Allogeneic stem cell transplantation in the treatment of acute myeloid leukemia: An overview of obstacles and opportunities.

As an important treatment for acute myeloid leukemia, allogeneic hematopoietic stem cell transplantation (allo-HSCT) plays an important role in reducing relapse and improving long-term survival. With rapid advancements in basic research in molecular biology and immunology and with deepening understanding of the biological characteristics of hematopoietic stem cells, allo-HSCT has been widely applied in clinical practice. During allo-HSCT, preconditioning, the donor, and the source of stem cells can be tailored to the patient's conditions, greatly broadening the indications for HSCT, with clear survival benefits. However, the risks associated with allo-HSCT remain high, i.e. hematopoietic reconstitution failure, delayed immune reconstitution, graft-versus-host disease, and post-transplant relapse, which are bottlenecks for further improvements in allo-HSCT efficacy and have become hot topics in the field of HSCT. Other bottlenecks recognized in the current treatment of individuals diagnosed with acute myeloid leukemia and subjected to allo-HSCT include the selection of the most appropriate conditioning regimen and post-transplantation management. In this paper, we reviewed the progress of relevant research regarding these aspects.

The roles of reactive oxygen species (ROS) and autophagy in the survival and death of leukemia cells.

As a clonal disease of hematopoietic stem cells (HSCs), the etiology and pathogenesis of leukemia is not fully understood. Recent studies suggest that cellular homeostasis plays an essential role in maintaining the function of HSCs because dysregulation of cellular homeostasis is one of the major factors underlying the malignant transformation of HSCs. Reactive oxygen species (ROS) and autophagy, key factors regulating cellular homeostasis, are commonly observed in the human body. Autophagy can be induced by ROS through a variety of signaling pathways, and conversely inhibits ROS-induced damage to cells and tissues. ROS and autophagy coordinate to maintain cellular homeostasis. Previous studies have demonstrated that both of ROS and autophagy play important roles in the development of leukemia and are closely involved in drug resistance in leukemia. Interference with cellular homeostasis by promoting programmed leukemia cell death via ROS and autophagy has been verified to be an efficient technique in the treatment of leukemia. However, the critical roles of ROS and autophagy in the development of leukemia are largely unknown. In this review, we summarize the roles of ROS and autophagy in the pathogenesis of leukemia, which may allow the identification of novel targets and drugs for the treatment of leukemia based on the regulation of HSCs homeostasis through ROS and autophagy.

The role of RIP1 and RIP3 in the development of aplastic anemia induced by cyclophosphamide and busulphan in mice.

This study aimed to investigate the role of RIP1 and RIP3 in the pathogenesis of aplastic anemia (AA) induced by cyclophosphamide and busulphan in mice. Animals were randomly divided into three groups: the control group, the AA group, and the Nec-1 group. Mouse AA model was established by intraperitoneal injection of cyclophosphamide (40 mg/kg/d) and busulfan (20 mg/kg/d) for 12 days. The Nec-1 group mice received intraperitoneal injection of Nec-1 (2 mg/kg/d) for 12 days prior to intraperitoneal injection of cyclophosphamide (40 mg/kg/d) and busulfan (20 mg/kg/d) for 12 days. The control mice received intraperitoneal injection of equal volume of saline. At 12 h after the last intraperitoneal injection, blood and bone marrow tissues were collected from mice. Peripheral blood cells were analyzed using hematology analyzer and the histological changes of bone marrow tissues were examined using scanning electron microscopy (SEM). The levels of RIP3 and RIP3 in bone marrow were measured using Western blot analysis and the interaction of RIP1 and RIP3 proteins was investigated on the basis of immunoprecipitation analysis. ELISA was used to measure the levels of IL-6, TNF-α, and FLT-3L in bone marrow tissue supernatant. Apoptosis and necrosis of bone marrow cells were analyzed using flow cytometry. Western blot showed that the expression of RIP1 and RIP3 was significantly increases in AA mice compared to the normal controls. Immunoprecipitation detected the pro-necrotic RIP1-RIP3 complex, suggesting that RIP1 and RIP3 mediated necroptosis may involved in the damage of bone marrow cells. Compared to the AA mice, Nec-1 group mice exhibited significantly increase of peripheral blood cells and mononuclear cells in bone marrow tissues and decrease of the apoptosis/necrosis of bone marrow cells. In addition, we observed significant decrease of IL-6, TNF-α, and FLT-3L in bone marrow tissue supernatant in the Nec-1 group mice compared to AA mice. Our results suggest that Nec-1 can prevent the development of AA by inhibiting bone marrow cells necrosis and the production of inflammatory mediators. RIP1 and RIP3-mediated necroptosis may involve in the pathogenesis of AA induced by cyclophosphamide and busulfan in mice.