Summary:Clinical evidence indicates that placental/umbilical cord blood (CB) is an alternative source of haematopoietic stem cells for bone marrow reconstitution. To establish a CB bank large panels of frozen, HLA-typed CB units need to be stored. Cryopreserved, unprocessed CB units require vast storage space. This study describes a method, using the Optipress II Automated Blood Component Extractor (Opti II) from Baxter Healthcare Corporation, to reduce the volume of the CB collection, preserving the quantity and quality of the progenitor cells, in a closed system. The CB collection was transferred to a triple bag system, centrifuged to produce a buffy coat layer and processed using a standard Opti II protocol to separate the whole blood into three components: plasma, buffy coat and buffy coat-depleted red cell concentrate. The buffy coat volume was standardised to 25 ml; mean reduced volume of 24.5 ml (s.d. 1.5 ml) with 53% red cell depletion. Good recovery of cells was observed: 92%, 98%, 96% and 106% recovery of nucleated, mononuclear, CD34 ϩ and total colonyforming cells, respectively. Using this method for processing CB units reduces storage requirement by two-thirds but preserves the quantity and quality of the progenitor cells. Keywords: cord blood; cord blood bank; processing; volume reduction; progenitor cells; transplantation Cord blood (CB) is increasingly used as an alternative source of stem and progenitor cells for the reconstitution of BM and sustaining long-term haemopoietic recovery in both unrelated and related recipients. 1-3 It offers several advantages over BM in that it is obtained without risk to either mother or infant, it has a decreased likelihood of transmitting infections -particularly pertinent for cytomegalovirus -and it can be stored fully tested and HLA typed, in the frozen state, available for immediate use. Recent clinical data 1-3 indicate that CB transplants may result in reduced severity of acute GVHD, allowing the use of parCorrespondence: S Armitage, London Cord Blood Bank, Deansbrook Road, Edgware, Middx HA8 9BG, UK Received 7 September 1998; accepted 24 September 1998 tially HLA-matched units and thus increasing the chance of finding donors for patients.To achieve a viable bank, providing a broad range of HLA-typed CB units, the storage of a large number of units is essential. The major logistical problem with such longterm banking is the required storage space, particularly when the CB units are stored unprocessed. Several different methods have been employed to reduce the volume of the CB unit, prior to cryopreservation of the cells, while minimising loss of either nucleated cells (NC) or progenitor cells: density gradient separation -standard 4 or modified techniques 5 -sedimentation of red cells by gelatin, 6 rouleaux formation induced by hydroxyethyl starch and centrifugation to reduce both erythrocytes and plasma 7,8 and differential centrifugation with manual 9 or automated 10 expression of RBC and plasma. The majority of these methods are not performed in a closed...

SummaryCord blood units (n ¼ 5500) stored at the London Cord Blood Bank, including 59 units transplanted into a high risk and heterogeneous group of patients, were analysed. Transplant outcome data was available for 44 patients with a median clinical follow-up of 14 months (range 3-44 months). Over 40% of the collected units were of ethnic minority origin with a median volume of 79 ml (range 40-240 ml) and a median total nucleated cell (TNC) count of 11AE9 · 10 9 /l (range 10AE0-24AE8 · 10 9 /l). The average patient's weight was 28 kg (range 5-80 kg) and the median age was 8 years (range 0AE7-40 years). The median number of nucleated cells infused was 4 · 10 7 / kg (range 1AE10-16 · 10 7 /kg). Neutrophil engraftment of 0AE5 · 10 9 /l was observed in 33 (74±%) patients with an average time of 28 days (range 11-60). The Kaplan-Meier estimate of acute graft-versus-host disease (grade II >) at day 100 was 37 ± 7% and in 27 (62%) patients, it was grade I or absent. The overall survival and disease-free survival at 2 years was 49 ± 8% and 41 ± 8%, respectively. Two years after transplantation the survival rate was 69% and 54% for patients receiving a 6/6 or 5/6 HLA matched units, respectively. Infection was the main cause of transplanted related mortality in these patients.

Summary:The London Cord Blood Bank was established with the aim of collecting, processing and storing 10 000 unrelated stem cell donations for the significant number of children in the UK requiring transplantation, for whom a matched unrelated bone marrow donor cannot be found. Collection is performed at two hospitals by dedicated cord blood bank staff after delivery of the placenta. Mothers are interviewed regarding medical, ethnic and behavioural history by nurse counsellors and sign a detailed consent form. Donations are returned to the bank for processing. Volume reduction is undertaken by a simple, closed, semi-automated blood processing system, with excellent recovery of progenitor cells. Units are cryopreserved and stored in the vapour phase of liquid nitrogen. Blood samples from mothers and cord blood donations are tested for the UK mandatory red cell and microbiology markers for blood donors. Donations are typed for HLA-A, B and DR at medium resolution (antigen split) level using sequencespecific oligonucleotide probing and sequence-specific priming techniques. The selection of collection hospitals on the basis of ethnic mix has proven effective, with 41.5% of donations derived from non-European caucasoid donors. Bacterial contamination of collections has been dramatically reduced by implementation of improved umbilical cord decontamination protocols. Keywords: cord blood; cord blood banking; stem cells; progenitor cellsCord blood (CB) is rich in haematopoietic progenitor cells and can be used as an alternative to bone marrow (BM) for transplantation. The collection of CB poses no risk to the donor, in contrast to BM harvesting which requires general anaesthesia. To facilitate the provision of CB units for transplantation, cord blood banks (CBB) have been developed worldwide.1-4 CBB utilise a waste product that is abundantly available from a diverse ethnic mix and there is a huge potential donor base, with about 600 000 births per year in the United Kingdom. Successful haematopoietic and immunological engraftment can occur when CB is the source of stem cells, even when there is one or more HLA antigen disparity between donor and recipient. bone marrow donor registries of hundreds of thousands, can provide adequate matches for large numbers of potential recipients. Tracking back to the donor at the time of final selection of the CB unit for transplantation is not required, therefore the time taken to identify a matched unit will be weeks rather than the months typically required to identify an unrelated BM donor. An additional advantage of CB is the low viral carriage rate of neonatal/fetal blood compared to adult blood. 7Prompted by the unavailability of suitable BM donors for a significant number of children requiring transplantation in England, the National Blood Service (NBS) founded the London Cord Blood Bank (LCBB). The bank aims to collect, process and store 10 000 CB donations. Its geographical location allows it to concentrate recruitment efforts in those ethnic groups that are not adequately re...

There is a need for standardization to ensure adoption of best practice.

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