Comparison of liver and plasma metabolic profiles in piglets of different ages as animal models for paediatric population

Liver plays an important role in drug metabolism, so studying the grade of maturation of this organ would help to develop more appropriate dosing regimens for paediatric populations. Nevertheless, considering the invasive nature of liver analyses there are obvious ethical boundaries, particularly in babies and children. In this work, we investigated the suitability of blood plasma as an alternative matrix to evaluate the biological age of liver. With this aim, we studied the correlation of plasma and liver metabolomic profiles obtained by HPLC-TOF-MS for piglets of different ages (newborns, neonates and infants). By means of Pearson correlation analysis we observed that 360 and 1784 pairs of metabolite features were significantly correlated in positive and negative ionization mode, respectively. Procrustes analysis was applied in order to assess the similarity of the clustering resulting from the data obtained from the two matrices and the two ionisation modes. The Procrustes distances were low for both ESI+ (0.3753) and ESI- (0.3673) and, hence, liver and plasma are expected to provide similar discriminatory information. Furthermore, we found that Multiblock Principal Component Analysis (MB-PCA) readily allowed us to combine the data obtained from both matrices and to better understand the clustering according to the three study groups. Considering all these results, we suggest that plasma can provide valuable insight into the maturation grade of liver in order to provide accurate dosing in paediatric population.