Figure 1. The schematic diagram of storage for blood, urine and tissue samples.
Once the donor's informed consent is obtained and the sample is collected, the samples from donors need to be safely stored. Most biological samples must be stored at low temperatures and the collected samples should be stored immediately as required (Figure 1). At the same time, the information of samples should be well documented.
Figure 2. The schematic diagram of storage location for blood samples.
At present, the processed blood and urine samples are stored in three different places (Figure 2). Three samples from the same donor are placed into 3 different cryoboxes, which are stored at different liquid nitrogen tanks. Fresh tissue samples are stored in liquid nitrogen tanks in a timely manner.
1 Containers for Storing Samples
1.1 Cryoboxes and Cryotubes
Cryoboxes and cryotubes are low temperature resistant and can be used in liquid nitrogen. The processed samples are dispensed into the cryotubes according to Standard Operating Procedures (SOPs). Each cryotube or cryobox has a one-dimensional code or two-dimensional code number that records the position of the sample. Before the samples are placed into the liquid nitrogen tanks, the cryotubes and cryoboxes are scanned and the corresponding information is recorded.
1.2 Ultra-Low Temperature Refrigerators
The ultra-low temperature refrigerator are used to preserve biological samples such as plasma, biological materials, bacteria and reagents. The temperature of these refrigerator need to be properly controlled to ensure the stability of the stored objects. They are usually cleaned once a month to keep clean.
1.3 Liquid Nitrogen Tanks
Liquid nitrogen keeps the samples at a low temperature of -196 ℃, which is the best storage temperature that can be achieved under current technical conditions. In Zhongnan Biobank, most of the samples are stored in the gas-liquid nitrogen tanks, in which mutual contamination between samples can be avoided.
2 Storage Temperature
2.1 Effect of storage temperature on the samples
The temperature should be as low as possible for the samples to reduce biochemical reactions and ensure the stability of various components. The common storage temperature of biological macromolecules, cells, tissues and organs is -80 ℃ or -196 ℃. Generally, the lower the temperature, the longer the samples are kept.
2.2 Cryopreservation and use of samples
Samples should be stored under stable conditions to avoid repeated freezing and thawing. Before the samples are frozen, they are packed into a few small portions for storage, and the stability and quality of the samples must be ensured by the Standard Operating Procedures (SOP)Upon use, necessary measures such as melting and antibiosis should be used.
3 Daily management
3.1 Information
The information is recorded at every step of the sample management and the complete information is periodically imported into our information management system. The samples' information corresponds to the donors' information which can be queried from the Hospital Information System (HIS) by the patient's hospital number and identity number.
3.2 Storage
The position of the sample is pre-planned and all the cryoboxes placed into the refrigerators or liquid nitrogen tanks are pre-labeled. The labels contain the location information of samples and the cryoboxes. Cryotubes are placed in the cryoboxes according to the pre-assigned position information and the barcodes on the cryotubes are scanned to achieve synchronous storage using the software.
3.3 Management
With the management software, the information query, statistics and application management of samples could be achieved. Different colors are used to display storage situation of samples on the main interface of the computer and different types of samples are marked with different colors. The samples were stored at 3 different places to lower the storage risk.