Silver ion-doped calcium phosphate-based bone-graft substitute eliminates chronic osteomyelitis: An experimental study in animals.

Despite the latest technologies and advances in microbiology and orthopedic surgery, chronic osteomyelitis is still a challenging disorder. Antibiotic resistance and bacterially induced bone destruction can have very serious consequences. We hypothesized that calcium phosphate-based bone graft substitution with silver ion doping would simultaneously treat bone infection and the bony defect in the chronic osteomyelitis. An unicortical 10-mm-diameter bone was harvested in the proximal tibial metaphysis of 24 rabbits. After contaminating the wounds with an infective dose of methicillin-resistant Staphylococcus aureus (MRSA), osteomyelitis was proven radiographically and microbiologically in all rabbits. Animals were than divided into three groups. The first group received vancomycin-impregnated bone cement beads (comparative control group), the second/experimental group received silver ion-doped calcium phosphate beads and the third group received pure calcium phosphate beads (negative controls). Radiographs, intraosseous cultures, and histopathological examinations were performed on postoperative Week 10. The cultures showed no evidence of intramedullary infection in the silver ion-doped calcium phosphate beads group, but they were positive for MRSA in four of the six rabbits in the vancomycin- impregnated bone cement beads group and in all of the eight rabbits in the pure calcium phosphate beads group. Quantitative assessment of histopathological examination showed lowest total damage score in silver ion-doped calcium phosphate beads group (p < .001). Percentage of osteoid tissue + bony tissue was also higher in this group compared with other groups. In the final radiological examinations, it was observed that the changes caused by osteomyelitis in the bone tissue in the silver ion-doped calcium phosphate beads group were much improved compared with the vancomycin-impregnated bone cement beads group. Silver ion doped calcium phosphate-based bone-graft substitute offer the ability to stimulate bone growth, combat infection, and, ultimately, treat experimental chronic osteomyelitis in an animal model.

Adhesion profile and differentiation capacity of human adipose tissue derived mesenchymal stem cells grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite nano-coated surfaces.

Accelerated Mesenchymal Stem Cells (MSCs) condensation and robust MSC-matrix and MSC-MSC interactions on nano-surfaces may provide critical factors contributing to such events, likely through the orchestrated signal cascades and cellular events modulated by the extracellular matrix. In this study, human adipose tissue derived mesenchymal stem cells (hMSC)', were grown on metal ion (Zn, Ag and Cu) doped hydroxyapatite (HAP) nano-coated surfaces. These metal ions are known to have different chemical and surface properties; therefore we investigated their respective contributions to cell viability, cellular behavior, osteogenic differentiation capacity and substrate-cell interaction. Nano-powders were produced using a wet chemical process. Air spray deposition was used to accumulate the metal ion doped HAP films on a glass substrate. Cell viability was determined by MTT, LDH and DNA quantitation methods Osteogenic differentiation capacity of hMSCs was analyzed with Alizarin Red Staining and Alkaline Phosphatase Specific Activity. Adhesion of the hMSCs and the effect of cell adhesion on biomaterial biocompatibility were explored through cell adhesion assay, immunofluorescence staining for vinculin and f-actin cytoskeleton components, SEM and microarray including 84 known extracellular matrix proteins and cell adhesion pathway genes, since, adhesion is the first step for good biocompability. The results demonstrate that the viability and osteogenic differentiation of the hMSCs (in growth media without osteogenic stimulation) and cell adhesion capability are higher on nanocoated surfaces that include Zn, Ag and/or Cu metal ions than commercial HAP. These results reveal that Zn, Ag and Cu metal ions contribute to the biocompatibility of exogenous material.

Analyses of the modulatory effects of antibacterial silver doped calcium phosphate-based ceramic nano-powder on proliferation, survival, and angiogenic capacity of different mammalian cells in vitro.

In this study, the antibacterial, cytotoxic, and angiogenic activities of silver doped calcium phosphate-based inorganic powder (ABT or PAG) were systematically investigated. ABT powders containing varying silver content were fabricated using a wet chemical manufacturing method. Antibacterial efficiencies of the ABT powders were investigated using a standard test with indicator bacteria and yeast. The cytotoxic effects of ABT on three different fibroblast cells and human umbilical vein endothelial cells (HUVECs) were assessed using MTT assay. ABT powder exhibits concentration-related cytotoxicity characteristics. Apoptotic activity, attachment capability, and wound healing effects were examined on fibroblasts. The angiogenic activity of ABT was investigated by tube formation assay in HUVECs; 10 µg ml(-1) and 100 µg ml(-1) concentrations of the highest metal ion content of ABT did not disrupt the tube formation of HUVECs. All these tests showed that ABT does not compromise the survival of the cells and might impose regeneration ability to various cell types. These results indicate that silver doped calcium phosphate-based inorganic powder with an optimal silver content has good potential for developing new biomaterials for implant applications.