The effects of recombinant human bone morphogenetic protein-2, recombinant human bone morphogenetic protein-12, and adenoviral bone morphogenetic protein-12 on matrix synthesis in human annulus fibrosis and nucleus pulposus cells.
BACKGROUND
Bone morphogenetic proteins (BMPs) are potential therapeutic factors for degenerative discs, and BMP-12 does not have the osteogenic potential of BMP-2, making it better suited for intradiscal injection. However, no reports have compared the actions of BMP-2 and -12 on human annulus fibrosus (AF) and nucleus pulposus (NP) cells nor evaluated adenoviral-mediated gene therapy in human AF cells.


OBJECTIVE
To evaluate and compare the effects of recombinant human (rh) BMP-2, rhBMP-12, and adenoviral BMP-12 (Ad-BMP-12) on nucleus pulposus and annulus fibrosis cell matrix protein synthesis.


METHODS
In vitro study using rhBMP-2 and -12 and adenoviral BMP-12 with human intervertebral disc (IVD) cells.


METHODS
Human NP and AF IVD cells were isolated, maintained in monolayer, and incubated with BMP-2 or -12 for 2 days. AF and NP cells were transduced with Ad-BMP-12, pellets formed, and incubated for 6 days. Growth factor-treated cells were labelled with either 35-S or 3H-proline to assay matrix protein synthesis.


RESULTS
rhBMP-2 increased NP proteoglycan, collagen, and noncollagen protein synthesis to 355%, 388%, and 234% of control. RhBMP-12 increased the same NP matrix proteins' synthesis to 140%, 143%, and 160% of control. Effects on AF matrix protein synthesis were minimal. Ad-BMP-12 significantly increased matrix protein synthesis and DNA content of AF and NP cells in pellet culture. NP synthesis of all matrix proteins and AF synthesis of proteoglycans was increased when the data were normalized to pellet DNA. AF synthesis of noncollagen protein and collagen was not modulated by Ad-BMP-12 if the data are normalized to pellet DNA content.


CONCLUSIONS
Both rhBMP-2 and -12 increase human NP cell matrix protein synthesis while having minimal effects on AF cells. However, Ad-BMP-12 did increase matrix protein synthesis in both NP and AF cells, making it a potential therapy for enhancing matrix production in the IVD. These responses plus the proliferative action of Ad-BMP-12 seen in the current studies, and the lack of an osteogenic action noted in other studies justifies future studies to determine if gene therapy with BMP-12 could provide protective and/or reparative actions in degenerating discs.
Gilbertson
Lars
L
Department of Orthopedic Surgery, University of Pittsburgh, E1641 BST Pittsburgh, PA 15261, USA.
Ahn
Sang-Ho
SH
Teng
Pang-Ning
PN
Studer
Rebecca K
RK
Niyibizi
Christopher
C
Kang
James D
JD
D000256:Adenoviridae; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000494:pharmacology*; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000187:drug effects* / Q000378:metabolism; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006801:Humans; D007403:Intervertebral Disc / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D014161:Transduction, Genetic
D019485:Bone Morphogenetic Proteins; D016326:Extracellular Matrix Proteins; D011994:Recombinant Proteins