Cultured human monocytes and fibroblasts solubilize calcium phosphate crystals

Richard W. Evans, Herman S. Cheung, Daniel J. McCarty

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


Two rheumatic syndromes associated with deposition of calcium phosphate crystals in soft tissues of the shoulder have prompted us to study the cellular mechanisms of calcium phosphate crystal solubilization. Synthetic45Ca labeled calcium phosphate crystal aggregates were solubilized by cultured human fibroblasts or monocytes. Such solubilization required crystal cell contact and was inhibited by chloroquine and ammonium. We hypothesize that the mechanism of crystal solubilization involves phagocytosis followed by dissolution in the acidic environment of secondary lysosomes. Study of the mechanism of calcium phosphate solubilization may be important in understanding resorption of extra-osseus as well as osseus calcification. Intracellular release of calcium from calcium phosphate crystals may also explain our previous observation that hydroxyapatite and other calcium-containing crystals are mitogenic stimuli for fibroblasts and synovial cells.

Original languageEnglish (US)
Pages (from-to)645-650
Number of pages6
JournalCalcified Tissue International
Issue number1
StatePublished - Dec 1 1984
Externally publishedYes


  • Ammonium
  • Calcium phosphate
  • Chloroquine
  • Fibroblasts
  • Monocytes

ASJC Scopus subject areas

  • Endocrinology


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