UV‐killed Staphylococcus aureus enhances adhesion and differentiation of osteoblasts on bone‐associated biomaterials

Abstract

Titanium alloys (Ti) are the preferred material for orthopaedic applications. However, very often, these metallic implants loosen over a long period and mandate revision surgery. For implant success, osteoblasts must adhere to the implant surface and deposit a mineralized extracellular matrix. Here, we utilized UV-killed Staphylococcus aureus as a novel osteoconductive coating for Ti surfaces. S. aureus expresses surface adhesins capable of binding to bone and biomaterials directly. Furthermore, interaction of S. aureus with osteoblasts activates growth factor-related pathways that potentiate osteogenesis. While UV-killed S. aureus cells retain their bone-adhesive ability, they do not stimulate significant immune modulator expression. All of the above properties were utilized for a novel implant coating so as to promote osteoblast recruitment and subsequent cell functions on the bone-implant interface. In the present study, osteoblast adhesion, proliferation, and mineralized extracellular matrix synthesis were measured on Ti surfaces coated with fibronectin with and without UV-killed bacteria. Osteoblast adhesion was enhanced on Ti alloy surfaces coated with bacteria compared to uncoated surfaces while cell proliferation was sustained comparably on both surfaces. Osteoblast markers such as collagen, osteocalcin, alkaline phosphatase activity and mineralized nodule formation were increased on Ti alloy coated with bacteria compared to uncoated surfaces.

Staphylococcus aureus vs. Osteoblast: Relationship and Consequences in Osteomyelitis

“…Controversies arose from Somayaji et al work in which they have figured out that UV-killed S. aureus coated on titanium alloys favored osteoblast adhesion, osteoblast differentiation and mineralization (Somayaji et al, 2010 ). These results in opposition with all the previous statements suggest that the effect of S. aureus on osteoblast activity is not totally elucidated.…”

Evaluation of the collagen-binding properties and virulence of killed Streptococcus mutans in a silkworm model

“…Staphylococcus aureus and Enterococcus faecalis are the major causative agents of IE 4 . S. aureus has adhesion properties to osteoblasts and kidney cells, even when the bacteria are killed by ultraviolet rays or formalin 25 , 26 . Additionally, E. faecalis killed by antibiotic treatment was able to adhere to the artificially injured heart valves of rats, resulting in the development of IE 27 .…”

Membrane perturbation, altered morphology and killing of Staphylococcus epidermidis upon contact with a cytocompatible peptide-based antibacterial surface

“…However, the increased cell number on bare and silanized titanium could not be related to the presence of BMAP27 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). This observation is intriguing because it suggests that bacteria themselves could in some way affect cell adhesion [52] . Taking into account what has been reported for the oral environment [53,54] , currently we cannot rule out possible stimulating effects of bacteria on tissue cell expression of adhesion molecules that would in turn improve cell adhesion and spreading.…”