Postmortem mitochondrial membrane potential dynamics as a temperature-independent biomarker for early postmortem
Yehui Lv1, Li Tao2, Luyuyan Hu3
1Institute of Wound Prevention and Treatment, School of Basic Medical Sciences, Shanghai University of Medicine & Health Sciences, Shanghai 201318, China.
Background:
Accurate determination of postmortem interval (PMI) and cause of death (COD) is a critical challenge in forensic pathology, with significant implications for criminal investigations. Traditional PMI estimation methods are based on macroscopic changes and are influenced by environmental factors and investigator subjectivity. Recent advances in molecular biology have shown that certain cellular structures, such as mitochondria, retain functionality after death, making them potential biomarkers for forensic assessment. As mitochondria play a central role in cellular metabolism and respond dynamically to post-mortem hypoxia, investigation of mitochondrial membrane potential (ΔΨm) may provide a quantifiable and objective method for estimating PMI.
Results:
We successfully isolated mitochondria from post-mortem tissues and cultured cells, confirming their purity and membrane integrity. Regression analysis showed a strong linear correlation between ΔΨm and PMI in brain, myocardium and skeletal muscle within the first 15-18 h postmortem, with skeletal muscle showing the highest correlation coefficient. ΔΨm values remained stable at different temperatures, suggesting that it is a robust biomarker for estimating PMI. In vitro experiments under hypoxic conditions revealed a transient increase in ΔΨm at 24 h, accompanied by ATP depletion, ROS accumulation and shifts in mitochondrial fission and fusion dynamics, indicating mitochondrial adaptation to oxygen deprivation.
Conclusions:
These findings highlight ΔΨm as a promising temperature stable biomarker for early assessment of PMI. The observed mitochondrial adaptations suggest that ΔΨm-based models may improve forensic accuracy and provide insights into postmortem metabolic processes. Further validation with human postmortem samples is essential to refine these models and explore their applicability to COD determination.
Insights
Mitochondrial membrane potential (ΔΨm) offers a stable, quantifiable biomarker for estimating early postmortem interval (PMI). This method shows promise for improving forensic accuracy in determining time since death.
Area of Science:
- Forensic Science
- Molecular Biology
- Cellular Biology
Background:
- Accurate postmortem interval (PMI) and cause of death (COD) determination are crucial in forensic pathology.
- Traditional PMI methods rely on subjective macroscopic changes, impacted by environmental factors.
- Mitochondria retain post-mortem functionality, offering potential as objective biomarkers.
Purpose of the Study:
- To investigate mitochondrial membrane potential (ΔΨm) as a quantifiable biomarker for PMI estimation.
- To assess the stability and reliability of ΔΨm in postmortem tissues.
Main Methods:
- Isolation of mitochondria from postmortem tissues and cultured cells.
- Regression analysis to correlate ΔΨm with PMI.
- In vitro experiments simulating postmortem hypoxic conditions.
Main Results:
- Successful isolation and confirmation of mitochondrial integrity.
- Strong linear correlation between ΔΨm and PMI in brain, myocardium, and skeletal muscle within 18 hours.
- ΔΨm demonstrated temperature stability, indicating robustness as a biomarker.
- Observed mitochondrial adaptations to hypoxia, including ATP depletion and ROS accumulation.
Conclusions:
- Mitochondrial membrane potential (ΔΨm) is a promising, temperature-stable biomarker for early PMI assessment.
- ΔΨm-based models could enhance forensic accuracy and elucidate postmortem metabolic changes.
- Further validation with human samples is necessary for refining models and exploring COD applications.
