Effects of Filtration on Glyceraldehyde-3-Phosphate Dehydrogenase mRNA in the Plasma of Trauma Patients and Healthy Individuals

Circulating RNA in blood plasma as diagnostic tool for clinical oncology

One of the key challenges facing today’s oncology is the discovery of early predictors of malignant neoplasms in patients’ biological samples. Liquid biopsy is a noninvasive diagnostic technique based on the detection and isolation of tumor cells, tumor-derived nucleic acid and exosomes circulating in the blood plasma of cancer patients. There is a plethora of research studies of circulating tumor DNA in patients with MN. The active proliferation of tumor cells occurs in the backdrop of altered gene expression. The presence of tissue-specific transcripts in the circulating RNA fraction suggests that levels of circulating RNA reflect the development of the primary tumor. We think that cell-free RNA circulating in the blood plasma is a promising molecular biomarker for early cancer detection.

Circulating human leucine-rich α-2-glycoprotein 1 mRNA and protein levels to detect acute appendicitis in patients with acute abdominal pain

BACKGROUND

Elevated levels of circulating plasma and urine leucine-rich-2-glycoprotein-1 (LRG1) protein has been found in patients with acute appendicitis (AA) and may be useful for diagnosis. This study aimed to investigate whether combined tests including circulating LRG1 mRNA levels improve the early diagnosis of AA.

METHODS

Between December 2011 and October 2012, a prospective study was conducted on patients aged 18years or older presenting to the ED with acute abdominal pain (<7days of symptom onset). Levels of whole blood LRG1 mRNA and plasma LRG1 protein taken from these patients within 24h of arrival (mean 12.4h) were analyzed. The primary outcome was AA.

RESULTS

Eighty-four patients (40 (47.6%) with AA and 44 (52.4%) without AA; mean age 35years; 41.6% males) were recruited. Median whole blood LRG1 mRNA and plasma LRG1 levels were higher in AA patients than in non-AA. Of 40 AA patients, 13 (32.5%) were diagnosed as complicated AA. In ROC analysis of LRG1 mRNA (normalized to GAPDH), LRG1 protein and Alvarado score for discriminating AA and non-AA, the areas under the curve (AUC) were 0.723, 0.742 and 0.805 respectively. The AUC of combination of normalized LRG1 mRNA, LRG1 protein and Alvarado score was 0.845.

CONCLUSION

A combination of modified whole blood LRG1 mRNA levels, plasma LRG1 protein and Alvarado score at the ED may be useful to diagnose simple and complicated AA from other causes of abdominal pain.

Recovering circulating extracellular or cell-free RNA from bodily fluids

The presence of extracellular circulating or cell-free RNA in biological fluids is becoming a promising diagnostic tool for non invasive and cost effective cancer detection. Extracellular RNA or miRNA as biological marker could be used either for the early detection and diagnosis of the disease or as a marker of recurrence patterns and surveillance. In this review article, we refer to the origin of the circulating extracellular RNA, we summarise the data on the biological fluids (serum/plasma, saliva, urine, cerebrospinal fluid and bronchial lavage fluid) of patients suffering from various types of malignancies reported to contain a substantial amount of circulating extracellular (or cell-free) RNAs and we discuss the appropriate reagents and methodologies needed to be employed in order to obtain RNA material of high quality and integrity for the majority of the experimental methods used in RNA expression analysis. Furthermore, we discuss the advantages and disadvantages of the RT-PCR or microarray methodology which are the methods more often employed in procedures of extracellular RNA analysis.

Quantitative analyses and transcriptomic profiling of circulating messenger RNAs as biomarkers of rat liver injury

Serum aminotransferases have been the clinical standard for evaluating liver injury for the past 50-60 years. These tissue enzymes lack specificity, also tracking injury to other tissues. New technologies assessing tissue-specific messenger RNA (mRNA) release into blood should provide greater specificity and permit indirect assessment of gene expression status of injured tissue. To evaluate the potential of circulating mRNAs as biomarkers of liver injury, rats were treated either with hepatotoxic doses of D-(+)-galactosamine (DGAL) or acetaminophen (APAP) or a myotoxic dose of bupivacaine HCl (BPVC). Plasma, serum, and liver samples were obtained from each rat. Serum alanine aminotransferase and aspartate aminotransferase were increased by all three compounds, whereas circulating liver-specific mRNAs were only increased by the hepatotoxicants. With APAP, liver-specific mRNAs were significantly increased in plasma at doses that had no effect on serum aminotransferases or liver histopathology. Characterization of the circulating mRNAs by sucrose density gradient centrifugation revealed that the liver-specific mRNAs were associated with both necrotic debris and microvesicles. DGAL treatment also induced a shift in the size of plasma microvesicles, consistent with active release of microvesicles following liver injury. Finally, gene expression microarray analysis of the plasma following DGAL and APAP treatment revealed chemical-specific profiles.

CONCLUSION

The comparative analysis of circulating liver mRNAs with traditional serum transaminases and histopathology indicated that the circulating liver mRNAs were more specific and more sensitive biomarkers of liver injury. Further, the possibility of identifying chemical-specific transcriptional profiles from circulating mRNAs could open a range of possibilities for identifying the etiology of drug/chemical-induced liver injury.

Circulating nucleic acids as a new diagnostic tool

The discovery of circulating nucleic acids in the 1940s opened up new possibilities for the non-invasive detection, monitoring and screening of various human disorders. Several tumour markers that enable early cancer detection or tumour behaviour prediction have been detected in the plasma of cancer patients. Maternal plasma analysis can be used to detect certain fetal abnormalities, with the quantification of cell-free nucleic acids used to screen for several pregnancy-associated disorders. Some other applications are in transplant monitoring and graft rejection assessment, and in certain medical emergencies such as trauma and burn severity stratification. Many studies have yielded promising results in this field, but the techniques have yet to be applied in routine clinical practice. Large-scale studies using similar technologies and a broad spectrum of patients are still needed to verify the results of the various studies.

Quantification of circulating cell-free plasma DNA and endothelial gene RNA in patients with burns and relation to acute thermal injury

BACKGROUND

Major burn represents a multi-system insult to the human body. Despite improvements in mortality and morbidity, reliable predictors of outcome are lacking. Raised levels of cell-free nucleic acids have been detected in various pathological processes including burns. We quantified circulating nucleic acids as potential objective measures of burn severity with predictive and prognostic value.

METHODS

Expression of endothelial specific cell-free mRNA and cell-free DNA were measured in plasma of 19 burn patients at days 1-3 and week 10 following acute thermal injury and in 19 healthy controls by real-time quantitative PCR.

RESULTS

Expression of endothelial specific mRNA was higher in burn patients compared to controls (p<0.001). DNA levels were significantly higher in the burn population in the first 48 h following injury. Plasma RNA and DNA levels related to %TBSA burn in the first 24h and to the levels of circulating endothelial progenitor cells.

CONCLUSIONS

We show that plasma levels of endothelial specific mRNA and DNA are elevated acutely following burns, and relate to severity in terms of %TBSA burnt.

Short-term clearance of cell-free nucleic acids after first-trimester termination of pregnancy

To determine the kinetics of the short-term clearance of cell-free nucleic acids in maternal plasma, we conducted a prospective cohort study of 36 women who underwent first-trimester elective surgical termination. By using real-time polymerase chain reaction (PCR) amplification and measurement of the sex-determining region of the Y chromosome (SRY) gene (as a marker of fetal DNA), beta-hCG (a placental messenger RNA transcript), and glyceraldehyde phosphate dehydrogenase (GAPDH; as a marker of both total DNA and mitochondrial RNA), we found that cell-free nucleic acids in maternal plasma are not cleared within 90 minutes after the procedure, in contrast to the case of term delivery, in which levels decrease rapidly after birth.

Circulating nucleic acid analysis: diagnostic applications for acute pathologies

Much research interest has been shown in recent years for the development of molecular diagnostic strategies based on the analysis of DNA/RNA molecules that are present in the plasma/serum of human subjects. Reported applications include the diagnosis, prognostication or monitoring of malignancies and pregnancy-associated complications. While researchers have speculated that cell death is a potential mechanism that leads to the release of DNA/RNA into the circulation, studies have demonstrated that indeed increased amounts of plasma DNA and RNA could be detected in patients sustaining acute traumatic injuries. The degree of plasma DNA elevation correlated with the severity of injury. Similarly, plasma DNA concentrations have been shown to correlate with indices of prognostic significance in patients with acute stroke. It is expected that new diagnostic markers based on plasma RNA detection could be developed for the evaluation of acute pathologies.

Detecting cell-free circulating hTERT mRNA in the plasma may identify a subset of nonsmall cell lung cancer patients

Human telomerase reverse transcriptase (hTERT), the catalytic subunity of telomerase, a marker of cell immortalization, is upregulated in most tumors, including nonsmall cell lung cancer (NSCLC). However, little is known about the role of assessing cell-free plasma circulating hTERT mRNA for tracing these tumors. We investigated by RT-polymerase chain reaction (PCR) and real-time quantitative PCR the prevalence and functional implications of hTERT mRNA in both tumor tissue and paired plasma samples in 34 (27 males and 7 females) stages I-IIIB NSCLC patients (21 adenocarcinomas and 13 squamous-cell carcinomas) by using intron- and exon-spanning primers. Plasma samples of ten healthy volunteers and normal lung tissue were used as negative controls. We detected hTERT mRNA in the plasma of 4 out of 34 (12%) tumor patients, but none was detected in the ten plasma samples of healthy volunteers. Normal lung tissue was completely devoid of hTERT mRNA. No association was found between hTERT plasma mRNA and clinicopathologic variables of the patients' population. We conclude that cell-free circulating hTERT mRNA is detectable in a subset of patients, whereas it is consistently absent in healthy volunteers. It can be added to the panel of multiple genetic tracers to detect lung cancer in the plasma of patients, although, per se, it is not specific for this tumor.

Diagnostic developments involving cell-free (circulating) nucleic acids

BACKGROUND

The detection of circulating nucleic acids has long been explored for the non-invasive diagnosis of a variety of clinical conditions. In earlier studies, detection of circulating DNA has been investigated for the detection of various forms of cancer. Metastasis and recurrence in certain cancer types have been associated with the presence of high levels of tumor-derived DNA in the circulation. In the case of pregnancies, detection of fetal DNA in maternal plasma is a useful tool for detecting and monitoring certain fetal diseases and pregnancy-associated complications. Similarly, levels of circulating DNA have been reported to be elevated in acute medical emergencies, including trauma and stroke, and have been explored as indicators of clinical severity. Apart from circulating DNA, much attention and effort have been put into the study of circulating RNA over the last few years. This area started from the detection of tumor-derived RNA in the plasma of cancer patients. Soon after that, detection of circulating fetal RNA in maternal plasma was described. Plasma RNA detection appears to be a promising approach for the development of gender- and polymorphism-independent fetal markers for prenatal diagnosis and monitoring. This development also opens up the possibility of non-invasive prenatal gene expression profiling by maternal blood analysis. Besides circulating DNA and RNA in plasma and serum, cell-free DNA in other body fluids, such as urine, has been detected in patients with different clinical conditions. Regardless of the sources of cell-free DNA for clinical use, the amount is frequently scarce.

METHODS

Technical advancements in detecting free DNA have been made over the years.

CONCLUSIONS

It is likely that further developments in the field of circulating nucleic acids will provide us with new diagnostic and monitoring possibilities over the next few years.

The biology and diagnostic applications of plasma RNA

The detection of cell-free RNA in the plasma and serum of human subjects has opened up new investigational opportunities. Tumor-derived RNA was detected in the plasma and serum of patients with various forms of cancer. Through the development of robust extraction and quantification protocols for circulating RNA, new information regarding its biology and characteristics has been obtained. Plasma RNA was shown to be particle associated and to be surprisingly stable. Recently, fetal RNA was also demonstrated in maternal plasma. The placenta was shown to be an important source of such circulating fetal RNA. This discovery has created new prenatal diagnostic and monitoring possibilities. It is expected that circulating RNA will find application in many other clinical scenarios, including emergency medicine.