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Spine (Phila Pa 1976). 2013 May 20;38(12):E691-8. doi: 10.1097/BRS.0b013e31828cb977.

Characterizing the host response to rhBMP-2 in a rat spinal arthrodesis model.

Author information

1
*Department of Orthopaedic Surgery †Departments of Radiology and Biomedical Engineering, Northwestern University Feinberg School of Medicine, Chicago, IL; and ‡Department of Research and Development, Medtronic Sofamor Danek, Inc, Memphis, TN.

Abstract

STUDY DESIGN:

Prospective, randomized, controlled preclinical trial.

OBJECTIVE:

This study seeks to characterize the localized and systemic host response to recombinant human bone morphogenetic protein-2 (rhBMP-2) in a well established rodent spine arthrodesis model utilizing cytokine analysis and magnetic resonance imaging (MRI).

SUMMARY OF BACKGROUND DATA:

Although high fusion rates are achieved with rhBMP-2 in the spine, several complications have also been reported, including a localized response leading to radiculitis and seroma formation. The mechanism in which this occurs clinically is yet unknown.

METHODS:

One hundred female Fischer rats underwent a posterolateral intertransverse lumbar spinal fusion, with paraspinal muscle tissue resection, using iliac crest autograft, type I absorbable collagen sponge (ACS), 10- or 100-μg rhBMP-2/ACS. The animals underwent magnetic resonance imaging evaluation, serum cytokine analysis, manual palpation, and gross tissue inspection at 2, 4, 7, 10, and 21 days, postoperatively.

RESULTS:

Qualitative evaluation of MR images demonstrated a transient fluid collection at the surgery site in the rhBMP-2 animals as early as 4 and 7 days that was greater than the autograft or ACS groups. Quantitative analysis on T2-weighted axial images demonstrated greater signal intensity in the rhBMP-2 animals compared with the ACS and autograft groups in a time-dependent fashion. Higher concentrations of several cytokines were also detected at 2, 4, and 7 days, including interleukin 1β, interleukin 18, tumor necrosis factor α, macrophage inflammatory protein 1α, and monocyte chemotactic protein 1 in animals treated with rhBMP-2/ACS relative to ACS alone.

CONCLUSION:

Our data suggest that the in vivo host response to rhBMP-2 in an animal model may be associated with circulating proinflammatory and osteoclastic cytokines.

PMID:
23429681
DOI:
10.1097/BRS.0b013e31828cb977
[Indexed for MEDLINE]

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