[Histonet] Histogel

[dusko trajkovic]

Jennifer,
You might have seen one of my posts from 2-3 years ago. I had the exact same problems you described. Could not get anyone to come up with a solution. I ran various programs on our VIP and finally came up with a solution. 
Fix your specimens as you normally would do. Drain of the fixative add your histogel (dissolved in hot water, which you have been doing), fill the mold with the histogel. Let solidify on ice or 4C in fridge. Place the solid histogel in a cassette and process on a 12 hour program. Since I have instituted this procedure, have not had one bad block to date. Longer processing is the answer, and nothing else.
Good Luck.
Dusko Trajkovic 
Pfizer Inc. La Jolla
858-638-6202
 

________________________________
 From: "Jennifer.Arcand-Johnson <@t> genzyme.com" <Jennifer.Arcand-Johnson <@t> genzyme.com>
To: histonet <@t> lists.utsouthwestern.edu 
Sent: Monday, January 20, 2014 7:56 AM
Subject: [Histonet] Histogel
  

Dear Histonetters,

I have been reading up on the archives for info on Histogel.  Previous posts discuss how they had problems with it - some samples would come out great and some would shrivel up or even dissolve.
These posts on the Histogel were from a few years ago and was hoping, and praying that someone out there may have solved this issue and have a little info you could share with me on this subject.  Did anyone out there ever figure out how to get consistent results?
I have spoken with RA Scientific and they have no additional insights.

Here is the background:  I have used Histogel for about 4 years now.  In September of last year, we started seeing the shriveling Histogel samples.  Like others who posted, it was random.  I could embed two serial pieces of nerve, from the same mouse, into two blocks and one would shrivel and one would look great.  So I have tried many things, always in multiples of 3 or more per condition per run...

Fixing in formalin only, embedding in Histogel and storing in PBS until processing
Fixing in formalin only, embedding in Histogel and storing in 40% reagent alcohol until processing (the first step of our processor is 40%)
Fixing in formalin only, embedding in Histogel and storing in formalin until processing
Fixing in formalin, rinsing in 40% alcohol, embedding in Histogel, and storing in 40% or formalin until processing
For all of these conditions, I have tried using a small cycle (30 min/bath) and a biopsy cycle (15 minutes/bath).
Once processed, there was no rhyme or reason to the results.  Some blocks looked great; others within the same group looked shriveled.  Sometimes the blocks were white, sometimes they were clear.

Next, I thought it was my pre-processing - so I heated the Histogel in a water bath, rather than microwaving.  That way all of the samples were embedded with the Histogel at the same temperature - about 55 degrees.
Again, no rhyme or reason, some looked good, some looked bad.

Lastly I thought that maybe I was carrying over too much liquid from my sample to the Histogel so I tried the following:
I made Histogel only blocks or added 3-4 drops of 40% alcohol or formalin to the liquid Histogel before a tissue/cell free block was made.
Yep, you guessed it - no luck.  Some looked good, some looked shriveled.

So here I have this great tool to embed tiny samples, but I am afraid to use it because I don't know if it will work or shrivel!  Can anyone out there help me?
Thanks,
Jenn


Jennifer Johnson

Staff Scientist

Genzyme, a Sanofi Company

Department of Pathology

5 Mountain Road

Framingham, MA 01701-9322

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