Longitudinal gene expression from dried blood microsamples: a pilot study

Traditional blood collection for whole blood gene expression profiling and biomarker analysis often requires a visit to a healthcare professional, posing challenges for special populations (sick, fragile health, immobile), or for large-scale studies requiring repeated sampling. Blood microsampling, the process of obtaining small volumes of capillary blood, holds great promise to overcome these challenges. We have developed a cost-effective, high-throughput platform for processing self-collected blood microsamples using Mitra Volumetric Adsorptive Microsampling (VAMS) devices for downstream RNA sequencing.

To evaluate the power of our technology, we conducted a study with 12 healthy volunteers. Participants used VAMS devices pre-treated with an RNA stabilizer to collect blood microsamples at 7 designated timepoints on the same day: before breakfast, 30 minutes and 3 hours after breakfast, 30 minutes and 3 hours after lunch, after sports (optional), and before sleep. Upon returning the samples, RNA was isolated using Maxwell RSC-simplyRNA blood kit (Promega). A cDNA sequencing library was prepared using the QuantSeq Pool kit (Lexogen) with in-house globin blockers and sequenced on the NextSeq 2000 P2 flow cell (Illumina).

Results showed high donor dependent gene expression patterns and hemoglobin RNA levels, and timepoint-specific variability across donors. Differential expression and gene set enrichment analyses revealed specific patterns, such as significant upregulation of insulin metabolism-related genes post-breakfast. Future data analysis strategies will include the enumeration of specific immune cells and the determination of the donor’s molecular age.

This study showcases the power of a robust, low-cost and self-collected capillary blood microsampling platform that preserves RNA quality and enables the detection of changes in gene expression before and after specific perturbations. Several applications can be envisaged, including at-home collection of blood by a cancer patient undergoing chemotherapy, sparing a visit to the clinic.