To the homeRNAmax: Developing an Improved Blood Self-Collection and Stabilization Platform for Remote Transcriptomic Studies.

Shifting human subjects research from research sites to participants' homes removes barriers to participation. Previously, we developed homeRNA, a kit for stabilization of RNA in self-collected blood using a custom-engineered tube containing RNA stabilizer fluid. The stabilized RNA is extracted and used for downstream gene expression analysis. Here, we introduce homeRNAmax, which improves our original design by interfacing with a commercially available blood collection tube (BD Microtainer), allowing homeRNAmax to be used with any blood collection method that uses this tube and doubling the possible sample volume that can be collected and stabilized compared to the original homeRNA. Through a pilot study (n = 19 participants), we show that homeRNAmax (with the Tasso+ blood collection device) produces RNA samples of sufficient quality (mean RIN = 7.8) and yield (mean yield = 1.93 μg) for downstream analysis and can reach participants across the United States, who generally (n = 17/19) found the homeRNAmax kit easy to use. We also present RNA integrity data from an ongoing longitudinal clinical study using homeRNAmax in rheumatology (mean RIN = 7.1). A key aspect of the homeRNA and homeRNAmax platforms is a fluidic feature that prevents the RNA stabilizer from spilling, for which we developed a theoretical model. In brief, fluid in the tube is suspended due to a balance of pressures; an increase in air volume within the tube reduces the air pressure above the fluid, creating a small vacuum, and preventing fluid leakage. Overall, we show that homeRNAmax is a user-friendly, effective tool for remote blood RNA stabilization.