A novel intravertebral tumor model in rabbits.
OBJECTIVE
Although the majority of human epidural spinal metastases originate in the vertebral body, current animal models of spinal epidural tumors are limited to extraosseous tumor placement. We investigated the onset of paraparesis, radiographic changes (magnetic resonance imaging [MRI] and computed tomographic [CT] scans), and histopathological findings after intraosseous injection of VX2 carcinoma cells into the lower thoracic vertebrae of rabbits.


METHODS
New Zealand white rabbits (n = 23) were injected with a 15-mul suspension containing 300,000 VX2 carcinoma cells in the lowest thoracic vertebral body. Lower extremity motor function was assessed daily. For the first 3 animals, MRI scans (T2-weighted and T1-weighted +/- gadolinium) were acquired at postoperative day (POD) 14 and at the onset of paraparesis. Noncontrast CT scans were obtained on POD 7 and at the time of paraparesis. At the onset of paraparesis, the animals ware killed and the spines were dissected. After demineralization, hematoxylin and eosin cross sections were obtained.


RESULTS
Before the onset of paraparesis, the CT and MRI scans revealed no gross tumor. At the onset of paraparesis, CT scans demonstrated an osteolytic tumor centered at the junction of the left pedicle and vertebral body, and MRI scans demonstrated epidural tumor arising from the body and compressing the spinal cord. Histopathological examination confirmed carcinoma arising from the body and extending into the canal, with widespread osteolytic activity. By POD 28, 72% of the animals had become paraparetic, and by the termination of the experiment on POD 120, 89% had become paraparetic.


CONCLUSIONS
We established a novel intraosseous intravertebral tumor model in rabbits and characterized it with respect to onset of paraparesis, imaging features, and histopathological findings.
Amundson
Eric
E
Department of Neurosurgery, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
Pradilla
Gustavo
G
Brastianos
Priscilla
P
Bagley
Carlos
C
Riley
Lee H
LH
Garonzik
Ira M
IM
McCarthy
Edward
E
Wolinsky
Jean-Paul
JP
Gokaslan
Ziya L
ZL
D000818:Animals; D002277:Carcinoma / Q000209:etiology / Q000473:pathology*; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D008279:Magnetic Resonance Imaging / Q000379:methods; D008488:Medical Illustration; D009362:Neoplasm Metastasis / Q000473:pathology / Q000503:physiopathology; D009368:Neoplasm Transplantation / Q000379:methods; D011817:Rabbits; D013120:Spinal Cord Neoplasms / Q000209:etiology / Q000473:pathology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods