The effect of CD34 count and clonogenic potential of hematopoietic stem cells on engraftment Tamer Sarı a , Meltem Kurt Yüksel b,⇑ , Pervin Topçuog ˘lu c , Meltem Tol d , Erol Ayyıldız d , Muhit Özcan c , Osman _ Ilhan c a Department of Cardiovascular Surgery, Ankara Bayındır Hospital, Turkey b Department of Hematology and Stem Cell Transplantation Unit, Ankara Oncology Research and Education Hospital, 06200 Demetevler Yenimahalle, Ankara, Turkey c Department of Hematology, Ankara University School of Medicine, Turkey d Hemapheresis Unit, Ankara University School of Medicine, Turkey article info Keywords: Stem cell transplantation Colony forming units Hematological recovery CD34 (+) cell abstract In this study we have determined that the number of the CD34 (+) cells in the grafts that were infused to 48 patients who underwent autologous and allogeneic hematopoietic cell transplantation and evaluated the number of colony forming units in vitro. Our aim was to determine whether there is a relation between these cell counts and post transplantation engraftment kinetics. A negative correlation was detected (p < 0.05) between the CD34 (+) cell count and all colony forming units. A correlation between the CD34 (+) cell count and the kinetics of engraftment could not be demonstrated. In the autologous group, only a weak negative correlation between the CFU–GEMM and neutrophil engraftment was detected. In the allogeneic group, colony forming units did not determine the engraftment. Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved. 1. Introduction Mobilized peripheral blood (PB) progenitors are being used in autologous and allogeneic transplantation since 1978 [1]. It has been hypothesized that if sufficient num- bers of committed progenitor cells can be infused at the time of transplant it may be possible to decrease or elimi- nate the period of post transplant pancytopenia. Therefore, it is important to determine whether progenitors produced in culture will engraft and contribute to the reconstitution of hematopoiesis in vivo. The numbers of CFU-GM in cul- ture media have been utilized for determining the amount of progenitor cells. Since this is a time consuming method, today the count of CD34 + stem cells that can easily be determined with flowcytometry at the same day, is being utilized. Engraftment kinetics in BM or PBSC transplanta- tion depends on the number and efficiency of stem cells in the graft. In general the higher the count of CD34 + cells the more rapid the engraftment. However infusion of a low number of the CD34 + cells has also been shown to be suf- ficient for engraftment [2]. Although CD34 + stem cells are mostly used there are still questions to be answered for example is there any subgroup of stem cells such as Lin- CD34- or CD34+/CD33- that will better correlate with engraftment? Nowadays the answer to this question is no [3–6]. CFU-GMs are more reliable to predict engrafment than CD34 count in cord blood transplantations [7]. We have searched the literature and found few studies on CD34 positive mononuclear cells and colony formation of myeloid hematopoietic progenitor cells in a clonogenic as- say [8,9]. We attempted to correlate the CD34 count with the cloning efficiency determined after a 14 day culture period in the methylcellulose-based clonogenic assay. Our aim in this study is to evaluate the CD34 (+) cell count and in vitro colony forming ability, to investigate whether the CD34 (+) cell count and colony forming units 1473-0502/$ - see front matter Crown Copyright Ó 2010 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.transci.2010.09.020 ⇑ Corresponding author. Tel.: +90 5055025421; fax: +90 3123344917. E-mail address: meltemkurt@hotmail.com (M.K. Yüksel). Transfusion and Apheresis Science 43 (2010) 315–320 Contents lists available at ScienceDirect Transfusion and Apheresis Science journal homepage: www.elsevier.com/locate/transci