Characterisation of body fluid specific microRNA markers by capillary electrophoresis

Advances in body fluid identification: MiRNA markers as powerful tool

Body fluids are one of the most encountered types of evidence in any crime and are commonly used for identifying a person's identity. In addition to these, they are also useful in ascertaining the nature of crime by determining the ty pe of fluid such as blood, semen, saliva, urine etc. Body fluids collected from crime scenes are mostly found in degraded, trace amounts and/or mixed with other fluids. However, the existing immunological and enzyme-based methods used for differentiating these fluids show limited specificity and sensitivity in such cases. To overcome these challenges, a new method utilizing microRNA expression of the body fluids has been proposed. This method is believed to be non-destructive as well as sensitive in nature and researches have shown promising results for highly degraded samples as well. This systematic review focuses on and explores the use and reliability of miRNAs in body fluid identification. It also summarizes the researches conducted on various aspects of miRNA in terms of body fluid examination in forensic investigations.

A stepwise strategy to distinguish menstrual blood from peripheral blood by Fisher's discriminant function

Blood samples are the most common and important biological samples found at crime scenes, and distinguishing peripheral blood and menstrual blood samples is crucial for solving criminal cases. MicroRNAs (miRNAs) are important molecules with strong tissue specificity that can be used in forensic fields to identify the tissue properties of body fluid samples. In this study, the relative expression levels of four different miRNAs (miR-451, miR-205, miR-214 and miR-203) were analysed by real-time PCR, with 200 samples from 5 different body fluids, including two kinds of blood samples (peripheral blood and menstrual blood) and three kinds of non-blood samples (saliva, semen and vaginal secretion). Then, a strategy for identifying menstrual and peripheral blood based on Fisher's discriminant function and the relative expression of multiple miRNAs was established. Two sets of functions were used: Z1 and Z2 were used to distinguish blood samples from non-blood samples, and Y1 and Y2 were used to distinguish peripheral blood from menstrual blood. A 100% accuracy rate was achieved when 50 test samples were used. Ten samples were used to test the sensitivity of the method, and 10 ng or more of total RNA from peripheral blood samples and 10 pg or more of total RNA from menstrual blood samples were sufficient for this method. The results provide a scientific reference to address the difficult forensic problem of distinguishing menstrual blood from peripheral blood.

The stability and persistence of blood and semen mRNA and miRNA targets for body fluid identification in environmentally challenged and laundered samples

The identification of body fluids in evidentiary stains may provide investigators with probative information during an investigation. In this study, quantitative reverse transcription polymerase chain reaction (RT-qPCR) assays were performed to detect the presence of mRNA and miRNA in fresh and environmentally challenged samples. Blood, semen, and reference markers were chosen for both mRNA/miRNA testing. Samples of blood and semen were exposed to heat, humidity, and sunlight, and controlled conditions (room temperature, low humidity, and darkness) for 6 months. All mRNA targets were observed through six months under controlled conditions, but were undetected after 30 days in experimental conditions. However, miRNA targets persisted under all test conditions for the duration of the study. Additionally, cotton stained with blood or semen was laundered using a liquid detergent in various washing and drying conditions. An unstained cutting was evaluated for potential transfer. Both miRNA targets were observed in all stained samples regardless of the wash protocol used. Of the mRNA markers, HBB was detected in all bloodstained samples and PRM1 persisted in all but one semen stained sample. The unstained samples showed transfer of at least one body fluid specific miRNA marker in all samples and at least one body fluid specific mRNA in approximately half of the samples. These results support that RNA markers can be used for body fluid identification in challenging samples, and that miRNA markers may be more persistent than mRNA for blood and semen stains. However, some caution is warranted with laundered items due to possible transfer.

Analysis of microRNA and modified oligonucleotides with the use of ultra high performance liquid chromatography coupled with mass spectrometry

The present study highlights the application of ultra high performance liquid chromatography coupled with mass spectrometry for the selective separation and sensitive quantification of microRNAs and modified phosphorothioate oligonucleotide. The Central Composite Design was used for comprehensive optimization of mass spectrometer parameters (for tandem mass spectrometer and quadrupole-time-of-flight mass spectrometer). Ion pair chromatography was used in order to separate the studied compounds. Furthermore, the optimization of concentration of ion pair reagents in the mobile phase was done with respect to mass spectrometry sensitivity and liquid chromatography separation. The greatest sensitivity for studied compounds was determined for the mixture of 100 mM hexafluoroisopropanol, 5 mM N,N-dimethylbutylamine and methanol. This mobile phase also provided the best separation results in the shortest time for two of the four columns used in the study. Finally, the Hypersil GOLD aQ was selected for routine analysis of microRNA and modified phosphorothioate oligonucleotide in serum samples. These compounds were extracted from the sample with the use of combined liquid-liquid and solid phase extraction. The method developed during the study was then applied for the qualitative and quantitative analysis with limits od quantification equal to 49-63 nM.

Use of Circulating and Cellular miRNAs Expression in Forensic Sciences

The current practice in the field of forensic medicine imposes the use of modern investigation techniques. The complexity of laboratory investigation methods needed for a final result of the investigation in forensic medicine needed new biomarkers of higher specificity and selectivity. Such biomarkers are the microRNAs (miRNAs), short, non-coding RNAs composed of 19–24 nucleotides. Their characteristics, such as high stability, selectivity, and specificity for biological fluids, differ from tissue to tissue and for certain pathologies, turning them into the ideal candidate for laboratory techniques used in forensic medicine. In this paper, we wish to highlight the biochemical properties and the usefulness of miRNAs in forensic medicine.

A strategy for co-analysis of microRNAs and DNA

MicroRNAs (miRNAs, 18-25 bases in length) are small, non-coding RNAs that regulate gene expression at the post-transcriptional level. The small size makes them more stable than conventional mRNA as a biomarker identifying body fluids in degraded or compromised samples. Compared to mRNA, however, due to the very short length of miRNAs, it is a challenge to design proper primers to achieve miRNAs/DNA co-extraction and co-analysis. Here we describe the design of a specific linear RT primer for the reverse transcription reaction and a pair of PCR primers to be used in the endpoint PCR reaction for each miRNA marker, and presented a strategy for co-analysis of a set of miRNAs and DNA on the same extract using the same detection platform. A set of 4 miRNA markers (miR214 as menstrual blood marker, miR451a as venous blood marker, miR888 and miR891a as semen markers) and a DNA STR multiplex kit were co-analyzed by capillary electrophoresis. The result demonstrated that the strategy of co-analysis of miRNAs/DNA could not only identify the body fluid, but also obtain a STR profile for the same sample.