Management of acquired aplastic anaemia

Medical Application of Hydrogen in Hematological Diseases

Hydrogen gas has been reported to have medical efficacy since the 1880s. Still, medical researchers did not pay much attention to hydrogen gas until the 20th century. Recent research, both basic and clinical, has proven that hydrogen is an important physiological regulatory factor with antioxidative, anti-inflammatory, and antiapoptotic effects. In the past two decades, more than 1000 papers have been published on the topic, including organ ischemia-reperfusion injury, radiation injury, diabetes, atherosclerosis, hypertension, or cancer. We have previously hypothesized and proven the therapeutic effects of hydrogen gas in graft-versus-host disease following stem cell transplantation. In the current manuscript, we present the clinical advances of hydrogen gas in hematological disorders.

Mesenchymal Stem Cell Benefits Observed in Bone Marrow Failure and Acquired Aplastic Anemia

Acquired aplastic anemia (AA) is a type of bone marrow failure (BMF) syndrome characterized by partial or total bone marrow (BM) destruction resulting in peripheral blood (PB) pancytopenia, which is the reduction in the number of red blood cells (RBC) and white blood cells (WBC), as well as platelets (PLT). The first-line treatment option of AA is given by hematopoietic stem cell (HSCs) transplant and/or immunosuppressive (IS) drug administration. Some patients did not respond to the treatment and remain pancytopenic following IS drugs. The studies are in progress to test the efficacy of adoptive cellular therapies as mesenchymal stem cells (MSCs), which confer low immunogenicity and are reliable allogeneic transplants in refractory severe aplastic anemia (SAA) cases. Moreover, bone marrow stromal cells (BMSC) constitute an essential component of the hematopoietic niche, responsible for stimulating and enhancing the proliferation of HSCs by secreting regulatory molecules and cytokines, providing stimulus to natural BM microenvironment for hematopoiesis. This review summarizes scientific evidences of the hematopoiesis improvements after MSC transplant, observed in acquired AA/BMF animal models as well as in patients with acquired AA. Additionally, we discuss the direct and indirect contribution of MSCs to the pathogenesis of acquired AA.

Amifostine Protects Bone Marrow from Benzene-Induced Hematotoxicity in Mice

Benzene is one of the most widely used industrial chemical agents. Long-term benzene exposure causes bone marrow aplasia and leads to a wide range of hematopoietic disorders including aplastic anaemia (AA). There are currently no effective approaches to protect people from benzene-induced hematotoxicity and AA. In addition, current treatments for AA have limitations with short- and long-term risks. Protective agents and new therapeutic approaches, therefore, are needed to prevent and treat the disease. Amifostine is a well-known cytoprotective agent and has been widely used in clinical for protecting normal tissues from the toxic effects of chemotherapy and radiotherapy. The authors utilized an established mouse model to determine the protective effect of amifostine on benzene-induced bone marrow hematotoxicity. Whole-blood cell count, morphological and histopathological alterations in the bone marrow and spleen, as well as the production of inducible toxic oxidative species were examined and compared among the mouse groups. Amifostine treatment in benzene-exposed mice significantly improved blood cell counts, and morphological and histopathological signs of hematotoxicity in the bone marrow as well as in the spleen. Moreover, amifostine prevented benzene-induced bone marrow and spleen cell apoptosis and rescinded the inhibition of cell proliferation induced by benzene exposure. Finally, amifostine significantly inhibited the levels of reactive oxidative species and lipid peroxidation induced by benzene exposure. These data suggest that amifostine appears to have substantial protective effect on benzene-induced bone marrow hematotoxicity.

Personalized nanomedicine advancements for stem cell tracking

Recent technological developments in biomedicine have facilitated the generation of data on the anatomical, physiological and molecular level for individual patients and thus introduces opportunity for therapy to be personalized in an unprecedented fashion. Generation of patient-specific stem cells exemplifies the efforts toward this new approach. Cell-based therapy is a highly promising treatment paradigm; however, due to the lack of consistent and unbiased data about the fate of stem cells in vivo, interpretation of therapeutic effects remains challenging hampering the progress in this field. The advent of nanotechnology with a wide palette of inorganic and organic nanostructures has expanded the arsenal of methods for tracking transplanted stem cells. The diversity of nanomaterials has revolutionized personalized nanomedicine and enables individualized tailoring of stem cell labeling materials for the specific needs of each patient. The successful implementation of stem cell tracking will likely be a significant driving force that will contribute to the further development of nanotheranostics. The purpose of this review is to emphasize the role of cell tracking using currently available nanoparticles.

Optimization of therapy for severe aplastic anemia based on clinical, biologic, and treatment response parameters: conclusions of an international working group on severe aplastic anemia convened by the Blood and Marrow Transplant Clinical Trials Network, March 2010

Although recent advances in therapy offer the promise for improving survival in patients with severe aplastic anemia (SAA), the small size of the patient population, lack of a mechanism in North America for longitudinal follow-up of patients, and inadequate cooperation among hematologists, scientists, and transplant physicians remain obstacles to conducting large studies that would advance the field. To address this issue, the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) convened a group of international experts in March 2010 to define the most important questions in the basic science, immunosuppressive therapy (IST), and bone marrow transplantation (BMT) of SAA and propose initiatives to facilitate clinical and biologic research. Key conclusions of the working group were: (1) new patients should obtain accurate, expert diagnosis and early identification of biologic risk; (2) a population-based SAA outcomes registry should be established in North America to collect data on patients longitudinally from diagnosis through and after treatment; (3) a repository of biologic samples linked to the clinical data in the outcomes registry should be developed; (4) innovative approaches to unrelated donor BMT that decrease graft-versus-host disease are needed; and (5) alternative donor transplantation approaches for patients lacking HLA-matched unrelated donors must be improved. A partnership of BMT, IST, and basic science researchers will develop initiatives and partner with advocacy and funding organizations to address these challenges. Collaboration with similar study groups in Europe and Asia will be pursued.

Allogeneic hematopoietic stem cell transplantation for acquired aplastic anemia using cyclophosphamide and antithymocyte globulin: a single center experience

Between February 1998 and October 2007, 97 (69 male, 28 female) patients with acquired aplastic anemia and a median age of 18 years (range, 2-39) received related allogeneic hematopoietic stem cell transplantation. Ninety-five patients received bone marrow grafts and two patients G-CSF primed peripheral blood stem cell transplantation. The donors were genotypically HLA-identical siblings in 94 cases, HLA-matched parents in 2 cases and a syngeneic twin in 1 case. Median time from diagnosis to transplantation was 2 months (range, 1-15). Conditioning regimen consisted of cyclophosphamide combined with antithymocyte globulin in all patients. For graft versus host disease (GVHD) prophylaxis, all patients received methotrexate and cyclosporine. Eighty-six patients showed evidence of hematopoietic engraftment. Eight patients died before engraftment. Rejection rate was 14.8% with three primary graft failures and eight secondary graft rejections occurring between 2 and 27 months post transplantation. Of the 11 rejecting patients, 3 died from infection and 8 proceeded to a second transplantation. Among the eight patients re-transplanted, seven are alive with successful second engraftments and one died from acute grade III GVHD. Acute GVHD occurred in 15.5% and extensive chronic GVHD in only 5.3% of patients. The 4-year overall probability of survival was 76.8%. Infection was the cause of 81.1% of deaths. The major factor affecting survival was onset of infection before transplantation. Major ABO donor-recipient incompatibility, disease severity and acute GVHD had also negative impact on survival. These results could be improved by reducing the time to transplant and by a more efficient supportive care policy.Bone Marrow Transplantation advance online publication, 27 July 2009; doi:10.1038/bmt.2009.175.

Hematopoietic stem cell transplantation for bone marrow failure syndromes in children

Bone marrow failure (BMF) syndromes include a broad group of diseases of varying etiologies, in which hematopoeisis is abnormal or completely arrested in one or more cell lines. BMF can be an acquired aplastic anemia (AA) or can be congenital, as part of such syndromes as Fanconi anemia (FA), Diamond Blackfan anemia, and Schwachman Diamond syndrome (SDS). In this review, we first address the evolution and current status of bone marrow transplantation (BMT) in the pediatric population in the most common form of BMF, acquired AA. We then discuss pediatric BMT in some of the more common inherited BMF syndromes, with emphasis on FA, in which experience is greatest. It is important to consider the possibility of a congenital etiology in every child (and adult) with marrow failure, because identification of an associated syndrome provides insight into the likely natural history of the disease, as well as prognosis, treatment options for the patient and family, and long-term sequelae both of the disease itself and its treatment.

Cardiac surgery in a patient with idiopathic aplastic anemia: a case report

Major surgery in a patient with pancytopenia might be associated with increased surgical risks, especially for bleeding and infection. A 66-yr-old man was admitted to the hospital due to shortness of breath. His dyspnea was classified by the New York Heart Association (NYHA) as functional class III. Prior to admission, he had a 5-yr history of medical management for idiopathic aplastic anemia. The severity of aplastic anemia of the patient was graded as non-severe aplastic anemia. Echocardiography revealed reduced left ventricular function and severe aortic valve regurgitation (grade IV) with left ventricular end diastolic dimension measuring 87 mm. Because of dyspnea and echocardiographically documented aortic valve insufficiency, the patient underwent elective aortic valve replacement. Although extracorporeal circulation for valve operations might be associated with aggravation of impaired blood cell function, the patient recovered from surgery uneventfully. Here, we report a successful cardiac surgery with extracorporeal cardiopulmonary bypass in a patient with severe aortic valve insufficiency and concomitant idiopathic aplastic anemia.

Acute myeloid leukemia with severe aplastic anemia following immunosuppressive therapy

Severe aplastic anemia (AA) is a life-threatening condition wherein bone marrow transplantation (BMT) is the therapy of choice in a young patient who has a matched sibling donor. Here, we report an 11-year-old boy with severe AA who was referred for BMT late in its course when he had developed acute myeloid leukemia following two courses of immunosuppressive therapy with antithymocyte globulin and cyclosporin. He was then treated with induction therapy using cytosine arabinoside and daunomycin for acute myeloid leukemia, but he succumbed due to infection and refractory leukemia. We discuss the relevance of early referral for BMT in severe AA.

Current concepts in the pathophysiology and treatment of aplastic anemia

Aplastic anemia, an unusual hematologic disease, is the paradigm of the human bone marrow failure syndromes. Almost universally fatal just a few decades ago, aplastic anemia can now be cured or ameliorated by stem-cell transplantation or immunosuppressive drug therapy. The pathophysiology is immune mediated in most cases, with activated type 1 cytotoxic T cells implicated. The molecular basis of the aberrant immune response and deficiencies in hematopoietic cells is now being defined genetically; examples are telomere repair gene mutations in the target cells and dysregulated T-cell activation pathways. Immunosuppression with antithymocyte globulins and cyclosporine is effective at restoring blood-cell production in the majority of patients, but relapse and especially evolution of clonal hematologic diseases remain problematic. Allogeneic stem-cell transplant from histocompatible sibling donors is curative in the great majority of young patients with severe aplastic anemia; the major challenges are extending the benefits of transplantation to patients who are older or who lack family donors. Recent results with alternative sources of stem cells and a variety of conditioning regimens to achieve their engraftment have been promising, with survival in small pediatric case series rivaling conventional transplantation results.