Proteins stay intact in dried blood samples
A drop of blood on filter paper, allowed to dry and kept until diagnosis – a considerably easier option than the present-day, resource-consuming method using frozen blood samples in plastic tubes. This current study from Uppsala university/SciLifeLab have successfully measured 92 different proteins in millimetre-sized circles punched out of dried samples. The results opens new doors for health care as resources can be saved and new diagnostic opportunities arise.
Stored blood samples are of utmost importance for finding disease markers that can be used for early detection of diseases, when they are still curable. Today, the patient must first visit healthcare unit where a trained nurse obtains a venous blood sample, which is sent to a lab for separation of plasma and blood cells. The test tubes holding blood plasma are then kept in big freezers. All in all, a resource-consuming method.
In the present study, led by Professor Ulf Landegren at Uppsala University/SciLifeLab, the researchers analysed dried blood spots. Some had been collected recently, while others had been preserved for up to 30 years in biobanks in Sweden and Denmark that store samples taken from all newborn babies for screening of congenital metabolic disorders. The samples were used to analyse levels of 92 proteins that are relevant in oncology. Wet plasma samples, kept in freezers for corresponding periods of time, were also used.
The examination reveal that, in many cases, proteins remain unaltered even after 30 years. Consequently, dried samples could be used for health services’ routine checks as well as to set up very large-scale biobanks. Costs in the healthcare sector would plunge, more samples could be analysed and a high proportion of all blood samples taken could be saved.
“Our conclusion is that we can measure levels of 92 proteins with very high precision and sensitivity using PEA (Proximity Extension Assay) technology in the tiny, punched-out discs from a dried blood spot. The actual drying process has a negligible effect on the various proteins.” says Johan Björkesten, doctoral student at Uppsala University and the first author of the study.
The use of dried blood spots has a range of advantages over using larger samples of blood. Examples are minimal stress for patients since a tiny, self-administered prick on the finger suffices; costs of collection and storage are low; no highly trained staff are required for the sampling; samples can be sent by letter post; and storage conditions are simple.
“This has several implications. First, you can prick your own finger and send in a dried blood spot by post. Second, at a minimal cost, it will be possible to build gigantic biobanks of samples obtained on a routine clinical basis. This means that samples can be taken before the clinical debut of a disease, to identify markers of value for early diagnosis, improving the scope for curative treatment,” says Ulf Landegren, Professor of Molecular Medicine at Uppsala University and member of SciLifeLab Faculty.