Single-nucleus RNA sequencing (sNuc-Seq) is a system that allows researchers to study the gene expression profiles of difficult-to-isolate cell types as well as cells from archived tissues. However, it hasn't been widely used since it was hard to scale. Recently, scientists from the Broad Institute of MIT and Harvard revealed DroNc-Seq, a single-cell expression profiling technique that merges sNuc-Seq with microfluidics. Doing this allows massively parallel measurement of gene expression in structurally complicated tissues. The work was published yesterday in Nature Methods.
Complex tissues like neurons from the brain were very difficult to isolate because the isolation procedures affected their RNA content. Therefore researchers were not able to capture the true proportions of cell types present in a sample. Moreover, the procedures did not work for frozen archived tissues. sNuc-Seq bypassed those problems by using individual nuclei extracted from cells as a starting point instead.
To scale up the SNuc-Seq method, researchers looked to microfluidics. They tested their new DroNc-Seq method for accuracy and speed against Drop-Seq, sNuc-Seq, and other lower throughput scRNAseq methods using a mouse cell line and mouse brain tissue. In addition, they also tried using it with human brain tissue and found that they could (a) identify expression signatures unique to neurons, glial cells, and other cell types in the brain (including rare types), and (b) differentiate between closely related cell subtypes.
Researchers believe that the DroNc-Seq method could be a valuable addition to the technologies being used as part of the Human Cell Atlas and other scRNAseq-based efforts.
Image: This family tree captures just a sampling of single-cell and single-nucleus RNA sequencing technologies that have burst onto the scene over the last eight years. Image courtesy of Susannah M. Hamilton and Tom Ulrich from Broad Communications.