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2030-01-01
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THE EFFECT OF AGING OF FORMALIN-FIXED PARAFFIN-EMBEDDED TISSUES ON THE IN SITU HYBRIDIZATION AND IMMUNOHISTOCHEMISTRY SIGNALS IN CERVICAL LESIONS
Author
Affilliation
The Ohio State University Medical Center. Ohio, USA.
The Ohio State University. The Comprehensive Cancer Center. Ohio, USA.
The Ohio State University. Columbus, USA.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório Interdisciplinar de Pesquisas Médicas. Rio de Janeiro, RJ. Brasil.
Fundação Oswaldo Cruz. Instituto Fernandes Figueira. Rio de Janeiro, RJ, Brasil.
The Ohio State University. The Comprehensive Cancer Center. Ohio, USA / Phylogeny Inc.. Powell, OH, USA.
The Ohio State University. The Comprehensive Cancer Center. Ohio, USA.
The Ohio State University. Columbus, USA.
Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório Interdisciplinar de Pesquisas Médicas. Rio de Janeiro, RJ. Brasil.
Fundação Oswaldo Cruz. Instituto Fernandes Figueira. Rio de Janeiro, RJ, Brasil.
The Ohio State University. The Comprehensive Cancer Center. Ohio, USA / Phylogeny Inc.. Powell, OH, USA.
Abstract
Formalin-fixed, paraffin-embedded tissues are widely
used in biomedical research but little is known about the effect
of the age of the block or unstained slides on the in situ hybridization
or immunohistochemistry signal. We compared the
in situ-based and immunohistochemistry-based signals for cervical
intraepithelial neoplasia samples that ranged from 0 to 15
years of age. There was a progressive and statistically significant
decrease in the strength of the p16INK4a signal when comparing
tissues prepared from recent unstained slides (0 to 1 y old, mean
score of 92%) to those of intermediate age (5 to 7 y old, mean
score of 49%) to old unstained slides (cut 13 to 15 y ago, mean
score of 10%). Equivalent, progressive, and significant decreases
in the intensity of the signals for microRNAs, CD45, and human
papillomavirus DNA were seen in tissues stored on slides
from 5 to 7 years and 13 to 15 years, respectively. However, the
diminution of signal was much less, although still statistically
significant, if the sections from the 13- to 15-year-old paraffin
blocks were prepared in 2012. The data likely does not represent
degradation of the targets as extraction of several microRNA
from the old blocks showed no detectable degradation, despite
the markedly weakened in situ hybridization signal. It is concluded
that in situ-based signal for DNA, microRNAs, and
proteins in paraffin-embedded tissues are significantly reduced
over time, especially when stored long term on glass slides
which, in turn, can lead to a significant underestimation of the
amount and presence of the nucleic acid or protein target.
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