Biological characterization of mouse erythroblastic leukemia cells in haploiden tical mice / 中国实验血液学杂志

Using transplantable erythroblastic leukemia cells of EL9611(H-2d), the cells were inoculated to CB6F(1)(H-2d/b) generation of BALB/c x C57BL/6 mouse, the biological characterization of erythroblastic leukemia in haploidentical mouse was studied, that provides an experimental model for the study of graft-versus leukemia (GVL) with bone marrow or stem cell transplantation. When 10(3) - 10(8) of the spleen cells of EL9611(H-2d) had been intravenously inoculated to CB6F(1) mouse, the erythroblastic leukemia cells were transplanted successively and the F(1) generation of erythroblastic leukemia model in mice was established with 100% incidence of erythroblastic leukemia. There was a linear relationship between the survival time and the number of leukemic cell. The survival time of the mice was (9.6 +/- 0.8) days when 10(6) cells were inoculated. If the CB6F(1) mouse was transplanted successively for four generations, the incidence was 100%. The main targets for the leukemic EL9611(H-2d) cells were liver, spleen and marrow. The reaction of the erythroblastic leukemia cells for hemoglobin staining was positive, while the peroxidase reaction was negative. These cells were sensitive to some chemotherapeutic drugs, such as cytosine arabinoside and cyclophosphamide. This study presents the convenience for the studies on the GVL with haplo-allogeneic transplantation, in the F(1) generation of erythroblastic leukemia model of the commonly-used CD57BL/6 x BALB/c mouse.

Study of Low Dose Irradiation Enhancing the Effect of Chemotherapeutic Agents against Leukemia and Its Mechanism / 中国实验血液学杂志

For effectively enhancing the anti-leukemia effect of chemotherapeutic agents, and meanwhile decreasing the side effect of these agents, the study has been made to explore the synergistic effect of low dose irradiation (LDI) combined with Ara-C on murine leukemia and its mechanism. Firstly, an optimal scheme of low dose total body irradiation combined with Ara-C was established in L615 leukemia (T lymphocytic leukemia) mouse model. The machanism of the enhancing effect was explored by patho-morphological observation, examination of residual leukemia cells, the expression of GM-CSF on the surface of marrow stromal cells and in the bone marrow cultural supernatants. The results showed that the optimal scheme was 300 cGy irradiation at 4 days after inoculation of leukemic cells followed by Ara-C 30 mg/kg x 3 days in an interval of 1, 2 or 3 days after irradiation. The mean survival time of the L615 leukemia mice in LDI + Ara-C combined treatment groups was longer than that of control groups. The percentage of long-term survival mice (> 30 days) was the highest (58% - 72%), too. 17% of the mice were be cured. The numbers of blood leukocytes and marrow nucleated cells were transiently decreased in combined treatment group, and then recovered rapidly. Slight myelosuppression and marrow sinus dilation and congestion were seen after 300 cGy irradiation. The expression of GM-CSF either on the stromal cells or in marrow cultural supernatant after irradiation increased strikingly (P < 0.05). Therefore, LDI combined with Ara-C possesses synergistic effect. The mechanism is possibly related to three facts: LDI could increase the permeability of bone marrow sinus; LDI could promote marrow stromal cells to produce some cytokines (such as GM-CSF, etc.) which drive leukemia cells into cell cycle to make the cells more sensitive to chemotherapeutic agents; and LDI could augment Ara-C-induced cytotoxicity through the mechanism of apoptosis.

Activation of auto-mesenchymal stem cells of skeletal muscle by bone morphogenetic protein for rescuing bone marrow failure / 中国医学科学院学报

<p><b>OBJECTIVE</b>To explore the effect of bone morphogenetic protein (BMP) to activate mesenchymal stem cells of skeletal muscle for rescuing bone marrow failure.</p><p><b>METHODS</b>The study was performed on lethal rat acute aplastic anemia model induced by combined 5-fluorouracil (5-FU) and busulfan. The rh-BMP-2 was implanted into the thigh muscle of the rats at 3 days before aplastic anemia was induced. In the control group the rats were implanted with agar into the thigh muscle. The blood picture, pathologic changes and the mortality in two groups were observed. At the same time, rh-BMP-2 were implanted into the thigh muscle of normal Kun-min mice for dynamic control observation of the implantation local morphological changes, colony forming units-spleen (CFU-S) and stem cell growth factor (SCF) expression of the stroma cells of ectopic ossicles induced by BMP.</p><p><b>RESULTS</b>At 7 days after BMP implantation in the mice the mesenchymal cells around BMP in muscle proliferated, and appeared in bone marrow to form an ectopic ossicles. The SCF expression of stroma cells in ectopic ossicles were higher than that of self-bone marrow. 56.3% of BMP-treated aplastic rats were survived over 3 months and its hematopoiesis was completely reconstituted and the histo-morphological picture of the spleen and bone marrow were recovered to normal. But in the control group only one of 23 rats was survived, the remainder died of hematopoietic failure.</p><p><b>CONCLUSIONS</b>BMP-implantation into the skeletal muscle could rescue the bone marrow hematopoietic failure. The mechanism might be related to the BMP activated auto-mesenchymal cells of skeletal muscles to direct hematopoietic cell differentiation. In our hands it might create a new pathway for utilization of auto-muscle derived mesenchymal cells to reconstitute hematopoiesis.</p>