Rapid liquid biopsy assessment through gene profiling from the kidney biopsy transport medium: A technical validation and a proof-of-concept pilot study

Rapid diagnosis is pivotal in kidney disease for timely and precise therapy. Conventional microscopic and molecular assessments from biopsy tissues rely on extra sample processing, making same-day diagnosis impractical. Therefore, we introduce the biopsy transport medium (BTM), a byproduct of the biopsy tissue storage process that could serve as a source of biomarkers, accelerating the assessment workflow. Biopsies from tumor-free nephrectomy tissues were used to create a mimicked BTM, allowing optimization of the RNA extraction procedure. RNA yield and integrity were then systematically evaluated before downstream analyses. Subsequently, gene expression analysis was performed through multiple techniques: quantitative polymerase chain reaction, RNA sequencing, and the NanoString nCounter system. The results showed that storage time (the duration a biopsy is stored in BTM), ranging from 0.5 to 24 hours, did not significantly affect RNA quality and yield. The transcriptomic signals detected in biopsy tissues are largely recapitulated in the corresponding BTM samples. The differential gene expression analysis based on BTM identified rejection-associated profiles, which are aligned with Banff lesion scores. This study confirms BTM's ability to provide transcriptomic information relevant to the state of the kidney and supports BTM's potential for same-day molecular diagnosis, especially with tailored quantitative polymerase chain reaction panels for rapid, targeted analysis.