Synchronization of Human Circadian Genes Between in vivo and Cultured Blood Samples

Transcriptomic studies of human circadian rhythm are limited in efficacy by the invasiveness of sampling. Studies of circadian dynamics should ideally use multiple blood samples drawn at regular intervals over the course of a day. This is difficult to achieve, particularly at night, without disrupting the very circadian rhythm that is being studied. We propose a method by which blood is drawn at a single initial timepoint, then cultured and repeatedly sampled over the course of a day. This method is minimally invasive to the subject. Our results demonstrate that the expression levels of circadian genes are more closely correlated between the cultured (ex vivo) cells and live (in vivo) samples than non-circadian genes, suggesting that this method can be used for effective circadian analysis.