Differential analysis of human kidney stone samples using electrospray ionization mass spectrometry

Abstract

Kidney stones may be caused by many factors, including ingestion of melamine for a relatively long time. The diagnosis of melamine-induced kidney stones and the understanding of how the melamine is involved in the formation of kidney stones are of practical importance. To establish a sensitive method based on widely used electrospray ionization mass spectrometry (ESI-MS) for diagnosis of melamine-induced kidney stones and to probe the differential formation of melamine-induced kidney stones at molecular levels. Human kidney stones were collected in hospital from 6 groups of patients at different ages. ESI-MS was employed as the main technique with the principal component analysis for data processing. Using principal component analysis (PCA) of the ESI-MS fingerprints, a set of 21 melamine-induced kidneystone samples and 21 uric acid derived kidney stone samples were successfully differentiated from the other groups, rendering ESI-MS method a potential platform for differential analysis of the human kidney stones of various causes at molecular levels. The experimental results also indicate that in addition to the melamine, the chemical compounds enwrapped in the melamine-induced kidney stone samples are different from other kidney stone samples. These findings suggest that ESI-MS is a useful tool for diagnosis of melamine-induced kidney stone samples and the melamine-induced kidney stone could be formed by different mechanisms. Key words: Toxicity of melamine, chemical profiling, uric acid, electrospray ionization-mass spectrometry (ESI-MS), kidney stone, melamine, principal component analysis.