Stimulatory effects of distinct members of the bone morphogenetic protein family on ligament fibroblasts.
OBJECTIVE
To investigate effects of cartilage derived morphogenetic protein-1 and -2 (CDMP-1, CDMP-2), bone morphogenetic protein (BMP)-7 and BMP-6 on metabolism of ligament fibroblasts and their osteogenic or chondrogenic differentiation potential.


METHODS
Ligament fibroblasts were obtained from 3 month old calves, plated as monolayers or micromass cultures, and incubated with or without CDMP-1, CDMP-2, BMP-7, and BMP-6. Expression of the indicated growth factors was assessed by RT-PCR and western immunoblotting. The presence of their respective type I and II receptors, and lineage related markers, was investigated in stimulated and unstimulated cells by RT-PCR and northern blotting. Biosynthesis of matrix proteoglycans was assessed by [(35)S]sulphate incorporation in monolayers. Alcian blue and toluidine blue staining was done in micromass cultures.


RESULTS
CDMP-1, CDMP-2, BMP-7, and BMP-6 were detected on mRNA and on the protein level. Type I and II receptors were endogenously expressed in unstimulated ligament fibroblasts. The growth factors significantly stimulated total proteoglycan synthesis as assessed by [(35)S]sulphate incorporation. Toluidine blue staining showed cartilage-specific metachromasia in the growth factor treated micromass cultures. Transcription analysis of stimulated ligament fibroblasts demonstrated coexpression of chondrocyte markers but no up regulation of osteogenic markers.


CONCLUSIONS
CDMP-1, CDMP-2, BMP-7, and BMP-6 and their receptors were expressed in ligament tissue. These growth factors induced matrix synthesis in fibroblasts derived from bovine ligament. The preferential expression of cartilage markers in vitro suggests that CDMP-1, CDMP-2, BMP-7, and BMP-6 have the potential to induce differentiation towards a chondrogenic phenotype in ligament fibroblasts. Thus, fibroblasts from ligaments may serve as a source for chondrogenesis and tissue repair.
Department of Internal Medicine III, Division of Rheumatology, Allgemeines Krankenhaus, Waehringer Guertel 18-20, A-1090 Vienna, Austria. klaus.bobacz@univie.ac.at
K
K
Bobacz
R
R
Ullrich
L
L
Amoyo
L
L
Erlacher
J S
JS
Smolen
W B
WB
Graninger
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D055395:Bone Morphogenetic Protein 1; D055396:Bone Morphogenetic Protein 2; D055418:Bone Morphogenetic Protein 6; D055419:Bone Morphogenetic Protein 7; D052004:Bone Morphogenetic Protein Receptors / Q000032:analysis; D019485:Bone Morphogenetic Proteins / Q000032:analysis / Q000494:pharmacology*; D002356:Cartilage / Q000166:cytology / Q000378:metabolism; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008022:Ligaments / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008666:Metalloendopeptidases / Q000032:analysis / Q000494:pharmacology; D011509:Proteoglycans / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000494:pharmacology
D015415:Biomarkers; D055396:Bone Morphogenetic Protein 2; D055418:Bone Morphogenetic Protein 6; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D011509:Proteoglycans; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D052004:Bone Morphogenetic Protein Receptors; D008666:Metalloendopeptidases; D055395:Bone Morphogenetic Protein 1