In vitro evaluation of a multifunctional nano drug delivery system based on tigecycline-loaded calcium-phosphate/ poly-DL-lactide-co-glycolide

Most drug delivery systems as treatment modalities for osteomyelitis have not been evaluated for resistant infections. Tigecycline (TG) is an antimicrobial agent that could be used in the treatment of multi-drug-resistant orthopedic infections. The objective of this in vitro study has been to determine what dosage of TG causes changes in the morphology and number of osteoblasts. We have also investigated whether nanoparticulate tigecycline-loaded calcium-phosphate/poly-DL-lactide-co-glycolide is biocompatible and whether it could release bioactive TG in a controlled manner during the observation time. The cytotoxicity was tested by analyzing the release of lactate dehydrogenase from dead osteoblasts to the medium. Staphylococcus aureus was used to verify the antibacterial effect of the multifunctional drug delivery system. At concentrations as achieved by local application, TG caused high toxic effect and impaired the normal osteoblastic morphology. The nanoparticulate multifunctional drug delivery system showed good compatibility and antibacterial effect during the observation time and thus appears to be suitable for the treatment of osteomyelitis caused by multi-drug-resistant microbes.

Ameloblastin promotes bone growth by enhancing proliferation of progenitor cells and by stimulating immunoregulators

In this study, we examined the role of the enamel matrix protein, ameloblastin, in bone growth and remodelling, and attempted to identify some of the molecular mechanisms involved in these processes. The effects of recombinant ameloblastin (rAmbn) were tested in vivo in rats, and in vitro in primary human mesenchymal stem cells, osteoblasts, chondrocytes, and osteoclasts. We used a microarray technique to identify genes that were regulated in human osteoblasts and verified our findings using multiplex protein analysis and real-time RT-PCR. Recombinant ameloblastin was found to stimulate bone healing in vivo, and to enhance the proliferation of mesenchymal stem cells and osteoblasts, as well as the differentiation of osteoclast precursor cells in vitro. The most profound effect was on the regulation of genes related to immune responses as well as on the expression of cytokines and markers of bone cell differentiation, indicating that ameloblastin has an effect on mesenchymal cell differentiation. A receptor has not yet been identified, but we found rAmbn to induce, directly and indirectly, signal transducer and activator of transcription (STAT) 1 and 2 and downstream factors in the interferon pathway.

A Novel Ultra-porous Titanium Dioxide Ceramic with Excellent Biocompatibility

The current study compares biocompatibility, cell growth and morphology, pore diameter distribution, and interconnectivity of a novel titanium dioxide (TiO2) bone graft substitute granules with three different commercially available bone graft granules Natix®, Straumann® BoneCeramic, and Bio-Oss®. Human primary mesenchymal stem cells were cultured on the bone graft substitutes and cell viability and proliferation were evaluated after 1 and 3 days. The microstructural properties of the bone graft substitutes were evaluated by scanning electron microscopy, micro-computed tomography analysis, and mechanical testing. The cell viability and proliferation, porosity, interconnectivity, open pore size, and surface area-to-volume ratio of TiO2 granules were significantly higher than commercial bone granules (Bio-Oss® and Straumann ® BoneCeramic).

A novel nano drug delivery system based on tigecycline-loaded calciumphosphate coated with poly-DL-lactide-co-glycolide

The purpose of the study presented in this paper has been to examine the possibility of the synthesis of a new nanoparticulate system for controlled and systemic drug delivery with double effect. In the first step, a drug is released from bioresorbable polymer; in the second stage, after resorption of the polymer, non-bioresorbable calcium phosphate remains the chief part of the particle and takes the role of a filler, filling a bone defect. The obtained tigecycline-loaded calcium-phosphate(CP)/poly(DL-lactide-co-glycolide)(PLGA) nanoparticles contain calcium phosphate coated with bioresorbable polymer. The composite was analyzed by FT-IR, XRD and AFM methods. The average particle size of the nanocomposite ranges between 65 and 95 nm. Release profiles of tigecycline were obtained by UV-VIS spectroscopy in physiological solution at 37 degrees C. Experimental results were analyzed using Peppas and Weibull mathematical models. Based on kinetic parameters, tigecycline release was defined as non-Fickian transport. The cytotoxicity of the nanocomposite was examined on standard cell lines of MC3T3-E1, in vitro. The obtained low values of lactate dehydrogenase (LDH) activity (under 37%) indicate low cytotoxicity level. The behaviour of the composite under real-life conditions was analyzed through implantation of the nanocomposite into living organisms, in vivo. The system with the lowest tigecycline content proved to be an adequate system for local and controlled release. Having in mind the registered antibiotics concentration in other tissues, delivery systems with a higher tigecycline content show both local and systemic effects.

Neural stem cells as novel cancer therapeutic vehicles

The startling resemblance of many of the behaviours of brain tumours to the intrinsic properties of the neural stem/progenitor cell has triggered a recent dual interest in arming stem cells to track and help eradicate tumours and in viewing stem cell biology as somehow integral to the emergence and/or propagation of the neoplasm itself. These aspects are reviewed and discussed here.