TRANSPLANTATION AND CELLULAR ENGINEERING Increased numbers of total nucleated and CD34+ cells in blood group O cord blood: an analysis of neonatal innate factors in the Korean population Hye Ryun Lee,* Jeong Su Park,* Sue Shin, Eun Youn Roh, Jong Hyun Yoon, Kyou Sup Han, Byung Jae Kim, RobertW. Storms, and Nelson J. Chao BACKGROUND: We analyzed neonatal factors that could affect hematopoietic variables of cord blood (CB) donated from Korean neonates. STUDY DESIGN AND METHODS: The numbers of total nucleated cells (TNCs), CD34+ cells, and CD34+ cells/TNCs of CB in neonates were compared accord- ing to sex, gestational age, birth weight, birth weight centile for gestational age, and ABO blood group. RESULTS: With 11,098 CB units analyzed, blood group O CB showed an increased number of TNCs, CD34+ cells, and CD34+ cells/TNCs compared with other blood groups. Although TNC counts were lower in males, no difference in the number of CD34+ cells was demon- strated because the number of CD34+ cells/TNCs was higher in males. An increase in the gestational age resulted in an increase in the number of TNCs and decreases in the number of CD34+ cells and CD34+ cells/TNCs. The numbers of TNCs, CD34+ cells, and CD34+ cells/TNCs increased according to increased birth weight centile as well as birth weight. CONCLUSION: CB with blood group O has unique hematologic variables in this large-scale analysis of Korean neonates, although the impact on the storage policies of CB banks or the clinical outcome of trans- plantation remains to be determined. I n cord blood (CB) transplantation, the number of total nucleated cells (TNCs) infused per kilogram of recipient body weight is a reliable variable for suc- cessful engraftment and long-term posttransplanta- tion survival. 1-5 The large number of CD34+ cells has selection priority among units that have similar TNC and human leukocyte antigen (HLA) types. 6-8 As larger cell numbers are required for successful transplantation and better clinical outcomes in larger recipients, CB banks try to store blood units with large numbers of TNCs and/or CD34+ cells. Many studies have been reported regarding the mater- nal and neonatal factors that could affect hematopoietic variables of CB units such as TNCs and CD34+ cells. 9-16 To advance the CB banking process in Korea, which com- prises a unique population different from western coun- tries, 17 the impact of maternal and neonatal factors on hematopoietic variables of CB should be clarified. ABBREVIATIONS: CB = cord blood; TNC(s) = total nucleated cell(s). From the Department of Laboratory Medicine, Seoul National University College of Medicine; Departments of Laboratory Medicine, Obstetrics and Gynecology, Seoul Metropolitan Gov- ernment Public Cord Blood Bank (Allcord), Boramae Hospital, Seoul, Korea; and the Division of Cellular Therapy/BMT, Duke University Medical Center, Durham, North Carolina. Address reprint requests to: Sue Shin, MD, Department of Laboratory Medicine, Seoul National University Boramae Hos- pital, 156-707, 39 Boramaegil, Dongjak-gu, Seoul, Korea; e-mail: jeannie@snu.ac.kr. *These authors equally contributed as first author. This work was supported by the National Research Foun- dation of Korea grant funded by the Korea Government (800-20100146). Received for publication February 1, 2011; revision received May 13, 2011, and accepted May 31, 2011. doi: 10.1111/j.1537-2995.2011.03262.x TRANSFUSION 2012;52:76-81. 76 TRANSFUSION Volume 52, January 2012