Histomorphological aspects of cadaveric skin and its possible use in forensic genetics

The Role of Protein Degradation in Estimation Postmortem Interval and Confirmation of Cause of Death in Forensic Pathology: A Literature Review

It is well known that proteins are important bio-macromolecules in human organisms, and numerous proteins are widely used in the clinical practice, whereas their application in forensic science is currently limited. This limitation is mainly attributed to the postmortem degradation of targeted proteins, which can significantly impact final conclusions. In the last decade, numerous methods have been established to detect the protein from a forensic perspective, and some of the postmortem proteins have been applied in forensic practice. To better understand the emerging issues and challenges in postmortem proteins, we have reviewed the current application of protein technologies at postmortem in forensic practice. Meanwhile, we discuss the application of proteins in identifying the cause of death, and postmortem interval (PMI). Finally, we highlight the interpretability and limitations of postmortem protein challenges. We believe that utilizing the multi-omics method can enhance the comprehensiveness of applying proteins in forensic practice.

Proteomic analysis by mass spectrometry of postmortem muscle protein degradation for PMI estimation: A pilot study

The determination of the postmortem interval is a topic of great forensic interest. The possibility of using new technologies has allowed the study of postmortem decay of biomolecules in the determination of PMI. Skeletal muscle proteins are promising candidates because skeletal muscle exhibits slower postmortem decay compared to other internal organs and nervous tissues, while its degradation is faster than cartilage and bone. In this pilot study, skeletal muscle tissue from pigs was degraded at two different controlled temperatures, 21 °C and 6 °C, and analysed at predefined times points: 0, 24, 48, 72, 96, and 120 h. The obtained samples were analysed by mass spectrometry proteomics approach for qualitative and quantitative evaluation of proteins and peptides. Immunoblotting validation was performed for the candidate proteins. The results obtained appeared significant and identified several proteins useful for possible postmortem interval estimation. Of these proteins, PDLIM7, TPM1, and ATP2A2 were validated by immunoblotting at a larger number of experimental points and at different temperatures. The results obtained are in agreement with those observed in similar works. In addition, the use of a mass spectrometry approach increased the number of protein species identified, providing a larger panel of proteins for PMI assessment.

Elastic fiber degradation as a possible indicator for PMI estimation on mummified and corified skin: a pilot study

Mummified and corified bodies are particularly complex scenarios to investigate, starting from identifying the post-mortem interval (PMI), even more so in indoor environments. In these bodies, the skin has the peculiar feature to resist for a long time. Among its components, there are elastic fibers, which are characterized by intrinsic resistance to post-mortem degenerative phenomena. Starting from these considerations, we investigated microscopically the persistence, detectability, and changes of elastic fibers in the skin of mummified and corified bodies with different known PMI. The aim was to evaluate whether they could provide an additional tool to aid in PMI estimation in these cases. Therefore, we collected skin samples from mummified or corified bodies found in a domestic environment with different known PMI, as well as from corified bodies that had been exhumed after 11 years of burial. Histochemical staining specific for elastic fibers, namely, Weigert's resorcin fuchsin, showed their prolonged persistence and a progressive and different degradation between mummified and corified skin as a function of PMI. Moreover, on the whole, we observed greater preservation of elastic fibers in mummified skin than in corified one at the same PMI. Therefore, histological analysis of elastic fibers in mummified and corified skin may help to provide valuable aid in estimating PMI, especially in those particular cases where more reliable alternatives are lacking.

Technical note: A comparison between rehydrating solutions in the pretreatment of mummified and corified skin for forensic microscopic examination

Microscopic examination of mummified or corified skin may be of extreme importance for forensic purposes. However, standard histological samples in these cases are low-end, and preparation is burdened by several problems and so are diagnostic results: an improvement of these types of specimens is therefore advantageous. This study aims to identify the best performing rehydration solution among a fabric softener, a body lotion, and Sandison's rehydrating solution. Samples of skin undergoing mummification or corification were collected from 25 corpses and each sample was divided into 4 fragments: one of these fragments was directly fixated in 4% formalin, one was previously treated with a tissue softener, another one was previously treated with a body lotion, and the last one was treated with Sandison's solution. After 72 h, the pretreated samples were post-fixated in 4% formalin and then prepared for standard histological examination staining the histological slides with hematoxylin-eosin and Masson's trichrome. At the microscopic examination, samples directly fixated in formalin were characterized by usual marked structural alterations and altered stainability, typical of such dry tissues. Vice versa, those previously treated appeared to be better-preserved even though with different improvement levels: body lotion made a medium-low-grade restoration of the tissues, and fabric softener a high-grade restoration, while Sandison's rehydrating solution produced an optimal grade restoration. Sandison's rehydrating solution was confirmed to be the best rehydrating substance for mummified and corified skin. Fabric softener could be, however, considered a valid substitute, being productive of high-grade microscopic yield.