Anti-infective efficacy of a 3D printed PLGA/HA scaffold grafted with quaternised chitosan

摘要

Contaminated or infectious bone defect remains a serious complicated challenge in current orthopedic surgery and the bone substitute with both osteoconductivity and antibacterial potential represents an ideal treatment strategy. In previous study, we have developed a novel quatemised chitosan (hydroxypropyltrimethyl ammonium chloride chitosan, HACC) and demonstrated that it exhibited strong antibacterial activity. In this study, the HACC was grafted to the 3D printed bioaclive porous scaffolds, which made of polylactide-co-glycolide (PLGA) or impregnated with hydroxyapatite (HA) (weight ratio, PLGA:HA=9:1). Three standard strains, Staphylococcus aureus (ATCC25923), Staphylococcus epidermidis (ATCC35984) and methicillin-resistant Staphylococcus aureus (ATCC43300), and one clinical isolates, methicillin-resistant S.epidermidis (MRSE287), were selected to evaluate the bacterial adhesion and biofilm formation on the materials at 4,24 and 48h using the spread plate method, tissue culture plate (TCP) method and confocal laser scanning microscopy (CLSM) in vitro. We found that both PLGA/HA/HACC and PLGA/HACC composites could significantly inhibit bacterial adhesion and biofilm formation compared with PLGA or PLGA/HA. Meanwhile, human bone marrow derived mesenchymal stem cells were used to assess the osteoactivity of the scaffold and we found that HA impregnated scaffolds including PLGA/HA and PLGA/HA/HACC exhibited significantly better cell attachment, proliferation, spreading and osteogenic differentiation compared with the PLGA or PLGA/HACC. Furthermore, the scaffold contaminated with a bioluminescent S.aureus strain (ATCC12600, Xen29) was implanted subcutaneously in SD rats. The real-time monitoring of the MS Imaging System showed more evident decrease in bacterial counts in the scaffolds of PLGA/ HA /HACC and PLGA/HACC compared with the other two scaffolds without HACC grafting. Taken all together, our findings may develop a good foundation for potential clinical validation of this inovative bioactive porous scaffold for combating infectious bone defect.