RNA profiling of cell-free saliva using microarray technology.

Saliva, like other bodily fluids, has been used to monitor human health and disease. This study tests the hypothesis that informative human mRNA exists in cell-free saliva. If present, salivary mRNA may provide potential biomarkers to identify populations and patients at high risk for oral and systemic diseases. Unstimulated saliva was collected from ten normal subjects. RNA was isolated from the cell-free saliva supernatant and linearly amplified. High-density oligonucleotide microarrays were used to profile salivary mRNA. The results demonstrated that there are thousands of human mRNAs in cell-free saliva. Quantitative PCR (Q-PCR) analysis confirmed the present of mRNA identified by our microarray study. A reference database was generated based on the mRNA profiles in normal saliva. Our finding proposes a novel clinical approach to salivary diagnostics, Salivary Transcriptome Diagnostics (STD), for potential applications in disease diagnostics as well as normal health surveillance.