(Extraction and bio-banking of Iranian population DNA for genomics studies)
Omics-based studies provide valuable information on current and future public health status. Access to high-quality biological samples is required to make omics-based analysis unbiased and fit for purpose. To date, there is no universal agreement on the standard operating protocol (SOPs) developed for sample collection, processing and biobanking. Depending on the research question/aim, different biological samples can be selected for omics analyses. Blood, serum, plasma, buffy coat and urine are extensively used for genomics, proteomics and metabolomics analyses owing to widespread availability and ease of processing. The most important step in omics-based studies is a fitting collection, labelling, and biobanking of biological samples. The STEPs (Large-Scale Cross-Sectional Studies of Surveillance of Risk Factors of Non-Communicable Diseases) and subsequent omics studies are aimed at assessing the health problem associated with non-communicable diseases in the Iranian population. Besides biological samples (e. g. whole blood, plasma, buffy coat and urine), Valuable information on demography, socioeconomic status, diet, physical activity, smoking, lifestyle, and diabetes, hypertension, and hyperlipidaemia treatment of all participants was also collected. The aim of this study is development of consensus omics-based SOPs that are generalizable and feasible for every research group in every laboratory.
We collected the biological samples (e. g. blood, plasma, buffy coat and urine) from 21000 participants randomly selected from the urban and rural area of 31 provinces of Iran, as a sub-component of STEPs survey (Large-Scale Cross-Sectional Studies of Surveillance of Risk Factors of Non-Communicable Diseases) 2016 in Iran. These samples were collected, processed, transferred and stored based on the standard protocols that ensure the quality and fitness of biological samples for all fields of omics analyses. The quality assured and validated protocols were developed for long-time storage of biological samples in the biobank. All variable parameters (i. e. contamination, maintenance, temperature, time, the number of freeze-thaw cycle and storage condition) that affect the quality of biological samples and omics outcomes were considered in protocol development. The information technology protocols were also developed to improve data recording/storage and biobank management.
The biological samples (e. g. blood, plasma, buffy coat and urine) were collected from 21000 volunteers aged 25 and above through STEPs survey. Immediately after sample delivery in central processing/archiving center, they were processed as soon as possible and subjected to biochemical tests, aliquotation and storage in the biobank. As multiple freeze/thaw cycles affect the stability of biomolecules and quality of biological samples, we prepared multiple aliquots of whole blood and plasma for each field of omics and using each aliquot only once. All sample aliquots were prepared under the sterile condition and respectively 2, 2, 1 and 1 separate aliquots of whole blood, plasma, buffy coat and urine stored in the biobank, per each participant. The biobank developed in this study can be used to store more than 600,000 cryotubes. At the end of this project, about 126,000 aliquot tubes (1.4 ml) were stored in STEPs biobank. In order to guarantee the long-term storage and integrity of biological samples, they archived in two geographically separated locations.
Freezers used in the STEPs study biobank were equipped with a cooling system which keeps the temperature up to minus eighty Celsius degrees and they also have an alarming system monitoring temperature changes.