Influence of Ionic Additives on Triclinic Calcium Pyrophosphate Dihydrate Precipitation

Abstract

Triclinic calcium pyrophosphate dihydrate (t-CPPD) crystals are one of the two polymorphs of microcrystals that have been found in the joints of patients suffering from pseudogout. However, there is currently no treatment for inhibiting the formation of these crystals, which present a high inflammatory potential. In this context we studied in vitro the precipitation of t-CPPD in a stirred reactor under pH-and temperature-controlled conditions and determined the effect of selected biologically relevant ionic additives (Mg 2+ , Cu 2+ , Fe 3+ , Zn 2+ , S 2 O 3 2− ) on its formation. The results showed that 1 mM Fe 3+ , Zn 2+ , or Cu 2+ induced the most significant changes by partly inhibiting the crystallization of t-CPPD and favoring the formation of an amorphous-CPP phase (98 wt %) in the presence of Fe 3+ or a monoclinic-CPPD phase (78 or 71 wt %, respectively) in the presence of Zn 2+ or Cu 2+ . Correlations between 31 P solid-state NMR, XRD, and elemental analyses showed that the additive cations are inserted into the monoclinic-CPPD and/or amorphous-CPP phases. This study, which combines structural, morphological, and elemental analyses, paves the way toward a deeper comprehension of the role of ionic additives in preventing the formation of CPPD crystalline phases, and is a key step in long-term development of an effective therapeutic treatment.

A Phage Display-Identified Short Peptide Capable of Hydrolyzing Calcium Pyrophosphate Crystals—The Etiological Factor of Chondrocalcinosis

“…All chemicals for this study have been supplied from Merck Life Science, Poznań, Poland, unless stated otherwise. Triclinic calcium pyrophosphate crystallization was carried out in 40 mM Tris buffer (pH 7.5, 40 mM CaCl 2 , 50 mM Na 2 P 2 O 7 •10H 2 O) over 4 months at 37 • C. It has been shown that initially some monoclinic and amorphous forms are formed during the crystallization (1 and 7% respectively) [29], so time seems to be a crucial factor, as it leads to the interconversion of all the other forms to biologically occurring triclinic form [9]. Before usage, crystals were filtered, washed with deionized water, and dried over vacuum.…”

Reactive crystallization: From mixing to control of kinetics by additives

“…For some cases (for instance, molar ratio [SO4] 2-/[CO3] 2-= 1.62), this transformation was reported to take up to 350 hrs. In addition, Ley-Ngardigal et al [125] have studied the influence of various ionic additives on the crystallization of triclinic calcium pyrophosphate dihydrate (t-CPPD). By combining, XRD and solid state P-NMR, they found that, even if the additives concentration were very low (trace), all the divalent ionic additives orient the crystallization calcium pyrophosphate from the stable phase (t-CPPD) to the less stable phase (m-CPPD) [134].…”

Amorphous phase-mediated crystallization of calcium pyrophosphate tetrahydrate: the role of alkaline earth metal ions

“…As important components in synovial fluid, some metal ions were believed to be involved in CPP deposition. [27][28][29][30] The impact of metal ions on the formation of CPP crystals has been reported in both in vitro and in vivo experiments, but the underlying mechanisms by which metal ions regulate the crystallization process are still not clear. [29][30][31] In this study, we investigate the roles of three alkaline earth metal cations, Mg 2+ , Sr 2+ and Ba 2+ , in the crystallization process of CPPT, especially their effects on the stabilization of ACPP.…”

“…[27][28][29][30] The impact of metal ions on the formation of CPP crystals has been reported in both in vitro and in vivo experiments, but the underlying mechanisms by which metal ions regulate the crystallization process are still not clear. [29][30][31] In this study, we investigate the roles of three alkaline earth metal cations, Mg 2+ , Sr 2+ and Ba 2+ , in the crystallization process of CPPT, especially their effects on the stabilization of ACPP. Our results showed that certain biologically essential metal cations can inhibit ACPP crystallization, and the inhibitory ability of the metal cations is closely related to their hydration characteristics.…”