[Cytometry] comparing post thaw absolute CD34 recovery and viability

George, Shadya S sgeorge1 at covhlth.com
Thu Feb 4 15:15:22 EST 2010


We are a small stem cell laboratory that switched to using post thaw
viable CD34 % recovery for our QC on all our collections since last
August.  We have been using recommendations of a cut-off for <50 % to
alert physicians of possible slow engraftment.  The flow lab is using FC
500, Stem Kit & software, and 7-AAD.  Most collections have been going
well (Average of 69% viable CD34 recovery post thaw and 72% viability),
but I've had three patients in the last month that had borderline post
thaw recoveries (47-49%) and at the same time also excellent viabilities
(80-88%).   I looked at the absolute CD45 cells and noticed that I'm
only recovering about 47% of my total WBCs as well, but they are not
somehow being counted as "non-viable" either.  They are just "missing."
The flow lab says there is no clumping or filtering of the samples and
they are being run immediately after staining, etc.


If we have lost these cells due to death post-thaw, shouldn't I be
seeing some effect on my total cell viability % number?  We've had about
10 patients so far, and my 7-AAD viability only seems to be effected by
the % of mononuclear cells present in the product (r=0.85; probably
because granulocytes are prone to death during freeze cycle) and does
not correlate at all with my absolute CD34 viable post thaw recovery
(r=0.018).  In other words, my viability has no way to predict the
number of CD34 cells left.


Does this seem reasonable to you in your experience?  I certainly
appreciate any wisdom you folks working in stem cell flow can share.




Shadya George, MT (ASCP)

Thompson Cancer Survival Center

1915 White Ave.; 5th Floor

Stem Cell Laboratory

Knoxville, TN

(865) 541-2373


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