The effect of synovial fluid and serum on the growth of calcium hydroxyapatite crystals

Abstract

The presence or absence of natural crystal growth inhibitors in joint tissues and fluids may be important in the pathogenesis of several arthropathies. Synovial fluid (SF) has therefore been examined for inhibitors of seeded hydroxyapatite growth rate (Vo) using a pH stat system. Pretreatment of seed crystals with SF reduced growth (Vo = 56 +/- 5, control 117 +/- 141 mol/base/min/g hydroxyapatite, p less than 0.001). Addition of small amounts of serum or SF to the growth medium caused a dose dependent growth inhibition (0.04% SF reduced Vo by 16%). Pretreatment with protease, but not hyaluronidase, abolished this activity and gel filtration localized it to the 55-80 kDa fraction. A macromolecular factor(s) with potent inhibitory activity has therefore been detected.