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Allogeneic hematopoietic cell transplantation (allo-HCT) is potentially curative for certain hematologic malignancies and nonmalignant diseases. The field of allo-HCT has witnessed significant advances, including broadening indications for transplantation, availability of alternative donor sources, less toxic preparative regimens, new cell manipulation techniques, and novel GVHD prevention methods, all of which have expanded the applicability of the procedure. These advances have led to clinical practice conundrums when applying traditional definitions of hematopoietic recovery, graft rejection, graft failure, poor graft function, and donor chimerism, because these may vary based on donor type, cell source, cell dose, primary disease, graft-versus-host disease (GVHD) prophylaxis, and conditioning intensity, among other variables. To address these contemporary challenges, we surveyed a panel of allo-HCT experts in an attempt to standardize these definitions. We analyzed survey responses from adult and pediatric transplantation physicians separately. Consensus was achieved for definitions of neutrophil and platelet recovery, graft rejection, graft failure, poor graft function, and donor chimerism, but not for delayed engraftment. Here we highlight the complexities associated with the management of mixed donor chimerism in malignant and nonmalignant hematologic diseases, which remains an area for future research. We recognize that there are multiple other specific, and at times complex, clinical scenarios for which clinical management must be individualized.

Although chimeric antigen receptor T (CAR-T) cell therapy has proven to be effective in treating relapsed or refractory B-cell hematological malignancies, severe hematological toxicities remain an intractable issue. This retrospective study assessed the characteristics and risk factors of new-onset severe cytopenia following CAR-T cell infusion in 76 patients with r/r acute lymphoblastic leukemia. The rates of new-onset severe cytopenia were high, including severe neutropenia (SN) (39/56, 70%), severe anemia (SA) (35/66, 53%), and severe thrombocytopenia (ST) (31/64, 48%). Comparatively, cohorts with higher cytokine release syndrome (CRS) grades had higher incidence of severe cytopenia with prolonged duration. Multivariable analyses showed that elevated maximum (max) lg D-dimer and delayed peak time of CRS are independent risk factors for SN recovery; increased max lg IL-10 and delayed CRS recovery are risk factors for SA; high max lg ferritin is a risk factor for ST; and longer period to CRS onset or CRS recovery and higher grade of CRS are risk factors for prolonged hematological toxicities. These observations led to the conclusion that profiles of CRS, including its duration, severity and serum markers are correlated to the incidence and recovery of new-onset severe cytopenia, prompting clinical intervention for post-CAR-T severe cytopenia.

Interleukin-18 (IL-18) is an immunoregulatory cytokine and a context-dependent regulator of hematopoietic stem/progenitor cell (HSPC) quiescence in murine models. In a previous study, high pre-conditioning levels of IL-18 were associated with increased non-relapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). To investigate the clinical impact of IL-18 status on hematopoietic function, the associations of pre-conditioning and day 0&ndash, 3 cytokine levels with platelet and neutrophil recovery were analyzed in a training cohort of 714 allografted patients. In adjusted logistic regression analyses, both increasing pre-conditioning and day 0&ndash, 3 IL-18 levels had a significantly higher adjusted odds ratio (aOR) of delayed platelet and neutrophil recovery on day +28 post-transplant (aOR per two-fold increase: 1.6&ndash, 2.0). The adverse impact of high pre-conditioning IL-18 on day +28 platelet recovery was verified in an independent cohort of 673 allografted patients (aOR per two-fold increase: 1.8 and 1.7 for total and free IL-18, respectively). In both cohorts, a platelet count &le, 20/nL on day +28 was associated with a significantly increased hazard of NRM (hazard ratio 2.13 and 2.94, respectively). Our findings support the hypothesis that elevated peritransplant IL-18 levels affect post-transplant HSPC function and may provide a rationale to explore modulation of IL-18 for improving alloSCT outcomes.

BACKGROUND: Successful hematopoietic stem cell transplantation (HSCT) requires a rapid and durable hematopoietic recovery.AIM: The aim of our study was to analyse factors that influence hematopoietic recovery after autologous HSCT.MATERIALS AND METHODS: Multiple regression analysis was used to analyse factors affecting neutrophil and platelet engraftment in 90 autologous transplanted patients – 30 with acute myeloid leukaemia (AML), 30 with lymphoma and 30 with multiple myeloma (MM) from 2008 till 2016.RESULTS: The neutrophil recovery in AML patients was significantly influenced by transfusion support with random-donor platelets, sex and number of transplanted mononuclear cells (MNC) and CD34+ cells; and in lymphoma patients, it was influenced by sex, age, mobilisation strategy and some transplanted MNC. The influence of investigated factors on neutrophil engraftment in MM patients was not statistically significant. The platelet recovery in AML patients was influenced by transfusion support with random-donor platelets; in lymphoma patients, it was influenced by sex, age, time from diagnosis to harvesting and time from diagnosis to HSCT; and in MM patients it was influenced by transfusion support with random-donor platelets.CONCLUSION: Additional studies are necessary to better understanding of engraftment kinetic to improve the safety of HSCT and to minimise potential complications and expenses related to HSCT.

Although the influence of transplanted bone marrow (BM) CD34+ cells on neutrophil engraftment (NE) and transplantation outcomes has been discussed controversially, thresholds between 2 and 4 × 106/kg CD34+ cells are commonly accepted. This has substantial consequences for a donor in terms of BM volume to be collected, which frequently covers up to 15 to 20 mL/kg. As the BM CD34+ compartment contains varying fractions of CD34+/CD19+ B lymphoid progenitors, we tested the hypothesis that the infused CD34+/CD45dim/CD19-/CD10- myeloid stem cells might reliably predict NE in 94 children who received BM from 37 HLA-identical sibling donors (MSD) and 57 matched unrelated donors after myeloablative conditioning. The grafts contained a median of 3.6 × 106/kg total CD34+ cells, which consisted of a median of 73% myeloid CD34+ cells and 27% B lymphoid progenitors. Grafts from donors

It is unclear whether higher CD34 + cell doses infused for ASCT have any influence on survival or relapse in patients with lymphoma. We analyzed the correlation of infused CD34 + cell dose with relapse, survival, and hematopoietic recovery in 146 consecutive patients undergoing ASCT for lymphoma. Higher doses (>5 × 106/kg) were significantly correlated with earlier hematopoietic recovery, fewer infectious episodes, lower transfusion needs. No differences were observed in lymphoma outcomes (4-year relapse incidence of 38% [95%CI: 29%–48%] in the lower dose group versus 51% [95%CI: 30%–69%] in the higher dose group, 10-year OS probabilities of 58% [95%CI: 48%–68%] versus 75% [95%CI: 59%–91%], 10-year DFS probabilities of 47% [95%CI: 37%–57%] versus 42% [95%CI: 23%–61%], p = NS for all outcomes). In this series, a higher infused CD34 + cell dose did not correlate with survival or relapse but correlated with earlier hematopoietic recovery and lower resource consumption.

Background— Angiotensin (Ang)-(1-7) attenuates the development of heart failure. In addition to its local effects on cardiovascular tissue, Ang-(1-7) also stimulates bone marrow, which harbors cells that might complement the therapeutic effect of Ang-(1-7). We studied the effects of Ang-(1-7) either produced locally in the heart or subcutaneously injected during the development of heart failure induced by myocardial infarction (MI) and explored the role of cardiovascular progenitor cells in promoting the effects of this heptapeptide. Methods and Results— Effects of Ang-(1-7) on bone marrow–derived mononuclear cells in rodents, particularly endothelial progenitor cells, were investigated in vitro and in vivo in rats, in mice deficient for the putative Ang-(1-7) receptor Mas, and in mice overexpressing Ang-(1-7) exclusively in the heart. Three weeks after MI induction through permanent coronary artery occlusion, effects of Ang-(1-7) either produced locally in the heart or injected into the subcutaneous space were investigated. Ang-(1-7) stimulated proliferation of endothelial progenitor cells isolated from sham or infarcted rodents. The stimulation was blunted by A779, a Mas receptor blocker, or by Mas deficiency. Infusion of Ang-(1-7) after MI increased the number of c-kit– and vascular endothelial growth factor–positive cells in infarcted hearts, inhibited cardiac hypertrophy, and improved cardiac function 3 weeks after MI, whereas cardiomyocyte-derived Ang-(1-7) had no effect. Conclusions— Our data suggest circulating rather than cardiac Ang-(1-7) to be beneficial after MI. This beneficial effect correlates with a stimulation of cardiac progenitor cells in vitro and in vivo. This characterizes the heptapeptide as a promising new tool in stimulating cardiovascular regeneration under pathophysiological conditions.

Major ABO incompatibility between donor and recipient is not considered a barrier to successful allogeneic hematopoietic stem cell transplantation (HSCT), even if it can be associated with several immunohematologic complications. Nevertheless, conflicting data still exist as to its influence on graft-versus-host disease (GVHD) incidence, relapse rate, and survival. To further investigate the relevance of ABO major mismatch on transplantation outcome, we retrospectively analyzed results from 414 patients with major or major/minor ABO-mismatched bone marrow (BM), peripheral blood (PB), and cord blood (CB) allogeneic HSCT. Transplantation outcome was assessed by comparison with results from a 395-patient ABO-compatible population with similar characteristics. Median time to red cell transfusion independence was significantly longer in ABO-incompatible BM recipients (median time, 63 days vs 41 days; P =.001), with faster disappearance of antidonor IgM hemagglutinins in unrelated recipients (median time, 36 days vs 44 days; P = .03) and in patients with gradeor =II acute GVHD (aGVHD) (median time, 35 days vs 59 days ; P = .001). In PB stem cell (PBSC) and CB transplantation, erythroid reconstitution was not significantly delayed, regardless of donor type or presence of aGVHD. A slight correlation between ABO incompatibility and GVHD incidence was found in PBSC recipients when considering gradeor =II aGVHD incidence (63% in ABO-matched HSCT vs 83% in ABO-mismatched HSCT; P = .055), but this was not confirmed in multivariate analysis. In patients with acute leukemia, multivariate analysis revealed an association between major ABO mismatch and decreased relapse rate with borderline statistical significance (hazard ratio, 0.65; P = .04). Major ABO incompatibility mainly, if not exclusively, affects red blood cell engraftment after BM transplantation. Somewhat surprisingly, the graft-versus-plasma cell effect seems to be confined to this stem cell source.

Long-term peripheral blood counts and factors influencing long-term trilineage haematological recovery of consecutive patients in a single institution treated with high-dose chemotherapy (HDC) and ABMT or PSCT for solid tumours were examined. Patients with a relapse-free survival of >1 year were included in the analysis (n = 131), Peripheral blood counts were examined 6 months and yearly following transplantation. Median follow-up was 4.1 years (range 1-10+ years), Three years after transplantation 91% of patients had normal white blood counts (WBC), 94% normal haemoglobin (Hb) and 75% normal platelets. Trilineage recovery was complete in 70% (n = 83) at 3 years and 85% (n = 50) at 5 years, Recovery of Hb occurred before WBC and platelet recovery. Approximately 25% of patients displayed an elevated MCV throughout the follow-up period. These long-term results were independent of age, high-dose regimen, number of reinfused stem cells and stem cell source. Double (n = 12) vs single (n = 119) transplantations showed significantly slower trilineage recovery and higher MCV, No secondary graft failure, myelodysplasia or leukaemia was encountered. In conclusion, complete trilineage recovery after HDC followed by ABMT or PSCT occurs slowly. PSCT and ABMT are capable of maintaining long-term haematopoiesis, Slower recovery is seen after double transplantations. The results suggest lasting implications for bone marrow function after autologous transplantation.

In this study, the impact of polymorphisms in the genes of proinflammatory (IL-β, TNF-α, IL-6, IFN-γ), anti-inflammatory (transforming growth factor [TGF]-β, IL-10, IL-Ra), and other immunoregulatory factors (FcγRIIa, NOS3) along with the conventional risk factors on the rate of hematopoietic recovery and first episodes of bacterial, viral, or invasive fungal infections in 102 patients with β-thalassaemia major who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) with relatively uniform protocols at our center from June 1995 to June 2004 with a minimum follow-up of at least 2 years were studied retrospectively for 180 days after hematopoietic stem cell transplantation (HSCT). Our data show that (1) donor IL-1RN∗2/2 (hazard ratio [HR], 2.4; 95% confidence interval [CI], 1.17-5.09; P = .018) and FCγRIIA +4481G/G genotypes (HR, 3.1; 95% CI, 1.56-6.31; P = .001) increased the incidence of bacterial infection; (2) fungal infection was increased in recipients with whose donors had IFN-γ +874T/T genotype (HR, 3.8; 95% CI, 1.08-13.62; P = .037); (3) time to neutrophil recovery was shorter in splenectomized patients (HR, 3.1; 95% CI, 1.70-5.64; P < .001), donors without IL-10 -1082A, -819T, and -592A haplotype (HR, 1.6; 95% CI, 1.02-2.39; P = .039), and recipients with IFN-γ +874A/A genotype (HR, 1.6; 95% CI, 1.05-2.56; P = .029); and (4) time to platelet recovery was shorter in patients with IL-10 -1082A/A genotype (HR, 1.8; 95% CI, 1.14-2.68; P = .010) and with donors having TNF-α -308G/G genotypes (HR, 1.8; 95% CI, 1.06-2.93; P = .028). These data suggest that outcome after allogeneic stem cell transplantation could be affected by many factors. The mechanisms by which they bring about such impact needs further evaluation.

To test the hypothesis that the outcome of hematopoietic stem cell (HSC) grafts is at least partially determined by the cellular composition of the graft, the National Marrow Donor Program (NMDP) analyzed the correlation of cellular phenotypes of unrelated grafts with graft outcome. Samples from 94 bone marrow (BM) and 181 peripheral blood progenitor cell (PBPC) grafts for transplantations at 40 U.S. transplant centers between 2003 and 2005 were analyzed at a single immunophenotyping reference laboratory. Samples were shipped from transplant centers upon receipt of graft. Graft cellular composition included analysis of leukocyte total cell numbers, and subsets of myeloid [CD34(+), CD34(+) CD38(-)], lymphoid [CD3(+), CD3(+) CD4(+), CD3(+) CD8(+)], and activated lymphoid cells [CD3(+) CD25(+), CD3(+) CD69(+), CD3(+) HLA-DR(+)] coexpressing CD3(+). There was substantial variability in the cellular composition of BM and PBPC grafts before and after graft processing by red blood cell (RBC) removal or plasma depletion in preparation for transplant. With BM grafts, cellular composition was not associated with hematopoietic recovery, graft-versus-host disease (GVHD), or survival. With PBPC grafts, survival rates were higher with CD34(+)5 x 10(6)/kg, 59% compared to 34% with CD34(+)or =5 x 10(6)/kg at 1 year. Platelet recovery was higher with PBPC containing CD3(+) CD8(+)8 x 10(7)/kg. Neutrophil recovery or GVHD could not be predicted by any cellular subsets of PBPC grafts. Although survival was superior with PBPC grafts containing5 x 10(6) CD34(+)/kg, an optimal graft mix of myeloid, lymphoid, and activated lymphoid subsets was not identified.