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 (TDP-43^APT), as described in Spence and Waldron et al., 2024 published in Acta Neuropathologica (in press at the time of release of this SOP on

01/03/2024)

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.

Reference for citations of this method

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 (2024). Acta Neuropathologica (in press at the time of release of this SOP on 01/03/2024).

*equal contributions, ^‡ corresponding author

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

TDP-43 RNA Aptamer_IHC _SOP_v1.0_01Mar24.pdf TDP-43 RNA Aptamer_IHC_TS_v1.0_01Mar24.pdf