[Histonet] unstained paraffin tissue slides storage--why cold?

[dusko trajkovic]

I did an experiment about 10 or 12 years ago, where I cut the sections and 
stained them at various intervals: Day1, Day 15, 1 month, 3 months, 6 months, 1 
year.
Before staining:
Set of slides were allowed to sit at room temp (RT).
Set of slides were stored at 4C.
Set of slides were vacuum sealed and stored at RT.
Set of slides were vacuum sealed and stored at 4C.

Slides stored at 4C consistently stained well, with a slight variance in 
staining after 1 year. Did not matter weather they were vacuum sealed or not.
Slides left out at RT did not fare so well. Staining variability was noticed 
after 1 month. When the slides were stained after one year, signal was almost 
eliminated. Variability and loss of antigenicity was observed with the vacuum 
sealed slides as well.
I did this experiment for just one antibody which was being extensively used at 
the time for one of our projects. It could be that other antibodies fare mach 
better under RT conditions, but why take a chance?

We keep all of our control slides at 4C.
Blocks are kept at RT.

Thanks
Dusko Trajkovic




________________________________
From: "Morken, Tim" <Timothy.Morken <@t> ucsfmedctr.org>
To: Helen Fedor <hfedor <@t> jhmi.edu>
Cc: "histonet <@t> lists.utsouthwestern.edu" <histonet <@t> lists.utsouthwestern.edu>
Sent: Thu, November 4, 2010 9:09:16 AM
Subject: RE: [Histonet] unstained paraffin tissue slides storage--why cold?

Helen, did you write a paper from that study? 

Tim Morken
Supervisor, Histology, IPOX
UCSF Medical Center
San Francisco, CA, USA

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu 
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Helen Fedor
Sent: Thursday, November 04, 2010 8:56 AM
To: sgoebel <@t> xbiotech.com; Emily Sours
Cc: histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] unstained paraffin tissue slides storage--why cold?

The study that we did showed that the staining on freshly cut slides from a 
block stored at room temperature was in fact not as good as slides that were 
sectioned 5 years earlier and stored at -20. Therefore the blocks should be 
stored in the cold as well. The tissue is degrading in the block and on the 
slides and the cold does slow down the process. The fixation in lots of the 
tissue is not optimal. Fixing for 48 hours will definitely  be better than the 
current fixation practices going on in most clinical labs,  if what you want is 
the best tissue preservation possible. But most of us do not have that option.

Helen L. Fedor 

Tissue Microarray Lab, Manager
Prostate Spore Lab, Manager
Johns Hopkins University
600 N. Wolfe St, | Marburg Room 406
Baltimore, MD | 21287-7065

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu 
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of 
sgoebel <@t> xbiotech.com
Sent: Thursday, November 04, 2010 11:21 AM
To: Emily Sours
Cc: histonet <@t> lists.utsouthwestern.edu
Subject: RE: [Histonet] unstained paraffin tissue slides storage--why cold?

-70 or -80 seems a little extreme to me, that's why I always just leave
them in a normal freezer (-20).  I think the main point of doing this
from what I understand is so that the antigens stay "viable".  I know
over time they can degrade and so your stain won't work with some
antibodies.  The weirdest part to me has always been that you don't have
to store the blocks this way.  So I think that was your question, if the
blocks aren't stored in a freezer why store the slides?  Won't the
antigens in the blocks start to degrade as well?  This is a question I
would like to know the answer to as well...

Sarah Goebel, B.A., HT (ASCP)
Histotechnician


XBiotech USA Inc.

8201 East Riverside Dr. Bldg 4 Suite 100

Austin, Texas  78744

(512)386-2907




-------- Original Message --------
Subject: Re: [Histonet] unstained paraffin tissue slides storage--why
cold?
From: Emily Sours <talulahgosh <@t> gmail.com>
Date: Thu, November 04, 2010 7:07 am
To: histonet <@t> lists.utsouthwestern.edu

Can I ask what the point of storing paraffin sections in freezing cold
storage?
They are wax sections, which never see any type of cold, so I don't
understand the point of this. I do understand putting them at 4 degrees
to
prevent mold, but -80 seems excessive.
We have kept our slides at room temperature for years and years, but
these
slides do not have an albumin coat (which I can see getting moldy), just
a
chemical coating.
Fixing for paraffin and paraffin infiltration seems to keep antigens
safe
without refrigeration because it's so intense, but that's just
conjecture on
my part.

Emily
--
Outside of a dog, a book is man's best friend. Inside of a dog it's too
dark
to read.
--Groucho Marx
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