Recombinant bone morphogenetic protein (BMP)-2 regulates costochondral growth plate chondrocytes and induces expression of BMP-2 and BMP-4 in a cell maturation-dependent manner.
This study examined the effect of recombinant human bone morphogenetic protein-2 on several parameters of growth, differentiation, and matrix synthesis and on the endogenous production of mRNA of bone morphogenetic proteins 2 and 4 by growth plate chondrocytes in culture. Chondrocytes from resting and growth zones were obtained from rat costochondral cartilage and cultured for 24 or 48 hours in medium containing 0.05-100 ng/ml recombinant human bone morphogenetic protein-2 and 10% fetal bovine serum. Incorporation of [3H]thymidine, cell number, alkaline phosphatase specific activity, incorporation of [3H]proline into collagenase-digestible protein and noncollagenase-digestible protein, and incorporation of [35S]sulfate were assayed as indicators of cell proliferation, differentiation, and extracellular matrix synthesis. mRNA levels for bone morphogenetic proteins 2 and 4 were determined by Northern blot analysis. Recombinant human bone morphogenetic protein-2 increased the incorporation of [3H]thymidine by quiescent resting-zone and growth-zone cells in a similar manner, whereas it had a differential effect on nonquiescent cultures. At 24 and 48 hours, 12.5-100 ng/ml recombinant human bone morphogenetic protein-2 caused a dose-dependent increase in cell number and DNA synthesis in resting-zone chondrocytes. No effect was seen in growth-zone cells. Recombinant human bone morphogenetic protein-2 stimulated alkaline phosphatase specific activity in resting-zone chondrocytes in a bimodal manner, causing significant increases between 0.2 and 0.8 ng/ml and again between 25 and 100 ng/ml. In contrast, alkaline phosphatase specific activity in growth-zone chondrocytes was significantly increased only between 12.5 and 100 ng/ml. Recombinant human bone morphogenetic protein-2 increased the production of both collagenase-digestible protein and noncollagenase-digestible protein by resting-zone and growth-zone cells, but incorporation of [35S]sulfate was unaffected. Administration of recombinant human bone morphogenetic protein-2 also increased incorporation of [3H]uridine in both resting-zone and growth-zone chondrocytes; these cells produced mRNA for bone morphogenetic proteins 2 and 4. Bone morphogenetic protein-2 mRNA levels in both resting-zone and growth-zone chondrocytes increased in the presence of recombinant human bone morphogenetic protein-2; however, bone morphogenetic protein-4 mRNA levels in growth-zone cells decreased under its influence, and those in resting-zone cells were upregulated only with a dose of 10 ng/ml. This indicates that recombinant human bone morphogenetic protein-2 regulates chondrocyte proliferation, differentiation, and matrix production, and the effects are dependent on the stage of cell maturation. Resting-zone chondrocytes were more sensitive, suggesting that they are targeted by bone morphogenetic protein-2 and that this growth factor may have autocrine effects on these cells.
Erickson
D M
DM
Wilford Hall Medical Center, Lackland Air Force Base, San Antonio, Texas, USA.
Harris
S E
SE
Dean
D D
DD
Harris
M A
MA
Wozney
J M
JM
Boyan
B D
BD
Schwartz
Z
Z
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000494:pharmacology*; D002356:Cartilage / Q000166:cytology / Q000201:enzymology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D006132:Growth Plate / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D013431:Sulfates / Q000378:metabolism / Q000494:pharmacology; D013462:Sulfur Radioisotopes; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000494:pharmacology
C525718:BMP2 protein, human; C525809:BMP4 protein, human; C525720:Bmp2 protein, rat; C525811:Bmp4 protein, rat; D055396:Bone Morphogenetic Protein 2; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D013431:Sulfates; D013462:Sulfur Radioisotopes; D016212:Transforming Growth Factor beta; C499469:recombinant human bone morphogenetic protein-2; D000469:Alkaline Phosphatase