Evaluation of 'out-of-specification' CliniMACS CD34-selection procedures of hematopoietic progenitor cell-apheresis products.

BACKGROUND: Immunomagnetic selection of CD34(+) hematopoietic progenitor cells (HPC) using CliniMACS CD34 selection technology is widely used to provide high-purity HPC grafts. However, the number of nucleated cells and CD34+ cells recommended by the manufacturer for processing in a single procedure or with 1 vial of CD34 reagent is limited. METHODS: In this retrospective evaluation of 643 CliniMACS CD34-selection procedures, we validated the capacity of CliniMACS tubing sets and CD34 reagent. Endpoints of this study were the recovery and purity of CD34+ cells, T-cell depletion efficiency and recovery of colony-forming units-granulocyte-macrophage (CFU-GM). RESULTS: Overloading normal or large-scale tubing sets with excess numbers of total nucleated cells, without exceeding the maximum number of CD34+ cells, had no significant effect on the recovery and purity of CD34+ cells. In contrast, overloading normal or large-scale tubing sets with excess numbers of CD34+ cells resulted in a significantly lower recovery of CD34+ cells. Furthermore, the separation capacity of 1 vial of CD34 reagent could be increased safely from 600 x 10(6) CD34+ cells to 1000 x 10(6) CD34+ cells with similar recovery of CD34(+) cells. Finally, T-cell depletion efficiency and the fraction of CD34+ cells that formed CFU-GM colonies were not affected by out-of-specification procedures. DISCUSSION: Our validated increase of the capacity of CliniMACS tubing sets and CD34 reagent will reduce the number of selection procedures and thereby processing time for large HPC products. In addition, it results in a significant cost reduction for these procedures.

Current status of JACIE accreditation in Europe: a special report from the Joint Accreditation Committee of the ISCT and the EBMT (JACIE).

JACIE (Joint Accreditation Committee of the ISCT and the EBMT) launched its first official inspection programme in January 2004. Since then, 35 centres in Europe have been inspected. Almost all 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 centres there were more significant deficiencies. The most common deficiencies were in quality management, and a survey of the applicant centres confirmed this was the area where centres experienced most difficulty in preparation for accreditation. Following correction of deficiencies, 28 centres have at the time of writing achieved full accreditation. Implementation of JACIE required a significant investment of time and resources by applicant centres. The majority required at least 18 months to prepare for accreditation and 85% needed to employ a quality manager and/or data manager on an ongoing basis. However, all centres felt their programme had benefited from the implementation of JACIE. In addition to the inspection and accreditation of individual centres, JACIE maintains an educational programme including training courses for inspectors and for centre preparation. JACIE is also working closely with other international organisations working in cellular therapy to develop international standards for all aspects of stem cell transplant. The recent implementation of Directive 2004/23/EC has provided an impetus for the implementation of JACIE in EU member states and in particular the requirements for safety of imported tissues and cells have emphasised the need for global harmonisation.

Terminology and labeling of cellular products-2: Implementation plan.

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.

Terminology and labeling of cellular products: 1. Standards.

The International Cellular Therapy Coding and Labeling Advisory Group was established to address the growing need for standardization of terminology and labeling for cellular therapy products as a result of increasing international transfer of these products. This paper presents new standards for terminology and labeling. These standards have been developed through a consultative process and are supported by key professional and accreditation bodies. By using these standards, together with the unique donation identification numbers and international product reference tables provided by the International Society of Blood Transfusion (ISBT) 128 Standard, consistency and traceability can be assured at the global level. A companion paper provides guidance on the implementation of the ISBT 128 system.

Efficacy of host-dendritic cell vaccinations with or without minor histocompatibility antigen loading, combined with donor lymphocyte infusion in multiple myeloma patients.

Donor lymphocyte infusions (DLI) can induce durable remissions in multiple myeloma (MM) patients, but this occurs rather infrequently. As the graft-versus-tumor (GvT) effect of DLI depends on the presence of host-dendritic cells (DCs), we tested in a phase I/II trial whether the efficacy of DLI could be improved by simultaneous vaccination with host-DCs. We also analyzed the possibility of further improving the GvT effect by loading the DCs with peptides of mismatched hematopoietic cell-specific minor histocompatibility antigens (mHags). Fifteen MM patients not responding to a first DLI were included. Eleven patients could be treated with a second equivalent dose DLI combined with DC vaccinations, generated from host monocytes (moDC). For four patients, the DC products did not meet the quality criteria. In four of the treated patients the DCs were loaded with host mHag peptides. Toxicity was limited and no acute GvHD occurred. Most patients developed objective anti-host T-cell responses and in one patient a distinct mHag-specific T-cell response accompanied a temporary clinical response. These findings confirm that DLI combined with host-DC vaccination, either unloaded or loaded with mHag peptides, is feasible, safe and capable of inducing host-specific T-cell responses. The limited clinical effects may be improved by developing more immunogenic DC products or by combining this therapy with immune potentiating modalities like checkpoint inhibitors.

A phase I/II minor histocompatibility antigen-loaded dendritic cell vaccination trial to safely improve the efficacy of donor lymphocyte infusions in myeloma.

Allogeneic stem cell transplantation (allo-SCT) with or without donor lymphocyte infusions (DLI) is the only curative option for several hematological malignancies. Unfortunately, allo-SCT is often associated with GvHD, and patients often relapse. We therefore aim to improve the graft-versus-tumor effect, without increasing the risk of GvHD, by targeting hematopoietic lineage-restricted and tumor-associated minor histocompatibility antigens using peptide-loaded dendritic cell (DC) vaccinations. In the present multicenter study, we report the feasibility, safety and efficacy of this concept. We treated nine multiple myeloma patients with persistent or relapsed disease after allo-SCT and a previous DLI, with donor monocyte-derived mHag-peptide-loaded DC vaccinations combined with a second DLI. Vaccinations were well tolerated and no occurrence of GvHD was observed. In five out of nine patients, we were able to show the induction of mHag-specific CD8+ T cells in peripheral blood. Five out of nine patients, of which four developed mHag-specific T cells, showed stable disease (SD) for 3.5-10 months. This study shows that mHag-based donor monocyte-derived DC vaccination combined with DLI is safe, feasible and capable of inducing objective mHag-specific T-cell responses. Future research should focus on further improvement of the vaccination strategy, toward translating the observed T-cell responses into robust clinical responses.

Feasibility of multiple courses of high-dose cyclophosphamide, thiotepa, and carboplatin for breast cancer or germ cell cancer.

PURPOSE: To determine the feasibility and safety of multiple, closely timed courses of high-dose cyclophosphamide, thiotepa, and carboplatin (CTC) with peripheral-blood progenitor-cell transplantation (PBPCT). PATIENTS AND METHODS: Forty-eight patients with advanced cancer were scheduled to undergo either two or three courses of CTC with PBPCT. All PBPCs were harvested before high-dose therapy began. Full-dose CTC courses incorporated cyclophosphamide (6,000 mg/m2), thiotepa (480 mg/m2), and carboplatin (1,600 mg/m2) divided over days -6, -5, -4, and -3. Tiny CTC courses (tCTC) contained 67% of the doses of each of these agents. Second or third courses of CTC or tCTC began on day 28. RESULTS: A sufficient number of PBPC could be harvested from all but two patients. Thirty-five first full-dose courses of CTC were given, 28 second courses, and 10 third courses. Second courses could be given on time and at full dose in 80% of the patients, but there was one toxic death from venoocclusive disease (VOD). Only four of 12 patients scheduled to receive three courses of full-dose CTC could be treated at the time and dose planned. There were three toxic deaths: one of VOD, one of sepsis, and one of hemolytic uremic syndrome (HUS). Eight patients were scheduled to receive three courses of tCTC. Eight first, seven second, and six third courses were given. One of the third courses had to be delayed and one had to be reduced in dose. CONCLUSION: A sufficient number of PBPCs for two or three transplantations can be harvested from most patients without much difficulty before high-dose therapy. Two full-dose CTC courses or three tCTC courses can be given safely and with acceptable toxicity at 5-week intervals. Organ toxicity rather than bone marrow toxicity has become dose-limiting for alkylating agents.

Subsets of CD34+ cells and rapid hematopoietic recovery after peripheral-blood stem-cell transplantation.

PURPOSE: To study whether there is a relationship between transplanted cell dose and rate of hematopoietic recovery after peripheral-blood stem-cell (PBSC) transplantation, and to obtain an indication whether specific subsets of CD34+ cell populations contribute to rapid recovery of neutrophils or platelets. PATIENTS AND METHODS: Based on data from 59 patients, we calculated for each day after PBSC transplantation the dose of CD34+ cells that resulted in rapid recovery of either neutrophils or platelets in the majority (> 70%) of patients. Using dual-color flow cytometry, subsets of peripheral-blood CD34+ cells were quantified and the numbers of CD34+ cells belonging to each of the reinfused subsets correlated with hematopoietic recovery following high-dose chemotherapy. RESULTS: The calculated threshold values with a high probability of engraftment showed a steep dose-effect relationship between CD34+ cell dose and time to recovery of both neutrophils or platelets. Predominantly CD34+ cells with the phenotype of myeloid precursors were mobilized. A minority of CD34+ cells expressed the erythroid and megakaryocytic lineage-associated antigens and a low but distinct population of CD34+ cells expressed antigens associated with multipotent stem cells. Analysis showed that the number of CD34+CD33- cells (r = -.74, P < .05), as well as the number of CD34+CD41+ cells (r = -.81, P < .005), correlated significantly better with time to neutrophil and platelet recovery, respectively, than with the total number of CD34+ cells (r = -.55 and r = -.56, respectively). CONCLUSION: The numbers of CD34+CD33- cells and CD34+CD41+ cells may help to predict short-term repopulation capacity of PBSCs, especially when relatively low numbers of CD34+ cells per kilogram are reinfused.

Combined measurement of growth and differentiation in suspension cultures of purified human CD34-positive cells enables a detailed analysis of myelopoiesis.

In this study we have made a detailed analysis of growth factor (granulocyte-macrophage colony-stimulating factor [GM-CSF], granulocyte colony-stimulating factor [G-CSF], and macrophage colony-stimulating factor [M-CSF])-induced proliferation and differentiation of highly purified CD34+ committed human myeloid progenitor cells in suspension cultures. The results were compared with colony formation in semisolid medium. Proliferation in suspension cultures was determined by means of incorporation of [3H]thymidine, differentiation by flow cytometric immunophenotyping using a panel of monoclonal antibodies against monomyeloid antigens, and by morphology. A good correlation was found between the number of granulocyte-macrophage colony-forming units (CFU-GM) in semisolid medium and [3H]thymidine incorporation in suspension (r = 0.82), both assessed at day 11. Moreover, the frequency of proliferating cells as determined in suspension cultures by limiting dilution analysis was similar to the frequencies of CFU-GM as measured in semisolid medium. Studies on GM-CSF- and G-CSF-induced cell-growth kinetics revealed distinct proliferation patterns. Immunophenotypically the subsequent induction of the mature granulocytic antigens CD15 and CD67 was observed to be accompanied by a gradual loss of the HLA-DR antigen, whereas little monocytic differentiation was observed. M-CSF, although inducing no colony formation of CD34+ cells and minimal proliferation in suspension, induced monocytic differentiation, demonstrated by the expression of HLA-DR, CD14, and CD36 in the absence of CD15 and CD67. The observed immunophenotypical profiles were confirmed by the results of cytological characterization. Thus, the combined measurement of growth factor-induced proliferation and differentiation of progenitor cells in suspension cultures can be a useful alternative for the CFU-GM assay. Moreover, because small numbers of cells are required, it allows for detailed studies on cell-growth kinetics and developmental stages within the granulocytic and monocytic lineages.

Effective purging of bone marrow by a combination of immunorosette depletion and complement lysis.

The effectiveness of a simple immunorosette technique for the depletion of common acute lymphatic leukemic (cALL) blasts from autologous bone marrow transplants was studied. Erythrocytes were sensitized with tetramolecular complexes consisting of rat anti-mouse IgG1 monoclonal antibodies (McAbs) that crosslink two different mouse McAbs. One of the McAbs was directed against glycophorin A, and the other was directed against marker glycoproteins of B cells and their precursors (CD9, CD10, CD19, or CD22). Immunorosettes were formed by addition of the sensitized erythrocytes to the cALL+ cells. After density-gradient separation of immunorosettes from mixtures of cALL+/terminal deoxynucleotidyl transferase-positive (TdT+) leukemic blasts and mononuclear bone marrow cells, nearly a 2-log depletion of leukemic cells was measured by flow cytometry. Clonogenic assays with two cALL+B-cell lines (Ros-17 and Nalm-16) were performed to compare the efficacy of complement-mediated cell lysis, immunorosette depletion, and a combination of both procedures. Complement-mediated cytotoxicity with the three McAbs in combination with baby rabbit complement yielded a 1- to 2-log cell kill. Immunorosette depletion resulted in a 3-log reduction of clonogenic units. Sequential application of the two methods (immunorosette depletion with CD19 McAb followed by a complement lysis with CD9 and CD10 McAbs) led to superior results in causing a 4- to 5-log purging effect. These purging procedures did not cause a loss of normal myeloid (granulocyte-macrophage colony-forming units, CFU-GM) or erythroid (erythroid burst-forming units, BFU-e) progenitors from the bone marrow. This study indicates that the combination of the two methods results in a highly efficient purging procedure for the removal of cALL+ cells from autologous bone marrow cells.

A nylon wool filter coated with human immunoglobulin for rapid depletion of monocytes and myeloid cells from peripheral blood stem cell transplants.

The aim of this study was to develop an inexpensive method for reducing the number of differentiated cells from granulocyte colony-stimulating factor-mobilized leukocytapheresis products (LPs) containing peripheral blood stem cells. Analysis of LPs showed the presence of significant numbers of monocytes and myeloid cells. The myeloid cells represented largely immature stages of the granulocyte lineage (myelocytes and metamyelocytes). We investigated whether these cells could be selectively depleted by filtration over nylon wool. Filtration of LP samples over nylon wool in a medium containing fetal calf serum resulted in variable but on average low yields of CD34+ cells (48 +/- 30%; n=13) and strongly variable depletions of myeloid cells. The adherence of CD34+ cells to the polyamide fiber was partially mediated by activated platelets that were present in the LPs. Removal of platelets by counterflow centrifugal elutriation before filtration resulted in increased yields of CD34+ cells in the filtrates (65 +/- 13%; n=10). The yield of progenitor cells was similarly enhanced when trisodium citrate, a chelating substance, was added to the filtration medium. Adherence of the myeloid cells to the nylon fiber was promoted by preincubation of the columns with human immunoglobulin (Ig) (2 mg/mL). Small-scale filtrations of LP samples in the presence of trisodium citrate over columns with Ig-coated nylon wool resulted in removal of 96 +/- 4% of the monocytes and 74 +/- 18% of the myeloid cells, with a yield of 71 +/- 15% CD34+ cells and 67 +/- 10% granulocyte-monocyte colony-forming units (CFU-GM) (n=23). There was no loss of primitive stem cells during the procedure: the yield of late-appearing cobblestone area-forming cells (CAFCs, week 6) was 110 +/- 30% (n=4). CFU-GM production per CAFC-derived clone was unchanged upon filtration, indicating that the quality of stem cells was not affected. Moreover, the proportions of CD34+ cells expressing a primitive immunophenotype (CD38low or Thy-1+) were unchanged after filtration. Further enrichment of progenitor cells was obtained by separation of LP samples by elutriation before filtration. The combination of these two techniques resulted in complete removal of platelets, 89 +/- 7% depletion of erythrocytes, and 91 +/- 6% reduction of leukocytes, with a 50% yield of CD34+ cells (n=14). In conclusion, we have developed a rapid filtration technique by which monocytes and myeloid cells can be depleted from LP samples, with only minor loss of colony-forming cells and complete recovery of primitive stem cells.

Interleukin-6 is a survival factor for committed myeloid progenitor cells.

In this study, we investigated the effect of recombinant human interleukin-6 (IL-6) on colony-forming cells for granulocytes and macrophages (CFU-GM) cultured in suspension. IL-6 when used alone did not induce proliferation of highly purified CD34+ human hematopoietic progenitors. Moreover, no influence of IL-6 was observed on the proliferation induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) or granulocyte (G)-CSF. However, a marked survival enhancement (GM-CSF 228 +/- 42%, p < 0.01, and G-CSF 137 +/- 9%, p < 0.05) was observed when CD34+ cells were preincubated with IL-6 for 6 days. This survival effect became even more pronounced under serum-poor conditions (GM-CSF 380 +/- 80%, p < 0.01, and G-CSF 180 +/- 20%, p < 0.01) and could also be demonstrated at the single cell level in a colony-forming assay. By analysis of subpopulations of CD34+ bone marrow (BM) cells selected on the basis of CD45RO expression, the observed IL-6-mediated survival effect was found to be restricted to the CFU-GM containing CD45RO- subset. Our data show that IL-6 is a survival factor for CFU-GM.

Biomarker profiling of steroid-resistant acute GVHD in patients after infusion of mesenchymal stromal cells.

We performed a prospective phase II study to evaluate clinical safety and outcome in 48 patients with steroid-refractory grade II-IV acute graft-versus-host disease (aGVHD) treated with mesenchymal stromal cells (MSCs). Clinical outcomes were correlated to comprehensive analyses of soluble and cellular biomarkers. Complete resolution (CR) of aGVHD at day 28 (CR-28) occurred in 12 (25%) patients, CR lasting >1 month (CR-B) occurred in 24 (50%) patients. One-year overall survival was significantly improved in CR-28 (75 versus 33%, P=0.020) and CR-B (79 versus 8%, P<0.001) versus non-CR patients. A six soluble biomarker-panel was predictive for mortality (HR 2.924; CI 1.485-5.758) when measured before MSC-administration. Suppression of tumorigenicity 2 (ST2) was only predictive for mortality 2 weeks after but not before MSC-administration (HR 2.389; CI 1.144-4.989). In addition, an increase in immature myeloid dendritic cells associated with decreased mortality (HR 0.554, CI 0.389-0.790). Patients had persisting T-cell responses against defined virus- and leukemia-associated antigens. In conclusion, our data emphasize the need to carefully assess biomarkers in cohorts with homogeneous GVHD treatments. Biomarkers might become an additional valuable component of composite end points for the rapid and efficient testing of novel compounds to decrease lifecycle of clinical testing and improve the success rate of phase II/III trials.

Increased incidence of EBV-associated lymphoproliferative disorders after allogeneic stem cell transplantation from matched unrelated donors due to a change of T cell depletion technique.

Here, the influence of T vs T and B cell depletion on the incidence of EBV-associated lymphoproliferative disorder (EBV-LPD) after bone marrow transplantation (BMT) from a matched unrelated donor (MUD) is analyzed. From 1982 to 1997 the soy bean agglutinin/sheep red blood cell (SBA/SRBC) method was used for T cell depletion. This technique is well established, but the use of SRBC has a risk of transmitting prions or viruses. Therefore, a new T cell depletion method was introduced, using CD2 and CD3 monoclonal antibodies (CD2/3 method) instead of SRBC. Unfortunately, this led to an unexpected high number of EBV-LPDs in patients receiving transplants from MUDs. SBA depletion was reintroduced and combined with the CD2/3 method (SBA/CD2/3) in this patient population, later replaced by B cell-specific (CD19 and CD22) antibodies (CD3/19/22 method). The number of T (x 10(5)/kg) and B (x 10(5)/kg) cells in the graft was 1.5 +/- 0.8 and 2 +/- 1 (T/B ratio 0.75), 2.2 +/- 2.0 and 41 +/- 21 (ratio 0.055), 5.0 +/- 0.0 and 2 +/- 1 (ratio 2.5), 2.5 +/- 1.2 and 10 +/- 6 (ratio 0.25) using the SBA/SRBC, CD2/3, SBA/CD2/3 and CD3/19/22 techniques, respectively. When B cell depletion was performed (SBA/SRBC, SBA/CD2/3, CD3/19/22) four out of 31 patients (13%) receiving a BMT from a MUD developed an EBV-LPD. Without B cell depletion (CD2/3) this occurred in five out of seven patients (71%) (P < 0.05). A T/B cell ratio in the graft of > or = 0.25 seems sufficient to significantly reduce the incidence of EBV-LPD after BMT from MUDs.

Failure of purged autologous bone marrow transplantation in high risk acute lymphoblastic leukaemia in first complete remission.

Patients in first remission of acute lymphoblastic leukaemia (ALL) considered to be at high risk of relapse were offered autologous bone marrow transplantation (ABMT) using purged marrow as a therapeutic alternative to cranial irradiation and maintenance chemotherapy. Twenty-seven bone marrows taken in remission, were purged using monoclonal antibodies (anti CD7 for T lineage and anti CD10 and/or anti CD19 for B lineage leukaemias) plus rabbit complement. Retrospective analysis of 19 purged marrows by immunophenotyping or immunoglobulin gene rearrangement studies demonstrated no evidence of disease. Engraftment was seen in 26 of the patients. No correlation was found between the numbers of infused nucleated cells or colony forming units-granulocyte-macrophage (CFU-GM) and subsequent engraftment kinetics. The actuarial disease-free survival (DFS) is 32% at 7 years (median follow-up 3.4 years). There were two transplant related deaths (actuarial risk 8%); the main cause of treatment failure has been disease recurrence with an overall actuarial risk of 67%; 76% for T-ALL (five of nine), 62% for common ALL (five of 10), two of five pre B and none of three patients with B-ALL. In these 27 high risk patients in vitro purging of remission marrow as part of ABMT appears not to improve patient outcome, although confirmation of this would require a randomized trial.

Mobilisation of blood progenitor cells with ifosfamide and etoposide (VP-16) in combination with recombinant human G-CSF (Filgrastim) in patients with malignant lymphomas or solid tumours.

The mobilisation characteristics of ifosfamide and etoposide followed by Granulocyte Colony-Stimulating Factor fGCSF, filgrastim) were analysed in 17 patients with malignant lymphoma and 24 patients with solid tumours, with respect to the optimum time to harvest progenitor cells and to the yields of progenitor cells that could be achieved. In addition, we analysed patient characteristics which could influence the size of the progenitor cell harvest. Clinical parameters which were co-related with the size of the circulating progenitor cells (CPC) harvests were: the dose of G-CSF, dose of if osfamide, sex, age, diagnosis and extent of pretreatment. CPC were mobilised with 3 g/m2 (n = 11) or 4 g/m2 (n = 30) ifosfamide on day 1 and etoposide 100 mg/m2/day, on days 1-3 i.v., followed by daily s.c. injections with filgrastim 5 micrograms/kg (n = 26) or 10 micrograms/kg (n = 15) from day 4. The maximal progenitor cell harvest was achieved on either day 12 or day 13 after the start of the ifosfamide/etoposide course. The median number of leukaphereses necessary to harvest the target quantity of 3 x 10(6) CD34+ cells/kg body weight was 1 (range 1-9). Thirteen/41 (32%) of the patients did not achieve the target yield of 3 x 10(6) CD34+ cells/kg. By multivariate analysis, the dose of GCSF and prior irradiation were associated with the number of progenitor cells harvested, while all other parameters, induding the dose of if osfamide and number of previous chemotherapy courses, were not. Sixteen patients received two or more mobilisation courses. Despite the fact that the same mobilisation schedule was used, the progenitor cell yields after the first mobilisation course did not predict the results after the subsequent mobilisation courses, indicating that unknown transient factors may significantly influence the CPC yield.

Ten years after the first inspection of a candidate European centre, an EBMT registry analysis suggests that clinical outcome is improved when hematopoietic SCT is performed in a JACIE accredited program.

In 2010, JACIE, the Joint Accreditation Committee of ISCT (International Society for Cell Therapy) Europe and EBMT (European group for Blood and Marrow Transplantation) celebrated the tenth anniversary of the first inspection of a European hematopoietic SCT program. JACIE standards establish the criteria for a comprehensive quality management program that covers all three major domains of activity that are necessary for the delivery of HSCT: clinical, collection and processing, as well as their interactions with ancillary and supportive activities. Although more than 200 European programs have applied for JACIE accreditation, and more than 100 have been granted accreditation, a recent retrospective analysis of the large-size EBMT registry of autologous and allogenic hematopoietic HSCT demonstrates that one of the factors affecting the overall survival of recipients of allogenic transplantation is the status of the transplant program regarding JACIE accreditation. This provides one of the first demonstrations that introduction of a quality management system contributes to the overall survival of patients treated with a highly specific medical procedure, and represents a milestone in the implementation of JACIE.

Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular Therapy position statement.

The considerable therapeutic potential of human multipotent mesenchymal stromal cells (MSC) has generated markedly increasing interest in a wide variety of biomedical disciplines. However, investigators report studies of MSC using different methods of isolation and expansion, and different approaches to characterizing the cells. Thus it is increasingly difficult to compare and contrast study outcomes, which hinders progress in the field. To begin to address this issue, the Mesenchymal and Tissue Stem Cell Committee of the International Society for Cellular Therapy proposes minimal criteria to define human MSC. First, MSC must be plastic-adherent when maintained in standard culture conditions. Second, MSC must express CD105, CD73 and CD90, and lack expression of CD45, CD34, CD14 or CD11b, CD79alpha or CD19 and HLA-DR surface molecules. Third, MSC must differentiate to osteoblasts, adipocytes and chondroblasts in vitro. While these criteria will probably require modification as new knowledge unfolds, we believe this minimal set of standard criteria will foster a more uniform characterization of MSC and facilitate the exchange of data among investigators.