REVIEW Quality rather than quantity: the cord blood bank dilemma S Querol 1,2 , SG Gomez 1 , A Pagliuca 3 , M Torrabadella 2 and JA Madrigal 1 1 The Anthony Nolan Research Institute, The Anthony Nolan Trust, London, UK; 2 Barcelona Cord Blood Bank, Banc de Sang i Teixits, Barcelona, Spain and 3 Haematology Department, King’s College Hospital NHS Foundation Trust, London, UK Growing inventories of cord blood units have facilitated access to umbilical cord cell transplantation for many patients lacking conventional stem cell donors. They are in principle ‘off-the-shelf’, ‘fit-for-use’, as well as safe and effective therapy products. Cellular enumeration is used as a surrogate of graft potency, and users rely on the rigorous assessment carried out in banks to avoid poor engraftment after thawing (loss of cells or poor function), when the patient’s situation is critical. However, in practice, when units are selected, initially on the basis of HLA matching and cell dose assessment, their absolute quality remains uncertain. Unfortunately, quality-related issues (particularly related to viability) are not uncommon in cord blood transplantation. The reasons for potency failures are diverse, but a lack of thorough validation during critical steps of the process and of appropriate use of quality-control tools for timely detection of problematic units are significant contributors. Moreover, incongruence between different sets of standards and regulations, and lack of common quality systems between banks result in a highly heterogeneous international inventory. Therefore, this complicates the matter for the end user of the product. To ameliorate this situation, it is essential to improve quality at each of the critical manufacturing steps wherein potency can be threatened, thereby creating homogeneous inventories of units with excellent quality and quantity. Bone Marrow Transplantation (2010) 45, 970–978; doi:10.1038/bmt.2010.7; published online 1 March 2010 Keywords: cord blood units; umbilical cord cell transplantation; quality control; viability; international accreditation Introduction Cord blood contains naturally mobilized progenitor cells that have the capacity to engraft and reconstitute the haematopoietic system of an individual. 1 This ability was shown when Gluckman et al. 2 performed the first cord blood transplantation (CBT), with subsequent confirma- tion over the past 20 years, with 20 000 procedures having been conducted. 3 In spite of the low blood volume left in the placenta and collected in the cord blood unit (CBU), in approximately half of the collections, a single unit may reconstitute the full haematopoietic system of an adult patient. 4–6 A combination of large-scale banking and transplantation development has made cord blood an alternative source for BMT. 7 Cord blood has a number of advantages compared with other stem cell sources. In terms of safety, although a waste product, adequately collected, it is not harmful to the donor and has a low risk of transmission of communicable diseases. 8–10 The ability to conduct HLA-incompatible transplants allows for the efficient and affordable design of national inventories improving access to stem cell therapy for almost all patients in need. 11 In terms of logistics, it develops the concept of ‘off-the-shelf’ therapy, providing near-immediate access for all patients who require an SCT. 12 Furthermore, it also opens new avenues for developing alternative transplantation therapies and novel non-haematopoietic applications. 13,14 During the past 20 years, outcomes of CBT progressively improved. 15–18 This was attributed to a combination of better clinical management and patient selection, develop- ment of standardized and novel clinical protocols and conditioning regimens, and overwhelmingly, especially in the adult setting, the increase in the number and quality of units offered, thus allowing transplantation of more cellular products with better match. Pitfalls in cord blood banking Despite this experience, many problems remain to be resolved to improve outcomes further. It is not unusual that the cell-processing laboratory at the transplant centre reports issues on receipt of the product and following thawing. Examples of serious events typically communi- cated are poor cell viability and yield (that is, far below 50%, or failure in colony-forming unit (CFU) growth after thawing); 19,20 mislabelling; 21 or accidents during transport, including receipt of thawed units, broken bags or impro- perly labelled products. 22,23 Cord blood is easily collected and manufactured but not without risk. Compared with typical adult sources, it Received 2 December 2009; accepted 2 December 2009; published online 1 March 2010 Correspondence: Dr S Querol, Cord Blood Bank, The Anthony Nolan Research Institute, Fleet Road, London NW3 2QG, UK. E-mail: sergio.querol@anthonynolan.org.uk Bone Marrow Transplantation (2010) 45, 970–978 & 2010 Macmillan Publishers Limited All rights reserved 0268-3369/10 $32.00 www.nature.com/bmt