Using Skin Gene Markers for Estimating Early Postmortem Interval at Different Temperatures

Potential Role of mRNA in Estimating Postmortem Interval: A Systematic Review

Although the postmortem interval estimation still represents one of the main goals of forensic medicine, there are still several limitations that weigh on the methods most used for its determination: for this reason, even today, precisely estimating the postmortem interval remains one of the most important challenges in the forensic pathology field. To try to overcome these limitations, in recent years, numerous studies have been conducted on the potential use of the mRNA degradation time for reaching a more precise post mortem interval (PMI) estimation. An evidence-based systematic review of the literature has been conducted to evaluate the state of the art of the knowledge focusing on the potential correlation between mRNA degradation and PMI estimation. The research has been performed using the electronic databases PubMed and Scopus. The analysis conducted made it possible to confirm the potential applicability of mRNA for reaching a more precise PMI estimation. The analysis of the results highlighted the usefulness of some mRNAs, such as β-actin and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA, especially in short time frames, within a few hours or days of death. The matrices on which these analyses were conducted were also analyzed, resulting in less exposure to the external environment, including the heart, brain, and dental pulp. The major limitations were also reported, including the short time intervals analyzed in most of the articles, the lack of mathematical models, and the failure to report the error rate between the mRNA degradation time and PMI. Given the still small number of published articles, the lack of globally recognized standardized methods, and the numerous techniques used to evaluate the mRNA degradation times, numerous and larger studies are still necessary to reach more solid and shared evidence.

The impact of RNA stability and degradation in different tissues to the determination of post-mortem interval: A systematic review

Postmortem interval (PMI) in legal medicine is extremely important for both criminal and civil cases, and several sorts of techniques have been recommended. This systematic review solely focuses on approaches linked to RNA analysis, instead of including all proposed methods for determining the PMI. The term PMI will be used in this review to indicate the time between a person's death and the postmortem examination of the body. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines when conducting this systematic review. The majority of studies on various tissues at various time intervals at various temperatures are non-human, and just a small number are on humans. The results are then provided using various statistical approaches. To calculate the PMI, post-mortem RNA degradation was examined using several tissues. The result so obtained had an opposite polarity. While some studies show that RNA stability in various tissues remained constant for several days after death, the other group of studies showed evident RNA degradation over time post-mortem, which was significantly influenced by temperature and other agonal factors. These factors have an impact on the multi-parametric mathematical model of ante and post-mortem factors on RNA degradation, as well as its applicability and feasibility. The estimation of PMI using RNA degradation can prove to be highly objective and efficient after controlling for the various factors and challenges that pose the estimation of RNA in forensic samples difficult.

The Role of miRNAs as New Molecular Biomarkers for Dating the Age of Wound Production: A Systematic Review

BACKGROUND

The timing of wounds production is a significant issue in forensic pathology. Although various methods have been evaluated, obtaining an accurate dating of lesions is still a challenge. The pathologist uses many parameters to value wound age, such as histological and immunohistochemical. In recent years, there have been many studies regarding the use of miRNAs in wound-age estimation; indeed, miRNAs have multiple potential uses in forensic pathology.

SCOPE

This review aims to verify the efficacy and feasibility of miRNAs as a tool for determining the timing of lesions.

MATERIALS AND METHODS

The authors conducted the systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed was used as a search engine to find articles published between January, 1st 2016 and October, 1st 2021, to evaluate the current state of the art regarding wound-age estimation.

RESULTS

A total of 256 articles were collected; after screening according to PRISMA guidelines, the systematic review included 8 articles. The studies included in this review were all Original articles evaluating the use of biomarkers for wound-age determination.

DISCUSSION AND CONCLUSION

The literature review showed that analysis of miRNA is an innovative field of study with significant potentiality in forensic pathology. There are few studies, and almost all of them are at an early stage. The challenge is to understand how to standardize the samples' selection to obtain reliable experimental data. This observation represents a necessary prerequisite to planning further clinical trials.

Role of molecular techniques in PMI estimation: An update

The time frames between death and reporting of the cadaver, known as post Mortem interval (PMI), is essential in investigation of homicide deaths, suspicious deaths, or other untimely deaths as well as natural deaths. Such information helps to connect the missing links in homicide or other relevant cases. Over the time several methods are developed which depends upon factors as several methods physiological, biochemical, entomological, and archaeological for the estimation of degradation of body with time. These methods lack precision, require expertise to achieve worthy results or authentic estimate. Although these methods are currently in use but, these evaluations are still unreliable and imprecise. Hence, we still need new methods for better estimation of PMI. Initially, the predictable morphological and chemical changes in cadaver are used as PMI indicators but, as the time since death increases, the above methods become less useful for as they can't pin point the time of death rather give a ballpark idea. With the advent of the field of molecular biology, the estimation of PMI is proposed to be executed by evaluating the degradation pattern of the biological markers (DNA, RNA, and Proteins). It is now proved that the DNA is fairly unwavering over long post-mortem phases, RNA is much more labile in nature, and sensitive to degradation in a tissue-specific manner. Thus, the main purpose (aim, agenda) of this document is to provide review that mainly focuses on potential use of RNA markers in estimation of PMI. For this Critical Review, the systematic evaluation of 47 studies is executed according to the chosen inclusion and exclusion criteria.

Histological changes in human skin 32 days after death and the potential forensic significance

To observe the histological changes in human skin within 32 days after death to explore its potential significance in forensic practice. The intact full-thickness skin and subcutaneous tissue from the sternum of eight corpses were placed in an environment of 4–6 °C for 4 h, 6 h, 12 h, 18 h, 24 h, 36 h, 48 h, 60 h, 72 h, 84 h, 96 h, 6 d, 8 d, 10 d, 12 d, 16 d, 20 d, 24 d, 28 d, and 32 d. Then, the whole layer of the skin was stained with haematoxylin & eosin. The histological morphology of the epidermis, dermis and appendages (sweat glands, hair follicles, and sebaceous glands) was observed under an light microscope. The epithelial nucleus condensed at 24 h after death, and cell lysis was exhausted after 20 days. The post-mortem changes in the dermis occurred later than that of the epidermis (72 h), but after epidermal changes started, the change was more rapid. At 16 d, the layers had become homogenized. The epidermis and dermis had completely separated 24 d after death. The changes in the sweat glands appeared earlier (24 h) and disappeared later (32 days); the sebaceous glands and hair follicles began to undergo degenerative changes at 96 h after death, and at approximately 20 d, only their contour remained. There were individual and structural differences in the post-mortem histological changes in the skin. At 4–6 °C ambient temperature, some structures of the human skin still exist for a long time after death, and these structures can be used to identify the source of the tissue; post-mortem histological changes in the skin occur at specific times, which can be used to help infer the time of death. A comprehensive observation of changes in the skin composition/structure is required to comprehensively analyse possible death times.

Postmortem interval determination using mRNA markers and DNA normalization

Postmortem interval (PMI) determination is an important part of criminal investigations, but it is still subject to uncertainty. Degradation of mRNA in PMI determination has been studied in decays; however, some studies have reported no correlation between PMI and RNA degradation. Thus, we aimed to determine whether RNA quantity was correlated with PMI. Heart and brain tissues were separated from a mouse model of a 0-48 h PMI with 29 time points. We then coextracted the DNA and RNA in one tube with Bioteke coextraction kits and selected some mRNA markers associated with cell oxygen deprivation and apoptosis as target genes, such as hypoxia-associated factor (HAF), apoptosis-inducing factor (AIF), hypoxia-inducible factor 2 alpha (HIF2a), and factor inhibiting HIF (FIH). We measured the quantity of these markers using real-time quantitative PCR (qPCR), and Caspase-3 DNA and 18S were each used for normalization. The results showed that in the heart tissue, the degradation of HIF2a, AIF, and FIH was correlated with PMI, as was the degradation of HIF2a, FIH, and AIF in brain tissue when normalized with Caspase-3 DNA. However, when normalized with 18S, only the degradation of HIF2a in brain tissue was correlated with PMI. Interestingly, the quantity of HAF in brain tissue was found to increase after death with either 18S or Caspase-3 DNA normalization, and it was significantly correlated with 0-48 h PMI. These results indicated that mRNA quantity can be used to determine PMI and that Caspase-3 DNA is feasible for PMI estimation. In summary, we established mathematical models for PMI determination using multiple mRNA markers and multiple tissues and further studies are needed to validate and investigate these markers and mathematical models in human tissues.Duo Peng and Meili Lv contributed equally to this work.