Biomarkers for monitoring pre-analytical quality variation of mRNA in blood samples

The Effect of Blood Clots on the Quality of RNA Extracted from PAXgene Blood RNA Tubes

Background: PAXgene® Blood RNA tubes are routinely used in clinical research and molecular biology applications to preserve the stability of RNA in whole blood. However, in practice, blood clots are occasionally observed after blood collection and are often ignored. Currently, there are few studies on whether blood clots affect the quality of RNA extracted from these tubes. Materials and Methods: Fifteen pairs of non-clot and clot PAXgene Blood RNA tube samples (n = 30) were collected to form two matched groups from 15 patients. According to the maximum diameter (d) of the blood clot observed visually at the time of sample reception, the clot groups were divided into a small-clot group (0 cm < d < 0.5 cm) and a large-clot group (d ≥ 0.5 cm). RNA was extracted by the PAXgene Blood RNA Kit. To analyze the quality of RNA, its yield and purity were assessed by spectrophotometry, and integrity was measured by microfluidic electrophoresis. An A260/280 ratio between 1.8 and 2.2 indicated purified RNA, and RNA integrity number (RIN) values ≥7.0 were considered to represent qualified integrity. Results: The median yields of RNA from the non-clot and clot groups were 3.84 (2.80-6.38) μg and 4.87 (2.77-8.30) μg, respectively. The median A260/280 ratios were 2.08 (2.06-2.09) and 2.09 (2.07-2.11), whereas the median A260/230 ratios were 1.77 (1.31-1.91) and 1.67 (1.21-1.94) in the two groups. In addition, the median RINs were 8.20 (8.00-8.40) and 7.20 (6.60-7.70), respectively. There were no significant differences in RNA yields, A260/280, or A260/230 between the two groups. However, the RIN value of the clot group was significantly lower compared with the non-clot group (p < 0.05), with RIN ≥7.0 found in all non-clot samples and 60% of clot samples (p < 0.05). Furthermore, in the clot groups, the small-clot samples had higher RIN values than large-clot samples (8.25 [7.75-8.75] vs. 6.90 [6.60-7.30], p < 0.001). Conclusions: The formation of large blood clots in PAXgene Blood RNA tubes will reduce the integrity of extracted RNA.

Recommendations for Method Development and Validation of qPCR and dPCR Assays in Support of Cell and Gene Therapy Drug Development

The emerging use of qPCR and dPCR in regulated bioanalysis and absence of regulatory guidance on assay validations for these platforms has resulted in discussions on lack of harmonization on assay design and appropriate acceptance criteria for these assays. Both qPCR and dPCR are extensively used to answer bioanalytical questions for novel modalities such as cell and gene therapies. Following cross-industry conversations on the lack of information and guidelines for these assays, an American Association of Pharmaceutical Scientists working group was formed to address these gaps by bringing together 37 industry experts from 24 organizations to discuss best practices to gain a better understanding in the industry and facilitate filings to health authorities. Herein, this team provides considerations on assay design, development, and validation testing for PCR assays that are used in cell and gene therapies including (1) biodistribution; (2) transgene expression; (3) viral shedding; (4) and persistence or cellular kinetics of cell therapies.

The Effect of Tropical Temperatures on the Quality of RNA Extracted from Stabilized Whole-Blood Samples

Whole-blood-derived transcriptional profiling is widely used in biomarker discovery, immunological research, and therapeutic development. Traditional molecular and high-throughput transcriptomic platforms, including molecular assays with quantitative PCR (qPCR) and RNA-sequencing (RNA-seq), are dependent upon high-quality and intact RNA. However, collecting high-quality RNA from field studies in remote tropical locations can be challenging due to resource restrictions and logistics of post-collection processing. The current study tested the relative performance of the two most widely used whole-blood RNA collection systems, PAXgene^® and Tempus™, in optimal laboratory conditions as well as suboptimal conditions in tropical field sites, including the effects of extended storage times and high storage temperatures. We found that Tempus™ tubes maintained a slightly higher RNA quantity and integrity relative to PAXgene^® tubes at suboptimal tropical conditions. Both PAXgene^® and Tempus™ tubes gave similar RNA purity (A260/A280). Additionally, Tempus^™ tubes preferentially maintained the stability of mRNA transcripts for two reference genes tested, Succinate dehydrogenase complex, subunit A (SDHA) and TATA-box-binding protein (TBP), even when RNA quality decreased with storage length and temperature. Both tube types preserved the rRNA transcript 18S ribosomal RNA (18S) equally. Our results suggest that Tempus^™ blood RNA collection tubes are preferable to PAXgene^® for whole-blood collection in suboptimal tropical conditions for RNA-based studies in resource-limited settings.

Effect of preservation time of formalin-fixed paraffin-embedded tissues on extractable DNA and RNA quantity

OBJECTIVES

This study aimed to investigate the factors affecting the quantity of DNA and RNA extractable from human formalin-fixed paraffin-embedded (FFPE) tissues stored for different lengths of time.

METHODS

We randomly selected 20 FFPE specimens harvested from hysteromyoma patients with uterine fibroids during 2010, 2015, and 2017 at the Department of Pathology, Jiading District Central Hospital Affiliated Shanghai University of Medicine and Health Sciences. DNA and RNA extractions were performed using a DNA/RNA FFPE kit. DNA and RNA concentrations and their OD₂₆₀/OD₂₈₀ ratios were determined by a NanoDrop 2000 spectrophotometer. The human β-globin gene and aldehyde dehydrogenase-2 (ALDH₂) gene were amplified from nucleic acids using a LightCycler 480 Real-Time PCR System, and PCR amplification products were electrophoresed on 1% agarose gels.

RESULTS

Specimens that were stored for longer showed more degradation and a reduced concentration of DNA and RNA after nucleic acid extraction. However, there was no significant difference in DNA or RNA purity. β-globin and ALDH₂ genes could be amplified from more than 99% of specimens.

CONCLUSION

We found that FFPE tissues stored for longer had a reduced quantity of extractable DNA and RNA. However, these tissues could be used for the analysis of some small target genes.

Preanalytical robustness of blood collection tubes with RNA stabilizers

Background

Efficient blood stabilization is essential to obtaining reliable and comparable RNA analysis data in preclinical operations. PAXgene (Qiagen, Becton Dickinson) and Tempus (Applied Biosystems, Life Technologies) blood collection tubes with RNA stabilizers both avoid preanalytical degradation of mRNA by endogenous nucleases and modifications in specific mRNA concentrations by unintentional up- or down-regulation of gene expression.

Methods

Sixteen different preanalytical conditions were tested in PAXgene and Tempus blood samples from seven donors: different mixing after collection, different fill volumes and different 24-h transport temperature conditions after collection. RNA was extracted by column-based methods. The quality of the extracted RNA was assessed by spectrophotometric quantification, A260/A280 purity ratio, RNA Integrity Number (Agilent Bioanalyzer), miRNA quantative real time polymerase chain reaction (qRT-PCR) on two target miRNAs (RNU-24 and miR-16), mRNA quality index by qRT-PCR on the 3′ and 5′ region of the GAPDH gene, and the PBMC preanalytical score, based on the relative expression levels of the IL8 and EDEM3 coding genes.

Results

When PAXgene RNA and Tempus blood collection tubes were used following the manufacturers’ instructions, there was no statistically or technically significant difference in the output RNA quality attributes. However, the integrity of the RNA extracted from Tempus collection tubes was more sensitive to fill volumes and effective inversion, than to storage temperature, while the integrity of RNA extracted from PAXgene collection tubes was more sensitive to effective inversion and storage temperature than to fill volumes.

Conclusions

Blood collection tubes with different RNA stabilizers present different robustness to common preanalytical variations.

Obtaining High-Quality Blood Specimens for Downstream Applications: A Review of Current Knowledge and Best Practices

Blood is a biological fluid that contains multiple blood fraction and cellular components. High-quality blood specimens are essential prerequisites for various downstream applications such as molecular epidemiology studies, genomics, and proteomics studies. Currently, protocols and research publications concerning the collection, handling, preservation, and stability of blood or blood fractions are constantly emerging. Moreover, standardized guidelines are a requirement for biorepositories to tightly control preanalytical variables originating from these procedures and obtain high-quality blood specimen for downstream analyses. In this review article, we summarize the best practices and fit-for-purpose protocols regarding blood collection, processing, storage, and stability. In addition, we present some typical quality biomarkers, which could be used to evaluate the integrity of blood specimens.

MicroRNA in diagnosis and therapy monitoring of early-stage triple-negative breast cancer

Breast cancer is a heterogeneous disease with distinct molecular subtypes including the aggressive subtype triple-negative breast cancer (TNBC). We compared blood-borne miRNA signatures of early-stage basal-like (cytokeratin-CK5-positive) TNBC patients to age-matched controls. The miRNAs of TNBC patients were assessed prior to and following platinum-based neoadjuvant chemotherapy (NCT). After an exploratory genome-wide study on 21 cases and 21 controls using microarrays, the identified signatures were verified independently in two laboratories on the same and a new cohort by RT-qPCR. We differentiated the blood of TNBC patients before NCT from controls with 84% sensitivity. The most significant miRNA for this diagnostic classification was miR-126-5p (two tailed t-test p-value of 1.4 × 10⁻⁵). Validation confirmed the microarray results for all tested miRNAs. Comparing cancer patients prior to and post NCT highlighted 321 significant miRNAs (among them miR-34a, p-value of 1.2 × 10⁻²³). Our results also suggest that changes in miRNA expression during NCT may have predictive potential to predict pathological complete response (pCR). In conclusion we report that miRNA expression measured from blood facilitates early and minimally-invasive diagnosis of basal-like TNBC. We also demonstrate that NCT has a significant influence on miRNA expression. Finally, we show that blood-borne miRNA profiles monitored over time have potential to predict pCR.

EFLM WG-Preanalytical phase opinion paper: local validation of blood collection tubes in clinical laboratories

The selection or procurement of blood collection devices in healthcare facilities is often an underestimated issue. This is probably due to different factors including the lack of knowledge of policymakers, hospital administrators and even laboratory managers about the importance of preanalytical quality and phlebotomy process, as well as to the absence of reliable guidelines or recommendations on how to precisely assess the quality of blood collection devices around the globe. With the awareness that a gap remains between manufacturers' and local validation of blood collection devices, the Working Group for Preanalytical Phase (WG-PRE) of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) has drafted a consensus document aimed to provide a set of essential requisites, technical criteria (e.g. presence of physical defects, malfunctioning, safety problems) and clinical issues for supporting laboratory professionals in organization blood collection tubes tenders and validating new devices before local routine implementation. The laboratory professionals should also make sure that the tenders accurately and strictly define the responsibilities for validation experiments and the potential consequences in the case the validation outcome shows that tubes due not fulfill the expectations.

Stabilization of circulating thyroglobulin mRNA transcripts in patients treated for differentiated thyroid carcinoma

Background The clinical utility of serum thyroglobulin in the follow-up of patients with differentiated thyroid carcinoma may be compromised by the presence of endogenous antithyroglobulin antibodies. To prevent interference by antithyroglobulin antibodies several groups have developed real-time PCR-based assays for quantification of blood thyroglobulin mRNA levels. For accurate quantification of thyroglobulin mRNA in blood preanalytical factors must be recognized and controlled. In this study, we evaluate the effect of different blood RNA stabilizing systems - the Tempus Blood RNA system and the PAXgene Blood RNA system - and storage time on RNA yield and quality, and thyroglobulin mRNA stability. Methods Blood samples from 11 patients previously treated for differentiated thyroid carcinoma were collected in K₂-EDTA, Tempus and PAXgene tubes and maintained at room temperature. RNA was isolated following storage for 0 and 72 h, and RNA yield, integrity and purity was determined. Thyroglobulin, GAPDH and ACTB mRNA levels were quantified by semi-quantitative real-time PCR. Results The RNA yield was significantly higher for blood collected in Tempus tubes compared with PAXgene tubes following storage for 72 h at room temperature ( P = 0.0011). High-quality RNA could be extracted from blood collected in PAXgene and Tempus tubes. Blood collected in K₂-EDTA tubes, but not in PAXgene and Tempus tubes, showed significant changes in thyroglobulin mRNA levels following storage for 72 h at room temperature ( P = 0.0263). Conclusions Stabilization of blood in PAXgene and Tempus tubes enables storage at room temperature for up to 72 h, without compromising thyroglobulin mRNA levels.

Effects of post-mortem and physical degradation on RNA integrity and quality

The precision and reliability of quantitative nucleic acid analysis depends on the quality of the sample analyzed and the integrity of the nucleic acids. The integrity of RNA is currently primarily assessed by the analysis of ribosomal RNA, which is the by far dominant species. The extrapolation of these results to mRNAs and microRNAs, which are structurally quite different, is questionable. Here we show that ribosomal and some nucleolar and mitochondrial RNAs, are highly resistant to naturally occurring post-mortem degradation, while mRNAs, although showing substantial internal variability, are generally much more prone to nucleolytic degradation. In contrast, all types of RNA show the same sensitivity to heat. Using qPCR assays targeting different regions of mRNA molecules, we find no support for 5' or 3' preferentiality upon post-mortem degradation.

Preanalytical Variables Affecting the Integrity of Human Biospecimens in Biobanking

BACKGROUND

Most errors in a clinical chemistry laboratory are due to preanalytical errors. Preanalytical variability of biospecimens can have significant effects on downstream analyses, and controlling such variables is therefore fundamental for the future use of biospecimens in personalized medicine for diagnostic or prognostic purposes.

CONTENT

The focus of this review is to examine the preanalytical variables that affect human biospecimen integrity in biobanking, with a special focus on blood, saliva, and urine. Cost efficiency is discussed in relation to these issues.

SUMMARY

The quality of a study will depend on the integrity of the biospecimens. Preanalytical preparations should be planned with consideration of the effect on downstream analyses. Currently such preanalytical variables are not routinely documented in the biospecimen research literature. Future studies using biobanked biospecimens should describe in detail the preanalytical handling of biospecimens and analyze and interpret the results with regard to the effects of these variables.