Fixation of calcein stained cells

Edgar Rivedal edgar.rivedal at
Mon Nov 4 08:28:54 EST 1996

Does anyone have experience with fixation of cells stained with Calcein-AM?
We fix epithelial cell lines stained with Calcein-AM in 4 % formalin.
Formalin is supposed to fix the calcein to the cells. What we see is a
relatively large drop in the calcein level over a few hours after fixation,
in spite of keeping the samples in the dark and on ice. What we do is to
detach the cells into 0.5 ml trypsin  and mix this with 0.5 ml 8% formalin
and run this at the flow cytometer within some hours, i.e. we do not remove
the trypsin or formalin prior to analysis because the fixed cells seem to
dislike centrifugation.

Edgar Rivedal, Ph.D.      (edgar.rivedal at
Institute for Cancer Research
The Norwegian Radium Hospital      tel. +47 22 93 47 00
N-0310 Oslo, Norway                fax  +47 22 93 57 67

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