Histological changes of an injectable rhBMP-2/calcium phosphate cement in vertebroplasty of rhesus monkey.
METHODS
A histologic study of recombinant human bone morphogenetic protein-2/calcium phosphate cement (rhBMP-2/CPC) using adult rhesus monkeys in vivo.


OBJECTIVE
To evaluate the histologic changes of rhBMP-2/CPC in vertebroplasty and determine the feasibility of this bone substitution instead of polymethylmethacrylate (PMMA).


BACKGROUND
Previous studies have shown that the new rhBMP-2/nanoscale CPC has a suitable strength and injection for vertebroplasty. However, the osteoinductive properties and biodegradable characteristics are still unclear.


METHODS
Percutaneous vertebroplasty (PVP) was performed in 4 adult rhesus monkeys of 2 groups. Ten vertebral bodies (VBs) from T10-L7 of each rhesus were selected, and the 20 VBs in each group were randomly divided into 3 subgroups. Subgroup A (rhBMP-2/CPC): 8 VBs, filled with rhBMP-2/CPC; Subgroup B (PMMA): 6 VBs, filled with injectable PMMA; Subgroup C (control): 6 VBs, filled with normal saline. The 2 rhesus monkeys from each of the groups were killed at 2 and 6 months after operation, respectively. Individual specimens from the 40 VBs were collected for histologic observation.


RESULTS
In subgroup A, radiographic and histologic observations showed that the part of the rhBMP-2/CPC cement degraded with new bone and new vessel ingrowths, into the material, after 2 months. In addition, gaps, fibrous hyperplasia, or sclerotic callus were not found in the interface. After 6 months, the cement was nearly all replaced by mature bone tissue. In subgroup B, the inflammatory cell infiltration and fibrous membrane gapping were found after 2 months, and subsided partly at 6 months. But no new bone formation and material degradation were discovered. In subgroup C, the tunnels were filled with irregular new trabeculae after 2 months and unrecognizable from the surrounding mature bone after 6 months.


CONCLUSIONS
It is confirmed that the rhBMP-2/CPC is an osteoinductive and biodegradable material (in animal trials). It may also be an alternative to PMMA in order to achieve biostabilization in a vertebroplasty.
Bai
Bo
B
Department of Orthopaedic Surgery, the First Affiliated Hospital of Guangzhou Medical College, 151 Yanjing Road, Guangzhou, China. drbobai@yahoo.com
Yin
Zhixun
Z
Xu
Qian
Q
Lew
Megan
M
Chen
Yi
Y
Ye
Jiandong
J
Wu
Jingming
J
Chen
Dongfeng
D
Zeng
Yanjun
Y
D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage / Q000378:metabolism; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000008:administration & dosage* / Q000378:metabolism; D001861:Bone Regeneration / Q000187:drug effects; D018786:Bone Substitutes / Q000008:administration & dosage* / Q000378:metabolism; D002130:Calcium Phosphates / Q000008:administration & dosage* / Q000378:metabolism; D006801:Humans; D007267:Injections; D008159:Lumbar Vertebrae / Q000293:injuries / Q000378:metabolism / Q000601:surgery; D008253:Macaca mulatta; D019904:Polymethyl Methacrylate / Q000008:administration & dosage / Q000378:metabolism; D011897:Random Allocation; D011994:Recombinant Proteins / Q000008:administration & dosage* / Q000378:metabolism; D016103:Spinal Fractures / Q000378:metabolism / Q000601:surgery; D013904:Thoracic Vertebrae / Q000293:injuries / Q000378:metabolism / Q000601:surgery; D016212:Transforming Growth Factor beta / Q000008:administration & dosage* / Q000378:metabolism; D054854:Vertebroplasty / Q000379:methods*
D001672:Biocompatible Materials; D001843:Bone Cements; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D018786:Bone Substitutes; D002130:Calcium Phosphates; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D019904:Polymethyl Methacrylate; C020243:calcium phosphate