Peripheral dendritic cell chimerism in allogeneic hematopoietic stem cell recipients

BACKGROUND: Relapse and graft-versus-host disease (GVHD) represent major causes of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HSCT). Although leukocyte and T-cell chimerism analyses are performed routinely suggesting a predictive value on the patients outcome, little is known about chimerism of dendritic cells (DC) representing strong initiators of immune responses. METHODS: In this prospective study, peripheral DC1 (CD11c+) and DC2 (CD123+) chimerism was determined in hematopoetic stem cell recipients. DCs were isolated from peripheral blood by fluorescence activated cell sorting. Chimerism analyses were performed by fluorescent in situ hybridization or by polymerase chain reaction-based typing of short tandem repeats. RESULTS: At time of engraftment, DC chimerism analyses showed complete chimerism in 76.3% (DC1)/79.5% (DC2), mixed chimerism (MC) in 21.0% (DC1)/17.9% (DC2) and no chimerism in 2.7% (DC1)/2.6% (DC2) of the patients. Peripheral DC chimerism had no significant effect on relapse-free or overall survival. Although acute GVHD was observed more often in patients with MC for DC1/DC2 and chronic GVHD occurred more often in patients with MC for DC2, there was no statistically significant correlation. CONCLUSIONS: Although DCs as antigen presenting cells are supposed to have an impact on the induction of GVHD, there was no significant correlation between incidence of GVHD and DC chimerism after HSCT.     

Endothelial cell-derived microparticles in allogeneic hematopoietic stem cell recipients

BACKGROUND: Alterations of microparticles derived from different cell types are described in a number of diseases associated with inflammation and hemostatic disorders. METHODS: In this prospective study, we firstly analyzed endothelial cell derived microparticles (EMP) in 19 hematopoietic stem cell recipients. Cultured human umbilical vein endothelial cells (HUVEC) stimulated with tumor necrosis factor-alpha (TNF-alpha) served as positive controls. EMP were analyzed by fluorescent activated cell sorting (FACS), detecting the particels via expression of CD62 (E-selectin) and anionic phospholipids binding to annexin V. RESULTS: EMP were not significantly influenced by conditioning regimens with non-myeloablative chemotherapy and 4 Gy total body irradiation (TBI) or by myeloablative regimens containing 12 Gy TBI. During acute graft versus host disease (aGVHD), significantly higher levels of EMP were detected than in patients without aGVHD (18.5/microl s=10.1 vs. 14.6/microl SD = 11.5; P = 0.004) while infectious complications did not alter EMP levels significantly. Immunosuppressive therapy with corticosteroids tendentially elevated EMP levels. HUVEC treated with TNF-alpha 1 ng/ml, 10 ng/ml and 100 ng/ml released significantly more EMP than unstimulated cultures (30.0/microl ss = 13.6 vs. 126.8/microl SD = 66.9, P = 0.032 / vs. 683.3/microl SD = 349.9; P = 0.03 / vs. 489.3 s = 184.4; P = 0.013). CONCLUSIONS: Elevation of EMP during aGVHD might express severe endothelial cell injury within this complication after hematopoietic stem cell transplantation and might serve as a diagnostic test for early differentiation of aGVHD from other transplanted related complications.     

Evaluation of readmissions in hematopoietic stem cell transplant recipients

BACKGROUND: There is a lack of information on health expenses caused by readmissions among hematopoietic stem cell transplant (HSCT) recipients. We analyzed the rate, causes, and evolution of hospitalization after HSCT. METHODS: We retrospectively studied 140 consecutive patients who received an autologous HSCT (n = 107; 76.4%) or an allogeneic HSCT (n = 33; 23.6%) in our institution from May 2001 through September 2004. RESULTS: There were 45 readmissions in 28 patients (20%): three (10%) in the autologous and 25 (90%), in the allogeneic HSCT cohorts. The overall median age was 35.3 +/- 13.5 years and 54% were women. Hematologic diseases were: multiple myeloma (n = 1, 4%), myelodysplastic syndrome (n = 2, 7%), acute lymphoblastic leukemia (n = 2, 7%), aplastic anemia (n = 2, 7%), chronic myeloid leukemia (n = 3, 11%), non-Hodgkin's lymphoma (n = 4, 14%), Hodgkin's disease (n = 4, 14%) and acute nonlymphoblastic leukemia (n = 10, 38%). The length of stay for each readmission was 25 +/- 21 days. The median day of readmission was +62.5 (range = +19 to +987); however, 75% occurred between days +30 and +70. The causes of hospitalization were: infections (n = 24, 54%), due to the graft (n = 14, 31%), graft failure (n = 4, 9%), coagulation disorders (n = 2, 4%), and second neoplasm (n = 1, 2%). Mortality due to the transplant was 10 patients (14%) including: graft-versus-host disease (n = 3), sepsis (n = 3), thrombotic thrombocytopenic purpura (n = 1), and relapse (n = 3). CONCLUSIONS: Although there was a frequent use of hospital resources (20%) after HSCT with patients hospitalized for a median of 25 days, it was beneficial since there were 86% survivors at 36 months follow-up.     

Porcine stem cell engraftment and seeding of murine thymus with class II+ cells in mice expressing porcine cytokines: toward tolerance induction across discordant xenogeneic barriers

BACKGROUND: Mixed hematopoietic chimerism is a reliable means of tolerance induction, but its utility has not been demonstrated in discordant xenogeneic combinations because of the difficulty in achieving lasting hematopoietic engraftment. Miniature swine are likely to be suitable organ donors for humans. To evaluate the ability of mixed chimerism to induce swine-specific tolerance in widely disparate xenogeneic recipients, this study aimed to achieve long-lasting chimerism in a pig to mouse combination. METHODS: Immunodeficient transgenic mice were developed by crossing transgenic founders carrying porcine interleukin-3, granulocyte macrophage-colony stimulating factor, and stem cell factor genes with severe combined immunodeficient mice or non-obese diabetic/severe combined immunodeficient mice. Swine bone marrow transplantation was performed in these mice, and porcine chimerism was followed for 20 weeks. RESULTS: Whereas swine cells became undetectable in all non-Tg littermates by 7 weeks, high levels of porcine hematopoietic chimerism, including the presence of porcine class II+ cells in the host thymus were maintained in Tg mice for >20 weeks. Colony-forming assays revealed the presence of large numbers of swine hematopoietic progenitor cells in the marrow of these mice at 20 weeks after bone marrow transplantation. CONCLUSIONS: These transgenic mice demonstrate for the first time that spontaneous migration of marrow donor antigen-presenting cells to an intact recipient thymus can occur and that porcine stem cells can persist in this highly disparate species combination. These data therefore support the feasibility of the eventual goal of tolerance induction by mixed chimerism in discordant xenogeneic combinations.     

Splenectomy and partial splenectomy improve hematopoietic stem cell engraftment in hypersplenic mice

Background

Hematopoietic stem cell (HSC) engraftment is delayed after transplantation in children with hypersplenism, increasing the morbidity and costs of care. Preliminary clinical data suggest that splenectomy before HSC transplantation may improve HSC engraftment, although this observation has not been tested in an animal model.

Methods

We performed total splenectomy (n = 22), partial splenectomy (n = 16), or sham laparotomy (n = 21) on erythrocyte protein 4.2 knockout mice, a murine model of hereditary spherocytosis with hypersplenism. After 10 days, we lethally irradiated the mice, transplanted 3 × 10⁶ allogeneic bone marrow cells, and then assessed engraftment using serial complete blood counts. Successful engraftment was defined as recovery of hemoglobin, neutrophil, or platelet counts. We compared engraftment rate using χ² test and time to engraftment using Student's t test analysis, with significance defined as P < .05.

Results

Total splenectomy increased the rate of successful HSC engraftment and decreased the interval to HSC engraftment compared with controls. Similarly, partial splenectomy decreased the interval to HSC engraftment, with a nonsignificant trend toward improved overall rate of successful HSC engraftment.

Conclusion

Partial or total splenectomy before HSC transplantation improves HSC engraftment in hypersplenic mice. This model supports consideration of splenic resection in hypersplenic children requiring HSC transplantation.     

Conditions that enable human hematopoietic stem cell engraftment in all NOD-SCID mice

BACKGROUND: Transplantation of human hematopoietic stem cells is the only true test of their long-term repopulation potential. Models are readily available to evaluate murine hematopoietic stem cells, but few exist that allow reliable quantification of human stem cells. The non-obese diabetic-severe combined immunodeficient (NOD-SCID) mouse model enables quantification of human hematopoietic stem cells, but the conditions that permit human engraftment in all animals have yet to be defined. The aims of the project were, therefore, to describe the variables that allow human engraftment in the NOD-SCID mouse model and the techniques that accurately quantify this engraftment. METHODS: NOD-SCID mice that had or had not received 250, 325, or 400 cGy irradiation received cord blood (CB) mononuclear or CD34+ cells i.v. or i.p. Mice were killed 6 weeks after transplantation, and the bone marrow, spleen, and thymus were harvested. Four-color flow cytometric analysis, semi-quantitative PCR, myeloid and erythroid progenitor, and stem cell assays were used to monitor human engraftment. RESULTS: A 250 or 325 cGy and i.v. injection of CB mononuclear or CD34+ cells is required to detect multilineage human engraftment in the bone marrow, spleen, or thymus of NOD-SCID mice. Four-color flow cytometric analysis and semi-quantitative PCR enable accurate detection of 0.1% human cells. Progenitor and stem cell assays provide functional information about the engrafted cells. CONCLUSIONS: Successful development of the NOD-SCID mouse model and techniques to assess human engraftment now allow it to be used reliably to analyze the effects of short-term cytokine exposure on the long-term repopulating capacity of CB stem cells.     

Leishmaniasis in solid organ and hematopoietic stem cell transplant recipients

Leishmaniasis occurs in <1% of solid organ and hematopoietic stem cell transplant recipients in endemic countries in which transplants are performed. Visceral leishmaniasis (VL) makes up the bulk of reported cases. The onset generally occurs months after transplantation and the mode of acquisition is often impossible to determine, but de novo vector‐borne infection and reactivation of inapparent infection are thought to be the principal means. The potential role of clinically inapparent donor infection is uncertain and screening is not currently recommended, nor is it recommended for recipients from endemic areas, some of whom may have detectable circulating protozoan nucleic acid. While transplant recipients with VL often present with the non‐specific findings of fever and cytopenia, the additional presence of hepatosplenomegaly in patients from endemic areas should lead to a directed diagnostic evaluation with bone marrow examination and PCR testing of marrow and peripheral blood having a high yield. Management may often be complicated by the presence of concomitant infections. A lipid formulation of amphotericin B is the preferred treatment, especially for VL, but the relapse rate in transplant recipients is approximately 25%. PCR monitoring of blood for either secondary prophylaxis or preemptive therapy requires further study.     

Prospective study of infectious complications in allogeneic hematopoietic stem cell transplant recipients

Martín‐Peña A, Aguilar‐Guisado M, Espigado I, Parody R, Cisneros JM. Prospective study of infectious complications in allogeneic hematopoietic stem cell transplant recipients.
Clin Transplant 2011: 25: 468–474. © 2010 John Wiley & Sons A/S. Abstract: This is a prospective, observational study of a consecutive cohort of allogeneic hematopoietic stem cell transplantation (allo‐HSCT) adult recipients conducted between July 2003 and May 2006, with the aim of identifying the current incidence, etiology, risk factors for infections and associated mortality up to two yr after allo‐HSCT. Seventy‐four episodes of infection were recorded in 38 patients, 50 consecutive adult patients underwent 54 allo‐HSCT. The incidence of infection was 1.36 (68/50) episodes/patient after the first year of transplantation and 1.48 (74/50) episodes/patient after first two yr of transplantation. The most common syndrome was cytomegalovirus (CMV) infection, followed by catheter‐related bloodstream infection and pneumonia. An etiological diagnosis was established in 85.1% of the episodes. Bacteria were the most common etiology (55.5%), followed by viruses (41.3%) and fungi (4.8%). CMV was the most common viral agent (73%), and all fungal infections were caused by molds. Myeloablative conditioning regimen, chronic graft‐versus‐host disease, and medical complications post‐transplant were independent risk factors for infection. The global mortality two yr after transplantation was 32%, and death was infection related in 12%. In spite of advances, infections continue to be a common cause of morbidity and mortality following allo‐HSCT.     

Intra-bone marrow cotransplantation of donor mesenchymal stem cells in pig-to-NOD/SCID mouse bone marrow transplantation facilitates short-term xenogeneic hematopoietic engraftment

We directly injected porcine donor mesenchymal stem cells (MSC) into murine bone marrow (BM) cavities to examine the effects of intra-BM cotransplantation of MSC in pig-to-NOD/SCID mouse bone marrow transplantation (BMT) on xenogeneic engraftment. Porcine MSC prepared by aspiration of iliac BM of miniature swine were identified as CD90+CD29+CD45-CD31- and shown to differentiate into osteoblastocytes and adipocytes. A few weeks after expansion, MSC (1 x 10(6) cells/mouse) were directly injected with BM cells (30 x 10(6) cells/mouse) obtained from vertebrae through a microsyringe into BM cavities of both tibiae of NOD/SCID mice after 3-Gy total body irradiation. Controls were injected with only BM cells. Porcine chimerisms of BM cells of tibiae (injection site) and of femurs (non-injection site) in recipient mice were evaluated with porcine and murine cell markers using FACS. The chimerism of porcine class I+ cells at the injection site in the MSC group and the controls were 3.45%, 1.43%, and 0.17%, and 2.27%, 0.81%, and 0.1% at 1, 3, and 6 weeks, respectively. The chimerism at the noninjection site in the MSC group and the controls were 0.21%, 1.34%, and 0.11%, and 0.06%, 0.42%, and 0.09% at 1, 3, and 6 weeks, respectively. The total chimerisms of injection site in the MSC group to 6 weeks were significantly higher than those in the control group (1.60% vs 0.99%; P < .05), whereas the chimerism of the noninjection site in MSC group was remarkably higher at 3 weeks. In conclusion, intra-BM cotransplantation of porcine donor MSC in pig-to-NOD/SCID mouse BMT improved short-term xenogeneic engraftment, presumably due to humoral factors.     

Facilitation of syngeneic stem cell engraftment by anti-class I monoclonal antibody pretreatment of unirradiated recipients

We have established a murine model of syngeneic bone marrow transplantation based on the use of monoclonal antibody as the sole conditioning regimen in unirradiated recipients. Administration of a single injection of monoclonal antibody directed against major histocompatibility complex-encoded class I determinants facilitated permanent hemopoietic stem cell engraftment without any apparent side-effects. Whereas untreated hosts exhibited a maximal chimerism of 15% at donor cell doses of up to 12 X 10(7) bone marrow cells, pretreatment by 2 mg of anti-class I antibody one week prior to transplantation of 3 X 10(7) syngeneic bone marrow cells resulted in a mean donor representation of about 80%. The antibody can be given up to four weeks prior to transplantation, and the degree of donor engraftment observed is a function of the dose of antibody administered. The fact that specific antibody enhanced engraftment in two strain combinations indicates that antibody is the active agent in facilitating engraftment and that facilitation is not strain-restricted. Anti-class I antibodies of the IgG2a, but not IgG1, isotype are effective in promoting engraftment. Although the isotype requirement suggests a role for antibody-mediated cytotoxicity in promoting stem cell engraftment, the extensive time-frame of facilitation suggests that other effects of the antibody may also be involved. The model of syngeneic bone marrow transplantation we describe here will be useful in studying the mechanisms regulating stem cell engraftment and may have potential clinical application as an approach to autologous marrow transplantation.     

Solid organ transplantation following end-organ failure in recipients of hematopoietic stem cell transplantation in children

Hematopoietic stem cell transplantation (HSCT) is an accepted treatment modality for various malignant and non-malignant disorders of the lympho-hematopoietic system. Patient survival rate has increased significantly with the use of this procedure. However, with the increase in disease-free patient survival rates, complications including various organ toxicities are also common. Kidney, liver, lung, heart, and skin are among those solid organs that are commonly affected and frequently lead to organ dysfunction and eventually end-organ disease. Conservative measures may or may not be successful in managing the organ failure in these patients. Solid organ transplantation has been shown to be promising in those patients who fail conservative management. This review will summarize the causes of solid organ (kidney, liver, and lung) dysfunction and the available data on transplantation of these solid organs in post-HSCT recipients.     

Fluid balance of pediatric hematopoietic stem cell transplant recipients and intensive care unit admission

Fluid administration is essential in patients undergoing hematopoietic stem cell transplant (HSCT). Admission to pediatric intensive care unit (PICU) is required for 11–29% of pediatric HSCT recipients and is associated with high mortality. The objective of this study was to determine if a positive fluid balance acquired during the HSCT procedure is a risk factor for PICU admission. The medical records of 87 consecutive children who underwent a first HSCT were reviewed retrospectively for the following periods: from admission for HSCT to PICU admission for the first group (PICU group), and from admission for HSCT to hospital discharge for the second group (non-PICU group). Fluid balance was determined on the basis of weight gain (WG) and fluid overload (FO). PICU group consisted of 19 patients (21.8%). Among these, 13 (68.4%) developed ≥10% WG prior to PICU admission compared with 15 (22.1%) in the non-PICU group (p < 0.001). Thirteen patients (68.4%) developed ≥10% FO prior to PICU admission compared with 31 (45.6%) in the non-PICU group (p = 0.075). Following multivariate analysis, ≥10% WG (p = 0.018) and cardiac dysfunction on admission for HSCT (p = 0.036) remained independent risk factors for PICU admission. Smaller children (p = 0.033) and patients with a twofold increase in serum creatinine (p = 0.026) were at risk of developing ≥10% WG. This study shows that WG is a risk factor for PICU admission in pediatric HSCT recipients. Further research is needed to better understand the pathophysiology of WG in these patients and to determine the impact of WG prevention on PICU admission.     

Limited efficacy of lamivudine against hepatitis B virus infection in allogeneic hematopoietic stem cell transplant recipients

BACKGROUND: Reactivation of chronic hepatitis B virus (HBV) infection is a major complication when HBV carriers receive immunosuppressive therapy. Recipients of allogeneic hematopoietic stem cell transplantation (HSCT) carry the highest risk of fatal HBV disease (up to 12%). METHODS: In an attempt to identify a suitable procedure for the prevention and management of HBV reactivation, the administration of lamivudine over the course was tested in two patients. RESULTS: Generally, the patients transplant courses were successfully managed despite their difficult clinical situations: a high HBV load before transplant in one patient and intense steroid therapy for complicated acute graft-versus-host disease (GVHD) in the other patient. However, one patient showed a reactivation of HBV after discontinuing lamivudine and the other showed persistently high DNA polymerase activity despite prolonged administration of lamivudine. CONCLUSIONS: We concluded that lamivudine could have a place in the management of patients who suffer from chronic HBV infection and who are undergoing allogeneic HSCT. However, the efficacy of lamivudine seemed to be limited compared with other settings, including solid organ transplantation and autologous HSCT.     

Partial hepatectomy and subsequent radiation facilitates engraftment of mouse embryonic stem cells in the liver

For liver-targeted regenerative medicine, embryonic stem (ES) cell-derived hepatocyte-like cells proffer great expectation. In vitro exposure to a combination of various growth factors, such as hepatocyte growth factor and fibroblast growth factor-4, as well as cytokines, leads to differentiation of ES cells into hepatocyte-like cells. We sought to determine the in vivo environment that allowed engraftment of ES cells transplanted to the liver. Thus, we examined the effect of partial hepatectomy (50%) (PHT) and subsequent radiation (RT) of the male Balb/c mouse host liver on ES cell engraftment. ES cells (5 x 10(6)) derived from 129Sv mice were transplanted into the residual liver. The controls were ES cells transplanted into a normal liver. Bromo-deoxy-residine (BrdU)-uptake was performed to evaluate the effect of hepatectomy and RT on hepatocyte regeneration. Mouse ES cells engrafted, forming teratomas in the normal liver without showing any mononuclear infiltration. A liver modified by PHT and RT facilitated engraftment of mouse ES cells compared with a normal liver. Hepatic RT significantly suppressed hepatocytic uptake of BrdU.