Feasibility of hepatic fine needle aspiration as a minimally invasive sampling method for gene expression quantification of pharmacogenetic targets in dogs

BACKGROUND: Quantifying hepatic gene expression is important for many pharmacogenetic studies. However, this usually requires biopsy (BX), which is invasive. OBJECTIVES: The objectives of this study were to determine the feasibility of using minimally invasive fine needle aspirate (FNA) to quantify hepatic gene expression and to assess expression variability between different sampling sites. METHODS: Biopsy and FNA samples were acquired from central and peripheral locations of the right and left lateral liver lobes of a dog. Relative expression of ABCB1, GSTT1 and CYP3A12 were measured via reverse transcriptase, quantitative PCR. The effect of sampling method, lobe and location within the lobe on gene expression was assessed using a three‐way ANOVA. RESULTS: Relative expression of ABCB1 and GSTT1 were not statistically different between sampling methods but CYP3A12 expression was higher in samples collected by BX (p = .013). Lobe sampled affected ABCB1 expression (p = .001) and site within lobe affected ABCB1 (p = .018) and GSTT1 (p = .025) expression. CONCLUSIONS: FNA appears to be a feasible technique for minimally invasive evaluation of hepatic gene expression but results should not be directly compared to biopsy samples. Sampling location impacts expression of some targets; combination of FNAs from multiple sites may reduce variation.