Dr. Christina Sengstock (Dortmund, DE), Natalie Wolff (Essen, DE), Kaja Reiffert (Dortmund, DE), Katja Loza (Essen, DE), Prof. Dr. Matthias Epple (Essen, DE), Marc Heggen (Jülich, DE), Martin Stenzel (Dortmund, DE), Archana Brenda Krishnacoumar (Dortmund, DE), Anika Grüneboom (Dortmund, DE)
Abstract text (incl. figure legends and references)
Introduction
Implant-associated infections are still the most common healthcare-mediated problem. The inhibition of initial bacterial colonization by supportive antimicrobial agents such as silver (Ag) might be effective to avoid implant-related infections. By the use of Ag nanoparticles (NP), a rapid and time-limited Ag-ion release can be achieved at reduced total Ag amount. Further, using ultramall NP and the combination with other metals might be a promising approach to obtain materials with tunable properties. In addition, platinum (Pt) was already reported to reduce bone loss by inhibition of osteoclastogenesis [Nomura et al., 2011].
Objectives
Here, we analyzed the cytotoxicity, uptake and localization of Ag NP, Au NP and Pt NP within human mesenchymal stem cells (hMSC), because ultrasmall NP are particularly mobile in cells, are of the size of biological macromolecules such as proteins, and are biologically active in ways that are currently not well predicted or understood.
Materials & Methods
Ultrasmall Ag NP, Au NP and Pt NP (about 1-2 nm) were synthesized by with GSH as capping agent and AF647 as covalently attached fluorescent dye. hMSC viability, uptake and localization were analyzed by different methods such as confocal laser scanning microscopy, spectrophotometry, and flow cytometry.
Results
In contrast to Au NP and Pt NP, Ag NP showed a significant impact on hMSC viability depending on the Ag NP concentration and the AF647 labeling. NP were taken up by hMSC and could be colocalized within endo-lysosomes. A long term exposure of hMSC with Pt NP caused the formation of cell nodules.
Conclusion
We demonstrated that ultrasmall Ag NP were cytotoxic to hMSC in a concentration-dependent way, and that under subtoxic concentrations, ultrasmall NP were taken up by cells and localized inside endo-lysosomes. Our results suggest that NP with tunable properties can be obtained by reducing the size or metal composition for a directed biological response.