Relationship among the Oxygen Concentration, Reactive Oxygen Species and the Biological Characteristics of Mouse Bone Marrow Hematopoietic Stem Cells / 中国实验血液学杂志

<p><b>OBJECTIVE</b>To investigate the effects of oxygen concentration and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and to analyzed the relationship among the oxygen concentration, ROS and the biological characteristics of mouse HSC through simulation of oxygen environment experienced by PB HSC during transplantation.</p><p><b>METHODS</b>The detection of reactive oxygen species (ROS), in vitro amplification, directional differentiation (BFU-E, CFU-GM, CFU-Mix), homing of adhesion molecules (CXCR4, CD44, VLA4, VLA5, P-selectin), migration rate, CFU-S of NOD/SCID mice irradiated with sublethal dose were performed to study the effect of oxgen concentration and reactive oxygen species on the biological characteristics of mouse BM-HSC and the relationship among them.</p><p><b>RESULTS</b>The oxygen concentrations lower than normal oxygen concentration (especially hypoxic oxygen environment) could reduce ROS level and amplify more Lin(-) c-kit(+) Sca-1(+) BM HSC, which was more helpful to the growth of various colonies (BFU-E, CFU-GM, CFU-Mix) and to maintain the migratory ability of HSC, thus promoting CFU-S growth significantly after the transplantation of HSC in NOD/SCID mice irradiated by a sublethal dose. BM HSC exposed to oxygen environments of normal, inconstant oxygen level and strenuously thanging of oxygen concentration could result in higher level of ROS, at the same time, the above-mentioned features and functional indicators were relatively lower.</p><p><b>CONCLUSION</b>The ROS levels of BM HSC in PB HSCT are closely related to the concentrations and stability of oxygen surrounding the cells. High oxygen concentration results in an high level of ROS, which is not helpful to maintain the biological characteristics of BM HSC. Before transplantation and in vitro amplification, the application of antioxidancs and constant oxygen level environments may be beneficial for transplantation of BMMSC.</p>

MIP-1α promotes the migration ability of Jurkat cell through human brain microvascular endothelial cell monolayer / 中国实验血液学杂志

This study was purposed to explore the mechanism of central nervous system (CNS) leukemia resulting from brain metastasis of human acute T-cell leukemia (T-ALL) cells and the role of MIP-1α in migration of Jurkat cells through human brain microvascular endothelial cells (HBMEC). The real-time PCR, siRNA test, transendothelial migration test, endothelial permeability assay and cell adhesion assay were used to detect MIP-1α expression, penetration and migration ability as well as adhesion capability respectively. The results showed that the MIP-1α expression in Jurkat cells was higher than that in normal T cells and CCRF-HSB2, CCRF-CEM , SUP-T1 cells. The MIP-1α secreted from Jurkat cells enhanced the ability of Jurkat cells to penetrate through HBMEC, the ability of Jurkat cells treated by MIP-1α siRNA to adhere to HBMEC and to migrate trans endothelial cells decreased. It is concluded that the MIP-1α secreted from Jurkat cells participates in process of penetrating the Jurkat cells through HBMEC monolayer.

Role of antioxidant in protecting the biological function of hematopoietic stem cells / 中国实验血液学杂志

In peripheral blood hematopoietic stem cell transplantation (PBHSCT) , the mobilization and circulating of bone marrow hematopoietic stem cells in blood with higher oxygen concentration all increase reactive oxygen species(ROS) production, which has negative effect on the biological function of BMHSC. In order to investigate the protective effect of antioxidant on hematopoietic stem cells (HSC), the ascorbic acid 2-phosphate (AA2P), an ascorbic acid derivative of vitamin C, was added in HSC culturing by imitating oxygen conditions which BMHSC experienced in peripheral blood stem cell transplantation. The protective effect of above-mentioned culture methods on the biologic functions of BMHSC was evaluated by vitro amplification assay, committed division assay, reactive oxygen species (ROS) measurement, CD34(+) HSC engraftment. The results showed that the ROS level in HSC from in vitro cultures was much higher than that freshly separated BMHSC, and the amplified AC133(+)CD34(+) HSC, BFU-E, CFU-GM, CFU-GEMM colonies, migration rate and severe combined immunodeficiency (SCID)-repopulating cells (SRC) were all much more than HSC cultured without AA2P. It is concluded that antioxidant intervention may be an effective methods for protecting the biological function of PBHSC and improving the therapeutic effect of PBHSCT.

Influence of reactive oxygen species on mouse bone marrow hematopoietic stem cell apoptosis / 中国实验血液学杂志

Objective of this study was to investigate the mechanism of the biological function damage resulting from increased ROS in peripheral blood stem cells during peripheral blood stem cell transplantation. Bone marrow hematopoietic stem cells (BMHSC) were cultured at the oxygen concentration imitated according to the bone marrow oxygen concentration (5% O2) including mean venous oxygen concentration (12% O2), mean arterial oxygen concentration (20% O2). The ROS level in BMHSC was detected by using fluorescent probe, the percentage of BM-HSC in cell cycle was determined by flow cytometry, the apoptosis rate was assayed by Annexin V/PI double staining, the expression levels of ATM gene and P21 protein were measured by PCR and Western respectively. The results showed that as compared with control group (5% O2), the ROS levels were lower, the percentage of cells in G1, S,G2/M phase increased (P < 0.01), the apoptosis rate of cells obviously increased (P < 0.01), the expression level of ATM gene obviously decreased (P < 0.01), while the expression level of P21 protein significantly was enhanced (P < 0.01) in 12% O2, 20% O2 and 5%-12%-20% O2 groups. It is concluded that ROS results in the apoptosis of BMHSC through inhibiting the expression of ATM gene and activating P21 protein.

Effect of different oxygen concentrations on biological properties of bone marrow hematopoietic stem cells of mice / 中国实验血液学杂志

This study purposed to investigate the effects of different oxygen concentrations and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and their possible mechanisms through simulating oxygen environment to which the peripheral blood HSC are subjected in peripheral blood HSCT. The proliferation ability, cell cycle, directed differentiation ability, ROS level and hematopoietic reconstitution ability of Lin(-)c-kit(+)Sca-1(+) BMHSC were detected by using in vitro amplification test, directional differentiation test, cell cycle analysis, ROS assay and transplantation of Lin(-)c-kit(+)Sca-1(+) HSC from sublethally irradiated mice respectively. The results showed that oxygen concentrations lower than normal oxygen concentration, especially in hypoxic oxygen environment, could reduce ROS generation and amplify more primitive CD34(+)AC133(+) HSC and active CD34(+) HSC, and maintain more stem cells in the G(0)/G(1) phase, which is more helpful to the growth of CFU-S and viability of mice. At the same time, BMHSC exposed to normal oxygen level or inconstant and greatly changed oxygen concentrations could produce a high level of ROS, and the above-mentioned features and functional indicators are relatively low. It is concluded that ROS levels of HSC in BMHSCT are closely related with the oxygen concentration surrounding the cells and its stability. Low oxygen concentration and antioxidant intervention are helpful to transplantation of BMHSC.

Effect of various oxygen concentrations on biological function of human bone marrow hematopoietic stem/progenitor cells / 中国实验血液学杂志

Hypoxia in bone marrow is suitable for the perfect preservation of biological functions of bone marrow hematopoietic stem cells (BM HSC). It is deserved to study whether the biological functions of BM HSC are influenced when being exposed to environment of oxygen at various concentration during amplification of BM HSCs in normal oxygen condition in vitro and process of peripheral blood hematopoietic stem cell transplantation (PBSCT). This study was purposed to investigate the effects of various oxygen concentrations on biological functions of human BM HSCs. The BM HSCs were amplified in vitro, the amplification level of CD34(+) HSCs and CD34(+)AC133(+) HSCs were detected by flow cytometry, the apoptosis and cell cycle distribution of CD34(+) HSCs amplified in various oxygen concentrations were assayed by flow cytometry with Annexin V/PI double staining as well as PI and Ki-67 antibody, respectively, the differentiation of amplified CD34(+) HSCs in vitro was determined by direction differentiation assay, the migration ability of amplified CD34(+)AC133(+) HSCs was measured by migration test. The results indicated that the oxygen environment below normal oxygen, especially hypoxia, could amplify more primitive CD34(+)AC133(+) HSCs and CD34(+) HSCs with activity, arrest more HSCs in G₀/G₁ phase, promote the generation of BFU-E, CFU-GM, CFU-GEMM, and better preserve the migration ability of HSCs. While the above functional indicators of BM HSCs were poor when HSCs exposed to normoxia, oxygen-unstable and oxygen-severe changeable environments. It is concluded that the biological functions of BM HSCs in PBSCT are related with oxygen concentration and its stability, the culture of BM HSCs in lower oxygen environment may be more beneficial for PBSCT.