Evaluation of post-mortem interval based on gingival tissue hypoxia inducible factor-1α gene expression

In the realm of forensic science, the Post Mortem Interval (PMI) is a critical component that determines the time that has passed since the person's physiological death. Although techniques exist to precisely determine the PMI, the results are often unreliable. Hypoxia inducible factor-1 (HIF-1) is a transcriptional factor, and in hypoxic conditions, HIF-1α protein is expressed after proteosomal degradation and ubiquitination pathway involving von Hippel-Lindau protein (pVHL). The aim of the study was to assess HIF-1α mRNA expression in human gingival tissues at different PMIs.

Gum tissues were collected from cadavers at three definite intervals, namely short PMI (SPMI), medium PMI (MPMI), and long PMI (LPMI). The relative fold change in gene expression of HIF-1α was studied by RT PCR. Histopathological analysis of the tissue samples was done to determine the PMI.

In the case of short PMI (SPMI), the relative fold change in gene expression of HIF-1α is 26.90 ± 23.62. However, in the medium PMI (MPMI) and long PMI (LPMI), the relative fold change in gene expression decreased to 6.32 ± 10.90 and 5.33 ± 8.12, respectively. Histopathological analysis of the post mortem samples revealed less necrosis in SPMI than LPMI. Inflammatory cell infiltration is more in SPMI than MPMI, with their notable absence in LPMI. Ulceration was prominent in LPMI. Destructive vasculitis was visible in SPMI and MPMI. Cystic changes were increased in MPMI and LPMI.

Combined gene expression of HIF-1α and histopathological analysis is a good option for determination of PMI.