Our results indicate that MSX1 may be associated with the invasion capacity of Wilms tumors. RIN1 is a downstream effector of RAS and Bcl2A1 functions as an anti-apoptotic protein. EphB2 is an ephrin receptor and is up-regulated in invasive tumors but its role needs to be confirmed in further cases of Wilms tumors.

Despite neuroblastoma being the most common extracranial solid cancer in childhood, it is still a rare disease. Consequently, the unavailability of tissue for research limits the statistical power of studies. Pathology archives are possible sources of rare tissue, which, if proven to remain consistent over time, could prove useful to research of rare disease types. We applied immunohistochemistry to investigate whether long term storage caused any changes to antigens used diagnostically for neuroblastoma. We constructed and quantitatively assessed a tissue microarray containing neuroblastoma archival material dating between 1950 and 2007. A total of 119 neuroblastoma tissue cores were included spanning 6 decades. Fourteen antibodies were screened across the tissue microarray (TMA). These included seven positive neuroblastoma diagnosis markers (NB84, Chromogranin A, NSE, Ki-67, INI1, Neurofilament Protein, Synaptophysin), two anticipated to be negative (S100A, CD99), and five research antibodies (IL-7, IL-7R, JAK1, JAK3, STAT5). The staining of these antibodies was evaluated using Aperio ImageScope software along with novel pattern recognition and quantification algorithms. This analysis demonstrated that marker signal intensity did not decrease over time and that storage for 60 years had little effect on antigenicity. The construction and assessment of this neuroblastoma TMA has demonstrated the feasibility of using archival samples for research.

Tissue microarrays place tens to hundreds of formalin fixed, paraffin embedded tissue cores into a paraffin block in a systematic grid pattern that permits their simultaneous evaluation in a single section. The fragmented nature of the tissue cores often makes sectioning of tissue microarrays difficult so that the resulting disks of tissue lose their shape, fracture or fall out of the paraffin section altogether. We have evaluated an alternative sectioning protocol for stabilizing the tissue microarray surface by placing an adhesive tape "window" over the face of the paraffin block prior to sectioning. Once sectioned, the tape/sections are transferred directly onto coated microscope slides, thereby avoiding routine floating of sections on a water bath. After sectioning with either the tape transfer or standard protocols, slides were stained either using hematoxylin and eosin or immunohistochemistry using antibodies to S-100 protein and the tissue specific antigens, keratin (AE1/3) and the leukocyte common antigen CD45. We found that the tape method produced thicker sections that were darker and more densely packed with loss of tissue definition compared to sections prepared using water bath flotation. Quantitative image analysis of immunohistochemical staining demonstrated that the tape method produced a higher incidence of nonspecific staining, which raised the potential for false positive staining.

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