Dose-dependent Nerve Inflammatory Response to rhBMP-2 in a Rodent Spinal Nerve Model.

Abstract

STUDY DESIGN:

We developed a spinal nerve root wrapping rodent model to evaluate the relationship between recombinant human bone morphogenetic protein 2 (rhBMP-2) dosage and the degree of inflammation.

OBJECTIVE:

To investigate the direct effects of recombinant human bone morphogenetic protein 2 (rhBMP-2) dosage and the degree of inflammation in rodent spinal nerve roots.

SUMMARY OF BACKGROUND DATA:

rhBMP-2 is commonly used in clinical practice to augment spinal fusion. However, complications such as postoperative leg pain, and a higher rate of postoperative neurologic deficits have been reported. These may be attributable to the exposure of adjacent nerve roots to high doses of rhBMP-2.

METHODS:

Eighteen rats were randomized into three groups as follows: Group 1: absorbable collagen sponge (ACS) + 10 μg rhBMP-2, Group 2: ACS + 1 μg rhBMP-2, and Group 3 ACS with 20 μL saline. The ACS containing rhBMP-2 or saline were then wrapped around the L5 nerve root and secured loosely with nonabsorbable sutures. At 1-week postoperation, the rats were sacrificed, and the L5 nerve root and dorsal root ganglion harvested for reverse transcription polymerase chain reaction (RT-PCR), histology and immunohistochemical staining.

RESULTS:

In our study, 10 μg rhBMP-2 induced a 10-fold increase in seroma compared with 1 μg group. Using RT-PCR, macrophage markers MIP3-α, and CD-68 were upregulated by 8- and 2-fold respectively in comparison with the saline group. Haematoxylin and eosin (H&E) images demonstrated disruption of nerve structures in the high dose 10 μg rhBMP-2, but not at 1 μg rhBMP-2 and with saline.

CONCLUSION:

High doses of rhBMP-2 induced neuroinflammation in a dose dependent manner, resulting in higher seroma volume, macrophage marker gene expressions, and higher proportions of immunohistochemically stained TNF-alpha and more macrophage infiltration.

LEVEL OF EVIDENCE:

2.

• Authors: Zi Qiang Glen Liau, Raymond Wing Moon Lam, Tao Hu, Hee-Kit Wong
• Journal: Spine (Spine (Phila Pa 1976)) Vol. 42 Issue 16 Pg. E933-E938 (Aug 15 2017) ISSN: 1528-1159 [Electronic] United States
• PMID: 27997503 (Publication Type: Journal Article)

Chemical References

• Bone Morphogenetic Protein 2
• Recombinant Proteins
• Transforming Growth Factor beta
• Tumor Necrosis Factor-alpha
• recombinant human bone morphogenetic protein-2

Topics

• Animals
• Bone Morphogenetic Protein 2 (pharmacology)
• Disease Models, Animal
• Inflammation (drug therapy, pathology)
• Lumbar Vertebrae (drug effects, surgery)
• Rats, Sprague-Dawley
• Recombinant Proteins (pharmacology)
• Spinal Fusion (methods)
• Spinal Nerves (drug effects, pathology)
• Transforming Growth Factor beta (pharmacology)
• Tumor Necrosis Factor-alpha (metabolism)