Current practices and prospects for standardization of the hematopoietic colony-forming unit assay: a report by the cellular therapy team of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative.

BACKGROUND AIMS: Wide acceptance of the colony-forming unit (CFU) assay as a reliable potency test for stem cell products is hindered by poor inter-laboratory reproducibility. The goal of this study was to ascertain current laboratory practices for performing the CFU assay with an eye towards identifying practices that could be standardized to improve overall reproducibility. METHODS: A survey to evaluate current laboratory practices for performing CFU assays was designed and internationally distributed. RESULTS: There were 105 respondents to the survey, of whom 68% performed CFU assays. Most survey recipients specified that an automated rather than a manual cell count was performed on pre-diluted aliquots of stem cell products. Viability testing methods employed various stains, and when multiple sites used the same viability stain, the methods differed. Cell phenotype used to prepare working cell suspensions for inoculating the CFU assay differed among sites. Most respondents scored CFU assays at 14-16 days of incubation, but culture plates were read with various microscopes. Of 57 respondents, 42% had not performed a validation study or established assay linearity. Only 63% of laboratories had criteria for determining if a plate was overgrown with colonies. CONCLUSIONS: Survey results revealed inconsistent inter-laboratory practices for performing the CFU assay. The relatively low number of centers with validated CFU assays raises concerns about assay accuracy and emphasizes a need to establish central standards. The survey results shed light on numerous steps of the methodology that could be targeted for standardization across laboratories.

Concise review: expanding roles for hematopoietic cellular therapy and the blood transfusion services.

Hematopoietic stem cells (HSCs) have remained at the forefront of stem cell research for the past 50 years, since the therapeutic potential of bone marrow transplantation was realized. Uniquely, among stem and progenitor cells, research progress has been made in parallel between the laboratory benchtop and hospital bedside during this period. Integral to this work has been the role of the transfusion medicine services in the collection, storage, and processing of HSCs. The next decade promises to bring further developments: with new fields of cellular therapies, stem cell vaccination, and stem cell drug testing opening up. This article summarizes exciting areas of research concerning the behavior and potential clinical applications of HSCs. For the purposes of clarity, we describe in turn the trafficking and transfer of HSCs; ex vivo expansion of HSC units from different sources; and finally, applications of specifically selected subsets of hematopoietic cells and their progeny.

Storage characteristics of cord blood progenitor cells: report of a multicenter study by the cellular therapies team of the Biomedical Excellence for Safer Transfusion (BEST) Collaborative.

BACKGROUND: Most hematopoietic progenitor cell (HPC) products are infused or processed shortly after collection, but in some cases this may be delayed for up to 48 hours. A number of variables such as temperature and cell concentration are of critical importance for the integrity of HPCs during this time. STUDY DESIGN AND METHODS: We evaluated critical variables using cord blood HPC units that were divided equally and stored at 4 °C versus room temperature (RT) for up to 96 hours. Total nucleated cell (TNC) and mononuclear cell (MNC) counts, viable CD34+ cell counts, and CD45+ cell viability as well as colony-forming unit-granulocyte-macrophage (CFU-GM) present over time at each temperature were determined. RESULTS: Overall, the data indicate that with the exception of viable CD34+ cells, there was a significant decrease in each variable measured for 72 to 96 hours and, with the exception of viable CD34+ cells and CFU-GM, the reductions were significantly greater in RT units than 4 °C units. There was an increase in viable CD34+ count for units where TNC count was greater than 8.5 × 10(9) /L, compared with units where TNC count was less than 8.5 × 10(9) /L, that was different for each storage temperature. CONCLUSIONS: Cord blood HPC collections maintained at 4 °C retained higher TNC counts, MNC counts, and CD45+ cell viability over a 72- to 96-hour storage period.

A rapid culture technique produces functional dendritic-like cells from human acute myeloid leukemia cell lines.

Most anti-cancer immunotherapeutic strategies involving dendritic cells (DC) as vaccines rely upon the adoptive transfer of DC loaded with exogenous tumour-peptides. This study utilized human acute myeloid leukemia (AML) cells as progenitors from which functional dendritic-like antigen presenting cells (DLC) were generated, that constitutively express tumour antigens for recognition by CD8(+) T cells. DLC were generated from AML cell lines KG-1 and MUTZ-3 using rapid culture techniques and appropriate cytokines. DLC were evaluated for their cell-surface phenotype, antigen uptake and ability to stimulate allogeneic responder cell proliferation, and production of IFN-γ; compared with DC derived from normal human PBMC donors. KG-1 and MUTZ-3 DLC increased expression of CD80, CD83, CD86, and HLA-DR, and MUTZ-3 DLC downregulated CD14 and expressed CD1a. Importantly, both KG-1 and MUTZ-3-derived DLC promoted proliferation of allogeneic responder cells more efficiently than unmodified cells; neither cells incorporated FITC-labeled dextran, but both stimulated IFN-γ production from responding allogeneic CD8(+) T cells. Control DC produced from PBMC using the FastDC culture also expressed high levels of critical cell surface ligands and demonstrated good APC function. This paper indicates that functional DLC can be cultured from the AML cell lines KG-1 and MUTZ-3, and FastDC culture generates functional KG-1 DLC.

Stem cell donation--what advice can be given to the donor?

Haematopoietic stem cell transplantation (HSCT) is widely used to treat patients with a range of haematological and non-haematological disorders. Both bone marrow and peripheral blood stem cell collection are associated with morbidity and, very rarely, mortality. We investigated the information that exists to adequately inform donors about the relative merits of each procedure. We carried out a systematic review analysing data from six prospective randomised controlled trials of related donors and discuss here the merits and drawbacks of this approach. Registry data mostly describes patient outcome but stem cell donor registries collect and report information on unrelated donors which could easily be extended to related donors. Further well-designed, randomised studies are required.

Bone marrow harvest versus peripheral stem cell collection for haemopoietic stem cell donation in healthy donors.

BACKGROUND: Haemopoietic stem cells can be collected from a donor either as a bone marrow harvest or by peripheral blood collection. Both techniques have risks for the donor. OBJECTIVES: The aim of this review was to identify the adverse effects of haemopoietic stem cell donation and to compare the tolerability and safety of the two methods. SEARCH STRATEGY: We searched bibliographic databases including the Cochrane Central Register of Controlled trials (CENTRAL) (The Cochrane Library 2008, issue 2), MEDLINE and EMBASE up to May 2008. We also searched reference lists of articles and contacted experts in the field. SELECTION CRITERIA: Randomised controlled trials enrolling haemopoietic stem cell donors and evaluating the different methods of donating haemopoietic stem cells were eligible. DATA COLLECTION AND ANALYSIS: Two authors independently screened studies for inclusion. We extracted data and evaluated methodological quality. Quantitative analysis was not possible for most outcomes, but where used we preferred random-effects models due to the variability between the included studies. MAIN RESULTS: Six trials (807 donors) were eligible: all were substudies, or constituent parts of, larger randomised controlled trials of bone marrow and peripheral blood stem cell allogeneic transplantation. No included trial was designed solely to measure and assess the experience of stem cell donors. The donors in all studies were related to the stem cell recipient. Overall, both types of donors experienced pain subsequent to donation, and psychological morbidity. The trend was for bone marrow donors to experience more pain at the donation site, more overall adverse events, and more days of restricted activity. They were also more likely to require hospitalisation than peripheral blood stem cell donors. In contrast, peripheral blood stem cell donors experienced more pain prior to donation, which may be related to the pre-donation administration of granulocyte colony stimulating factor (G-CSF). The methodological quality of the studies was poor and indicated limitations due to the risk of selection and attrition bias. The proportion of donors from the parent trial not included in the donor substudies was also inadequately explained. AUTHORS' CONCLUSIONS: The different short-term morbidities associated with each type of haemopoietic stem cell donation were clear, with bone marrow donors experiencing more pain and more restriction post-donation than peripheral blood donors. However, the studies were limited by their methodological quality, failure to provide long-term follow up (for which larger numbers of donors would be required) and a failure to apply consistent measures of quality of life in a way which allows more meaningful evaluation across studies.

Immunotherapeutic strategies in acute lymphoblastic leukaemia relapsing after stem cell transplantation.

Acute lymphoblastic leukaemia (ALL) responds well to chemotherapy and the majority of children and a significant proportion of adults are cured of their disease after primary therapy. However, a number of patients relapse and allogeneic transplantation following conditioning with chemotherapy and radiotherapy offers the possibility of long-term survival in a proportion of these patients. A significant number of patients with ALL develop disease that is refractory to further therapy. The infusion of unmodified donor lymphocytes (DLI) following relapse after allogeneic transplantation has been shown to be curative in patients with chronic myeloid leukaemia (CML). However, in ALL the success rate is much lower. The results of in vitro and limited in vivo studies suggest that it may be possible to manipulate lymphocytes from the transplant donor to produce cytotoxic T-lymphocytes (CTL) with increased effectiveness in killing patients' ALL cells. This may be done in a number of ways. For example, some strategies utilise the patients dendritic cells (DC) to present tumour antigens to donor lymphocytes and convert them into CTL either by pulsing DC taken in remission with ALL cells or lysate, fusing such 'normal' DC with ALL cells or using DC cultured from the patient's ALL cells. Other approaches include exploiting the expression of leukaemia-specific antigens such as the proteinase PR-3 or the zinc finger transcription factor Wilms tumour-1 protein (WT-1) to stimulate CTL responses. Alternatively, immunotherapeutic strategies might exploit differences in minor histocompatibility antigens such as HA-1 and HA-2 between donor and recipient. These are expressed solely on haemopoietic cells making them suitable targets for donor derived anti-leukaemic cells. In vivo studies to date suggest that educated T-cells may have a role to play in the treatment of relapsed and refractory ALL in the future.

Detection of residual donor leucocytes in leucoreduced red blood cell components using a fluorescence microplate assay.

In November 1999, universal leucoreduction of blood components was introduced in the UK to minimise the risk of variant Creutzfeldt-Jakob Disease (vCJD) transmission by blood transfusion. The UK specifications for leucodepletion processes state that 99% of leucodepleted components should contain < 5 x 10(6) leucocytes/unit, within 95% confidence limits. However, this leucocyte concentration is below the detection limits of standard haematology analysers. The development of a fluorometric immunoassay to detect the residual donor leucocytes in leucoreduced blood components is described. Monoclonal antibodies to leucocyte-specific cell surface antigens, CD45 and CD15, were adsorbed to the well surface in 96-well microplates. Red blood cell samples containing low numbers of leucocytes were added to the wells and the cells of interest captured by the monoclonal antibodies. Since leucocytes are the only nucleated cells found in significant numbers in blood components they were quantified using PicoGreen, a fluorescent stain specific for dsDNA. In comparison to flow cytometry, the method currently used to detect low numbers of leucocytes, the microplate assay demonstrated excellent sensitivity (1.00) and acceptable specificity (0.81) when standard leucodepleted samples were tested. There was no significant difference between the two methods (p < or = 0.175). In conclusion, the fluorescence microplate assay represents a simple, high throughput alternative to flow cytometry for monitoring leucodepletion compliance in blood banks.

Transfusion strategies in patients undergoing stem-cell transplantation.

Hemopoietic stem-cell transplant patients may require intensive blood component support. Complications of transfusions include transmission of viral and bacterial infections, transfusion-associated graft-versus-host disease and transfusion-related acute lung injury. Alloimmunization to red cell antigens may cause difficulties in selecting compatible blood, while alloimmunization to HLA expressed on platelets may cause subsequent platelet transfusion refractoriness. It is essential to define robust transfusion policies and procedures and these should be regularly audited. This article reviews blood component transfusion in the setting of hemopoietic stem-cell transplant and specifically discusses the management of ABO-mismatched transplants, the prevention of cytomegalovirus transmission, the prevention of transfusion-associated graft-versus-host disease and the use of granulocyte transfusions.

JACIE accreditation in 2008: demonstrating excellence in stem cell transplantation.

JACIE was initiated as a small pilot project in Spain in 2000 and launched as a formal Europe-wide inspection program in January 2004. Since 2000, over 150 applications for accreditation have been received by the JACIE Office and more than 130 inspections have been completed in European centers and facilities. Almost all of these were found to be functioning at a high level of excellence, with the majority having only minor deficiencies in compliance with the standards. In one-third of centers there were more significant deficiencies. The most common deficiencies were in quality management. Following correction of deficiencies 86 centers have to date achieved full accreditation and many more are nearing the completion of the process. Implementation of JACIE involves a significant investment of time and resources by applicant centers. The majority require at least 18 months to prepare for accreditation and 85% have needed to employ a quality manager and/or data manager on an ongoing basis. However, all centers felt their program had benefited from the implementation of JACIE. JACIE is also working closely with other international organisations related to cellular therapy as part of the Alliance for the Harmonisation of Cell Therapy Accreditation (AHCTA), which is examining the differences in existing standards and aiming to develop international standards for all aspects of stem cell transplantation. In particular the requirements for safety of imported tissues and cells has emphasised the need for global harmonisation. The recent implementation of Directive 2004/23/EC and the associated Commission Directives 2006/17/EC and 2006/86/EC has provided an impetus for the implementation of JACIE in European Union (EU) member states. It will be important in the future to examine how JACIE can co-operate with the EU Competent Authorities (CA) to ease the burden of the inspection process for haemopoietic stem cell (HSC) transplant programs.

The use of granulocyte-colony-stimulating factor in volunteer unrelated hemopoietic stem cell donors.

Granulocyte-colony-stimulating factor (G-CSF) is used for the mobilization of hemopoietic stem cells in healthy donors. It has a number of common side effects such as bone pain, which resolve rapidly after administration is discontinued. Recent publications have raised concern that it might act as a trigger for the development of hematologic malignancy in susceptible individuals, possibly by causing genomic instability, but to date there is no evidence that healthy volunteer donors who receive G-CSF are at any increased risk. Ongoing studies aim to confirm whether or not G-CSF can cause chromosomal abnormalities in healthy donors. In the UK, the British Bone Marrow Registry and Anthony Nolan Trust give G-CSF to donors who have agreed to donate peripheral blood stem cells. It is recommended by the UK Registries at present that all stem cell donors are given updated information explaining the current uncertainties with regard to the use of G-CSF before they give informed consent to its administration. This information is based on a statement agreed by the World Marrow Donor Association for use by individual donor registries. Further, it is our current practice that all donors who have received G-CSF, as well as marrow donors who do not, should be under regular review for at least 10 years to allow the occurrence of any long-term adverse events to be documented.

Viability does not necessarily reflect the hematopoietic progenitor cell potency of a cord blood unit: results of an interlaboratory exercise.

BACKGROUND: Clinical transplant outcome with umbilical cord blood (UCB) as source of hematopoietic progenitor cells (HPCs) is, among other factors, determined by the total number of viable nucleated cells and/or CD34+ cells in the unit. Quantitative and qualitative losses by processing and cryopreservation and by thawing and washing before transfusion may occur, however. Another reason for a discrepancy between the number of cells in the unit released by the cord blood bank and found in the transplant center may be technical differences in cell counting methods between the two sites. STUDY DESIGN AND METHODS: With the collaborative group for Biomedical Excellence for Safer Transfusion (BEST), an interlaboratory exercise was conducted among nine sites for thawed UCB variables: total nucleated cells, CD34+ cells, viability, and HPC cultures. Three frozen UCB samples were shipped, with instructions for thawing, counting, and HPC plating. RESULTS: Unexpectedly samples arrived at all nine receiving centers without detectable hematopoietic progenitor colony-forming cells. Nevertheless, wide interlaboratory ranges for viability were obtained. The proportion of viable cells was found higher with manual methods, but all viability assays used in the study overestimated functional progenitor cells. CONCLUSIONS: The results underscore the complexity of evaluation of frozen-thawed cord blood cells and the need for standardization of assessment.

Harvesting, processing and inventory management of peripheral blood stem cells.

By 2003, 97% autologous transplants and 65% of allogeneic transplants in Europe used mobilised peripheral blood stem cells (PBSC). Soon after their introduction in the early 1990's, PBSC were associated with faster haemopoietic recovery, fewer transfusions and antibiotic usage, and a shorter hospital stay. Furthermore, ease and convenience of PBSC collection made them more appealing than BM harvests. Improved survival has hitherto been demonstrated in patients with high risk AML and CML. However, the advantages of PBSC come at a price of a higher incidence of extensive chronic GVHD. In order to be present in the blood, stem cells undergo the process of "mobilisation" from their bone marrow habitat. Mobilisation, and its reciprocal process - homing - are regulated by a complex network of molecules on the surface of stem cells and stromal cells, and enzymes and cytokines released from granulocytes and osteoclasts. Knowledge of these mechanisms is beginning to be exploited for clinical purposes. In current practice, stem cell are mobilised by use of chemotherapy in conjunction with haemopoietic growth factors (HGF), or with HGF alone. Granulocyte colony stimulating factor has emerged as the single most important mobilising agent, due to its efficacy and a relative paucity of serious side effects. Over a decade of use in healthy donors has resulted in vast experience of optimal dosing and administration, and safety matters. PBSC harvesting can be performed on a variety of cell separators. Apheresis procedures are nowadays routine, but it is important to be well versed in the possible complications in order to avoid harm to the patient or donor. To ensure efficient collection, harvesting must begin when sufficient stem cells have been mobilised. A rapid, reliable, standardized blood test is essential to decide when to begin harvesting; currently, blood CD34+ cell counting by flow cytometry fulfils these criteria. Blood CD34+ cell counts strongly correlate with the apheresis yields. These are, in turn, predictive of the speed of haemopoietic recovery after transplantation, which has helped establish the adequate cell dose for transplantation. Following collection, PBSC may be transfused unmanipulated, processed to select specific cell subtypes, or stored for future use. Cryopreservation techniques allow long term storage of stem cells without significant loss of viability. Increasingly demanding calls for safety led to introduction of vapour phase storage, separate storage of infected material, and mandatory quality control measures at all stages of the cryopreservation process and subsequent thawing and transfusion. At the same time, safety of the personnel working in stem cell processing and storage laboratories is safeguarded by a set of regulations devised to minimize the risk of infection, injury or hypoxia. Requirements for quality and safety have been shaped into a number of documents and directives in Europe and USA, emphasising the importance of product traceability, reporting of adverse reactions, quality management systems (standard operating procedures, guidelines, training records, reporting mechanisms and records), requirements for cell reception, quarantine, process control, validation and storage. Establishments that collect, process and store stem cells must be accredited or licensed by appropriate national or international authorities on a regular basis. These regulatory measures have recently become law across the European Union.

Storage of hemopoietic stem cells.

BACKGROUND: Autologous, and in some cases allogeneic, hemopoietic stem cells (HSC) are stored for varying periods of time prior to infusion. For periods of greater than 48 h, storage requires cryopreservation. It is essential to optimize cell storage and ensure the quality of the product for subsequent reinfusion. METHODS: A number of important variables may affect the subsequent quality of infused HSC and therapeutic cells (TC). This review discusses these and also reviews the regulatory framework that now aims to ensure the quality of stem cells and TC for transplantation. RESULTS: Important variables included cell concentration, temperature, interval from collection to cryopreservation, manipulations performed. They also included rate of freezing and whether controlled-rate freezing was employed. Parameters studied were type of cryoprotectant utilized [dimethyl sulphoxide (DMSO) is most commonly used, sometimes in combination with hydroxyethyl starch (HES)]; and storage conditions. It is also important to assess the quality of stored stem cells. Measurements employed included the total cell count (TNC), mononuclear cell count (MNC), CD34+ cells and colony-forming units - granulocyte macrophage (CFU-GM). Of these, TNC and CD34+ are the most useful. However, the best measure of the quality of stored stem cells is their subsequent engraftment. The quality systems used in stem cell laboratories are described in the guidance of the Joint Accreditation Committee of ISCT (Europe) and the EBMT (JACIE) and the EU Directive on Tissues and Cells plus its supporting commission directives. Inspections of facilities are carried out by the appropriate national agencies and JACIE. CONCLUSION: For high-quality storage of HSC and TC, processing facilities should use validated procedures that take into account critical variables. The quality of all products must be assessed before and after storage.

Robin Coombs: his life and contribution to haematology and transfusion medicine.

Robin Coombs was the last survivor of the distinguished group of immunologists that included Philip Gell, John Humphrey, John Marrack, Peter Medawar and Robert White and who were responsible for the renaissance of British Immunology after the Second World War. He is best remembered for describing the antiglobulin test that bears his name. The antiglobulin test revolutionised the diagnosis of haemolytic diseases and the compatibility testing of blood for transfusion. In all, Coombs authored over 200 scientific papers. Haemagglutination reactions became widely used in the diagnosis of a range of infectious agents. Together with Philip Gell, he devised the classification of allergic reactions; these were published in the textbook "Clinical Aspects of Immunology", which he and Gell first edited in 1963 and which became the leading textbook on medical immunology. Robin Coombs was also one of the founders of the British Society for Immunology.

Directed sibling cord blood banking for transplantation: the 10-year experience in the national blood service in England.

Umbilical cord blood (UCB) is an important source of hematopoietic stem cells for transplantation. Although UCB is often collected from unrelated donors, directed umbilical cord blood (DCB) from sibling donors also provides an important source of UCB for transplantation. This report summarizes the experience in collection, testing, storage, and transplantation of DCB units by the National Blood Service for England and North Wales over 10 years. Eligibility for collection was based on an existing sibling suffering from a disease that may be treated by stem cell transplantation or a family history that could result in the birth of a sibling with a disease that could be treated by stem cell transplantation. Collections were made on the provision that the sibling's clinician was willing to financially support the collection and to take responsibility for medical review of the mother and potential recipient. Given the high investment in UCB banking and the introduction of new regulations and mandatory licensing under the European Union Tissues and Cells Directive and those proposed in the U.S., this report details the procedures that we have used for DCB donations, the outcome data where donations have been used for transplantation, and it provides some timely recommendations for best practices. Disclosure of potential conflicts of interest is found at the end of this article.

ISBT 128 implementation plan for cellular therapy products.

The publication of new standards for terminology and labeling marks an important step in ensuring consistency and traceability of cellular therapies at the global level. However, it is only with the widespread implementation of the standard that the benefits can be truly realized. This paper provides guidance on the practical aspects of adopting these new standards for organizations with differing current levels of computerization. It discusses project management, equipment, licensing, and validation topics.