Ultrasensitive detection of telomerase activity in a single cell using stem-loop primer-mediated exponential amplification (SPEA) with near zero nonspecific signal

Telomerase is a crucial biomarker for cancers. Its reliable and sensitive detection, particularly in a single cell, has great significance for the early diagnosis of cancers, studies on tumor progression and anticancer therapy, which remain a challenge, due to nonspecific amplification. Herein, we developed a novel stem-loop primer-mediated exponential amplification (SPEA) strategy, which can specifically and efficiently amplify the telomerase-elongated telomere repeat unit with near zero nonspecific signal. The SPEA-based assay can accurately detect telomerase activity in the crude lysate of a single cell and is suited for detecting the cellular heterogeneity arising from cell-to-cell variations.