Regarding Sharon Vogt's original query regarding CFU assays, and Scott Burger's response (below): I echo Dr. Burger's point of view with respect to the desirability of having a functional measure to complement the phenotypic measurement afforded by flow cytometry. I would like to support this point of view with an anecdote. We recently transplanted a patient with a T-cell depleted marrow in which there were ample CD34+ cells. Fourteen days after the T cell depletion, and all of the flow results, we discovered, much to our dismay, that there were very few colony forming cells present in the starting bone marrow product, and as a result, there were also very few in the final infused material. Our dismay turned to horror when the patients graft never produced hematologic recovery. Unfortunately, the CFU assay does not provide a real time assessment, and so I am not sure how useful it was in this instance. The take-home message remains the same. Namely, that a measure of CD34+ cells by itself does not give a complete picture of stem cell integrity in a graft. Our lab continues to do CFU assays on our stem cell products. At the very least, this is still an excellent quality assurance assay, and it does provide information that CD34 enumeration by itself does not provide. One last thought. There is a tendency to to equate the terms 'CD34 positive cell' and 'stem cell'. This is not a good thing. CD34 exists on cells other than stem cells, and its function on stem cells is unclear. -William E. Janssen, Ph.D. Director, Stem Cell Processing Lab H. Lee Moffitt Cancer Center, University of South Florida Tampa, Florida -----Original Message----- From: Scott R Burger (Scott Burger) <burge009@gold.tc.umn.edu> To: cyto-inbox <cytometry@flowcyt.cyto.purdue.edu> Cc: Cytometry Mailing List <cytometry@flowcyt.cyto.purdue.edu> Date: Sunday, January 18, 1998 8:35 PM Subject: Re: CD34+ subsets & CFU-GM > >Dear Dr. Vogt: > >A few years ago, our transplanters asked for CFU assay results on almost all >products. We have supported this, doing a progenitor assay on any cell >product we process. The logic here makes some sense -- flow cytometry, cell >counts, and viability measurement are all invaluable, but do not evaluate >the functional characteristics of the cells. The progenitor assay allows >one to assess the proliferation and differentiation functions of the cells, >which is what you care about in transplant in the first place. So, I'm >pretty strongly biased in favor of CFU measurement. > >As CD34 measurement has improved, however, our transplant docs now are >saying that they are less interested in progenitor assay results. I'm the >one who isn't comfortable with this, but it is an increasingly common >viewpoint among transplant clinicians. While we still do the assay and also >get flow cytometry results, I know that a number of transplant centers now >do CFU's only under special circumstances. > >I'm not surprised your reference lab doesn't offer CFU assays. It's a >fairly time-consuming test, and I'm not sure it would be one of the more >profitable. I'd be interested in knowing the preferences of your transplant >docs on this one. > >Scott > > >*********************************************************** **** >Scott R. Burger, M.D. >Medical Director, Cell Therapy Clinical Laboratory >Department of Laboratory Medicine and Pathology >University of Minnesota >burge009@gold.tc.umn.edu >612-626-4919 >612-624-5411 (Fax) > >
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