Alterations to the adhesion, growth and osteogenic differentiation of human osteoblast-like cells on nanofibrous polylactide scaffolds with diamond nanoparticles

Abstract

Nanofibrous scaffolds are promising materials for engineering various types of tissues, including bone tissue. The properties of nanofibers for bone tissue engineering can be improved by adding ceramic or carbon nanoparticles, including diamond nanoparticles (DNPs). In this study, poly(l-lactide) (PLLA) nanofibrous membranes reinforced with detonation DNPs (concentration from 0 to 12.28 wt%), provided by the NanoCarbon Research Institute (Japan) under the name NanoAmando®, were prepared by a needle-less electrospinning process. The biocompatibility of these DNP-reinforced PLLA membranes was tested in vitro using two human lines of osteoblast-like cells, MG-63 and Saos-2. Microscopic and biochemical methods were used. In addition, the expression of cell survival markers, focal adhesion proteins and osteogenic markers were studied in both cell types at mRNA level and at protein level. The mitochondrial activity of both cells types decreased with increasing DNP concentration in the PLLA matrix. At the same time, the expression of cyclin D and survivin, i.e. factors supporting cell growth and survival were downregulated on the DNP-loaded PLLA scaffolds, while KLF6, an antiproliferative factor, was often upregulated, at least in MG-63 cells. Thus, loading the nanofibrous polymeric scaffolds with detonation DNPs had rather adverse effects on the behavior of human bone-derived cell lines. These results are mostly in conflict with our earlier studies on poly(lactide-co-glycolide) (PLGA) scaffolds, loaded with DNPs prepared by etching the diamond layer fabricated by radiofrequency plasma-assisted chemical vapour deposition. The cell behavior on DNP-loaded scaffolds is therefore markedly influenced by the origin and the properties of the DNPs.