Microbial adhesion on biomaterials and the sources of human beta-defensin-3 in septic joint implant loosening
Year: 2017
Type: dissertation
Abstract: In the novel diamond-like carbon polymer hybrid (DLC-p-h) coatings, the useful properties of diamond-like carbon (DLC) and a chosen polymer can be combined. So far two unique biomaterials, diamond-like carbon polytetrafluoroethylene hybrid (DLC-PTFE-h) and diamond-like carbon polydimethylsiloxane hybrid (DLC-PDMS-h) with dirt-repelling hydrophobic and oleophobic properties have been developed. These novel coatings were studied in this thesis. The Diamond Group at the ORTON Research Institute have produced novel biomaterial coatings with the in-house developed Filtered Pulsed Arc Discharge (FPAD)-method. The FPAD method enables the production of thick (>200 µm), high quality (> 80% diamond sp3 bonds) DLC coatings with properties needed in high-load bearing applications such as the Total Hip Arthroplasty (THA). Bacterial adhesion is the initial step in the prosthetic joint infection (PJI) and leads to biofilm formation and the establishment of a full-scale deep biofilm infection. The main hypothesis was that some biomaterials, such as DLC and non-fouling DLC-PDMS-h and DLC-PTFE-h, could be more resistant to bacterial adhesion and biofilm formation than the conventional implant materials. To mimic conditions prevailing in the human body, serum incubations, and dynamic flow conditions are useful in the investigation of bacterial adhesion and biofilm formation in vitro. Under static conditions and in the presence of serum proteins, the DLC was more microbe-repellent than conventional biomaterials tantalum, titanium, and chromium and resisted the most the adhesion of S.aureus cells. In this study, it was also found that micropatterned surfaces are useful for quantitative evaluation of bacterial adhesion to biomaterials. Different sizes of microtextures enabled data collection regarding alignment of bacteria on sample surfaces. Under dynamic flow conditions, DLC and DLC-PTFE-h were as good as conventional biomaterials in their ability to inhibit adhesion of S.aureus and S.epidermidis. The DLC-PDMS-h bound significantly more S.aureus bacteria than DLC-PTFE-h and tantalum. Otherwise, the DLC-PDMS-h behaved similarly to the other materials tested. Biofilm formation was examined in the presence of serum. The DLC-PTFE-h was superior compared to all materials tested in its ability to resist biofilm formation. The DLC came out next in the ranking order and resisted biofilm formation soundly compared to conventional biomaterials and DLC-PDMS-h. The DLC-PDMS-h was similar to conventional materials in its ability to inhibit biofilm formation. Antimicrobial peptides (AMPs) are defense proteins of innate immunity found widely in plants, vertebrates, and non-vertebrates with multiple functions even beyond immunity. The cellular sources and expression of AMP human β-defensin-3 (hBD-3) in septic joint implant loosening were examined by immunohistochemistry and double immunofluorescence stainings of peri-implant tissue samples. hBD-3 was associated with monocyte/macrophage-like cells, fibroblast-like cells, and vascular endothelial cells. It was weakly present in foreign body giant cells and not found in neutrophils. The variable topological expression of hBD-3 in peri-implant tissues in septic implant loosening indicated local induction, as has been reported in the literature before. In summary, the three studies of this thesis suggest that DLC and DLC-PTFE-h coatings could inhibit bacterial adhesion and subsequent biofilm formation, thus preventing infections more efficiently than current implant biomaterials. The cellular sources of the antimicrobial peptide hBD-3 in peri-implant tissues in septic implant loosening are mainly macrophages and vascular endothelial cells.
Source: Työväentutkimus Vuosikirja
Author: Jaakko Levón
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2612729439