Surgical site infections (SSIs) are one of the most common nosocomial infections, which can result in serious complications after surgical interventions. Foreign materials such as implants or surgical sutures are optimal surfaces for the adherence of bacteria and subsequent colonization and biofilm formation. Due to a significant increase in antibiotic-resistant bacterial strains, naturally occurring agents exhibiting antibacterial properties have great potential in prophylactic therapies. The aim of this study was to develop a coating for surgical sutures consisting of the antibacterial substance totarol, a naturally occurring diterpenoid isolated from Podocarpus totara in combination with poly(lactide-co-glycolide acid) (PLGA) as a biodegradable drug delivery system. Hence, non-absorbable monofilament and multifilament sutures were coated with solutions containing different amounts and ratios of totarol and PLGA, resulting in a smooth, crystalline coating. Using an agar diffusion test (ADT), it became evident that the PLGA/totarol-coated sutures inhibited the growth of Staphylococcus aureus over a period of 15 days. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that the coated sutures were not cytotoxic to murine fibroblasts. Overall, the data indicates that our innovative, biodegradable suture coating has the potential to reduce the risk of SSIs and postoperative biofilm-formation on suture material without adverse effects on tissue.

Endothelial progenitor cells (EPCs) are one of the most important stem cells for the neovascularization of tissues damaged by ischemic diseases such as myocardial infarction, ischemic stroke, or critical limb ischemia. However, their low homing efficiency in the treatment of ischemic tissues limits their potential clinical applications. The use of synthetic messenger RNA (mRNA) for cell engineering represents a novel and promising technology for the modulation of cell behavior and tissue regeneration. To improve the therapeutic potential of EPCs, in this study, murine EPCs were engineered with synthetic mRNAs encoding C-X-C chemokine receptor 4 (CXCR4) and P-selectin glycoprotein ligand 1 (PSGL-1) to increase the homing and migration efficiency of EPCs to inflamed endothelium. Flow cytometric measurements revealed that the transfection of EPCs with CXCR4 and PSGL-1 mRNA resulted in increased expressions of CXCR4 and PSGL-1 on the cell surface compared with the unmodified EPCs. The transfection of EPCs with mRNAs did not affect cell viability. CXCR4-mRNA-modified EPCs showed significantly higher migration potential than unmodified cells in a chemotactic migration assay. The binding strength of the EPCs to inflamed endothelium was determined with single-cell atomic force microscopy (AFM). This showed that the mRNA-modified EPCs required a three-fold higher detachment force to be released from the TNF-α-activated endothelium than unmodified EPCs. Furthermore, in a dynamic flow model, significantly increased binding of the mRNA-modified EPCs to inflamed endothelium was detected. This study showed that the engineering of EPCs with homing factors encoding synthetic mRNAs increases the homing and migration potentials of these stem cells to inflamed endothelium. Thus, this strategy represents a promising strategy to increase the therapeutic potential of EPCs for the treatment of ischemic tissues.