Effects of Vancomycin and Ceftazidime on Osteogenesis of Mesenchymal Stem Cells

Despite the advances in surgical techniques and the availability of newly developed antibiotics, bone infections after surgical procedures and trauma continue to be a difficult problem for surgeons. At present, the combination of surgical intervention and an effective antibiotic agent remains the mainstay of treatment. Vancomycin and ceftazidime have been commonly formulated with bone cement for infection treatment. Vancomycin is effective against Gram-positive bacteria and ceftazidime is effective against many Gram-negative bacteria. The authors developed a biodegradable delivery system of antibiotics and mesenchymal stem cells (MSC) for the treatment of bone defects. However, previous studies have primarily utilized wound models that lack an infectious component. The functional activity of MSCs may be altered in the presence of inflammatory mediators as well as bacterial components that may accumulate within a chronic wound. In this study we will investigate the impact of the cell wall components lipopolysaccharide (LPS), lipoteichoic acid (LTA), vancomycin, and ceftazidime on osteogenesis of MSCs. Microarray analysis is a powerful technique to study gene expression. Researchers have used this technology to study gene expression during osteogenesis of MSC. Wnt pathway is one of the signals that regulate expression of osteogenic marker Cbfa1. Epigenetic mechanisms include microRNAs, histone modifications, and DNA methylation. In human MSCs, miRNA profiling analysis revealed 33 miRNAs being significantly altered between undifferentiated and differentiated cells. Tigecycline induces cell-cycle arrest and inhibits glioma growth by regulating miRNA-199b-5p–HES1–AKT pathway. Histone modifications involving acetylation and deacetylation strongly impact the endochondral and intramembranous ossification. Histone deacetylase (HDAC) inhibitors promote osteoblastic differentiation of MSCs. HDACs 1, 3, and 4 have been shown to be transiently up-regulated by gentamicin (GM), and are associated with GM induced hair cell loss. SIRT1 and SIRT4 are differentially regulated in self-renewing, differentiating, and aging stem cells. Rapamycin increased SIRT1 but decreased SIRT4 expression in stem cells However, the effect of LPS, LTA, vancomycin, and ceftazidime on the Wnt/β-catenin pathway, MicroRNA profiling, and histone modifications in MSCs has never been reported. We will establish a 3-year’s study in this research project. We will harvest the MSCs from 15 patients who undergo iliac bone grafting for repairing long bone fracture nonunions or spinal fusion in each year: In the first year (DNA microarray analysis): We will focus the effects of LPS, LTA, vancomycin, and ceftazidime on identifying gene expression in osteogenesis of MSCs by microarray analysis. In addition, we will find the effects on osteogenesis of MSCs via Wnt signaling regulation as well as TCF-dependent transcription. In the second year (Micro-RNA profiling analysis): We will find the effects of LPS, LTA, vancomycin, and ceftazidime on MicroRNA profiling and the interactions between miRNAs and Wnt/β-catenin pathway in MSCs. In the third year (Histone modifications analysis): We will find the effects of LPS, LTA, vancomycin, and ceftazidime on histone modifications in MSCs. We will find the interactions among HDACs, SIRT1, SIRT4, β-catenin, and MicroRNA in MSCs.

Project ID:PC10608-1473
External Project ID:MOST106-2314-B182-011-MY2