Effect of osteogenic protein-1 on the development and mineralization of primary cultures of avian growth plate chondrocytes: modulation by retinoic acid

J Cell Biochem. 1997 Dec 15;67(4):498-513. doi: 10.1002/(sici)1097-4644(19971215)67:4<498::aid-jcb8>3.0.co;2-n.


Osteogenic protein-1 (OP-1), a member of the TGF-beta family of proteins, induces endochondral bone formation. Here we studied the effect of OP-1 on the development of primary cultures of avian growth plate (GP) chondrocytes in either serum-free or serum-containing medium, in the absence or presence of retinoic acid (RA). OP-1 was added on day 7 of culture and continued for 7 days, or until the cultures were harvested, typically on day 21. Alone, OP-1 caused approximately 2-fold increase in proteoglycan synthesis into both the medium and the cell:matrix layer. Additionally, OP-1 caused a dosage-dependent increase in alkaline phosphatase (ALP) activity, and an increase in protein, when given from days 7-14 and examined on day 14. This stimulation was greater in cells grown in serum-free than in serum-containing media (3-5-fold vs. 2-3-fold increase in ALP; approximately 40% vs. approximately 20% increase in protein). Such stimulation of ALP activity and proteoglycan (PG) synthesis in cultured GP cells indicates that OP-1 elicits differentiation of chondrocytes. OP-1 minimally affected cell division (DNA content); however, a slight increase was seen when examined early in the culture. Alone, OP-1 increased mineral (Ca and Pi) content of the cultures by approximately 2-fold in both types of media. As early as day 14, clusters of mineral encircled many of the OP-1 treated cells. Thus, as in vivo, OP-1 strongly promoted mineral formation by the cultured GP chondrocytes. When present together, OP-1 and RA generally blocked the action of the other. Separately OP-1 and RA each stimulated protein synthesis, ALP activity, and Ca2+ deposition; together they were inhibitory to each. Also, RA blocked the stimulation of PG synthesis induced by OP-1; whereas OP-1 decreased cell division engendered by RA. Thus, this GP chondrocyte culture system is a good model for studying factors that influence differentiation and mineral deposition during bone growth in vivo.

Publication types

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

MeSH terms

  • Alkaline Phosphatase / biosynthesis
  • Animals
  • Bone Morphogenetic Protein 7
  • Bone Morphogenetic Proteins / pharmacology*
  • Calcification, Physiologic / drug effects*
  • Calcification, Physiologic / physiology
  • Calcium Phosphates / metabolism*
  • Cartilage, Articular / cytology
  • Cartilage, Articular / drug effects*
  • Cartilage, Articular / metabolism
  • Cell Differentiation / drug effects
  • Cell Division / drug effects
  • Cells, Cultured
  • Chickens
  • Growth Plate
  • Kinetics
  • L-Lactate Dehydrogenase / analysis
  • Proteoglycans / biosynthesis
  • Time Factors
  • Transforming Growth Factor beta / pharmacology
  • Tretinoin / pharmacology*


  • Bone Morphogenetic Protein 7
  • Bone Morphogenetic Proteins
  • Calcium Phosphates
  • Proteoglycans
  • Transforming Growth Factor beta
  • Tretinoin
  • L-Lactate Dehydrogenase
  • Alkaline Phosphatase