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Short answer
Single-nuclei RNA-seq (snRNA-seq, also called single-nucleus RNA-seq) profiles gene expression from isolated cell nuclei instead of whole cells. It is the usual route when tissue is frozen or archived, or when dissociating tissue into intact cells would damage or lose the cell types of interest. In one matched comparison, nuclei detected fewer genes per sample than whole cells (about 7,000 versus about 11,000) but resolved the same neuronal types once intronic reads were counted.
Definition and scope
snRNA-seq is a variant of single-cell RNA sequencing. The sequencing chemistry and downstream analysis are largely shared, and the difference sits upstream: the input is a suspension of nuclei released from tissue rather than a suspension of intact cells. Because nuclei contain only a fraction of a cell’s transcripts (the authors of one comparison estimate at least about 20%), the RNA captured is a subset of the whole-cell transcriptome, with a higher share of nascent, intron-containing transcripts.
This page is general laboratory information. Instruments, kits and assays discussed here are labelled by their manufacturers for research use only.
How nuclei are prepared and used in practice
For frozen tissue, vendors sell standardised isolation kits. The 10x Genomics Chromium Nuclei Isolation Kit user guide (CG000505 Rev A, May 2022) describes the kit as an all-in-one solution for isolating nuclei from frozen tissue for 10x Single Cell assays: frozen tissue is homogenised with a pestle in Lysis Buffer and passed through a column, debris is removed by centrifugation in Debris Removal Buffer, and the nuclei are washed, resuspended and loaded directly into a compatible assay. The guide lists no stopping points in the workflow, and the compatible assays include Single Cell 3′ and 5′ Gene Expression and Multiome ATAC + Gene Expression. The guide states the kit is for research use only and not for diagnostic procedures.
The same guide’s optimisation appendix offers three levers for tissues that do not isolate cleanly: run a lysis-time series for a new tissue type; dilute the lysis buffer with 1X PBS for gentler lysis if nuclei quality is poor; and add washes to reduce debris and ambient RNA. Plan sample storage before this step: see cryogenic sample storage for the storage side, and RNA extraction kits for bulk-RNA contrast.
Single-nucleus versus single-cell: what a matched comparison shows
Bakken and colleagues (PLoS One 2018;13(12):e0209648) compared single nuclei and single cells from the same cell types in mouse visual cortex layer 5. The table summarises what they report.
| Question | Finding in Bakken et al. 2018 |
|---|---|
| Genes detected per sample | More in whole cells (about 11,000) than in nuclei (about 7,000); more than 20,000 genes were detected about equally in both |
| Cell-type resolution | Both methods discriminated the same 11 neuronal types when intronic reads were included; marker scores were about 15% higher in cells |
| Intronic reads | Required for high-resolution cell-type identification from snRNA-seq |
| Dissociation effects | Some cell types are more vulnerable to tissue dissociation; immediate early genes such as Fos were up to 10-fold higher in cells, possibly dissociation-related |
| Archived tissue | snRNA-seq can be applied to archived frozen specimens |
Where it matters for labs and supply decisions
Use these sourced points as a checklist when planning, not as a rule:
- Tissue is frozen or archived: the nuclei isolation workflow above is built for frozen tissue, and Bakken et al. report snRNA-seq is applicable to archived frozen specimens.
- Cell types may not survive dissociation: the same paper reports some types are more vulnerable to dissociation and that dissociation-related stress genes can be elevated in whole cells.
- Maximum genes per profile matters: whole cells detected more genes per sample in that comparison, so expect lower per-profile gene counts from nuclei.
- Analysis pipeline: confirm your reference and counting settings include intronic reads before processing nuclei data.
- Debris and ambient RNA: budget bench time for optimisation using the manufacturer’s lysis and wash levers.
For project costing, see single-cell sequencing cost.
Common misunderstandings
- “Nuclei give a different answer about cell identity.” In the matched comparison, closely related neuronal types were similarly discriminated by both methods once intronic reads were used.
- “Nuclei are the same as cells with less material.” Nuclei hold a subset of the transcripts, enriched for nascent RNA, which is why intronic reads matter.
- “Nuclei isolation removes the need for optimisation.” The manufacturer’s own guide includes an optimisation appendix for new tissues.
Frequently asked questions
What is single nuclei RNA-seq?
It is single-cell RNA sequencing performed on isolated nuclei rather than whole cells, commonly written snRNA-seq.
Can snRNA-seq use frozen tissue?
Yes. Bakken et al. report it can be applied to archived frozen specimens, and the 10x Genomics nuclei isolation kit guide describes isolating nuclei from frozen tissue.
Does snRNA-seq detect fewer genes than single-cell RNA-seq?
In the mouse cortex comparison, about 7,000 genes per nucleus versus about 11,000 per cell.
Sources
- Bakken TE, Hodge RD, Miller JA, et al. Single-nucleus and single-cell transcriptomes compared in matched cortical cell types. PLoS One 2018;13(12):e0209648. PMC6306246 (read 2026-11-08).
- 10x Genomics. Chromium Nuclei Isolation Kit, Sample Prep User Guide, CG000505 Rev A (May 2022) (read 2026-11-08). A later revision may exist.
