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

J Orthop Res. 1997 May;15(3):371-80. doi: 10.1002/jor.1100150309.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Animals
  • Blotting, Northern
  • Bone Morphogenetic Protein 2
  • Bone Morphogenetic Protein 4
  • Bone Morphogenetic Proteins / biosynthesis
  • Bone Morphogenetic Proteins / genetics*
  • Bone Morphogenetic Proteins / pharmacology*
  • Cartilage / cytology
  • Cartilage / enzymology
  • Cell Differentiation / drug effects
  • Cell Division / drug effects
  • Extracellular Matrix Proteins / biosynthesis
  • Gene Expression Regulation, Developmental / drug effects
  • Growth Plate / cytology*
  • Growth Plate / metabolism
  • Humans
  • Male
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Proteins / pharmacology
  • Sulfates / metabolism
  • Sulfates / pharmacology
  • Sulfur Radioisotopes
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / pharmacology

Substances

  • BMP2 protein, human
  • BMP4 protein, human
  • Bmp2 protein, rat
  • Bmp4 protein, rat
  • Bone Morphogenetic Protein 2
  • Bone Morphogenetic Protein 4
  • Bone Morphogenetic Proteins
  • Extracellular Matrix Proteins
  • RNA, Messenger
  • Recombinant Proteins
  • Sulfates
  • Sulfur Radioisotopes
  • Transforming Growth Factor beta
  • recombinant human bone morphogenetic protein-2
  • Alkaline Phosphatase