Manuel Abecasis

IBMTR Severity Index for grading acute graft-versus-host disease: retrospective comparison with Glucksberg grade.

Acute graft‐versus‐host disease (GVHD) severity is graded by pattern of organ involvement and clinical performance status using a system introduced by Glucksberg and colleagues 21 years ago. We examined how well Glucksberg grade predicted transplant outcome and constructed a Severity Index not requiring subjective assessment of performance in 2881 adults receiving an HLA‐identical sibling T‐cell‐depleted (n = 752) or non‐T‐cell‐depleted (n = 2129) bone marrow transplant for leukaemia between 1986 and 1992. Relative risks (RR) of relapse, treatment‐related mortality (TRM) and treatment failure (TF) (relapse or death) were calculated for patients with Glucksberg Grade I, II or III/IV acute GVHD versus those without acute GVHD and for patients with distinct patterns of organ involvement regardless of Glucksberg grade. Using data for non‐T‐cell‐depleted transplants, a Severity Index was developed grouping patients with patterns of organ involvement associated with similar risks of TRM and TF. Higher Glucksberg grade predicted poorer outcome; however, patients with the same grade but different patterns of skin, liver or gut involvement often had significantly different outcomes. The revised Severity Index groups patients in four categories, A–D. Compared to patients without acute GVHD, RRs (95% confidence interval) of TF were 0.85 (0.69, 1.05) for patients with Index A, 1.21 (1.02, 1.43) with B, 2.19 (1.78, 2.71) with C, and 5.69 (4.57, 7.08) with D. Prognostic utility of the Index was tested in patients receiving T‐cell‐depleted transplants; similar RRs of TF were observed. An acute GVHD Severity Index is proposed to enhance design and interpretation of clinical trials in the current era of allogeneic blood and bone marrow transplantation.

Ex vivo expansion of human mesenchymal stem cells: A more effective cell proliferation kinetics and metabolism under hypoxia

The low bone marrow (BM) MSC titers demand a fast ex vivo expansion process to meet the clinically relevant cell dosage. Attending to the low oxygen tension of BM in vivo, we studied the influence of hypoxia on human BM MSC proliferation kinetics and metabolism. Human BM MSC cultured under 2% (hypoxia) and 20% O2 (normoxia) were characterized in terms of proliferation, cell division kinetics and metabolic patterns. BM MSC cultures under hypoxia displayed an early start of the exponential growth phase, and cell numbers obtained at each time point throughout culture were consistently higher under low O2, resulting in a higher fold increase after 12 days under hypoxia (40 ± 10 vs. 30 ± 6). Cell labeling with PKH26 allowed us to determine that after 2 days of culture, a significant higher cell number was already actively dividing under 2% compared to 20% O2 and BM MSC expanded under low oxygen tension displayed consistently higher percentages of cells in the latest generations (generations 4–6) until the 5th day of culture. Cells under low O2 presented higher specific consumption of nutrients, especially early in culture, but with lower specific production of inhibitory metabolites. Moreover, 2% O2 favored CFU‐F expansion, while maintaining BM MSC characteristic immunophenotype and differentiative potential. Our results demonstrated a more efficient BM MSC expansion at 2% O2, compared to normoxic conditions, associated to an earlier start of cellular division and supported by an increase in cellular metabolism efficiency towards the maximization of cell yield for application in clinical settings. J. Cell. Physiol. 223: 27–35, 2010.

Toward a Clinical-Grade Expansion of Mesenchymal Stem Cells from Human Sources: A Microcarrier-Based Culture System Under Xeno-Free Conditions

The immunomodulatory properties of mesenchymal stem cells (MSCs) make them attractive therapeutic agents for a wide range of diseases. However, the highly demanding cell doses used in MSC clinical trials (up to millions of cells/kg patient) currently require labor intensive methods and incur high reagent costs. Moreover, the use of xenogenic (xeno) serum-containing media represents a risk of contamination and raises safety concerns. Bioreactor systems in combination with novel xeno-free medium formulations represent a viable alternative to reproducibly achieve a safe and reliable MSC doses relevant for cell therapy. The main goal of the present study was to develop a complete xeno-free microcarrier-based culture system for the efficient expansion of human MSC from two different sources, human bone marrow (BM), and adipose tissue. After 14 days of culture in spinner flasks, BM MSC reached a maximum cell density of (2.0±0.2)×10⁵ cells·mL⁻¹ (18±1-fold increase), whereas adipose tissue-derived stem cells expanded to (1.4±0.5)×10⁵ cells·mL⁻¹ (14±7-fold increase). After the expansion, MSC expressed the characteristic markers CD73, CD90, and CD105, whereas negative for CD80 and human leukocyte antigen (HLA)-DR. Expanded cells maintained the ability to differentiate robustly into osteoblast, adipocyte, and chondroblast lineages upon directed differentiation. These results demonstrated the feasibility of expanding human MSC in a scalable microcarrier-based stirred culture system under xeno-free conditions and represent an important step forward for the implementation of a Good Manufacturing Practices-compliant large-scale production system of MSC for cellular therapy.

Maximizing the ex vivo expansion of human mesenchymal stem cells using a microcarrier-based stirred culture system.

Bioreactor systems have been developed as alternatives to standard culture flasks due to their homogeneous nature, easiness of monitoring and increased cell production. Here we investigated the in vitro expansion of bone marrow (BM) mesenchymal stem cells (MSC) in spinner flasks, using gelatin microcarriers (Cultispher S) to support cell adhesion and proliferation. MSC expansion was performed using a low-serum containing medium (2% of fetal bovine serum, FBS). A strategy was defined for the maximization of cell expansion: microcarriers were pre-coated with FBS in order to increase cell seeding efficiency and an adequate feeding regime was established (25% medium exchange everyday). The maximum cell density, 4.2 x 10(5)cells/mL, was obtained at day 8, corresponding to a fold increase in total cell number of 8.4+/-0.8. Expanded MSC retained their differentiation potential into adipogenic and osteogenic lineages, as well as their clonogenic ability. Harvested cells expressed >90% of CD73, CD90 and CD105 markers. These results demonstrated that a microcarrier-based stirred culture system is adequate for human MSC expansion, using a low-serum containing medium, allowing the generation of significant cell numbers for potential applications in regenerative medicine.

Impact of prior imatinib mesylate on the outcome of hematopoietic cell transplantation for chronic myeloid leukemia

Imatinib mesylate (IM, Gleevec) has largely supplanted allogeneic hematopoietic cell transplantation (HCT) as first line therapy for chronic myeloid leukemia (CML). Nevertheless, many people with CML eventually undergo HCT, raising the question of whether prior IM therapy impacts HCT success. Data from the Center for International Blood and Marrow Transplant Research on 409 subjects treated with IM before HCT (IM(+)) and 900 subjects who did not receive IM before HCT (IM(-)) were analyzed. Among patients in first chronic phase, IM therapy before HCT was associated with better survival but no statistically significant differences in treatment-related mortality, relapse, and leukemia-free survival. Better HLA-matched donors, use of bone marrow, and transplantation within one year of diagnosis were also associated with better survival. A matched-pairs analysis was performed and confirmed a higher survival rate among first chronic phase patients receiving IM. Among patients transplanted with advanced CML, use of IM before HCT was not associated with treatment-related mortality, relapse, leukemia-free survival, or survival. Acute graft-versus-host disease rates were similar between IM(+) and IM(-) groups regardless of leukemia phase. These results should be reassuring to patients receiving IM before HCT.

Voriconazole for secondary prophylaxis of invasive fungal infections in allogeneic stem cell transplant recipients: results of the VOSIFI study

Background Recurrence of prior invasive fungal infection (relapse rate of 30–50%) limits the success of stem cell transplantation. Secondary prophylaxis could reduce disease burden and improve survival. Design and Methods A prospective, open-label, multicenter trial was conducted evaluating voriconazole (4 mg/kg/12 h intravenously or 200 mg/12 h orally) as secondary antifungal prophylaxis in allogeneic stem cell transplant recipients with previous proven or probable invasive fungal infection. Voriconazole was started 48 h or more after completion of conditioning chemotherapy and was planned to be continued for 100–150 days. Patients were followed for 12 months. The primary end-point of the study was the incidence of proven or probable invasive fungal infection. Results Forty-five patients were enrolled, 41 of whom had acute leukemia. Previous invasive fungal infections were proven or probable aspergillosis (n=31), proven candidiasis (n=5) and other proven or probable infections (n=6); prior infection could not be confirmed in three patients. The median duration of voriconazole prophylaxis was 94 days. Eleven patients (24%) died within 12 months of transplantation, but only one due to systemic fungal disease. Three invasive fungal infections occurred post-transplant: two relapses (one candidemia and one fatal scedosporiosis) and one new zygomycosis in a patient with previous aspergillosis. The 1-year cumulative incidence of invasive fungal disease was 6.7±3.6%. Two patients were withdrawn from the study due to treatment-related adverse events (i.e. liver toxicity). Conclusions Voriconazole appears to be safe and effective for secondary prophylaxis of systemic fungal infection after allogeneic stem cell transplantation. The observed incidence of 6.7% (with one attributable death) is considerably lower than the relapse rate reported in historical controls, thus suggesting that voriconazole is a promising prophylactic agent in this population.

Differences between graft product and donor side effects following bone marrow or stem cell donation

Summary:We report graft product stem cell yields and donor safety results of a randomized multicenter study comparing allogeneic peripheral blood stem cell (PBSC) PBSC transplantation with BM transplantation. Matched HLA-identical sibling donors (n=329) were randomized to filgrastim-mobilized PBSC or bone marrow (BM) donation groups. Median yields per kg recipient weight of CD34+ cells, T cells, and natural killer (NK) cells, respectively, were approximately two-fold, eight-fold, and greater than eight-fold in the PBSC group than in the BM group (CD34+ cells, 5.8 × 106/kg vs 2.7 × 106/kg; T cells, 300.1 × 106/kg vs 35.7 × 106/kg; NK cells, 28.2 × 106/kg vs 3.6 × 106/kg; P<0.001 for each). In connection with the cell collection procedures, PBSC donors spent a shorter median time in hospital than BM donors (0 vs 2 days; median difference −2 days, 95% CI −2 to 2) and had fewer median days of restricted activity (2 vs 6 days; median difference −3 days, 95% CI −4 to 2). Overall, 65% of PBSC donors and 57% of BM donors reported at least one adverse event (AE), most of which were transient, mild–moderate in severity, and without clinical sequelae. PBSC donors experienced predominantly filgrastim-related AEs, while BM donors experienced predominantly harvest-related AEs.

Outcome of pandemic H1N1 infections in hematopoietic stem cell transplant recipients.

During 2009, a new strain of A/H1N1 influenza appeared and became pandemic. A prospective study was performed to collect data regarding risk factors and outcome of A/H1N1 in hematopoietic stem cell transplant recipients. Only verified pandemic A/H1N1 influenza strains were included: 286 patients were reported, 222 allogeneic and 64 autologous recipients. The median age was 38.3 years and the median time from transplant was 19.4 months. Oseltamivir was administered to 267 patients and 15 patients received zanamivir. One hundred and twenty-five patients (43.7%) were hospitalized. Ninety-three patients (32.5%) developed lower respiratory tract disease. In multivariate analysis, risk factors were age (OR 1.025; 1.01–1.04; P=0.002) and lymphopenia (OR 2.49; 1.33–4.67; P<0.001). Thirty-three patients (11.5%) required mechanical ventilation. Eighteen patients (6.3%) died from A/H1N1 infection or its complications. Neutropenia (P=0.03) and patient age (P=0.04) were significant risk factors for death. The 2009 A/H1N1 influenza pandemic caused severe complications in stem cell transplant recipients.

Fertility recovery and pregnancy after allogeneic hematopoietic stem cell transplantation in Fanconi anemia patients

Reduced fertility is one clinical manifestation among other well known Fanconi anemia features. Most recipients of allogeneic hematopoietic stem cell transplantation suffer from secondary infertility owing to gonadal damage from myeloablative conditioning. In order to evaluate the rate of pregnancy in Fanconi anemia transplanted patients, we performed a retrospective analysis of female patients transplanted in 15 centers from 1976 to 2008. Among 578 transplanted Fanconi anemia patients, we identified 285 transplanted females of whom 101 patients were aged 16 years or over. Ten became pregnant (4 twice). Before hematopoietic stem cell transplantation all had confirmed Fanconi anemia diagnosis. Median age at transplantation was 12 years (range 5–17 years). Conditioning regimen consisted of cyclophosphamide with or without irradiation. During follow up, 5 of 10 patients presented signs of ovarian failure. Among those, 2 patients spontaneously recovered regular menses, and 3 received hormonal replacement therapy. Pregnancy occurred from four to 17 years after hematopoietic stem cell transplantation. Three patients had preterm deliveries, one patient had a hysterectomy for bleeding. All 14 newborns had normal growth and development without congenital diseases. In conclusion, recovery of normal ovarian function and a viable pregnancy is a realistic but relatively rare possibility even in Fanconi anemia patients following hematopoietic stem cell transplantation. Mechanisms of fertility recovery are discussed.

Impact of hypoxia and long-term cultivation on the genomic stability and mitochondrial performance of ex vivo expanded human stem/stromal cells.

Recent studies have described the occurrence of chromosomal abnormalities and mitochondrial dysfunction in human stem/stromal cells (SCs), particularly after extensive passaging in vitro and/or expansion under low oxygen tensions. To deepen this knowledge we investigated the influence of hypoxia (2% O(2)) and prolonged passaging (>P10) of human bone marrow stromal cells (BMSCs) and adipose-derived stromal cells (ASCs) on the expression of genes involved in DNA repair and cell-cycle regulation pathways, as well as on the occurrence of microsatellite instability and changes in telomere length. Our results show that hypoxic conditions induce an immediate and concerted down-regulation of genes involved in DNA repair and damage response pathways (MLH1, RAD51, BRCA1, and Ku80), concomitantly with the occurrence of microsatellite instability while maintaining telomere length. We further searched for mutations occurring in the mitochondrial genome, and monitored changes in intracellular ATP content, membrane potential and mitochondrial DNA content. Hypoxia led to a simultaneous decrease in ATP content and in the number of mitochondrial genomes, whereas the opposite effect was observed after prolonged passaging. Moreover, we show that neither hypoxia nor prolonged passaging significantly affected the integrity of the mitochondrial genome. Ultimately, we present evidence on how hypoxia selectively impacts the cellular response of BMSCs and ASCs, thus pointing for the need to optimize oxygen tension according to the cell source.