Abstract
Introduction Many pathological conditions may benefit from cell therapy using mesenchymal stromal cells, particularly from adipose tissue (ASCs). Cells may be grafted in an environment with a remnant polymicrobial component. The aim is to investigate the behavior of ASCs when brought in contact with a large panel of bacteria. Materials and Methods Carboxyfluorescein-labelled bacterial interaction with ASCs was followed by confocal time-lapse microscopy. Costaining with LAMP-1 was also analyzed. Viability of 4 gram-negative and 4 gram-positive bacterial strains after 6 h of coculture with ASCs was assessed by agar colony counting and by flow cytometry using SYTO-62®/propidium iodide (PI) for membrane permeabilization and DiOC6 for depolarization. A murine model of periodontitis was used to assess in vivo antibacterial capacities of ASCs. Results A significant increase of PI-positive events for all bacterial strains and an increase of the DiOC6 signal were obtained after contact with ASCs. The number of CFU was also significantly decreased for several bacterial strains. 0.4 μm transwell systems illustrated the necessary direct contact to induce maximal bacterial membrane damages. Some bacteria were observed into phagolysosomes, confirming macrophage-like properties of ASCs. In vivo, the bacterial load was significantly lower in the ASC-grafted side compared to the control. Conclusion Our results highlight for the first time a broad range of antibacterial actions of ASCs, by phagocytosis, secretion of oxygenated free radicals and antibacterial molecules. These data are in line with the development of new therapeutic strategies based on ASC transplantation, appropriated in immune-dysbiotic tissue context such as periodontitis or chronic wounds.
Highlights
Many pathological conditions may benefit from cell therapy using mesenchymal stromal cells, from adipose tissue (ASCs)
For the four strains tested (Lc, Escherichia coli (Ec), Sg, and Staphylococcus aureus (Sa)), we consistently observed a significant decrease in the number of colony-forming units (CFUs) when bacteria were brought into contact with Adipose-derived mesenchymal stromal cells (ASCs)
Proportion of propidium iodide(PI-) positive bacteria suggested a maximum of permeabilized bacteria at 24,000 to 48,000 cells by well in 12-well plates (Figure S3), allowing us to define the working condition at 80% confluence and 6-hour incubation
Summary
Many pathological conditions may benefit from cell therapy using mesenchymal stromal cells, from adipose tissue (ASCs). Our results highlight for the first time a broad range of antibacterial actions of ASCs, by phagocytosis, secretion of oxygenated free radicals and antibacterial molecules These data are in line with the development of new therapeutic strategies based on ASC transplantation, appropriated in immune-dysbiotic tissue context such as periodontitis or chronic wounds. Periodontitis is a dysbiotic chronic inflammatory disease of the soft and hard tissues supporting the teeth, affecting 15-50% of adults in developed countries [3]. This is even more important than periodontitis affecting general health and overall quality of life [3]. Bacterial ecology undergoes complex spatial and temporal changes [5]; the establishment of primary colonizers
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