At-home blood collection and stabilization in high temperature climates using home RNA

Abstract

Expanding whole blood sample collection for transcriptome analysis beyond traditional phlebotomy clinics will open new frontiers for remote immune research and telemedicine. Determining the stability of RNA in blood samples exposed to high ambient temperatures (>30°C) is necessary for deploying home-sampling in settings with elevated temperatures (e.g., studying physiological response to natural disasters that occur in warm locations or in the summer). Recently, we have developed homeRNA, a technology that allows for self-blood sampling and RNA stabilization remotely. homeRNA consists of a lancet-based blood collection device, the Tasso-SST™ which collects up to 0.5 ml of blood from the upper arm, and a custom-built stabilization transfer tube containing RNAlater™. In this study, we investigated the robustness of our homeRNA kit in high temperature settings via two small pilot studies in Doha, Qatar (no. participants = 8), and the Western and South Central USA during the summer of 2021, which included a heatwave of unusually high temperatures in some locations (no. participants = 11). Samples collected from participants in Doha were subjected to rapid external temperature fluctuations from being moved to and from air-conditioned areas and extreme heat environments (up to 41°C external temperature during brief temperature spikes). In the USA pilot study, regions varied in outdoor temperature highs (between 25°C and 43.4°C). All samples that returned a RNA integrity number (RIN) value from the Doha, Qatar group had a RIN ≥7.0, a typical integrity threshold for downstream transcriptomics analysis. RIN values for the Western and South Central USA samples (n = 12 samples) ranged from 6.9-8.7 with 9 out of 12 samples reporting RINs ≥7.0. Overall, our pilot data suggest that homeRNA can be used in some regions that experience elevated temperatures, opening up new geographical frontiers in disseminated transcriptome analysis for applications critical to telemedicine, global health, and expanded clinical research. Further studies, including our ongoing work in Qatar, USA, and Thailand, will continue to test the robustness of homeRNA.

Keywords: RNA stabilization; global health; high temperature sampling; home blood sampling; personalized medicine.

Figure 1

Typical process for using homeRNA from collection to processing of samples. (A) Collection and stabilization of blood using homeRNA. (i) Process of collecting blood from the upper arm with Tasso device and stabilizing the sample with the homeRNA custom stabilizer tube. Image was reprinted with permission from Haack, Lim et al. homeRNA: A Self-Sampling Kit for the Collection of Peripheral Blood and Stabilization of RNA. Anal. Chem. 2021, 93, 39, 13196–13203. Copyright 2021 American Chemical Society (23). (ii) Map depicting locations of participants in the small pilot studies conducted in Qatar and the Western and South Central USA. Note, participants in Qatar collected samples themselves in a lab setting. (iii) illustration demonstrating a participant connecting the Tasso blood tube and the homeRNA stabilizer tube, (iv) homeRNA kit on a coffee table, depicting a home setting for blood collection. (B) Illustration demonstrating two possible locations where samples may be exposed to high temperatures including (i) located on a front porch waiting to be picked up (which was the pickup location for many participants in the Western and South Central USA pilot study) and (ii) in transit in a delivery truck or courier service. (C) final step of sample processing for downstream analysis in a laboratory setting.

Figure 2

Quality of isolated RNA from stabilized homeRNA samples exposed to high external temperature spikes in Doha, Qatar. (A) External temperature fluctuation experienced by self-collected and stabilized blood samples after storage at ambient temperature (21°C) for 27 h. External temperature reached a maximum of 41°C. Black data points indicate the measured temperature; gray dashed lines are included to connect the points to guide the eye only (transitions between temperatures may not be linear). (B) Digital gel image of RNA isolated from homeRNA blood samples with corresponding RIN values. Samples 2a and 2b were from the same participant. Samples 1 and 2a did not undergo temperature fluctuations (they were frozen down at −80°C after overnight ambient temperature incubation to use as controls). (C) Scorable RIN values for each blood sample not exposed (control) and exposed (temperature fluctuation) to high temperature spikes along with the reported approximate blood volume collected by each participant. Participants 6 and 8 yielded too low of a RNA concentration to be detected using the RNA 6000 Nano kit.

Figure 3

Quality of isolated RNA from stabilized homeRNA samples collected during the summer in the Western and South Central USA. (A) Digital gel image of RNA isolated from homeRNA stabilized blood samples with corresponding RIN values, with (i) samples diluted 1:5 with nuclease-free water and run with a RNA 6000 Pico kit and (ii) samples run with a RNA 6000 Nano kit without dilution. Participant 1 contributed two samples, 1a and 1b, that were collected and stabilized on different days and at different temperatures. (B) (i) RIN values from blood collected and stabilized at different indoor ambient temperatures during summer and (ii) RIN values according to the outdoor temperature high reported on the day of collection. Each participant was asked to report the approximate blood volume collected before stabilization based on Supplementary Figure S6 in the collection survey.