Sample Collection and Preservation

Täby, Sweden: – In the current ‘omics’ era, there seems to be no limit to the number of ways we can investigate our favorite organism or cell type. We can study genomes, transcriptomes, epigenomes, metabolomes, proteomes, kinomes, and more. Parallel advances in flow cytometry and other immunological techniques make it possible for us to simultaneously detect and profile new and characterized biomarkers in robust multiplex setups.

With continuous method improvements and an ever-expanding choice of high performance commercial kits and reagents, it’s never been easier to perform cutting edge research. However, the success of all applications hinges upon on one critical starting point. High quality samples!

Our last article focused on how proper sample collection and preservation are critical in the field of microbiomics. This article will look at sample collection and preservation more broadly, describing why they are so critical, and how you can address these for virtually any sample type.

So What Could Possibly Go Wrong?

The exact consequences of poor sample collection and storage will differ depending on the downstream application, and most protocols have certain critical steps that require extra attention. That being said, the final results from any experiment are likely to be influenced by every single step in the process, starting with sample collection.

Samples for Nucleic Acid Analysis

Samples destined for nucleic acid isolation and analysis e.g., PCR and sequencing are particularly sensitive to nucleic acid degradation through enzymatic activity, biological, and environmental factors. Degradation affects not only the overall yield, but it may also lead to a false representation of the genomic or transcriptomic profile of your sample.

Changes to the overall nucleic acid profile of a sample are of particular concern in microbiomics research. However, the implications can be just as severe for gene expression studies. For instance, it’s easy to assume that good quality and high yield RNA obtained after careful RNA isolation from bacterial cells will result in reliable gene expression data if nothing goes wrong with downstream cDNA synthesis and PCR. But what about the changes those bacterial cells might undergo between the time you harvest them and when you start isolating RNA? If you’re not extremely well prepared, the expression levels of the gene(s) of interest could fluctuate while you wipe your bench down and get your reagents ready for RNA isolation! If you’re comparing your data to a previous experiment carried out the same way, you may never find out about these fluctuations!

Samples for Immunological Applications

Immunological applications such as flow cytometry, ELISA, Western blotting, and immunoprecipitation rely on the formation of immune complexes between the target antigen (e.g., a cell surface marker or a blood-borne biomarker) and the specific antibody that recognizes it. Proper sample handling and storage are critical for such applications because alterations to the antigen(s) of interest can severely impact the experimental outcome. For instance, freezing may alter the protein structure of the marker you are trying to detect and prevent it from being bound by an antibody, leading to false negative results. Avoiding such problems is critical where clinical samples are concerned.

Something for Everyone

Whether you work with nucleic acids or immunological techniques or both, we can assist you in finding the best way to protect your samples. The following sections will detail the collection and preservation options we currently offer for a wide range of sample types.

Whole Blood

Through Streck Inc., we supply direct-draw Cyto-Chex Blood Collection Tubes (BCT) for the preservation of whole blood samples for immunophenotyping by flow cytometry. The preservative in Cyto-Chex BCT maintains the integrity of the white blood cell cluster of differentiation (CD) markers for up to 14 days at room temperature for convenient transport, storage and processing.

Streck’s Cell Preservative can also be purchased as a standalone reagent, and is ideal for the storage and stabilization of bone marrow aspirates, surgical tissue samples, fine needle aspirates, and peripheral and umbilical cord blood for up to 7 days at room temperature.

For a complete stabilization solution for phenotyping, we offer Cytomark’s TransFix® range, which stabilizes cellular antigens and prevents cellular degradation in a variety of sample types, including: whole human and animal blood, cerebrospinal fluid (CSF), bone marrow, and circulating tumor cells. The range includes CE/IVD marked EDTA Vacuum Blood Collection Tubes, Sample Storage Tubes (without coagulant), specialized EDTA CSF Sample Storage Tubes, and Phlebotomy Packs for the drawing and stabilization of whole blood samples.

For flexibility, Cytomark’s CE/IVD cellular antigen stabilization reagent can be purchased alone in a variety of sizes (TransFix Bulk). Cytomark’s collection devices and reagents ensure sample stabilization upon refrigeration for up to 14 days.

DNA/RNA Shield™ from Zymo Research is suitable for storage and stabilization of whole blood samples, and is available in specialized Blood Sample Collection Tubes or as a more concentrated stand-alone preservative for flexibility in storing larger volume samples (2x concentrate).

Finally, Norgen Biotek offers a specialized Blood DNA Preservative Buffer (3x) for DNA stabilization in high volume samples, rendering them suitable for 2 weeks storage at room temperature.

cfDNA and cfRNA from Blood

Streck’s cfDNA Blood Collection Tubes (BCT) contain a preservative that stabilizes nucleated blood cells and prevents genomic DNA release, allowing cfDNA isolation for use in a range of downstream applications e.g., liquid biopsy, assay development, sequencing, and real-time PCR.

Streck’s cfRNA BCT contain a patented preservative that stabilizes cfRNA in plasma and prevents the release of non-target background RNA during sample processing and storage. With Streck’s BCT, cfDNA and cfRNA are stable for 14 days or 7 days, respectively, at ambient temperature. Streck’s BCT are available in research-use only and CE-IVD formats.

Norgen Biotek provides cfDNA and cfRNA Preservative Tubes that allow room temperature preservation of cfDNA and cfRNA for up to 30 days, while samples for cfDNA analysis can be stored for 8 days at 37 °C for even greater flexibility. Both cfDNA and cfRNA tubes preserve circulating tumour cells (CTCs) for 14 days at ambient temperature, and are available in research-use only and CE-IVD formats.

Stool

Quantitative nucleic acid profiling of stool samples has taken off in recent years, fuelled largely by the explosion in microbiome research. Here, one of the most critical aspects is obtaining a molecular snapshot of the sample at the exact point of collection. To this end, we offer a range of stool collection devices containing specialized preservatives to stabilize and protect nucleic acids while simultaneously deactivating microbes, thus ‘freezing the sample in time’, rendering it safe for transport at ambient temperature.

Specifically, we offer Norgen Biotek’s Stool Nucleic Acid Collection and Preservation Tubes, Stool Nucleic Acid Collection and Preservation System, and a complete Fecal Swab Collection and Preservation System, all of which stabilize both DNA and RNA at ambient temperature for 2 years or 7 days, respectively. For smaller sample amounts (30 mg), we also offer the Fecal DNA Collection and Preservation Mini Tubes from Norgen Biotek. DNA can be preserved in these tubes for up to 27 months at room temperature. The mini tubes also contain an aliquot of beads for convenient mechanical lysis of stool samples.

DNA/RNA Shield™ from Zymo Research is also available in Fecal Collection Tubes, permitting room temperature storage of stool samples (1 g) for up to 1 month (for RNA) or 2 years (for DNA).

Urine

Streck Cell-Free DNA Urine Preserve is a formaldehyde-free aqueous reagent that stabilizes cellular components and cfDNA in urine for up to 7 days across a wide temperature range (6 °C – 37 °C). The preservative enhances the stability of cfDNA and prevents lysis of nucleated blood cells and release of cellular genomic DNA. Isolated cfDNA is highly suited to a range of downstream applications, such as prenatal diagnosis, disease diagnosis, treatment efficacy monitoring, and organ transplant rejection monitoring.

Zymo Research offers a specialized Urine Conditioning Buffer, which is a highly concentrated preservative to facilitate convenient storage of large volumes of urine. Urine in this buffer can be stored for up to 1 month at room temperature. The Urine Collection Kit from Zymo Research combines the Urine Collection Cup and the Urine Conditioning Buffer offering you an all-in-one solution for urine collection and preservation.

From Norgen Biotek, we offer a Urine Preservative that ensures long-term stability of RNA, miRNA, DNA and proteins for up to 2 years at room temperature. This reagent is highly versatile, stabilizing cell-free macromolecules, exfoliated cells and microorganisms. The same preservative is also available as a dried powder in Norgen Biotek’s Urine Collection and Preservation Tubes, which are conveniently available in 3 different sizes.

Saliva and Swabs

Saliva and swab analysis is gaining traction throughout research and diagnostics e.g., study of the oral microbiome, study of disease biomarkers, and non-invasive genetic testing in saliva. Obtaining and preserving a good saliva or swab sample is critical to success in these areas.

For simple and non-invasive saliva collection and preservation, we offer Norgen Biotek’s collection devices for room temperature preservation of DNA or RNA for up to 5 years or 2 months, respectively. The preservatives contained in these devices are aqueous storage buffers that simultaneously stabilize nucleic acids, while ensuring rapid cell lysis and complete microbial inactivation. Preserved nucleic acids can be isolated from saliva and swabs using most commercially available isolation kits. For DNA analysis, these saliva collection and preservation devices are available in research-use only and CE-IVD formats.

For swab collection and preservation, we offer solutions from Norgen Biotek and Zymo Research. Norgen Biotek’s Swab Collection and DNA Preservation Kit permits sample storage for up to 2 years at room temperature. Zymo Research supplies swabs in collection tubes with DNA/RNA Shield™, which preserves both DNA and RNA for up to 2 years or 1 month, respectively, when samples are stored at room temperature.

Tissues

DNA/RNA Shield™ from Zymo Research is suitable for collection and storage of all tissue types and can be custom-filled into customer-supplied vials or collection tubes to meet the varied needs of researchers. To facilitate a smoother sample collection and tissue lysis process, Zymo Research also offers lysis tubes containing DNA/RNA Shield™ and Bashing Beads™ for highly efficient mechanical lysis of all tissue types e.g., insect tissue and biopsies. With DNA/RNA Shield™ , DNA or RNA is stable for up to 2 years or 1 month at room temperature, respectively.

Note: DNA/RNA Shield™ exhibits cell lysis activity and may therefore not be suitable for samples destined for immunological applications

Milk

Norgen Biotek’s Milk DNA Preservation and Isolation kit provides an all-in-one solution for the collection, preservation and isolation of DNA from milk at room temperature. Milk samples are stable for 1 month at room temperature or 1 week at 37°C, and DNA from both mammalian and bacterial cells can be isolated from as little as 100 μl milk.

Take the Lab to the Field

For those who work in the field, we can provide the TerraLyzer™ from Zymo Research, a handheld mechanical disruption device for cordless, portable, and convenient homogenization of difficult-to-lyse biological and environmental samples. This device allows researchers to “Take the Lab to the Field” and allows on-the-spot lysis of samples at the sites of collection. Although ideal for those who carry out fieldwork, the TerraLyzer™ may also be an excellent solution for labs that don’t have access to high-throughput mechanical disruption equipment.

By Your Side™ in Life Science Research

We regularly update our portfolio to meet the varied needs of our academic and clinical researchers and we hope you will easily find something that suits your sample type. If not, let us know and we will put you in touch with a local team member who will assist you in your search.

To take a closer look at the products featured in this article, download our Sample Collection and Preservation Booklet, or get in touch with us at [email protected].