The osteoinductive capability of BMPs appears diminished in the setting of acute infection. We applied rhBMP-2 to a segmental
defect in a rat femur and measured the expression of key bone formation genes in the presence of acute infection. Types I
and II collagen, osteocalcin, and BMP Type II receptor mRNA expression were characterized in 72 Sprague-Dawley rats, which
received either bovine collagen carrier with 200 μg rhBMP-2 plus Staphylococcus aureus, carrier with bacteria only, carrier
with rhBMP-2 only, or carrier alone. Six animals from each group were euthanized at 1, 2, and 4 weeks. Total RNA was isolated
and extracted, and mRNA was determined by real-time comparative quantitative PCR. Infected defects had little expression of
collagen I and II and osteocalcin mRNAs, while BMP receptor II expression with infection was greater than carrier-only controls
at Weeks 2 and 4. Notably, all four genes were upregulated in infected defects in the presence of rhBMP-2. Thus, in a clinical
setting with a high risk of infection and nonunion, such as a compound fracture with bone loss, rhBMP-2 may increase the rate
and extent of bone formation. Even if infection does occur, rhBMP-2 may allow a quicker overall recovery time.
One or more of the authors have received funding from the Orthopaedic Trauma Association, Rosemont, IL (AHS), and Minneapolis
Medical Research Foundation, Minneapolis, MN (LSK,WDL).
Each author certifies that his or her institution has approved the animal protocol for this investigation and that all investigations
were conducted in conformity with ethical principles of research.