home RNA: A Self-Sampling Kit for the Collection of Peripheral Blood and Stabilization of RNA

Abstract

Gene expression analysis (e.g., targeted gene panels and transcriptomics) from whole blood can elucidate mechanisms of the immune function and aid in the discovery of biomarkers. Conventional venipuncture offers only a small snapshot of our broad immune landscape as immune responses may occur outside of the time and location parameters available for conventional venipuncture. A self-operated method that enables flexible sampling of liquid whole blood coupled with immediate stabilization of cellular RNA is instrumental in facilitating capture and preservation of acute or transient immune fluxes. To this end, we developed homeRNA, a kit for self-collection of peripheral blood (∼0.5 mL) and immediate stabilization of cellular RNA, using the Tasso-SST blood collection device with a specially designed stabilizer tube containing RNAlater. To assess the feasibility of homeRNA for self-collection and stabilization of whole blood RNA, we conducted a pilot study (n = 47 participants) in which we sent homeRNA to participants aged 21-69, located across 10 US states (94% successful blood collections, n = 61/65). Among participants who successfully collected blood, 93% reported no or minimal pain/discomfort using the kit (n = 39/42), and 79% reported very easy/somewhat easy stabilization protocol (n = 33/42). Total RNA yield from the stabilized samples ranged between 0.20 and 5.99 μg (mean = 1.51 μg), and all but one RNA integrity number values were above 7.0 (mean = 8.1), indicating limited RNA degradation. The results from this study demonstrate the self-collection and RNA stabilization of whole blood with homeRNA by participants themselves in their own home.

Figure 1.. Workflow and design of homeRNA blood collection and RNA stabilization kits.

A) Workflow for homeRNA, where blood is first collected using the Tasso-SST^™, screwed on tightly to the stabilizer tube, and then shaken to mix with the stabilizer, RNAlater^™. B) Cross-sectional schematic of the stabilizer tube after the cap has been removed. C) Cross-sectional schematic depicting a Tasso-SST^™ blood collection tube filled with blood attached to the stabilizer tube, prior to shaking to mix the blood with the stabilizer.

Figure 2.. Performance of Tempus^™ vs. RNAlater^™ on total RNA yield and RNA quality.

Effect of storage temperature and duration on total RNA yield (μg) and quality (RIN value) of samples stabilized in Tempus^™ vs. RNAlater^™. Digital gel image of Tempus and RNAlater^™ stabilized blood stored at 4°C, 25°C, 30°C and 37°C over 8 days.

Figure 3.. RNA yield and RIN value of peripheral blood samples self-collected and stabilized with homeRNA.

A) Total RNA yield (μg) and B) RIN value and C) droplet digital PCR of GAPDH and UBC from RNA isolated from peripheral blood samples collected and stabilized by participants in their home using homeRNA.

Figure 4.. Survey responses to assess kit usability.

A) Histogram showing total self-estimated time required for each participant to use the kit from start to finish. B) Participant ratings for level of pain or discomfort using the Tasso-SST^™. Numbers represent number of participants. C) Participant ratings for the usability of the different kit components. Numbers represent number of participants.

Figure 5.. Survey responses to assess kit performance.

A) i) Participant responses when asked to estimate the approximate blood level they filled the Tasso-SST^™ blood collection tube based on the ii) picture provided in the online survey. The volumes corresponding to each level are noted in Aii. B) Participant responses when asked how long they left the Tasso-SST^™ blood collection tube on their arm - this includes time before collection and after collection has stopped before removal of the device.