Haematopoietic Transplant Potential of Unrelated and Related Cord Blood: The first six Years of the EUROCORD/NETCORD Bank Germany

Abstract

To date, human umbilical cord blood (CB) has been employed successfully in well over 1000 allogeneic (unrelated and sibling) stem cell transplantations. Because of primary limitations in volume and cell numbers, over 90% of these transplantations were performed in children. Therefore requests for well standardised cord blood units of high quality are now increasing constantly. Examination and standardisation of unrelated and related cord blood stem cell preparations and banking as well as their biological characterisation was already initiated in Düsseldorf in 1992. Hitherto a total of 3236 CB samples with a mean volume of 89±25 ml, a mean total number of nucleated cells (NC) of 10±5 × 10⁸ and a mean number of CFU-GM of 6±5 × 10⁵ have also been validated by haematological, immunological and microbiological criteria. In addition to that, 97 directed CB donations of siblings with a clinical indication have been characterised and banked along the same lines. All CB units were collected from the umbilical cord vein immediately after vaginal full term delivery or caesarean section, then frozen and stored in liquid nitrogen. 1940 CB units were stored unseparated, the other 1296 were volume reduced using Hetastarch (HES) with a mean recovery of 85±13% of the nucleated cells, 86 ±12% and 84±13% for CFC and CD34⁺ cells, respectively. Only 5.0 ml of a CB sample is required for routine laboratory testing as there are HLA-class I typing, HLA-class II typing by sequence specific oligonucleotide probes (PCRSOP), ABO typing, sterility control, assessment of progenitor and stem cells by colony forming assays, and CD34⁺ status as well as certain viral infections such as CMV, Hepatitis B, C, HIV, Parvo B19 by PCR technology before releasing the CB unit for transplantation. For apparent viral infections, maternal sera obtained at birth were tested for HBsAg, anti-HBc, anti-HCV, -HAV- (IgG, IgM), -HIV-1-2, -EBV- (IgG, IgM), -HTLVI-II, -I CMV (IgM, IgG), toxoplasmosis and syphilis. Within the last three years a total of 4860 preliminary searches and 680 extended unit reports were submitted to the CB bank Düsseldorf by fax or World Wide Web. So far 68 unrelated and 3 related CB units were delivered. From these 70 have been transplanted in 30 different transplant centres world-wide. Until now the evaluation of the first 53 unrelated CB-transplantations was performed together with the EUROCORD transplant registry. Three patients were excluded from the analysis, since they received an unrelated CB-transplant for non-engraftment after previous allotransplants. The median patient age of these 50 patients was 5.0 years (range 0.3-44), the median weight 18 kg (range 4-70 kg). The majority of the patients transplanted for malignancies (66%) suffered from ALL (n = 19), AML (n = 7), CML (n = 4) and lymphoma (n = 2) with two third (75%) in an intermediate (2^nd CR) or advanced stage of disease (> 2^nd CR); 13 patients had metabolic diseases and immunodeficiencies and three had aplastic anaemia. All CB samples as well as the patients' blood samples were typed in Düsseldorf for HLA-class I by serology confirmed by PCR-SSP and by high resolution DNA typing for HLA-DRB1 and HLA-DQB1 alleles. 96% of the 50 patients receiving unrelated CB were mismatched at one or more HLA-antigens. 41 of the 50 patients transplanted with unrelated CB from Düsseldorf were evaluable for engraftment with an overall engraftment rate of 83%. According to the defined criteria of EUROCORD, 9 of the 50 patients were not evaluable for engraftment, since they died before day 60. The present median follow-up time is 14 months (1.4-38). The Kaplan- Meier estimate of survival at one year is 42 percent. The three paediatric patients after sibling CB transplantations (ALL, amegakaryocytic thrombocytopenia and CML) are alive with a follow-up time of 350,379 days and 531 days. The first two are disease free, the patient with CML after relapse at day 207 and subsequent several donor leukocyte infusions is in clinical remission with minimal residual disease as documented by molecular biology. The data demonstrate that CB is a potential alternative to bone marrow as stem cell transplant, if no HLA-identical family or unrelated donor is available or the transplantation is urgent in paediatric patients. Hämatopoetische Stamm- und Vorläuferzellen aus Nabelschnurblut wurden bereits bei über 1000 allogenen Nabelschnurbluttransplantationen sowohl bei der unverwandten Transplantation (überwiegend mit ein bis drei HLA-Antigenmismatchen) als auch bei Geschwistern (überwiegend HLA-identisch) erfolgreich eingesetzt. Die Anfragen für pädiatrische Patienten, aber auch für Erwachsene, die mit Nabelschnurblut transplantiert werden sollen, wachsen ständig. Aus diesem Grund wurde bereits 1992 eine Pilotstudie in Düsseldorf gestartet, um Nabelschnurblut hinsichtlich seiner biologischen Eigenschaften zu charakterisieren und entsprechende standardisierte Stammzelltransplantate mit hoher Qualität herstellen zu können. Bisher wurden 3236 Nabelschnurbluttransplantate (Stand Januar 1999) mit einer mittleren Volumenmenge von 89±25 ml und 10±5 × 10⁸ kernhaltigen Zellen und 6±5 × 10⁵ CFU-GM als unverwandte Stammzellasservate sowie für familiengerichtete Transplantate nach klinischer Indikation (n = 97) abgenommen, charakterisiert und in flüssigem Stickstoff gelagert. Die Abnahme des Nabelschnurblutes erfolgte aus der Nabelschnurblutvene nach normalen Geburten oder nach einem Kaiserschnitt. 1940 Nabelschnurbluttransplantate wurden unsepariert in flüssigem Stickstoff eingefroren, alle weiteren 1296 mit Hilfe von Hetastarch volumenreduziert mit einer mittleren Ausbeute von 85±13% für kernhaltige Zellen und...