new nagelschmidtite (NAGEL, Ca7Si2P2O16) ceramic has recently been prepared which shows excellent apatite mineralization ability and osteo-/cementostimulation properties in vitro. However, up to now porous NAGEL scaffolds have not been developed yet. There has been no systematic study of the effect of macropore morphology of bioceramic scaffolds on their physico-chemical and biological properties. The aim of this study was to prepare NAGEL scaffolds for bone tissue engineering applications. We applied a modified three-dimensional (3-D) plotting method to prepare highly controllable NAGEL scaffolds and investigated the effect of macropore morphology on the physico-chemical and biological properties. The results showed that the macropore size and morphology of 3-D plotted NAGEL scaffolds could be effectively controlled. Compared with β-tricalcium phosphate (β-TCP) scaffolds NAGEL scaffolds possess a significantly enhanced compressive strength, a higher modulus and better degradability. Nagel scaffolds with a square pore morphology presented a higher compressive strength, a higher modulus and greater weight loss rate than those with triangular and parallelogram pore morphologies. In addition, all of the NAGEL scaffolds with the three macropore morphologies supported the attachment and proliferation of MC3T3 cells. The proliferation of MC3T3 cells on NAGEL scaffolds with triangular and parallelogram structures was higher than that on β-TCP scaffolds with the same pore structure. Cells on all three groups of NAGEL scaffolds revealed higher alkaline phosphatase (ALP) activity compared with cells on β-TCP scaffolds, and among the three NAGEL scaffolds groups those with a parallelogram pore structure showed the highest ALP activity. Furthermore, the angiogenic cell experiments showed that the ionic products from NAGEL scaffolds promoted tube formation, expression of pro-angiogenic factors and their receptors on human umbilical vein endothelial (HUVECs) compared with β-TCP scaffolds, indicating that NAGEL scaffolds possessed improved angiogenesis capacity. Our results suggest that 3-D plotted NAGEL scaffolds are a promising bioactive material for bone tissue engineering by virtue of their highly controllable macropore structure, excellent mechanical strength, degradability and in vitro biological response to osteogenic/angiogenic cells.

Keywords: Bioceramics; Biological response; Bone tissue engineering; Macropore morphology; Three-dimensional plotted scaffolds.