Post-mortem RNA fragmentation and apoptosis marker gene expression in clinically relevant organs of the human body

Transcriptome analysis relies on intact RNA, and RNA integrity relies on intact cells. Death and cardiac arrest cause hypoxia and result in cell death and RNA fragmentation. Our study aims to systematically define the organ-specific post-mortem intervals (PMIs) at which RNA fragmentation has reached a level that hampers transcriptome analysis and at which apoptosis marker gene expression starts and reaches its maximum. A total of 453 biopsies were harvested from nine organs of seven body donors at 8, 10, 12, 18, and 24 hrs (h), and in four of them also at 6 h after confirmed death. From the livers, two biopsies were harvested. The material was used for calculating the percentage of RNA fragments > 200 nucleotides (DV200) and for determining the expression levels of marker genes of the intrinsic (BAX; CASP9) and extrinsic (FADD; FASLG; CASP8) apoptosis pathways. Additional material was collected from all organs and used for preparing histological sections. These were checked for pathologies. Detailed DV200 values and details of the expression levels of the selected genes of both apoptotic pathways are provided for each time point and organ. The DV200 and apoptosis marker expression levels of the different liver segments were almost identical. Our findings characterize post-mortem RNA fragmentation and the dynamics of apoptotic marker gene expression in nine organs. They define the time frame during which material harvested from these organs can be successfully used for transcriptomics projects, such as the Human Cell Atlas and similar programs.