TY - JOUR
T1 - Development of an ex vivo model to study Staphylococcus aureus invasion of the osteocyte lacuno-canalicular network
AU - Vanvelk, Niels
AU - Bentley, Karen L. de Mesy
AU - Verhofstad, Michael H. J.
AU - Metsemakers, Willem-Jan
AU - Moriarty, Thomas F.
AU - Siverino, Claudia
N1 - Publisher Copyright:
© 2024 Orthopaedic Research Society.
PY - 2025/2
Y1 - 2025/2
N2 - Staphylococcus aureus has multiple mechanisms to evade the host's immune system and antibiotic treatment. One such mechanism is the invasion of the osteocyte lacuno-canalicular network (OLCN), which may be particularly important in recurrence of infection after debridement and antibiotic therapy. The aim of this study was to develop an ex vivo model to facilitate further study of S. aureus invasion of the OLCN and early-stage testing of antibacterial strategies against bacteria in this niche. The diameter of the canaliculi of non-infected human, sheep, and mouse bones was measured microscopically on Schmorl's picrothionin stained sections, showing a large overlap in canalicular diameter. S. aureus successfully invaded the OLCN in all species in vitro as revealed by presence in osteocyte lacunae in Brown and Brenn-stained sections and by scanning electron microscopy. Murine bones were then selected for further experiments, and titanium pins with either a wild-type or ΔPBP4 mutant S. aureus USA300 were placed trans-cortically and incubated for 2 weeks in tryptic soy broth. Wild-type S. aureus readily invaded the osteocyte lacunae in mouse bones while the ΔPBP4 showed a significantly lower invasion of the OLCN (p = 0.0005). Bone specimens were then treated with gentamicin, sitafloxacin, R14 bacteriophages, or left untreated. Gentamicin (p = 0.0027) and sitafloxacin (p = 0.0280) significantly reduced the proportion of S. aureus-occupied lacunae, whilst bacteriophage treatment had no effect. This study shows that S. aureus is able to invade the OLCN in an ex vivo model. This ex vivo model can be used for future early-stage studies before proceeding to in vivo studies.
AB - Staphylococcus aureus has multiple mechanisms to evade the host's immune system and antibiotic treatment. One such mechanism is the invasion of the osteocyte lacuno-canalicular network (OLCN), which may be particularly important in recurrence of infection after debridement and antibiotic therapy. The aim of this study was to develop an ex vivo model to facilitate further study of S. aureus invasion of the OLCN and early-stage testing of antibacterial strategies against bacteria in this niche. The diameter of the canaliculi of non-infected human, sheep, and mouse bones was measured microscopically on Schmorl's picrothionin stained sections, showing a large overlap in canalicular diameter. S. aureus successfully invaded the OLCN in all species in vitro as revealed by presence in osteocyte lacunae in Brown and Brenn-stained sections and by scanning electron microscopy. Murine bones were then selected for further experiments, and titanium pins with either a wild-type or ΔPBP4 mutant S. aureus USA300 were placed trans-cortically and incubated for 2 weeks in tryptic soy broth. Wild-type S. aureus readily invaded the osteocyte lacunae in mouse bones while the ΔPBP4 showed a significantly lower invasion of the OLCN (p = 0.0005). Bone specimens were then treated with gentamicin, sitafloxacin, R14 bacteriophages, or left untreated. Gentamicin (p = 0.0027) and sitafloxacin (p = 0.0280) significantly reduced the proportion of S. aureus-occupied lacunae, whilst bacteriophage treatment had no effect. This study shows that S. aureus is able to invade the OLCN in an ex vivo model. This ex vivo model can be used for future early-stage studies before proceeding to in vivo studies.
UR - http://www.scopus.com/inward/record.url?scp=85205759240&partnerID=8YFLogxK
U2 - 10.1002/jor.25988
DO - 10.1002/jor.25988
M3 - Article
C2 - 39380444
SN - 0736-0266
VL - 43
SP - 446
EP - 456
JO - Journal of Orthopaedic Research
JF - Journal of Orthopaedic Research
IS - 2
ER -