Figure 2. Staphylococcus aureus prevents expression of osteogenic markers.

Osteoblasts (5×10⁵ cells/well) were incubated with either control buffer (——) or formaldehyde fixed S. aureus Newman (-----), Newman Δspa (⋅⋅⋅⋅⋅), or Newman spa (pCU1spa ⁺) (— ⋅ —) for a period of 21 days. (A) Osteoblasts were lysed with 1 ml of lysis buffer containing a substrate for alkaline phosphatase (0.1 M Na acetate, 2% Triton X-100 and 10 mM p-nitrophenol phosphate) and incubated in the dark for 1 hour at 37°C. RNA was isolated and reverse transcribed to cDNA. Analysis of bone formation marker expression was carried out specifically for the early bone marker (B) collagen type I, (C) osteopontin and (D) osteocalcin. *0.01, **0.05, ***0.0001, n = 3.