historical review
Milestones in umbilical cord blood transplantation Eliane Gluckman, Annalisa Ruggeri, Fernanda Volt, Renato Cunha, Karim Boudjedir and Vanderson Rocha Eurocord, Assistance publique des hoˆpitaux de Paris (APHP), Institut Universitaire d’He´matologie (IUH) Hoˆpital Saint Louis, Paris, France
Summary Much has been learned about umbilical cord blood (UCB) since the first human cord blood transplant was performed back in 1988. Cord blood banks have been established worldwide for the collection, cryopreservation and distribution of UCB for allogeneic haematopoietic stem cell transplantation. UCB has now become one of the most commonly used sources of haematopoietic stem cells for allogeneic transplantation. Today, a global network of cord blood banks and transplant centres has been established with a large common inventory, allowing for more than 20 000 transplants worldwide in children and adults with severe haematological diseases. Several studies have been published on UCB transplant, assessing risk factors such as cell dose and human leucocyte antigen mismatch. New strategies are ongoing to facilitate engraftment and reduce transplant-related mortality and include the use of reduced-intensity conditioning regimen, intra-bone injection of cord blood cells, double cord blood transplants or ex vivo expansion of cord blood cells. The absence of ethical concern and the unlimited supply of cells explain the increasing interest of using UCB for developing regenerative medicine.
used sources of haematopoietic stem cells for allogeneic transplantation. Currently, the global network of CBB has a common inventory of an estimated 600 000 UCB units, and more than 20 000 units have already been distributed to transplant centres worldwide for the treatment of both adults and children with severe haematological diseases. The main practical advantages of using cord blood as an alternative source of stem cells are the relative ease of procurement, the absence of risk for mothers and donors, the reduced likelihood of transmitting infections, particularly cytomegalovirus, and the ability to store fully tested and human leucocyte antigen (HLA) typed transplants in the frozen state, available for immediate use. Several studies have shown that the number of cells is the most important factor for engraftment. Furthermore, studies have shown that some degree of HLA mismatch is acceptable in the UCBT setting. The last two decades of UCB research have shown clear evidence that UCB is an acceptable and promising haematopoietic stem cell source for the treatment of both adults and children with haematological malignancies. Moreover, non-haematopoietic stem cells can also be isolated from UCB, and the absence of ethical concerns surrounding this product and its unlimited supply explain the increased interest regarding the use of UCB in the developing field of regenerative medicine.
Keywords: cord blood transplantation, cord blood banks, haematological disease.
Pre-clinical steps Since the first human cord blood transplant, performed in 1988, cord blood banks (CBB) have been established worldwide for the collection and cryopreservation of umbilical cord blood (UCB) for allogeneic haematopoietic stem cell transplantation (HSCT) (Gluckman et al, 1989). The advantages of umbilical cord blood transplantation (UCBT) were first recognized in related donors. Later, CBB established the criteria for the standardization of the collection, banking, processing, and cryopreservation, and distribution of UCB for unrelated donor transplants in patients with various haematological malignant and non-malignant diseases (Rubinstein et al, 1993). UCB has now become one of the most commonly
Correspondence: Professor Eliane Gluckman, Eurocord Hopital Saint Louis, 1 avenue Claude Vellefaux, 75475 Paris Cedex 10, France. E-mail:
[email protected]
The concept of using cord blood was developed in the late 1970s, but it was the pivotal work of H.E. Broxmeyer that moved UCB from the laboratory to clinical practice. E.A. Boyse validated concept studies in mice (Yeoman et al, 1993) while H.E. Broxmeyer evaluated the haematopoietic potential of human UCB in vitro, and developed practical and efficient methods for large volume collection and storage of UCB. It was postulated at that time that UCB collected at birth might contain enough haematopoietic stem/progenitor cells for clinical use (Broxmeyer et al, 1989). This possibility was strengthened by the knowledge that haematopoietic progenitor cells from UCB could be maintained for many weeks in longterm cultures, suggesting their production from more primitive cells. Mice studies showed that, in contrast to adult blood, the use of a small quantity of neonatal blood enabled the survival of approximately half of the lethally irradiated mice
ª 2011 Blackwell Publishing Ltd, British Journal of Haematology, 154, 441–447
First published online 5 July 2011 doi:10.1111/j.1365-2141.2011.08598.x
Review (Vormoor et al, 1994). These findings led to a multi institutional study that addressed the following: (i) reconstitution of cellular content by measurement of haematopoietic progenitor cells numbers in cord blood and (ii) collection, transportation and optimal cryopreservation of cord blood (Gluckman et al, 1989; Rubinstein et al, 1993). Researchers from the Indiana University School of Medicine found on 101 samples of UCB, collected in New York, that the number of progenitor cells was in the lower range of numbers associated with successful engraftment and, that the numbers were increased when erythrocyte depletion was not attempted (Broxmeyer et al, 1992). They observed that samples could be successfully frozen, stored and thawed without major loss of cells. At that time, this group believed that cord blood stem cells would be especially attractive for autologous purposes, providing a perfectly matched set of cells stored for future use. However, it was unlikely that autologous cord blood transplantation would be tested in the near future. This concept led to a long-lasting debate on patenting cord blood for clinical use and of setting up commercial cord blood banks for personal use. Next, testing the concept of allogeneic cord blood stem cell transplants, in which an HLA-identical sibling was available, was discussed. The first UCBT was made possible by an intensive collaboration between three researchers and their respective groups: A.D. Auerbach, from New York (USA), who described a method of prenatal diagnosis in Fanconi anaemia (FA) (Auerbach et al, 1990), H.. Broxmeyer, from Indianapolis (USA), who systematically analysed the number of haematopoietic cell progenitors in cord blood with the purpose of using the cells for haematopoietic reconstitution in humans (Smith & Broxmeyer, 1986), and E. Gluckman, from Paris (France), who demonstrated that the in vivo hypersensitivity of FA cells translated in an increased toxicity of the pre-transplant conditioning regimen and was the pioneer of modified attenuated dose conditioning in FA patients (Gluckman et al, 1983). Auerbach identified mothers of FA patients who were pregnant. By performing prenatal diagnosis on cultured amniotic fluid cells, she was able to select five pregnant women known to be expecting babies that were at unaffected by FA and HLA identical to their FA sibling. The UCB of the selected women were harvested and cryopreserved at birth. It was perceived by all involved in this study, including the Institutional Review Boards of the transplant centres, that the cord blood availability in these cases obviated the need for bone marrow aspiration from the infant siblings, especially with the knowledge that the siblings were available for bone marrow donation later, if necessary.
From the first UCB transplant to the development of UCB banks The first UCBT was performed in 1988 in a FA patient (Gluckman et al, 1989). This patient had a healthy HLA identical sibling shown by prenatal testing to be unaffected by the disorder and to have a normal karyotype. The UCB was 442
collected during the birth of the healthy sibiling, cryopreserved and used, after thawing, for the transplantation. The transplant conditioning consisted of low dose cyclophosphamide (20 mg/ kg instead of 200 mg/kg) and 5 Gy total lymphoid irradiation. This type of conditioning was developed specifically for the treatment of FA patients due to their extreme sensitivity to alkylating agents, such as cyclophosphamide. The cryopreserved UCB cells were transported from Indiana to Paris in a dry shipper container that maintained the temperature at )175C. The cells were thawed without further processing on day 0. Viability and progenitor cell assays were performed on the thawed product, and the results were similar to the ones before cryopreservation. The first signs of engraftment appeared on day 22, with subsequent complete haematological reconstitution and donor chimerism. The patient never developed graft-versus-host disease (GVHD) and is currently, more than 20 years after UCBT, healthy and showing a complete long-term haematological and immunological donor reconstitution. This first successful transplantation led to a new field in the domain of allogeneic HSCT as it demonstrated the following: (i) a single UCB contained enough haematopoietic stem cells to reconstitute the host lympho-haematopoietic compartment, (ii) an UCB unit could be collected at birth without any harm to the newborn and (iii) UCB haematopoietic stem cells were able to maintain their repopulating properties post cryopreservation, thawing and, subsequently, transplantation in a myeloablated host. Since then, knowledge regarding the biological characteristics of UCB cells has increased, emphasizing the advantages of using UCB stem cells for transplant (Griffiths-Chu et al, 1984; Linch & Brent, 1989; Durandy et al, 1990). Table I lists the questions raised during the last 20 years of cord blood biology and transplantation and milestones achieved in the field. All of the listed questions have been answered during the last 20 years thanks to the worldwide development of intense international cooperation between Europe, with Eurocord and Netcord, the USA, with the Center for International Blood and Marrow Transplant Research (CIBMTR) and National Marrow Donor Program (NMDP), Asia, with Asia Cord, Australia, with Australia Cord, and others, including single transplant centres.
The international organization of cord blood transplantion Since the first UCB, more than 20 000 UCBT have been reported worldwide and more than 600 000 UCB units have been stored in more than 100 CBB (http://www.bmdw.org) (http://www.nmdp.org). The Eurocord group was established in 1995 on behalf of a European framework programme and the European Group for Blood and Marrow Transplantation, with the principal objective of collecting the clinical data regarding European patients transplanted with cord blood grafts shipped by European or
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Review Table I. Cord blood biology and transplantation: questions answered and milestones achieved. Questions Would a single cord blood unit contain enough stem cells to sustain permanent engraftment in both children and adults? Would maternal cell contamination in cord blood also engraft and cause severe GVHD in the recipient? Would the same results be obtained in patients transplanted for conditions other than Fanconi anaemia, such as leukaemia? Would engraftment also occur in adults? Are the properties of haematopoietic cord blood cells different from adult haematopoietic cells? What are the immunological properties of cord blood cells? What is the impact of cord blood cells in GVHD, graft-versus-leukaemia, and immune reconstitution? Would the immune immaturity of cord blood lymphocytes be able to overcome the HLA barrier and allow for HLA -mismatched transplants? Would it be possible to establish CBB for both unrelated and related transplants? What would be the criteria for collection, processing, and quality control of UCB Would it be possible to collect cord blood not only for related transplants, but also for unrelated ones? What would be the necessary inventory capacity of UBC banks if it was demonstrated that HLA incompatibilities were not recognized in cord blood because of the immaturity of the immune system at birth? Milestones achieved First HLA identical sibling cord blood transplant in a patient with Fanconi anaemia (Gluckman et al, 1989) Optimization of UCB collection and storage (Gluckman et al, 1989; Rubinstein et al, 1993, 1995) Development of CBB for related and unrelated transplants (Paris, Dusseldorf, New York, Milan) First unrelated mismatched cord blood transplant in children (Kurtzberg et al, 1996) First unrelated cord blood transplant in adult (Laporte et al, 1996) Creation of the Eurocord-Netcord network (Gluckman et al, 1997) Description of donor selection criteria based on the number of nucleated cells and the possibility of using mismatched cord blood (Wagner et al, 2002; Gluckman et al, 2004) Demonstration that cord blood transplants in HLA identical siblings resulted in delayed engraftment and lower incidence of GVHD with similar survival when compared to bone marrow transplants in children (Rocha et al, 2000). Demonstration that long term leukaemia-free survival in children (Wagner et al, 1996; Locatelli et al, 1999) and adults (Cairo & Wagner, 1997; Rubinstein et al, 1998; Laughlin et al, 2001; Sanz et al, 2001) is similar for cord blood transplant recipients and matched unrelated bone marrow transplant recipients. Isolation of non-haematopoietic stem cells from cord blood as a first step for regenerative medicine (Kogler et al, 2004) Improved results, mostly in adults, with the use of double cord blood transplants and non-myeloablative conditioning regimens (Barker et al, 2005; Brunstein et al, 2007; Rocha et al, 2010) New approach on Notch-mediated ex vivo expansion system of cord blood progenitors (Delaney et al, 2010)
other international cord blood banks; therefore a registry of UCBT recipients was created and, currently, more than 7000 patients have been reported. Furthermore, the Eurocord registry provides clinical outcome data on each transplanted cord blood unit to the CBB, with the goal of obtaining national and international accreditation. In addition, Eurocord has contributed to the field of UCBT with numerous publications, including guidelines for donor selection. Eurocord has also launched an online program in cord blood technology and transplantation, in order to promote education and information, providing an educational tool on the scientific, technical, clinical, and regulatory aspects of cord blood. The program (http://www.eurocord-ed.org) is easily accessible and convenient for users. Netcord was created in 1998 to establish good practices in UCB storage, facilitate donor search, improve the quality of the grafts, standardize criteria on an international scale, and, importantly, establish procedures for bank accreditation. The inventory of Netcord, the cooperative network of large experienced UCB banks, currently has more than 300 000 cryopreserved UCB units ready for clinical use for unrelated recipients and more than 8624 grafts have been shipped. In the
United States, the NMDP has established a similar CBB network. Collaboration between Netcord-Eurocord and NMDP has been established with the goal of providing the most suitable and high quality cord blood unit for a specific patient. A summary of CBB activity can be seen at http:// www.wmda.org. National regulatory agencies and transplant centres are aware of the need of international standards to promote quality throughout all phases of cord blood banking with the goal of achieving a consistent production of high quality placental and UCB units for transplantation. These standards cover: (i) collection of cord blood cells, regardless of the methodology or site of collection, (ii) maternal and infant donor screening, testing, and eligibility determination in accordance with any applicable law, (iii) all phases of processing and storage, including quarantine, testing, and unit characterization, (iv) availability of the UCB unit for transplantation, either directly or through a search registry, (v) the search process for the selection of a specific UCB unit, (vi) transport and shipment of fresh and cryopreserved UCB units and (vii) UCB final disposition. All of the practical aspects of cord blood banking mentioned above have been extensively published and are detailed in the latest version of the Netcord-
ª 2011 Blackwell Publishing Ltd, British Journal of Haematology, 154, 441–447
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Review Table II. Number of unrelated UCBT reported to Eurocord registry according to diagnosis and recipient age.
Diagnosis Acute lymphoblastic leukaemia Acute myeloid leukaemia Myelodysplastic syndrome Chronic myeloid leukaemia Chronic lymphocytic leukaemia Hodgkin/non-Hodgkin lymphomas Myeloma Solid tumours Hystiocytosis Congenital and acquired bone marrow failure syndromes Haemoglobinopathies Primary Immunodeficiencies Metabolic diseases Other disease
Children (£18 years, n = 3566)
Adults (>18 years, n = 3210)
1167 608 291 77 – 64/9 – 18 132 353
(0Æ5) (3Æ7) (9Æ9)
671 1208 428 208 76 290/122 88 6 5 91
71 412 353 11
(2) (11Æ6) (9Æ9) (0Æ2)
(32Æ7) (17) (8Æ2) (2Æ2) (2Æ1)
(20Æ9) (37Æ6) (13Æ3) (6Æ5) (2Æ4) (12Æ8) (2Æ7) (0Æ2) (0Æ2) (2Æ8)
– 3 (0Æ1) 11 (0Æ3) 3 (0Æ2)
The values in parentheses are expressed as percentage.
FACT Standards (http://www.factwebsite.org). With an increasing number of cord blood units, it seemed necessary to improve the quality of the units for the cost efficiency management of the banks. The optimal number of cord blood units that should be available in CBB is not known, but it is estimated that it should approach 9 UCB units per 10 000 inhabitants. Most banks prefer to store the larger units of more than 70 ml in order to obtain a minimum of 3 · 107 nucleated cells (NC)/kg of recipient weight. The effect of increasing the inventory from 50 000 to 300 000 cord blood units with a minimum dose of 2Æ3 · 107 NC/kg results in an increment in the chances of finding a donor of 19% for children and 10% for adults. Recently, Querol et al (2009) showed that a bank containing 50 000 units is optimal for the UK and larger banks would only marginally increase the chance of finding suitable units .
Clinical experience with related and unrelated UCB transplantation A survey conducted by the CIBMTR estimated that after 1998, 20% of stem cell transplants performed in young patients (
