Calcified Tissue International

, Volume 54, Issue 5, pp 399–408

Matrix vesicles produced by osteoblast-like cells in culture become significantly enriched in proteoglycan-degrading metalloproteinases after addition of β-Glycerophosphate and ascorbic acid

Authors

  • D. D. Dean
    • Department of OrthopaadicsUniversity of Texas Health Science Center at San Antonio
  • Z. Schwartz
    • Department of OrthopaadicsUniversity of Texas Health Science Center at San Antonio
    • Faculty of Dental MedicineThe Hebrew University/Hadassah
  • L. Bonewald
    • Department of MedicineUniversity of Texas Health Science Center at San Antonio
  • O. E. Muniz
    • Miami VA Medical Center, Geriatric Research, Education and Clinical CenterUniversity of Miami School of Medicine
  • S. Morales
    • Miami VA Medical Center, Geriatric Research, Education and Clinical CenterUniversity of Miami School of Medicine
  • R. Gomez
    • Department of OrthopaadicsUniversity of Texas Health Science Center at San Antonio
  • B. P. Brooks
    • Department of OrthopaadicsUniversity of Texas Health Science Center at San Antonio
  • M. Qiao
    • Department of MedicineUniversity of Texas Health Science Center at San Antonio
  • D. S. Howell
    • Miami VA Medical Center, Geriatric Research, Education and Clinical CenterUniversity of Miami School of Medicine
  • B. D. Boyan
    • Department of OrthopaadicsUniversity of Texas Health Science Center at San Antonio
Laboratory Investigations

DOI: 10.1007/BF00305527

Cite this article as:
Dean, D.D., Schwartz, Z., Bonewald, L. et al. Calcif Tissue Int (1994) 54: 399. doi:10.1007/BF00305527

Abstract

Matrix vesicles, media vesicles, and plasma membranes from three well-characterized, osteoblast-like cells (ROS 17/2.8, MG-63, and MC-3T3-E1) were evaluated for their content of enzymes capable of processing the extracellular matrix. Matrix vesicles were enriched in alkaline phosphatase specific activity over the plasma membrane and contained fully active neutral, but not acid, metalloproteinases capable of digesting proteoglycans, potential inhibitors of matrix calcification. Matrix vesicle enrichment in neutral metalloproteinase varied with the cell line, whereas collagenase, lysozyme, hyaluronidase, and tissue inhibitor of metalloproteinases (TIMP) were not found in any of the membrane fractions examined. MC-3T3-E1 cells were cultured for 32 days in the presence of ascorbic acid (100 μg/ml), β-glycerophosphate (5 mM), or a combination of the two, to assess changes in matrix vesicle enzymes during calcification. Ascorbate or β-glycerophosphate alone had no effect, but in combination produced significant increases in both active and total neutral metalloproteinase in matrix vesicles and plasma membranes, with the change seen in matrix vesicles being the most dramatic. This correlated with an increase in the formation of von Kossa-positive nodules. The results of the present study indicate that osteoblast-like cells produce matrix vesicles enriched in proteoglycan-degrading metalloproteinases. In addition, the observation that matrix vesicles contain significantly increased metalloproteinases under conditions favorable for mineralization in vitro lends support to the hypothesis that matrix vesicles play an important role in extracellular matrix processing and calcification in bone.

Key words

Matrix vesiclesOsteoblast-like cellsMetalloproteinasesAscorbic acidβ-Glycerophosphate
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Copyright information

© Springer-Verlag New York Inc. 1994