Fig. 6

A Joint pathway analysis combining data from transcripts (n = 3) and metabolites (n = 3 biological replicates, each measured 3 times) showing statistically significant differences between 25 and 4 weeks in culture (see Additional files 3 and 4 for individual data values). Integration of transcriptomic and metabolomic data using Metaboanalyst (metaboanalyst.ca) and KEGG pathway database. Significance of pathway enrichment was calculated through query combination integration method and impact was estimated through degree centrality topology measurement. Pathways of high statistical significance (Holm adjusted p value < 0.01) are highlighted. B Glycerophospholipid (KEGG id: hsa00564) and C sphingolipid (KEGG id: hsa00600) metabolic pathway changes in RPE cells at the end (25 weeks) and beginning of the experiment (4 weeks in culture) using Pathview (pathview.uncc.edu). Edges show interactions between significant metabolites (adjusted p value < 0.05; circles) and DEGs (q value < 0.05; squares) involved in the metabolism of glycerophospholipids and sphingolipids detected in the cell samples. Red and green color of nodes indicate down or upregulation, respectively, in the RPE cells of 25 weeks when compared with cells of 4 weeks. Undetected genes and metabolites on the cell samples appear in white