Optimisation of mesenchymal stromal cells karyotyping analysis: implications for clinical use.

PURPOSE: The aim of this study was to optimise the yield of metaphases in mesenchymal stromal cells (MSC) in vitro cultures and to study the karyotype of MSC expanded in good manufacturing practice (GMP) conditions for clinical use. BACKGROUND: MSC are being increasingly used in clinical trials for a number of diseases. Biosafety demonstration in all cases is mandatory. Unfortunately, current standard karyotyping methods fail to obtain enough number of evaluable metaphases. METHODS AND MATERIALS: In the present work, to optimise the yield of metaphases in MSC expanded in vitro, we have tested several conditions by modifying colcemid concentration (we have tested 0.01, 0.05 and 0.1 µg mL(-1) ) and exposure time (during 5, 15 and 24 h). We further applied these optimised conditions to 61 MSC expansions in GMP conditions for clinical use. RESULTS: Our results show that the highest number of metaphases was obtained when MSC were incubated with 0.05 µg mL(-1) of colcemid overnight (15 h), compared to the remaining experimental conditions. In most cases (59/61 cases) enough number of metaphases was obtained. And what is more relevant, only in one case a karyotypic abnormality was found (trisomy of chromosome 10), and cells were subsequently discarded for clinical use. CONCLUSION: We describe here an optimal method to obtain enough number of metaphases for karyotype analysis of in vitro expanded MSCs, what is essential for their clinical use in cell therapy programmes.

In leukapheresis products from non-Hodgkin's lymphoma patients, the immature hematopoietic progenitors show higher CD90 and CD34 antigenic expression.

Damage to the stem cell progenitors caused by the chemotherapy received in patients diagnosed with non-Hodgkin's lymphoma (NHL) may be an important factor limiting progenitor cell mobilization. The aim of the present analysis was to evaluate the effect of the chemotherapy on the different progenitor cell subpopulations obtained in the leukapheresis. For this purpose, a combination of immunophenotype and functional assays has been performed in 26 mobilized peripheral blood (PB) samples from NHL patients and 36 healthy donors. The different progenitor subpopulations analyzed by flow cytometry significantly correlated with the corresponding populations assessed by functional assays in both healthy donors and NHL patients (p<0.05, r>0.5). The number of committed CFU-GM was similar in both groups (p=0.246), but we found significant decrease in the number of BFU-E and more immature progenitors in PB from NHL patients as compared to donors (p<0.05). Moreover, the number of total CFU was significantly lower in NHL patients (p=0.007). Accordingly, CD34+ cells (p=0.018) and CD34+ subpopulations was decreased in NHL patients. Nevertheless, CD90 and CD34 intensity was significantly higher within CD34+ cells from NHL patients as compared to donors. However, although numerically reduced non-committed CD34+ cells are more immature in chemotherapy mobilized NHL patients. In summary, our results show that all NHL hematopoietic progenitors, analyzed by both immunophenotypical and functional approaches, are impaired in leukapheresis products.

Next Generation Flow for highly sensitive and standardized detection of minimal residual disease in multiple myeloma.

Flow cytometry has become a highly valuable method to monitor minimal residual disease (MRD) and evaluate the depth of complete response (CR) in bone marrow (BM) of multiple myeloma (MM) after therapy. However, current flow-MRD has lower sensitivity than molecular methods and lacks standardization. Here we report on a novel next generation flow (NGF) approach for highly sensitive and standardized MRD detection in MM. An optimized 2-tube 8-color antibody panel was constructed in five cycles of design-evaluation-redesign. In addition, a bulk-lysis procedure was established for acquisition of ⩾107 cells/sample, and novel software tools were constructed for automatic plasma cell gating. Multicenter evaluation of 110 follow-up BM from MM patients in very good partial response (VGPR) or CR showed a higher sensitivity for NGF-MRD vs conventional 8-color flow-MRD -MRD-positive rate of 47 vs 34% (P=0.003)-. Thus, 25% of patients classified as MRD-negative by conventional 8-color flow were MRD-positive by NGF, translating into a significantly longer progression-free survival for MRD-negative vs MRD-positive CR patients by NGF (75% progression-free survival not reached vs 7 months; P=0.02). This study establishes EuroFlow-based NGF as a highly sensitive, fully standardized approach for MRD detection in MM which overcomes the major limitations of conventional flow-MRD methods and is ready for implementation in routine diagnostics.

Prognostic value of S-phase white blood cell count in B-cell chronic lymphocytic leukemia.

Eighty previously untreated patients with B-cell chronic lymphocytic leukemia (B-CLL) were analyzed to study the proliferation rate of their peripheral blood (PB) leukocytes to determine its relationship with the extension of the disease and its value in discriminating among patients with similar tumor cell mass. The 80 B-CLL patients were distributed into two different groups according to the absolute count of PB S-phase leukocytes: a low proliferative group (less than 1 x 10(9)/I) of 48 patients and a high proliferative group (greater than or equal to 1 x 10(9)/I) of 32 patients. The high proliferative group displayed a higher incidence of splenomegaly (p less than 0.005), hepatomegaly (p less than 0.08), anemia (p less than 0.02) and thrombocytopenia (p less than 0.03) as well as a higher lymphocytic infiltration both in PB (p less than 0.0004) and in bone marrow (BM) (p less than 0.003). These patients also showed a higher incidence of a diffuse pattern of BM involvement (p less than 0.04), advanced clinical stages [stage III/IV (p less than 0.03) and group C (p less than 0.04)] and infections (p less than 0.0008) together with significantly lower IgG (p less than 0.03) and IgM (p less than 0.03) serum levels. Regarding the immunophenotype, there was a greater percentage of either CD19+ (p less than 0.06) and CD19+ CD5+ (p less than 0.05) B-cells, together with a greater reactivity for both the CD25 (p less than 0.04) and CD9 (p less than 0.08) antigens in the high proliferative group. According to the prognostic value of the PB S-phase leukocyte count it was seen that patients with low S-phase white blood cell (WBC) numbers displayed a significantly higher survival (p less than 0.03). In addition, multivariate analysis revealed that the S-phase WBC count, although partially related to other clinical and biological prognostic factors, displayed an important independent value in predicting early deaths in patients with B-CLL.

In leukemic hematopoiesis CD34 antigen does not have the same significance as it does normal hematopoiesis.

The aim of the present study was to analyze whether or not leukemic clonogenic cells are restricted to the CD34+ cell fraction and to investigate the effect of IL-3 and G-CSF on blast cell populations dissected according to their CD34 reactivity. For this purpose 34 patients were studied. Patients were classified into three groups according to CD34 antigen expression: (1) cases in which all blast cells (100%) were positive for the CD34 Ag (n = 9); (2) cases in which all blast cells lacked the expression of this antigen (n = 10); and (3) patients in whom both, CD34 positive and negative blast cell subsets coexisted (n = 15). In 15 cases immunomagnetic cell selection was performed and two subpopulations were separated: one, phenotypically more immature (CD34+), and another, theoretically more differentiated (CD34-/33+). In addition, in three cases both CD34+ and CD34- blast cell subpopulations were sorted using a FACStar flow cytometer. Blast colony assays were performed using 0.9% methylcellulose and two different recombinant human hematopoietic growth factors (HGFs), IL-3 and G-CSF, were used as growth stimulants. Either, a single or a combination of the growth factors was added to cultures. Colony formation was observed in both 100% positive or 100% negative cases for the CD34 antigen as well as in the CD34+ and CD34- cell fractions separated by immunomagnetic selection or flow cytometry. The effect of G-CSF and IL-3 on both cell fractions was as follows: cases with a uniform population according to CD34 expression (100% positive or negative) showed a better growth response with IL-3 especially for the CD34+ cases (87% vs 40% of CD34+ and CD34- cases, respectively). Within the CD34-/33+ selected fractions, IL-3 tended to induce a higher proliferative response than G-CSF while the opposite was found within the CD34+ cell selected fractions. In contrast it was observed that both IL-3 and G-CSF induced a higher PE on the CD34- blast cells (both selected and 100% negative), although the difference was not statistically significant. The existence of a possible synergistic effect (SE) between HGFs was also explored. Overall, a synergistic growth was observed in nine out of the 13 selected cases studied and this effect could be seen in both CD34- or CD34+ blast cell fractions. The analysis of the complete phenotypic characteristics of these cells revealed that cell fractions showing SE were more immature according to the expression of CD15 and HLA-DR antigens. We can conclude that in leukemic hematopoiesis, CD34 antigen expression does not have the same significance as it does in normal hematopoiesis since clonogenic cells are not restricted to the CD34+ acute myeloid leukemia (AML) blast cell fraction. Moreover, our study shows that the heterogeneous response to HGFs observed in AML patients may be associated with the existence of immunophenotypically different blast cell subsets.

Effect of cumulative etoposide doses on the outcome of autologous peripheral-blood progenitor-cell transplantation for lymphoma.

Studies evaluating the effects of previous chemotherapy on stem-cell yield and hematological recovery after autologous peripheral-blood progenitor-cell transplantation (PBPCT) have shown conflicting results. We have retrospectively analyzed 103 consecutive lymphoma patients treated with the BEAM regimen and autologous PBPCT. The impact of the different chemotherapeutic drugs (cumulative doses) on stem-cell yield and transplant-related toxicity was investigated. Highly significant differences in platelet recovery (>20 x 10(9)/l) were observed between patients receiving less or more than 750 mg/m(2) of etoposide before transplant (15 vs 29 days, P=0.001), and between patients receiving less or more than 1.2 x 10(6)/kg CD34(+) cells (27 vs 14 days, P<0.001). Differences in neutrophil engraftment between groups were not clinically significant. Pre-transplant cumulative doses of etoposide >750 mg/m(2) were associated with low CD34(+) cell collections on multivariate analysis. The actuarial incidence of transplant-related mortality (TRM) was 14% at 5 years. Pre-transplant cumulative doses of etoposide >350 mg/m(2) and previous administration of procarbazine were found to be independent prognostic factors for TRM.

Factors that influence long-term hematopoietic function following autologous stem cell transplantation.

The aim of the present study was to assess which factors influence hematopoietic function long term after transplantation. For this purpose, we have analyzed a series of 79 patients who underwent autologous transplantation. None of them received any further chemotherapy or radiotherapy after transplant. All patients were disease-free 1 year after autologous transplantation. Late impairment of hematopoietic function was defined as the presence of non-transient peripheral blood cytopenias, detected 6 and 12 months after autografting. Before transplantation, 38.7% of patients showed peripheral blood cytopenias. Six and 12 months after transplantation, cytopenias presented in 44.2% and 42.4% of patients, respectively. Cases displaying cytopenias 6 months after transplantation had received a significantly lower dose of CFU-GM and CD34+ cells than patients without cytopenias (P = 0.012 and P = 0.04, respectively). The same correlation, with even higher statistical significance, was observed 12 months after transplant (P = 0.007 and P = 0.005). Alkylating agents and radiotherapy administered prior to transplantation and age did not seem to influence the presence of permanent cytopenias. The incidence did not vary significantly according to the stem cell source (bone marrow or peripheral blood). The number of CFU-GM and CD34+ cells infused was the most important factor for maintenance of adequate hematopoiesis.

Diagnosis of secondary myelodysplastic syndromes (MDS) following autologous transplantation should not be based only on morphological criteria used for diagnosis of de novo MDS.

Secondary myelodysplastic syndromes (MDS) are increasingly being reported after autologous transplantation. Transient dysplastic changes have also been observed after this type of treatment. However, to the best of our knowledge no systematic morphological analysis has been performed to determine the influence of stem cell transplantation on bone marrow morphology. In 53 patients undergoing autologous transplantation, we evaluated the bone marrow, before and 6 and 12 months after the transplant, in order to analyze the appearance of dyshemopoietic changes, assessed according to a pre-established score. We also studied 25 bone marrow samples obtained at the time of diagnosis, prior to treatment, but we did not find morphological atypia. Six months after transplant, cellularity and thrombopoiesis had decreased in 38% and 49% of patients respectively, although 1 year after the process they were normal in most cases. Myelodysplasia was already present in bone marrow before transplantation and continued to be in evidence for a long time afterwards. This suggests that chemotherapy and radiotherapy used prior to transplantation are responsible for dysplastic changes. The myeloid line was the most affected with 100% of patients showing dysgranulopoiesis 1 year after autografting. Cytopenias were observed in 51% and 44% of patients 6 and 12 months after transplantation. Moreover, concomitant presence of cytopenia and myelodysplasia was observed in 37.7% of patients at 6 months after transplantation and 25% at 12 months, and therefore they could be diagnosed with MDS. These data contrast with the incidence of secondary MDS reported in earlier publications. According to these findings, the value of the French-American-British Co-operative Group criteria for the diagnosis of MDS following autologous transplantation is questionable. Moreover, since dyshemopoietic features are almost always present after autologous transplant, morphological criteria are not useful for early recognition of patients with secondary MDS after transplantation.

Peripheral blood is safer than bone marrow as a source of hematopoietic progenitors in patients with myelodysplastic syndromes who receive an allogeneic transplantation. Results from the Spanish registry.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for patients with myelodysplastic syndromes (MDSs). We have analyzed the outcome of 81 patients who underwent an allogeneic transplant from an HLA-identical sibling donor. The overall survival (OS) was 31% and disease-free survival was 30% at 5.8 years. Transplant-related complications were the cause of death in 44% and disease progression in 16% of patients. Acute graft-versus-host disease (aGVHD) grades II-IV occurred in 32 cases (39%). Extensive chronic GVHD (cGVHD) was observed in 27% of patients. When the log-rank test was performed, we observed that patients transplanted more than 6 months after diagnosis, and those transplanted with bone marrow (BM) displayed a shorter survival (P=0.009 and 0.005, respectively). Patients who developed cGVHD showed a trend towards better OS (P=0.07). Patients receiving BM had a higher incidence of aGVHD (65 vs 50%) and less cGVHD (52 vs 30%), although the differences did not reach statistical significance. Moreover, patients who received PB-HSC displayed a faster engraftment (P=0.000) and showed a significantly lower early transplant-related mortality (14 vs 42%; P=0.006) and longer OS (P=0.005). In summary, our results show that hematopoietic transplantation should be performed as soon as possible in MDS patients and that PB is preferable to BM as a source of HSC.

Intra-muscular vidarabine therapy for polyomavirus-associated hemorrhagic cystitis following allogeneic hemopoietic stem cell transplantation.

Hemorrhagic cystitis (HC) is a common complication following hemopoietic stem cell transplantation (HSCT), its incidence ranging from 7 to 52% of all patients. Late occurring HC frequently results from viral infections. We describe a patient who developed severe polyomavirus-associated HC, which responded dramatically to a single dose of intra-muscular vidarabine. Previous studies show an improvement in HC with vidarabine therapy, but to date only the intravenous route of administration has been described and responses described take from several days to weeks. This report confirms the safety and efficacy of vidarabine administered intramuscularly when used in patients with an adequate platelet count, thereby making its use feasible when intravenous vidarabine is not available.

BEAM chemotherapy followed by autologous stem cell support in lymphoma patients: analysis of efficacy, toxicity and prognostic factors.

In the present paper, we evaluate tolerability, outcome and prognostic factors in patients with poor prognosis non-Hodgkin's lymphoma (NHL) and Hodgkin's disease (HD) when uniformly treated with BCNU, etoposide, cytarabine and melphalan (BEAM) and autologous stem cell transplant (ASCT). On hundred and forty-eight patients with NHL (n = 112) or HD (n = 36) received BEAM followed by infusion of bone marrow (n = 55), peripheral blood stem cells (n = 79) or both (n = 14). Twenty-eight patients had low-grade lymphoma (LGL), 68 intermediate- and 16 high-grade lymphoma (IGL). Within the NHL group, 21 patients were in 2nd or subsequent complete remission (CR) at transplant, 34 had sensitive disease and 11 resistant disease; 46 patients were transplanted in 1st CR due to the presence of > or = 2 adverse prognostic features at diagnosis or to a slow CR. Of the HD patients at transplant 17 had active disease, 16 were in > or = 2 CR and three in 1st CR. The overall percentage of toxic deaths was 5.4%, while in the group of patients transplanted with PBSC it was only 1.3%. NHL patients: 78% were in CR following ASCT, including 25 out of 45 patients (56%) who were transplanted with active disease. Only two of the 11 patients transplanted with resistant disease achieved CR. Incidence of overall survival (OS) and disease-free survival (DFS) at 3 years was 65 and 75%, respectively. As far as histology was concerned, OS was significantly better for patients with LGL in comparison with IGL (88 vs 56%) (P = 0.002). DFS was significantly higher for patients transplanted in first CR or first partial remission (PR) than it was for those transplanted in a later CR or PR (86 vs 53%) (P = 0.02). Multivariate analysis for OS showed that histology, bulky disease, poor performance status at transplant and achievement of CR were independent prognostic factors. In addition, a high number of infused MNC was associated with poor DFS. HD patients: 30 (83%) were in CR after transplantation, with 25 maintaining CR at the end of the study. Only one of the four patients transplanted with resistant disease reached CR. Incidence of OS and DFS at 3 years was 78 and 81%. DFS was similar for patients transplanted with early or late relapse (95 and 93%). With multivariate analysis, the only independent variable for OS was CR after transplant. In conclusion, the present results demonstrate the efficacy and low toxicity of the BEAM regimen in high-risk lymphoma patients with sensitive disease. Other strategies should be investigated for patients with refractory lymphoma.

Discrepancies between morphologic, cytochemical, and immunologic characteristics in acute myeloblastic leukemia.

This study was designed to compare the cytochemical pattern with the immunologic phenotype in 108 cases of acute myeloblastic leukemia (AML) classified according to the French-American-British (FAB) criteria. Special attention was paid to the cases where discrepancy existed between these approaches and to a group of 11 patients considered as unclassifiable mainly because a second cell population--megakaryoblastic--was detected. Three types of discrepancies were observed: cases with typical morphologic characteristics and cytochemistry but devoid of lineage-specific antigens; these mainly include poorly differentiated leukemias (eight M1, four M2, and eight M5a), suggesting that the cytochemical enzymes are earlier myeloid markers than the currently available monoclonal antibodies; cases in which immunologic characteristics were discordant with morphologic characteristics and cytochemistry; these include two M2 cases positive for monocytic monoclonal antibodies (CD14); six M5b cases positive for granulocytic monoclonal antibodies (CD15); and seven M4 cases lacking in CD14 or CD15 antigens; cases with discrepancies between morphologic characteristics and cytochemistry and in which the immunologic markers permitted the correct assessment of cell lineage (six cases). These results show that the classification of these patients is better achieved by a combined morphologic, cytochemical, and immunologic approach.

Value of colony forming unit-granulocyte macrophage assay in predicting relapse in acute myeloid leukaemia.

AIM: To evaluate the validity of the colony forming unit-granulocyte macrophage (CFU-GM) assay for predicting relapse in patients with acute myeloid leukaemia (AML). METHODS: The study population comprised 32 patients with AML in remission, followed for a median of 18 months. A mean of four studies was carried out per patient. Three patterns of in vitro growth based on the number of CFU-GM in normal bone marrow were defined: 1 = normal (normal number of CFU-GM and a cluster:colony ratio < 2); 2 = hypoplastic (low number of CFU-GM and a cluster:colony ratio < 2); 3 = anomalous (low or normal number of CFU-GM and a cluster:colony ratio > 2). RESULTS: Eleven patients relapsed, all of whom had previously displayed an abnormal CFU-GM pattern: anomalous in nine and hypoplastic in two. The remaining 25 patients were in complete remission at the time of writing, 16 of whom had a normal growth pattern. The other nine had anomalous (eight patients) or hypoplastic (one patient) growth. The latter may be false positive results. The in vitro growth pattern was not constant during follow up analysis. All 15 patients in whom the growth pattern switched from abnormal to normal remain in complete remission. By contrast, of the five cases in whom the pattern changed from normal to abnormal, three have relapsed and the other two had other indicators of relapse. The growth pattern remained unchanged in the remaining 16 patients. CONCLUSION: The present data show that the sequential investigation of the CFU-GM growth pattern may be of value in predicting relapse in patients with AML.

Pathologic rupture of the spleen during induction with ATRA in a patient with acute promyelocytic leukemia.

Pathological rupture of the spleen is a rare but well recognized complication in hematological malignancies. Early clinical recognition of this life-threatening complication is necessary for rapid intervention. Here, we report on the case of a 26-year-old woman with acute promyelocytic leukemia who presented rupture of the spleen on day +2 of treatment with ATRA plus idarrubicin. In patients with acute leukemia, the presence of a painful abdomen and a sudden drop in hemoglobin levels, should alert of a possible splenic rupture, even without additional symptoms. This would facilitate an early treatment intervention with no modification to the chemotherapy schedule.

[Syndrome of abnormal chromatin clumping in leucocytes with a high fraction of bone marrow cells in S-phase and in vitro autonomous growth]. / Síndrome de condensación anómala de la cromatina de los leucocitos con elevada fase de síntesis medular y crecimiento autónomo in vitro.

Syndrome of abnormal chromatin clumping in leucocytes syndrome (ACCLS) is an uncommon entity which shares clinical and biological features with the myelodysplastic (MDS) and chronic myeloproliferative syndrome. In fact, as some authors consider ACCLS a new type of MDS, others maintain that it is in Ph'negative/bcr-abl negative chronic myeloid leukaemia. A new case of ACCLS appeared in a 68 year old woman, who presented with anaemic symptoms, bleeding and recurrent infections, and a haematological picture including progressive macrocytic anemia, thrombocytopenia and leuco-erythroblastosis. Marrow hypercellularity with granulocytic hyperplasia, and mature granulocytes presenting nuclear hyposegmentation and large peripheral blocks of chromatin separated by clear zones were the characteristic features of this case. No cytogenetic abnormalities were found and DNA flow-cytometry content was normal (euploid), supporting the thought that a disequilibrium exists in the hetero-chromatin/eucromatin ration in AACLS. Reverse PCR for bcr-abl transcripts was negative. The cell-cycle-phase analysis showed a high fraction of S-cells in the bone marrow (27%) in contrast to a very low S-phase (0.2%) in the peripheral blood, pattern that is different from both CMML and CML. In vitro clonogenic assays showed a high colony forming capacity and a certain grade of autonomous proliferation of the bone marrow cells, which is reminiscent of the CMML growth behaviour in culture. The patient was treated with vitamin D3, low dose Ara-C, prednisone and hydroxyurea until her demise, fifteen months after diagnosis. In total, the patient received 47 units of packed cells and 114 of platelet concentrates, and was transfused only when she presented anaemic or hemorrhagic symptoms. These clinical and haematological features suggest that ACCLS is a distinct entity that should be considered a sixth type of MDS, beside CMML, with which it has much in common.

[Immune reconstitution after autologous progenitor hemopoietic cell transplantation. A study comparing autologous bone marrow and autologous peripheral blood transplantation]. / Recuperación immune tras trasplante autólogo de células progenitoras hemopoyéticas. Comparación entre células progenitoras de sangre periférica y de médula ósea.

BACKGROUND: In order to find out the effect of peripheral blood (PB) hematopoietic progenitor cells on immune reconstitution the present study compares, through a randomized trial, some lymphoid subsets after peripheral blood (PBT) or bone marrow (BMT) autologous transplantation. MATERIAL AND METHODS: Twelve patients suffering from malignant hematological disorders were included (6 BMT and 6 PBT). From these patients 14 lymphoid and natural killer (NK) subsets were sequentially analyzed using appropriate dual staining. NK activity was analyzed by measuring Cr51 release from the K562 cell line. Studies were done in days and -6, +10, +17, +24, +31, +38, +52, +66, +90, +120, +180 and +360 after transplantation. RESULTS: The CD8+ cell regeneration was produced mainly by activated cells (CD38+), and no differences were observed between BMT and PBT, but CD8+ HLADR+ cells were higher in the PBT group. During the first year after transplantation CD4+ lymphoid cells were never within normal range, and its recovery was due to the memory subset (CD4+/CD45RO+). The CD19+ lymphocytes began their regeneration after the first month and it was produced mainly by by the CD19+/CD5+ subset. NK cells recovered faster in patients who underwent PBT, but NK activity was similar in both subgroups of patients and it was within normal range from day +17 until the end of the study. CONCLUSION: T, B and NK lymphoid reconstitution do not differ significantly between patients that receive BM or PB as hemathopoietic rescue, but PB seems influence a faster reconstitution of cytotoxic subsets (CD8+/HLADR+ and NK lymphoid cells).

Risk factors for thrombotic microangiopathy in allogeneic hematopoietic stem cell recipients receiving GVHD prophylaxis with tacrolimus plus MTX or sirolimus.

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a feared complication of allogeneic hematopoietic SCT (HSCT) owing to its high mortality rate. The use of calcineurin inhibitors or sirolimus (SIR) for GVHD prophylaxis has been suggested as a potential risk factor. However, the impact of tacrolimus (TAC) and SIR combinations on the increased risk of TA-TMA is currently not well defined. We retrospectively analyzed the incidence of TA-TMA in 102 allogeneic HSCT recipients who consecutively received TAC plus SIR (TAC/SIR) (n=68) or plus MTX (TAC/MTX)±ATG (n=34) for GVHD prophylaxis. No significant differences were observed in the incidence of TA-TMA between patients receiving TAC/SIR vs TAC/MTX±ATG (7.4% vs 8.8%, P=0.8). Only grade III-IV acute GVHD, previous HSCT and serum levels of TAC >25 ng/mL were associated with a greater risk of TA-TMA. Patients developing TA-TMA have significantly poorer survival (P<0.001); however, TA-TMA ceased to be an independent prognostic factor when it was included in a multivariate model. In conclusion, the combination of TAC/SIR does not appear to pose a higher risk of TA-TMA. By contrast, we identified three different risk groups for developing TA-TMA.

Results of allogeneic stem cell transplantation in the Spanish MDS registry: prognostic factors for low risk patients.

Although new agents have been approved for the treatment of MDS, the only curative approach is allogeneic hematopoietic stem cell transplantation (HSCT) and thus, in particular circumstances this procedure has been proposed as a treatment option for low risk patients. We have retrospectively analyzed the results of HSCT in 291 patients from the Spanish MDS registry with special attention to low risk MDS (LR-MDS) in order to define the variables that could impact their clinical evolution after transplantation. At 2 years OS was 51% and EFS was 50% (95% CI 0.7-4.5 years for OS and 95% CI 0.1-3.9 years for EFS). Among 43 LR-MDS, transplant-related mortality was 28%. At 3 years, OS was 67% (95% CI 264.7-8927.2 days for OS) and EFS was 64% (95% CI 0-9697.2 days for EFS). In the multivariate analysis only cytogenetics retained statistical significant effect on both OS (p=.047) and EFS (p=.046). Conditioning regimen could improve outcome among this subset of patients (OS 86% and RFS 100% for patients receiving RIC regimen). The present study confirms that specific disease characteristic as well as transplant characteristics have a significant impact on transplant outcome. Regarding low risk patients a non-myeloablative conditioning would be preferable especially in cases without high-risk cytogenetics.

Effects of MSC coadministration and route of delivery on cord blood hematopoietic stem cell engraftment.

Hematopoietic stem cell transplantation (HSCT) using umbilical cord blood (UCB) progenitors is increasingly being used. One of the problems that may arise after UCB transplantation is an impaired engraftment. Either intrabone (IB) injection of hematopoietic progenitors or mesenchymal stem cell (MSC) coadministration has been proposed among the strategies to improve engraftment. In the current study, we have assessed the effects of both approaches. Thus, NOD/SCID recipients were transplanted with human UCB CD34+ cells administered either intravenously (IV) or IB, receiving or not bone marrow (BM)-derived MSCs also IV or IB (in the right femur). Human HSC engraftment was measured 3 and 6 weeks after transplantation. Injected MSCs were tracked weekly by bioluminescence. Also, lodgment within the BM niche was assessed at the latter time point by immuno-fluorescence. Our study shows regarding HSC engraftment that the number of BM human CD45+ cells detected 3 weeks after transplantation was significantly higher in mice cotransplanted with human MSCs. Moreover, these mice had a higher myeloid (CD13+) engraftment and a faster B-cell (CD19+) chimerism. At the late time point evaluated (6 weeks), human engraftment was higher in the group in which both strategies were employed (IB injection of HSC and MSC coadministration). When assessing human MSC administration route, we were able to track MSCs only in the injected femurs, whereas they lost their signal in the contralateral bones. These human MSCs were mainly located around blood vessels in the subendosteal region. In summary, our study shows that MSC coadministration can enhance HSC engraftment in our xenogenic transplantation model, as well as IB administration of the CD34+ cells does. The combination of both strategies seems to be synergistic. Interestingly, MSCs were detected only where they were IB injected contributing to the vascular niche.