Redefining Preterm Birth Prediction: Study Discovering the Power of Small RNAs

Significant risk factors associated with maternal and neonatal health stem from spontaneous preterm labor (PTL), which accounts for approximately 70% of preterm births. Current biomarkers lack prediction reliability, highlighting the need for novel, non-invasive indicators. Emerging research on tRNA-derived small RNAs (tsRNAs), however, shows promise in this exploration yet remains underinvestigated in relation to PTL.

Recent study analyzed publicly available small RNA sequencing datasets (PRJNA415953 and PRJNA428989). The analysis included peripheral blood plasma and exosomes collected from women diagnosed with spontaneous PTL and term controls during early pregnancy (12±1 weeks of gestation). The tsRNA profiles were assessed for differential expression using normalized reads per million (RPM) and subjected to statistical analysis (Wilcoxon tests) against established thresholds (p ≤ 0.05, |log2(Fold Change)| ≥ 1). Specifically, tsRNA1 (tRNA-Gly-GCC-5p-tRF-921) was identified and subsequently validated through functional assays, RT-qPCR, and transcriptomic profiling of human HTR-8/SVneo trophoblast cells.

Key Results:

• Differential Expression: Analysis showed multiple tsRNAs were significantly upregulated in the samples from PTL cases compared to controls, particularly in plasma extracellular vesicles (EVs). This included 32 upregulated tsRNAs in whole blood and associated variations in terms of specific tRF types.

• Functional Role of tsRNA1: Overexpression of tsRNA1 in trophoblast cells induced apoptosis and inhibited critical processes like cell migration, adhesion, and invasion, pivotal for placental development.

• Epigenetic Modulation: Transcriptomic analysis indicated that tsRNA1 modulates genes involved in DNA methylation (in particular TET1 and DNMT1), suggesting tsRNA1’s role in establishing a hypermethylated state, which could contribute to impaired trophoblast function and further the risk of PTL.

Limitations:

• The primary use of the HTR-8/SVneo cell line may not fully replicate the behavior of primary extravillous trophoblasts (EVTs), necessitating validation in more physiologically relevant systems.

• There was no direct evidence provided concerning metabolic changes or validation methods for assessing extracellular vesicle purity. The absence of quantitative data, such as nanoparticle tracking analysis, limits the interpretation of the isolated vesicle types.

The findings position tsRNA1 and tsRNA3 as potential biomarkers for early prediction of PTL, emphasizing the necessity for further validation in larger cohorts and exploration of their mechanistic role in pregnancy complications.

Key Points -

Spontaneous Preterm Labor Contribution: Spontaneous preterm labor (PTL) is responsible for approximately 70% of preterm births, highlighting the urgency in identifying reliable biomarkers for early prediction and clinical intervention.

Biomarker Discovery and tsRNAs: Emerging research points to tRNA-derived small RNAs (tsRNAs) as promising candidates for novel, non-invasive biomarkers linked to PTL. However, their application in this area remains underexplored.

Differential tsRNA Expression in PTL: Analysis of publicly available small RNA sequencing datasets revealed significant upregulation of several tsRNAs in peripheral blood plasma and exosomes from women diagnosed with PTL. Specifically, 32 tsRNAs were identified as upregulated in whole blood, with notable variations in specific tRNA fragment types.

Functional Implications of tsRNA1: The overexpression of tsRNA1 (tRNA-Gly-GCC-5p-tRF-921) in trophoblast cells induced apoptosis and negatively impacted vital cellular processes, including migration, adhesion, and invasion, which are critical for healthy placental development.

Epigenetic Influence on Trophoblast Function: Transcriptomic profiling indicated that tsRNA1 influences the expression of genes associated with DNA methylation, such as TET1 and DNMT1, leading to a hypermethylated state that may compromise trophoblast function, thus increasing the risk of PTL.

Research Limitations and Future Directions: The reliance on the HTR-8/SVneo cell line may not accurately mimic primary extravillous trophoblast behavior, underscoring the need for validation in more relevant models. Additionally, a lack of quantitative data regarding extracellular vesicle purity limits the study's conclusions, indicating that larger cohort studies are necessary to validate tsRNA1 and tsRNA3 as biomarkers and to elucidate their mechanistic roles in PTL.

Reference –

Xinrui Sun et al. (2025). Maternal Plasma Extracellular Vesicles TsRNA As Potential Biomarkers For Assessing Preterm Labor Risk. *BMC Pregnancy And Childbirth*, 25. https://doi.org/10.1186/s12884-025-07672-3.