Time-dependent expression of SNAT2 mRNA in the contused skeletal muscle of rats: a possible marker for wound age estimation

Detection of multiple biomarkers associated with satellite cell fate in the contused skeletal muscle of rats for wound age estimation

From the perspective of forensic wound age estimation, experiments related to skeletal muscle regeneration after injury have rarely been reported. Here, we examined the time-dependent expression patterns of multiple biomarkers associated with satellite cell fate, including the transcription factor paired box 7 (Pax7), myoblast determination protein (MyoD), myogenin, and insulin-like growth factor (IGF-1), using immunohistochemistry, western blotting, and quantitative real-time PCR in contused skeletal muscle. An animal model of skeletal muscle contusion was established in 30 Sprague-Dawley male rats, and another five rats were employed as non-contused controls. Morphometrically, the data obtained from the numbers of Pax7 + , MyoD + , and myogenin + cells were highly correlated with the wound age. Pax7, MyoD, myogenin, and IGF-1 expression patterns were upregulated after injury at both the mRNA and protein levels. Pax7, MyoD, and myogenin protein expression levels confirmed the results of the morphometrical analysis. Additionally, the relative quantity of IGF-1 protein > 0.92 suggested a wound age of 3 to 7 days. The relative quantity of Pax7 mRNA > 2.44 also suggested a wound age of 3 to 7 days. Relative quantities of Myod1, Myog, and Igf1 mRNA expression > 2.78, > 7.80, or > 3.13, respectively, indicated a wound age of approximately 3 days. In conclusion, the expression levels of Pax7, MyoD, myogenin, and IGF-1 were upregulated in a time-dependent manner during skeletal muscle wound healing, suggesting the potential for using them as candidate biomarkers for wound age estimation in skeletal muscle.

State-of-the-Art on Wound Vitality Evaluation: A Systematic Review

The vitality demonstration refers to determining if an injury has been caused ante- or post-mortem, while wound age means to evaluate how long a subject has survived after the infliction of an injury. Histology alone is not enough to prove the vitality of a lesion. Recently, immunohistochemistry, biochemistry, and molecular biology have been introduced in the field of lesions vitality and age demonstration. The study was conducted according to the preferred reporting items for systematic review (PRISMA) protocol. The search terms were "wound", "lesion", "vitality", "evaluation", "immunohistochemistry", "proteins", "electrolytes", "mRNAs", and "miRNAs" in the title, abstract, and keywords. This evaluation left 137 scientific papers. This review aimed to collect all the knowledge on vital wound demonstration and provide a temporal distribution of the methods currently available, in order to determine the age of lesions, thus helping forensic pathologists in finding a way through the tangled jungle of wound vitality evaluation.

[Current views on methods of determining the age of injuries in the practice of the forensic expert]

The review objective is to summarize the current data on new methods development for detection and determination of the age of injuries (AI) and to analyze the prospects of their use in the practice of forensic medical experts. The injury healing processes in various human body tissues are described in detail, and data on biomarkers of healing and their role are provided. Three main diagnostic methods for AI were analyzed: immunohistochemical, molecular biological study, and biophysical objectivization. Their advantages and disadvantages, as well as ways of further improvement of these methods, are considered.

Investigating Transcriptional Dynamics Changes and Time-Dependent Marker Gene Expression in the Early Period After Skeletal Muscle Injury in Rats

Following skeletal muscle injury (SMI), from post-injury reaction to repair consists of a complex series of dynamic changes. However, there is a paucity of research on detailed transcriptional dynamics and time-dependent marker gene expression in the early stages after SMI. In this study, skeletal muscle tissue in rats was taken at 4 to 48 h after injury for next-generation sequencing. We examined the transcriptional kinetics characteristics during above time periods after injury. STEM and maSigPro were used to screen time-correlated genes. Integrating 188 time-correlated genes with 161 genes in each time-related gene module by WGCNA, we finally identified 18 network-node regulatory genes after SMI. Histological staining analyses confirmed the mechanisms underlying changes in the tissue damage to repair process. Our research linked a variety of dynamic biological processes with specific time periods and provided insight into the characteristics of transcriptional dynamics, as well as screened time-related biological indicators with biological significance in the early stages after SMI.

Early postmortem interval (EPMI) estimation using differentially expressed gene transcripts

Genes differentially expressed after death were selected to construct a mathematical model for early postmortem interval estimation. Sprague Dawley rats were sacrificed and placed at temperatures of 4 °C, 15 °C, 25 °C, and 35 °C. Brain tissues were collected at 0, 6, 12, 18, and 24 h after death and total RNA was extracted. Changes in gene transcript levels after death were detected using microarray expression profiling and differentially expressed genes was screened. Expanded experiments were performed to validate gene transcript levels at different temperatures using the reverse transcription real-time quantitative polymerase chain reaction. Six genes with high coefficients of determination were chosen for construction of mathematical models. Optimal ternary cubic equations were built using R software with temperature, postmortem interval and ΔCq defined as the independent variable x, y and z, respectively. Equations were converted into a three-dimensional visual statistical model using MATLAB. Animal samples were used to validate the mathematical models. Results showed that the 5srRNA showed best stability at four temperatures. The genes Ninj2, Grifin, Arpp19, and Hopx showed high coefficients of determination (>80%) and low error (<3h) in verification experiments which indicate that they are potential markers for early postmortem interval estimation.

Vitality and wound-age estimation in forensic pathology: review and future prospects

Determining the age of a wound is challenging in forensic pathology, but it can contribute to the reconstruction of crime scenes and lead to arrest of suspects. Forensic scholars have tended to focus on evaluating wound vitality and determining the time elapsed since the wound was sustained. Recent progress in forensic techniques, particularly high-throughput analyses, has enabled evaluation of materials at the cellular and molecular levels, as well as simultaneous assessment of multiple markers. This paper provides an update on wound-age estimation in forensic pathology, summarizes the recent literature, and considers useful additional information provided by each marker. Finally, the future prospects for estimating wound age in forensic practise are discussed with the hope of providing something useful for further study.

Forensic aspects of gene expression signatures for age determination in bruises as evaluated in an experimental porcine model

Determining the age of bruises and the force used to inflict the trauma is of crucial importance in both human and veterinary forensic pathology. In the present study, the expression of more than 50 different genes in subcutaneous fat and muscle tissue from experimental bruises in pigs was investigated. The aim was to evaluate if expression signatures of selected genes were capable of determining bruises according to age and the force of impact. Eighteen experimental pigs were anesthetized, and on each animal four blunt traumas were inflicted on the back with a low, moderate or high force. The pigs were euthanized from 1 to 10 h after infliction of the trauma and subcutaneous fat and muscle tissues were sampled. As control, subcutaneous fat and muscle tissues were sampled from two un-injured pigs. Quantitative real-time polymerase chain reaction was performed to evaluate mRNA expression of genes involved in inflammation, tissue damage and repair. Expression signatures of thirteen selected genes in subcutaneous fat but not in muscle tissue reflected the age of bruises with a precision of approximately ±2 h. Moreover, the gene expression signature in the subcutaneous fat was to some extend able to separate bruises inflicted with different forces. Expression signatures of selected genes in the subcutaneous fat will increase the precision of the age determination of bruises in pigs. Further, due to the similarity of porcine and human skin physiology and immunity, these results might also provide valuable information in human forensic science.

Simultaneous time course analysis of multiple markers based on DNA microarray in incised wound in skeletal muscle for wound aging

Assessment of incised wound age in skeletal muscles is important because fatal injuries are often complicated with muscle involvement. Transcriptome of injured skeletal muscle along with histopathological and immunohistochemistry staining, were analyzed to explore the biological effect of incised injuries using a mouse incised injury model. An incisional wound was made at the biceps femoris muscle of anesthetized mice, and the muscles were sampled at 6, 12, 24, 36 and 48h post-injury. DNA microarray analysis using RNA extracted from the muscle samples of 12h post-injury identified 3,655 upregulated and 3,583 downregulated genes. Referring to the results of the gene ontology and gene expression pathway analysis, time course expression of five cytokines, namely chemokine (C-C motif) ligand 4 (CCL4), chemokine (C-X-C motif) ligand 5 (CXCL5), interleukin-1 beta (IL-1β), interleukin- 6 (IL-6) and interleukin-7 (IL-7), were analyzed by quantative reverse transcription PCR (qRT-PCR). CXCL5 was the most upregulated gene throughout the post-injury period with higher expression from 6 through 36h post injury. Upregulation of CCL4 and IL-1β was also persisted until 36h post injury. IL-6 mRNA was highly and rapidly expressed at 6h post-injury followed by significant decrease at 12h. Unlike other four cytokines, IL-7 showed slow and steady increasing over time until 48h post-injury. Immunohistochemical staining of post-injury samples showed gradual mild increase of staining intensity proportional to increasing time points especially around the wound edges. The present study highlights the unique dynamics of each cytokine and reflects their roles in the process of muscle wound healing, and suggests the potential of them as a tool for forensic wound age estimation.

The impact of force on the timing of bruises evaluated in a porcine model

In animal models developed in order to estimate the age of bruises, focus has been on the changes over time and not considering the force used to inflict the trauma. In the present study, gross and histological changes in 2, 4, 6 and 8 h old bruises which were inflicted with a low, moderate and high force were compared. Twelve experimental pigs were randomly assigned to three groups of force (low, moderate and high force). All pigs were anesthetized, and on each animal four blunt traumas were inflicted on the back with the low, moderate or high force according to the groups. The pigs were kept in anesthesia for 2, 4, 6 or 8 h, after which they were euthanized, and skin and muscle tissues were sampled for histology. As control, two pigs were included. The gross appearance of bruises developed similarly until 0.5 h after infliction at which time the visibility of the bruises depended on the force. The infiltration of subcutaneous neutrophils depended on the time and force used which was confirmed by both manual evaluation and image analysis of immunostained skin sections. In the muscle tissue, the number of macrophages was found useful for age determination in bruises inflicted with the highest force. Therefore, when evaluating forensic cases of bruises in both human and veterinary pathology the impact of force and not only the timing should be taken into consideration.

A novel, comprehensive, and reproducible porcine model for determining the timing of bruises in forensic pathology

PURPOSE

Calculating the timing of bruises is crucial in forensic pathology but is a challenging discipline in both human and veterinary medicine. A mechanical device for inflicting bruises in pigs was developed and validated, and the pathological reactions in the bruises were studied over time in order to identify gross and histological parameters that may be useful in determining the age of a bruise.

METHODS

The mechanical device was able to apply a single reproducible stroke with a plastic tube that was equivalent to being struck by a man. In each of 10 anesthetized pigs, four strokes that resulted in bruises were inflicted on the back. In addition, 2 control pigs were included in the study. The pigs were euthanized consecutively from 1 to 10 h after the infliction of bruises. Following gross evaluation, skin, and muscle tissues were sampled for histology.

RESULTS

Grossly, the bruises appeared uniform and identical to the tramline bruises seen in humans and pigs subjected to blunt trauma. Histologically, the number of neutrophils in the subcutis, the number of macrophages in the muscle tissue, and the localization of neutrophils and macrophages in muscle tissue showed a time-dependent response. Combining these parameters, bruises could be grouped as being either less than 4 h old or between 4 and 10 h of age. Gross lesions and changes in the epidermis and dermis were inconclusive with respect to time determination.

CONCLUSIONS

The model was reproducible and resembled forensic cases of bruises in pigs and humans. Therefore, the histological parameters are suitable for age determination of bruises in pigs and likely also in humans.

Time-dependent Expression of MMP-2 and TIMP-2 after Rats Skeletal Muscle Contusion and Their Application to Determine Wound Age

The ability to determine vitality and estimate the survival period after a wound is critical in routine forensic practice. The mRNA levels of MMP-2 and TIMP-2 were examined using quantitative real-time RT-PCR to determine the age of a wound. Furthermore, the colocalization of them with Macrophage Marker, respectively, was detected by double immunofluorescence, and a standardized rat model of skeletal muscle contusion was established. In the antemortem contused groups, a large number of macrophages showed positive staining for MMP-2 and TIMP-2, and the expression of MMP-2 and TIMP-2 mRNA increased sharply at 3 days postinjury, with relative quantities of 5.75 and 2.98. No samples in the other groups showed relative quantities of >5.75 and 2.98; therefore, relative quantities exceeding 5.75 and 2.98 were strongly indicated 3 days after contusion. In addition, there was a significant decrease in the relative quantity in the postmortem contused groups, indicating that they were useful for diagnosing vitality.

Characterization and Regulation of the Amino Acid Transporter SNAT2 in the Small Intestine of Piglets

The sodium-dependent neutral amino acid transporter 2 (SNAT2), which has dual transport/receptor functions, is well documented in eukaryotes and some mammalian systems, but has not yet been verified in piglets. The objective of this study was to investigate the characteristics and regulation of SNAT2 in the small intestine of piglets. The 1,521-bp porcine full cDNA sequence of SNAT2 (KC769999) from the small intestine of piglets was cloned. The open reading frame of cDNA encodes 506 deduced amino acid residues with a calculated molecular mass of 56.08 kDa and an isoelectric point (pI) of 7.16. Sequence alignment and phylogenetic analysis revealed that SNAT2 is highly evolutionarily conserved in mammals. SNAT2 mRNA can be detected in the duodenum, jejunum and ileum by real-time quantitative PCR. During the suckling period from days 1 to 21, the duodenum had the highest abundance of SNAT2 mRNA among the three segments of the small intestine. There was a significant decrease in the expression of SNAT2 mRNA in the duodenal and jejunal mucosa and in the expression of SNAT2 protein in the jejunal and ileal mucosa on day 1 after weaning (P < 0.05). Studies with enterocytes in vitro showed that amino acid starvation and supplementation with glutamate, arginine or leucine enhanced, while supplementation with glutamine reduced, SNAT2 mRNA expression (P < 0.05). These results regarding the characteristics and regulation of SNAT2 should help to provide some information to further clarify its roles in the absorption of amino acids and signal transduction in the porcine small intestine.