Hi everyone:

Microarrays have really been around for a long time.  They have been
popularized due to the advent of functional genomics and now have been
applied to archival specimens.  Taking the concept of the multi-tissue block
developed by Dr. Battifora, and organizing the samples into an alpha numeric
grid, (which one can use to identilfy all specimens incorporated into the
block) the technique can allow high throughput analysis of paraffin embedded
tissues.

The Beecher instrument is one of the tools available for this type of
analysis and allows for the extraction 0.6 mm cores from a set of source
blocks in order to be placed into a dummy or recipient block in a grid
format, or however you wish.  The instrument has 1 micron precision and thus
allows for the high density arrays to be built (up to 1200 cores, which I
would not recommend).  There is quite a curve in learning to control the
insertion of your core into the recipient block, but once overcome, the
instrument is quite nice.  Important to keep in mind is the issue of
intratumoral heterogeneity.  To overcome this problem many have resorted to
sampling in triplicates or more.  In our laboratory we have chosen to make
lower density arrays (ranging from 12-54 cores) but that will allow us to
incorporate cores that will range from 6mm to 2mm.  For this density we do
not require the instrument or a recipient block.

As far as microtomy is concerned, we did not opt for the Tape transfer
system.  We chose and modified the second option in our instruction manual
and that was to warm the block to 45 degrees while sitting on a slide
(assuming that your recipient paraffin block melting temperature is 56
degrees) for 20 minutes.  At that point then we gently pressed the block
down to make the cut surface level.  This whole process provided us enough
annealing of the paraffin to obtain beautiful ribbons with very little
waste.  Sections are then separated and individually placed on the waterbath
for pick-up.  At the proper temperature you should not have distortion of
your array.  The instruction manual I believe recommended a 37 degree temp.

I recommend that you make some practice arrays and try out several
temperatures (annealing and waterbath) based on the paraffin that is
available to you.  The tape transfer system helps many people and you may
find it useful, but it is not the only way to section arrays just as the
Beecher instrument is not the only way to build them.

Search Olli Kallioniemi's papers or call Beecher Instruments @(301)-585-6621
for references.

Hope this helps!

Carlos Genty
Breast Center Pathology
Baylor College of Medicine
Houston, Texas
cgenty@breastcenter.tmc.edu

-----Original Message-----
From: Januttall@aol.com [mailto:Januttall@aol.com]
Sent: Monday, December 18, 2000 1:40 PM
To: histonet@pathology.swmed.edu
Subject: Tissue Microarrays


Does anyone have experience sectioning and/or using Tissue Microarrays?  I
am wondering if there are any other "tricks" to keeping the tissue on the
slide other than the Paraffin Tape-Transfer Method by Instrumedics.  My
thought is you might get better quality sections by floating them on a water
bath for a moment, and then picking them up on an adhesive coated slide.

I welcome any input on the subject!

Thanks,
Julie Nuttall