Evaluation of one-step RT-PCR multiplex assay for body fluid identification

Emerging roles of exosomal circRNAs in non-small cell lung cancer

Despite the prevalence of non-small cell lung cancer (NSCLC) is high, the limited early detection and management of these tumors are restricted since there is an absence of reliable and precise diagnostic biomarkers and therapeutic targets. Exosomes transport functional molecules for facilitating intercellular communication, especially in the tumor microenvironment, indicating their potential as cancer biomarkers and therapeutic targets. Circular RNA (circRNA), a type of non-coding RNA possessing a covalently closed loop structure, substantial abundance, and tissue-specific expression patterns, is stably enriched in exosomes. In recent years, significant breakthroughs have been made in research on exosomal circRNA in NSCLC. This review briefly introduces the biogenesis, characterizations, and functions of circRNAs and exosomes, and systematically describes the biological functions and mechanisms of exosomal circRNAs in NSCLC. In addition, this study summarizes their role in the progression of NSCLC and discusses their clinical significance as biomarkers and therapeutic targets for NSCLC.

A rapid identification system for vaginal fluid stains based on nested recombinant polymerase amplification and lateral flow dipstick

In forensic practice, identifying the species of unknown bodily fluid stains can provide assistance in the qualitative analysis and investigation of cases, and vaginal fluid stains, as one of the common bodily fluid stains, are most commonly seen at the scene of sexual assault. At present, the commonly used vaginal peptidase or microscopic detection methods currently have drawbacks such as high false negative rates, poor sensitivity, and high requirements for sample integrity and background color. However, in forensic investigations, the test materials have specificity and scarcity, making it difficult to ensure their quantity and quality. Thus, in order to achieve rapid and sensitive detection of vaginal fluid stains, in this study, we combined nested PCR and isothermal amplification technology to construct a rapid detection system for suspicious vaginal fluid stains using lateral flow dipstick. This system achieves detection by detecting the specific marker microbial community Lactobacillus crispatus in vaginal fluid, and has a high sensitivity and accuracy, which can achieve detection at template quantities as low as 2.31 copies. More importantly, the system can achieve detection at a constant temperature of 37 °C without the need for complex instruments. It can provide rapid and sensitive identification results, providing assistance for subsequent forensic material extraction and individual identification.

mRNA for Body Fluid and Individual Identification

Biological stains are one of the most important pieces of evidence, playing a multifaceted role in forensic investigations. An integral facet of forensic practice involves the identification of body fluids, typically achieved through chemical and enzymatic reactions. In recent decades, the introduction of mRNA markers has been posited as a pivotal advancement to augment the capabilities of body fluid identification (BFID). The mRNA coding region single-nucleotide polymorphisms (cSNPs) also present notable advantages, particularly in the task of individual identification. Here, we review the specificity and stability of mRNA markers in the context of BFID and the prowess of mRNA polymorphism in individual identification. Additionally, innovative methods for mRNA detection are discussed.

Quantitative evaluation of endometrium-expressed mRNAs for the purpose of discriminating between menstruation and traumatic vaginal injury in sexual assault cases

In sexual assault cases, it is crucial to discriminate between peripheral blood and menstrual blood to provide evidence for vaginal intercourse with traumatic injury. In this study, the menstrual blood mRNA markers progestagen-associated endometrial protein (PAEP), matrix metallopeptidase 7 (MMP7), and left-right determination factor 2 (LEFTY2) were evaluated by quantitative RT-PCR (RT-qPCR) for the discrimination of menstrual blood from peripheral blood and vaginal fluid. As a result, all markers with cutoff delta cycle quantification (ΔCq) values were specifically determined in menstrual blood among forensically relevant body fluids. Even though the changes in the expression levels of each marker differed during the menstrual cycle, all markers were determined to be positive in most of the randomly collected menstrual blood samples that were analyzed. Additionally, the markers with proposed cutoff ΔCq values could discriminate between menstrual blood and peripheral blood-mixed vaginal fluid samples. The determination of positive markers was less affected by storage temperature under dry conditions than under wet conditions, while PAEP was detectable in samples stored below room temperature under wet conditions. The detectability of PAEP was considered to be the result of its higher expression level compared with MMP7 and LEFTY2. In conclusion, menstrual blood markers for the RT-qPCR procedure evaluated in this study were highly specific for menstrual blood. The proposed procedure could be useful for discriminating between menstruation and traumatic bleeding in the female genital tract. In particular, PAEP is expected to be applicable to forensic casework samples because of its high specificity and robustness.

Research progress and potential application of microRNA and other non-coding RNAs in forensic medicine

At present, epigenetic markers have been extensively studied in various fields and have a high value in forensic medicine due to their unique mode of inheritance, which does not involve DNA sequence alterations. As an epigenetic phenomenon that plays an important role in gene expression, non-coding RNAs (ncRNAs) act as key factors mediating gene silencing, participating in cell division, and regulating immune response and other important biological processes. With the development of molecular biology, genetics, bioinformatics, and next-generation sequencing (NGS) technology, ncRNAs such as microRNA (miRNA), circular RNA (circRNA), long non-coding RNA (lncRNA), and P-element induced wimpy testis (PIWI)-interacting RNA (piRNA) are increasingly been shown to have potential in the practice of forensic medicine. NcRNAs, mainly miRNA, may provide new strategies and methods for the identification of tissues and body fluids, cause-of-death analysis, time-related estimation, age estimation, and the identification of monozygotic twins. In this review, we describe the research progress and application status of ncRNAs, mainly miRNA, and other ncRNAs such as circRNA, lncRNA, and piRNA, in forensic practice, including the identification of tissues and body fluids, cause-of-death analysis, time-related estimation, age estimation, and the identification of monozygotic twins. The close links between ncRNAs and forensic medicine are presented, and their research values and application prospects in forensic medicine are also discussed.

One-step endpoint RT-PCR assays for confirmatory body fluid identification

Messenger RNA (mRNA) expression analysis is increasingly used in casework, in the form of multiplex two-step reverse transcriptase PCR (RT-PCR) assays such as CellTyper 2 (CT2), developed by the Institute of Environmental Science and Research (ESR). This paper presents the development of a one-step endpoint RT-PCR workflow to improve the efficiency and precision of confirmatory body fluid identification. A comparative study of commercial one-step RT-PCR kits was undertaken, with the highest performing kit (RNA to C_T) retained for further development. Sensitivity, specificity across body fluids, and precision was assessed simultaneously using receiver operating characteristic (ROC) curves. An optimal RFU cut-off value which maximised sensitivity and specificity was determined for each marker. All assays performed significantly better when compared to the equivalent of a completely uninformative test (area under the curve of 0.5) for their target body fluid. Sensitivity varied between different donors, but the limit of detectionss were estimated as follows; saliva markers HTN3: 1 in 100 dilution of a whole buccal swab and FDCSP: 1 in 10 dilution of a whole buccal swab, circulatory blood marker SLC4A1: 0.1 µL blood, menstrual fluid markers STC1, MMP10: 1 in 10 dilution of a whole menstrual swab, spermatozoa markers PRM1, TNP1: 0.1 µL semen, seminal fluid markers KLK2: 0.1 µL semen and MSMB: 0.01 µL semen, and vaginal material marker CYP2B7P: 1 in 1000 dilution of a whole vaginal swab. The method successfully detected most body fluids in a range of simple mixtures with 77 out of 80 markers observed when expected. The developed one-step endpoint RT-PCR assays lack the sensitivity and precision required for forensic casework and provide little benefit when compared with standard two-step endpoint RT-PCR, other than minimal time and cost savings, similar sensitivity, and improved precision for some markers. As both methods utilise endpoint RT-PCR, they have the same narrow linear dynamic range. The novel method is therefore similarly susceptible to varied RNA input, a major disadvantage of this approach. The limited sensitivity and precision consistently encountered with endpoint RT-PCR - regardless of cDNA synthesis strategy - could be addressed by a real-time PCR approach.

A recombinase polymerase amplification (RPA) combined with strip visualization method for RNA-based presumptive tests of saliva and vaginal secretion

Identifying the origin of body fluids is a critical step in a forensic investigation. One widely used method to identify human body fluids is based on the color visualization of immune antigen detection strips for detecting hemoglobin in blood and prostate-specific antigen in semen. It is highly imperative to construct an easy-to-perform, mRNA-based method for the point-of-care identification of other human body fluids, such as saliva and vaginal secretion. Here, we established specific strips with the mRNA markers STATH (for saliva) and SPINK5 (for vaginal secretion) via reverse transcription recombinase polymerase amplification (RT-RPA) and lateral flow dipstick (LFD) assays (RT-RPA-LFD). RT-RPA could be accomplished in a single tube at a wide temperature range of 30-42 ℃ within 10-25 min if we do not count time for RNA extraction. The diluted RPA products were added onto the LFD strip pad to visually observe the color change of the Control/Test line. The tissue specificity and detection limit of the assays were evaluated using the optimized reaction conditions of RPA at 37 ℃ for 15 min. The positive signals of STATH were observed both in saliva and nasal secretions. SPINK5 was positive in a template-dependent manner in 4 out of 30 female urine samples in addition to vaginal secretion and menstrual blood samples. Cross-reactions were not detected in semen, skin swabs, sweat, or male urine. Both assays were capable of detecting aged samples, which were stored for 180 days (saliva) or 300 days (vaginal secretion) at room temperature. Moreover, saliva or vaginal secretion was successfully detected in all kinds of mixtures made from various body fluids. Overall, the rapid strip test method by the RT-RPA-LFD assay is simple, time-saving and highly sensitive for estimating the tissue origin of saliva and vaginal secretion. This method for the rapid RNA-based presumptive tests of the tissue type of body fluids is easy to perform prior to a multiplex mRNA analysis, which can demonstrate more reliable saliva or vaginal secretion identification.

On the Identification of Body Fluids and Tissues: A Crucial Link in the Investigation and Solution of Crime

Body fluid and body tissue identification are important in forensic science as they can provide key evidence in a criminal investigation and may assist the court in reaching conclusions. Establishing a link between identifying the fluid or tissue and the DNA profile adds further weight to this evidence. Many forensic laboratories retain techniques for the identification of biological fluids that have been widely used for some time. More recently, many different biomarkers and technologies have been proposed for identification of body fluids and tissues of forensic relevance some of which are now used in forensic casework. Here, we summarize the role of body fluid/ tissue identification in the evaluation of forensic evidence, describe how such evidence is detected at the crime scene and in the laboratory, elaborate different technologies available to do this, and reflect real life experiences. We explain how, by including this information, crucial links can be made to aid in the investigation and solution of crime.