A nidus, crystalluria and aggregation: key ingredients for stone enlargement
The in vitro study of calcium oxalate (CaOx) stone formation is usually based on crystallisation models but it is recognised that both healthy individuals and stone formers have crystalluria. We have established a robust in vitro stone growth model based on the principle of mixed suspension, mixed product removal system (MSMPR). Utilising this technique we studied the influence of CaOx crystallisation kinetics and the variation of calcium and oxalate concentrations on CaOx stone growth in vitro. Six stones received standard concentration of Ca (6 mM) and Ox (1.2 mM) in the medium while another six received variable concentrations of both Ca and Ox at various intervals. Stone mass was plotted against the experiment duration (typically 5–7 weeks). The stone growth was dependent on sufficient input calcium and oxalate concentrations and once triggered, stone growth could not be maintained at reduced calcium and oxalate inputs. The stone growth rate was positively correlated to the number of crystals in suspension around the stone and to the crystal nucleation rate and negatively correlated to the crystal growth rates. This leads to the conclusion that aggregation of crystals from the surrounding suspension was the dominant mechanism for stone enlargement.
KeywordsCalcium Oxalate Crystallisation kinetics Aggregation Stone growth
These studies were funded by Kidney Research UK and The Oxalosis and Hyperoxaluria Foundation. We also thank S. Gilpin and J. Dixon for their technical assistance.
- 5.Vermeulen CW (1972) Calculogenesis and stone triggering. National Academy of Sciences, WashingtonGoogle Scholar
- 17.Niederberger M, Colfen H (2006) Oriented attachment and mesocrystals: Non-classical crystallization mechanisms based on nanoparticle assembly. Phy Chem Chem Phy 8:3271–3287Google Scholar
- 19.David R, Espitalier F, Cameirao A, Rouleau L (2001) Developments in the understanding and modeling of the agglomeration of suspended crystals in crystallization from solution. KONA 21:40–53Google Scholar