Question: Can I perform Spatial Gene Expression analysis using older FFPE blocks?
Answer: As is common with sequencing-based assays using FFPE tissue, the quality of data will depend on the fragmentation level of the RNA in the analyzed tissue. Age, tissue type, cold ischemic time, healthy vs diseased tissue, etc. impact RNA quality. For this reason, we don't use age to gauge the expected assay performance.
RNA fragmentation has been found to be a reliable predictor of expected assay performance. DV200% is the percentage of total RNA fragments that are larger than 200 nt. Based on in-house experiments, we've found that as the DV200 metric drops lower than 50%, the reliability of generating high-quality gene expression data also declines. Therefore, we recommend that customers use tissue blocks with DV200 ≥50% (regardless of the age of the block) with our Visium for FFPE assay.
Details on how to perform RNA Quality Assessment are in our Tissue Preparation Guide.
Products: Visium for FFPE