Authors declare no conflicts of interest.

Here we provide a SOP to outline the correct procedures for performing Immunohistochemistry (IHC) to detect pathological TDP-43 in FFPE-preserved human tissue using the TDP-43 RNA Aptamer, as described in Spence and Waldron et al ., 2024 published in Acta Neuropathologica (DOI: 10.1007/s00401-024-02705-1).

Users with access to Sequenza immunostaining racks and histological facilities (with fume hood) should be able to carry out all steps over two days.

This protocol uses the TDP-43^APT sequence published in Zacco et al ., 2022. The sequence is: CGGUGUUGCU with a  3' Biotin-TEG modification, purified using HPLC, scale: 1.0 µM synthesis.

References for citation of this method

Please cite both of these below if using this method:

The citation, Spence and Waldron et al., 2024, for the first publication for the development, modification and employment of theTDP-43 RNA aptamer to stain human tissue published in Acta Neuropathologica.

RNA aptamer reveals nuclear TDP-43 pathology is an early aggregation event that coincides with STMN-2 cryptic splicing and precedes clinical manifestation in ALS.

Holly Spence*, Fergal M. Waldron*, Rebecca S. Saleeb, Anna-Leigh Brown, Olivia M. Rifai, Martina Gilodi, Fiona Read, Kristine, Roberts, Gillian Milne, Debbie Wilkinson, Judi O’Shaughnessy, Annalisa Pastore, Pietro Fratta, Neil Shneider, Gian Gaetano Tartaglia, Elsa Zacco, Mathew H. Horrocks, Jenna M. Gregory^‡. Acta Neuropathologica 2024 Mar 5;147(1):50. DOI: 10.1007/s00401-024-02705-1. *equal contributions, ^‡corresponding author.

The citation, Waldron and Spence et al., 2024, for this SOP published on protocols.io is:

TDP-43 RNA aptamer staining to detect pathological TDP-43 in FFPE human tissue, as described in Spence and Waldron et al., 2024 (Acta Neuropathologica): A SOP and tick-sheet. v2.

Fergal M. Waldron*, Holly Spence*, Jenna M. Gregory^‡. protocols.io 2024;

DOI: dx.doi.org/10.17504/protocols.io.eq2lyjo4mlx9/v2. *equal contributions, ^‡corresponding author.

Please see appendix for materials required to carry out this protocol.

TDP-43 RNA Aptamer_IHC _SOP_v2.0_July24.pdf TDP-43 RNA Aptamer_IHC_TS_v2.0_July24.pdf