Introduction:

The Norwegian Kidney Biopsy Registry holds formalin-fixed paraffin embedded (FFPE) tissue from approximately 5000 human kidney biopsies since 1988 and is the largest active kidney biopsy registry in the world. This tissue has previously been considered inaccessible for protein studies due to the formation of cross-bridges in FFPE stored tissue. Recently, methods for extracting proteins from FFPE tissue have been published (Sethi et al., 2009), making the Norwegian Kidney Register a potential very valuable resource.

Aim: 

Establish a method for extraction of proteins from microdissected FFPE kidney tissue. Furthermore, use targeted and quantitative proteomic approaches to determine whether proteins related to kidney disease are differently expressed in patients with hypertensive kidney disease compared to controls.

Methods: 

5 mm thick FFPE tissue-slices are placed on MembraneSlide 1.0 PEN (Zeiss), and microdissected using PALM Microbeam (Zeiss, P.A.L.M Microlaser Technologies). Samples are prepared as described by Sethi et al (Sethi et al., 2009). Samples are analysed using reverse-phase HPLC connected to a mass spectrometer (AB SCIEX, QTRAP 5500).

Results: 

Proteomic analysis of extract from microdissected glomeruli (FFPE) has resulted in reliable identification of high abundance proteins such as beta-actin and glyceraldehyde 3-phosphate dehydrogenase (GAPDH).

Conclusion: 

Analysis of FFPE kidney tissue has showed promising results, and we estimate that the method will be applicable for analysis of low abundant proteins within a short period of time.

Reference: 

Sethi, S., Gamez, J. D., Vrana, J. A., Theis, J. D., Bergen, H. R., 3rd, Zipfel, P. F., Dogan, A. & Smith, R. J. 2009. Kidney international, 75, 952–60.