Transcriptomic analysis at 48 h postmortem: a proof of concept for the identification of biomarkers to estimate time since death

Background The postmortem interval (PMI) refers to the time elapsed between an individual’s death and the examination of the body. Tissues undergo a sequence of anatomical changes following death, which are routinely used to estimate the PMI. Methods To determine if these anatomical changes are associated with identifiable genomic adaptations that could characterize the PMI more accurately, we analyzed the rat skeletal muscle transcriptome at 0 and 48 h postmortem using Clariom™ S arrays. This study investigates whether specific transcriptomic changes correlate with PMI progression, offering a potential molecular tool to complement established anatomical methods. Results A total of 3,873 differentially expressed mRNAs were identified, of which 2,787 downregulated and 1,086 upregulated transcripts. The most significantly downregulated mRNA was Tnni1 (FC = -30.95, p = 1 × 10 −3 ), while the most upregulated were mt-ATP6 , mt-ATP8 , and mt-CO3 (FC > 7.78, p < 1.36 × 10 −12 ). Gene ontology (GO) enrichment analyses revealed that mRNAs upregulated at 48 h in the PMI were primarily associated with vascular and endothelial processes, including nitric oxide transport and angiogenesis. Conversely, downregulated mRNAs were linked to mitochondrial activity and cellular metabolism, reflecting both a transient vascular response and metabolic pathway shutdown in the rat skeletal muscle. Conclusion Our results demonstrate significant transcriptomic changes at 48 h postmortem, highlighting specific genes and biological pathways that may serve as candidate biomarkers for PMI estimation.