Evaluation of the biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa on human umbilical cord CD146+ stem cells and stem cell-based decellularized matrix

Docosahexaenoic acid-loaded chitosan/alginate membrane reduces biofilm formation by P. aeruginosa and promotes MSC-mediated burn wound healing

Aims: Chitosan, like docosahexaenoic acid (DHA) and mesenchymal stem cells (MSCs), is used in medicine as a wound healing accelerator. Thus, in this study, chitosan-alginate (CA) membranes containing DHA and MSCs were produced, and their antibacterial and antibiofilm activities against burn infections caused by Pseudomonas aeruginosa were investigated.Methods: Physicochemical properties were assessed by SEM, Fourier transform infrared (FTIR), and X-ray diffraction (XRD). Porosity, cytocompatibility, and antibacterial and antibiofilm activities were evaluated both in vitro and in vivo. The viability and apoptosis of MSCs were studied using flow cytometry. Wound healing effects were analyzed based on histopathological features, the wound contraction rate (WCR) ratio, and bacterial clearance.Results: The CA membranes showed antibiofilm activity both in vivo and in vitro, accompanied by reduced lasI and rhlI expressions and pyocyanin production. The membranes were highly porous and biocompatible and showed favorable physicochemical properties. Docosahexaenoic acid incorporation to CA membranes improved their antibacterial and antibiofilm activities, as well as MSCs' viability by reducing crystallinity and increasing porosity (p = .008). Treatment with CA-DHA-MSC accelerated burn wound healing (with complete healing being observed after 14 days, WCR = 85%) and augmented antibacterial and antibiofilm activities in vivo compared to CA-DHA and CA-MSC. The CA-DHA-MSC group delivered a significantly higher WCR and lower inflammation than the CA-MSC group (p = .0001).Conclusion: In combination with DHA-loaded CA membranes, MSCs reduced the healing time of burn wounds, offering a viable option for designing effective wound dressings.

Dermal fibroblast cells interactions with single and triple bacterial-species biofilms

Polymicrobial biofilm leads to wound healing delay. We set up an in vitro co-culture model of single- and triple-species biofilms of Staphylococcus aureus, Pseudomonas aeruginosa and Enterococcus faecalis with dermal fibroblast to assess the fibroblast response against to the different biofilms. Scratch and viability assays and biofilm cell quantifications were performed by WST-1, CLSM and plating method, respectively. Quorum sensing-related gene expression levels in P. aeruginosa and E. faecalis were analysed by reverse-transcriptase PCR. The immune responses of cells against S. aureus, P. aeruginosa and E. faecalis biofilms were measured by cytokine and matrix metalloproteinase analyzes. The influence of biofilm soluble factors on fibroblasts was also determined. After 24 h, triple-species biofilm cells caused the removal of the fibroblasts from the surfaces indicating the negative synergistic effect of three species. After co-cultures, twenty-five cytokines were significantly increased in fibroblast cells compared to control. Compared to other strains, the most important cytokine, chemokine and growth factors increased was observed in P. aeruginosa co-cultures with fibroblast. While the expressions of fsrB and gelE genes were significantly upregulated in E. faecalis biofilm cells cultured with fibroblast cells, no significant difference was observed in P. aeruginosa. The wound healing and cell growth of fibroblasts were disrupted more aggressively in the presence of P. aeruginosa and triple-species biofilm cells. P. aeruginosa generally induced a stronger immune response in the fibroblasts than E. faecalis and S. aureus.

Sub-Inhibitory Concentrations of Ciprofloxacin Alone and Combinations with Plant-Derived Compounds against P. aeruginosa Biofilms and Their Effects on the Metabolomic Profile of P. aeruginosa Biofilms

INTRODUCTION

Alternative anti-biofilm agents are needed to combat Pseudomonas aeruginosa infections. The mechanisms behind these new agents also need to be revealed at a molecular level.

MATERIALS AND METHODS

The anti-biofilm effects of 10 plant-derived compounds on P. aeruginosa biofilms were investigated using minimum biofilm eradication concentration (MBEC) and virulence assays. The effects of ciprofloxacin and compound combinations on P. aeruginosa in mono and triple biofilms were compared. A metabolomic approach and qRT-PCR were applied to the biofilms treated with ciprofloxacin in combination with baicalein, esculin hydrate, curcumin, and cinnamaldehyde at sub-minimal biofilm inhibitory concentration (MBIC) concentrations to highlight the specific metabolic shifts between the biofilms and to determine the quorum sensing gene expressions, respectively.

RESULTS

The combinations of ciprofloxacin with curcumin, baicalein, esculetin, and cinnamaldehyde showed more reduced MBICs than ciprofloxacin alone. The quorum sensing genes were downregulated in the presence of curcumin and cinnamaldehyde, while upregulated in the presence of baicalein and esculin hydrate rather than for ciprofloxacin alone. The combinations exhibited different killing effects on P. aeruginosa in mono and triple biofilms without affecting its virulence. The findings of the decreased metabolite levels related to pyrimidine and lipopolysaccharide synthesis and to down-regulated alginate and lasI expressions strongly indicate the role of multifactorial mechanisms for curcumin-mediated P. aeruginosa growth inhibition.

CONCLUSIONS

The use of curcumin, baicalein, esculetin, and cinnamaldehyde with ciprofloxacin will help fight against P. aeruginosa biofilms. To the best of our knowledge, this is the first study of its kind to define the effect of plant-based compounds as possible anti-biofilm agents with low MBICs for the treatment of P. aeruginosa biofilms through metabolomic pathways.