1. ¹Centre de Thérapie Cellulaire et Génique, Département de Biologie, Institut Paoli-Calmettes, Marseille, France
2. ²Réseau Français du Sang Placentaire, France
3. ³Centre d'Investigations Cliniques en Biothérapies, Institut Paoli-Calmettes, INSERM, Université de la Méditerranée, Marseille, France
4. ⁴Département de Biostatistiques, Institut Paoli-Calmettes, Marseille, France
5. ⁵Etablissement Français du Sang Aquitaine-Limousin, Bordeaux, France
6. ⁶Etablissement Français du Sang Bourgogne-Franche Comté, Besançon, France
7. ⁷Cord Blood Bank Medicina Trasfusionale, Terapia Cellulare e Criobiologia, Milano, Italy
8. ⁸Transplantation Immunology and Stem Cell Bank, Heinrich-Heine-University, Medical Center, Düsseldorf, Germany
9. ⁹Unité de Thérapie Cellulaire, Hôpital Saint-Louis, Assistance Publique-Höpitaux de Paris, Paris, France
10. ¹⁰Service d'Hématologie Pédiatrique, Centre Hospitalier Universitaire Timone-Enfants, Assistance Publique-Höpitaux de Marseille, Marseille, France

Correspondence: Dr C Lemarié, Institut Paoli-Calmettes, Centre de Thérapie Cellulaire et Génique, Centre Régional de Lutte Contre le Cancer Provence-Alpes-Côte d'Azur, 232, Bd Sainte-Marguerite, 13273 Marseille cedex 9, France. E-mail: thercell@marseille.fnclcc.fr

Received 19 October 2006; Revised 16 January 2007; Accepted 19 January 2007; Published online 5 March 2007.

Abstract

Cord blood (CB) units are increasingly used for allogeneic transplantation. Cell dose, a major factor for CB selection, is evaluated before freezing by each CB bank, using various techniques. This may introduce variability and affect the prediction of cell recovery after thawing, or haematopoietic reconstitution. Forty-two children were transplanted at the same institution with unrelated CB units. All units were thawed and evaluated at the same cell therapy facility, using standard procedures. We investigated: (i) factors that affect cell loss after thawing, and (ii) the importance of CD34⁺ cell doses. Prefreeze and post-thaw CD34⁺ cell doses were statistically correlated, thus suggesting that variability in numeration techniques used by different CB banks does not compromise the biological and clinical value of these figures. CD34⁺ cell recovery appeared to be correlated with the absolute number of CD34⁺ cells per frozen bag. Infused CD34⁺ is the cell dose that better correlates with platelet reconstitution delay; in addition, when using a quartile comparison, haematopoietic recovery appeared to be related with prefreeze and post-thaw CD34⁺ cell doses. We conclude that enumeration of CD34⁺ cells in CB units is of biological significance, and may help select CB units and identify patients at risk of delayed recovery.