Capillary earlobe blood may be used for RNA isolation, gene expression assays and microRNA quantification

An increasing number of studies examining gene expression associated with diseases in children is likely, in the near future, to provide simple and easy to use methods for the isolation of RNA for gene expression profiling. Prerequisites for such studies are likely to encompass the use of small amounts of blood, as well as less invasive blood collection methods. In the current study, RNA was isolated from 20 µl capillary blood samples from the earlobes of 10 adults for quantitative PCR experiments. The results were compared with RNA isolated from venipuncture samples of the 10 samples. The expression of 4 mRNAs and 1 microRNA (miRNA), miRNA‑126, was measured. The quantitative PCR results obtained with the capillary blood probes were similar to results using venous blood samples. The few differences observed may result from a variation in the blood cell composition. The use of capillary blood samples from the earlobe for gene expression analysis is likely to allow this method to be used in newborns, babies and children. In addition, such a method, using microliters of blood samples, may also be useful for other medical studies e.g., in cases where repetitive blood sampling is necessary or in patients with bleeding disorders.