Re: Paraformaldehyde and PI

From: Maryalice Stetler-Stevenson (stetler@box-s.nih.gov)
Date: Wed Apr 18 2001 - 14:31:37 EST


PI is only excluded from live cells that are able to maintain their
cell membranes. Paraformaldehyde does kill cells.Therefore, fixing
live cells kills them. Then PI accurately demonstrates they are dead.
Who ever told you otherwise knows absolutely nothing about PI
exclusion from cells.


	Maryalice


>I wonder whether anyone has experience or opinions on this :
>
>Does 0.5-2 %paraformaldehyde fixation of endothelial cells or tumour
>cells permeabilise cells to PI or not.Different sources say yes and
>no , but we have found that after removal of adherent cells from
>culture plates with 2mM EDTA and fixation that almost all cells
>stain with PI . Does paraformaldehyde fixation preclude meaningful
>viability assessment or not .
>
>Many thanks.
>
><mailto:mascor@gofree.indigo.ie>mascor@gofree.indigo.ie
>

Maryalice Stetler-Stevenson
Director Flow Cytometry Unit
Laboratory of Pathology, NCI, NIH

"Learn the rules so you know how to break them properly."
The Dalai Lama



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