Reliability Assessment of Metal Quantification in Formalin-fixed, Paraffin-embedded Human Liver Tissue for Studying Liver Diseases.

Formalin-fixed paraffin-embedded (FFPE) human tissues are broadly available for retrospective studies. Whether the metal levels and their interindividual variability are preserved in FFPE samples remains unclear. We aim to compare metal levels and examine their variability between paired frozen and FFPE human liver tissues. The content of 25 metals in 30 pairs of human liver tissues was quantified using Inductively Coupled Plasma Quadrupole Mass Spectrometer and compared. Three metals, cadmium (Cd), iron (Fe), and zinc (Zn) exhibited linear and rank-based correlation (Pearson coefficient >0.5). Three metals (lead (Pb), aluminum (Al), and selenium (Se)) were linearly correlated but showed weak to moderate rank-based correlation (Pb and Al Kendall's Tau <0.3 and Se Kendall's Tau was 0.42). Our study suggests that FFPE liver tissue can be utilized to study the impact of at least three metals (cadmium, iron, zinc) on liver diseases. Selenium had a moderate relationship and is worth investigating further.