Canine bone marrow cytology as a means of supporting peripheral blood changes

The origin of induced changes in the peripheral blood frequently resides in the bone marrow. Although interim (within study) canine bone marrow analysis provides crucial and vital information supplementary to such changes, it is not a routine technique in normal toxicity studies. A two-tiered approach is reasonable and scientifically justified, with haemocytometry as the first tier, and interim bone marrow analysis as the second, only to be performed if indicated by peripheral blood values.Additionally, ethical and economic reasons play a decisive role in not performing interim canine marrow sampling on a routine basis, but only on selected occasions. Such an occasion would be the presence of a thrombocytopenia, where an objective assessment of megakaryoblast/megakaryocyte numbers and morphology would be a distinct advantage in determining the aetiology of the condition. However, such evaluations are normally hampered by the relatively small numbers of these cells, and a method for overcoming this problem is described.     

Thrombopoietin from human embryonic kidney cells causes increased thrombocytopoiesis and decreased erythropoiesis in mice

Recent studies have shown that large doses of erythropoietin (EPO) administered daily over a 7-day period elevate erythropoiesis and lead to marked thrombocytopenia. Conversely, anaemia was found in mice following stimulation of thrombocytopoiesis by an acute thrombocytopenic episode. Although erythropoiesis and thrombocytopoiesis have been studied in mice after treatment with either hypoxia or EPO injection, only the effects of endogenous thrombopoietin (released after an acute episode of thrombocytopenia caused by an injection of antiplatelet serum) on erythropoiesis have been investigated. Therefore, we injected mice with a potent source of thrombopoietin and evaluated both thrombocytopoiesis and erythropoiesis at 3 and 5 days after treatment. The data show that thrombopoietin elevated thrombocytopoiesis with a concomitant reduction in erythropoiesis. We found significantly elevated percentage ³⁵S incorporation into platelets, platelet sizes, and total circulating platelet masses following thrombopoietin injections at both 3 and 5 days; haematocrits, reticulocyte counts, and total circulating red blood cell masses were reduced significantly in these same mice. Compared to controls treated with human serum albumin, megakaryocyte size was increased on day 3, and megakaryocyte numbers were elevated on day 5 in mice treated with thrombopoietin. Thrombopoietin did not change the blood volume of mice, but did cause an increase in splenic weight. However, splenic sequestration of red blood cells was not the cause of anaemia in mice treated with thrombopoietin, since splenectomised mice also showed increased thrombocytopoiesis with decreased erythropoiesis. These data agree with previous studies showing an inverse relation between erythropoiesis and thrombocytopoiesis, and are consistent with the hypothesis that the erythrocytic and megakaryocytic cell lines are in competition.     

褪黑素对照射后小鼠血小板造血的保护作用

目的探讨褪黑素(melatonin,Mel)对照射后小鼠血小板和巨核细胞造血功能的影响。方法18只雌性BALB/c小白鼠随机分为3组正常组(N组),对照组(C组)和Mel组(M组),每组6只。其中N组不接受照射和药物注射,C组和M组小鼠予4Gy的60Coγ射线全身照射,照射后M组每天腹腔注射Mel10mg.kg-1.d-1,连续注射21d,C组注射生理盐水。于照射前及照射后的第7、14和21天采尾血,观察白细胞和血小板计数变化,在第21天采血后取骨髓行巨核细胞集落形成单位(CFU-MK)和骨髓基质细胞集落形成单位(CFU-F)培养。另外观察正常小鼠体外骨髓CFU-MK在不同浓度的Mel(0～500nmol/L)作用下的生长情况。结果M组血小板计数回升明显高于C组(P<0.05),M组的CFU-MK和CFU-F集落生长明显优于C组(P<0.001)。体外小鼠骨髓CFU-MK的生长对Mel有浓度依赖性,Mel浓度为200nmol/L时,CFU-MK集落数目最多,且集落大小和MK成熟度较对照均有明显提高。结论Mel对照射后小鼠骨髓的血小板造血功能有保护作用,Mel可促进骨髓基质细胞和MK增殖分化,从而提升外周血血小板数量。     

重组融合蛋白rTMP-GH促进放射损伤小鼠 血小板生成的实验研究

目的 研究TPO模拟肽(TMP)与人生长激素(GH)的重组融合蛋白rTMP-GH对放射损伤小鼠血小板生成的促进作用。方法 ⁶⁰Coγ射线全身一次性均匀照射5 Gy,照后皮下注射200 μg／kg 的rTMP-GH或rhGH,每日1次,连续用药7 d,对照组给予同等体积生理盐水。尾静脉取血检测血小板数量变化;照后16 d取小鼠股骨,组织切片观察骨髓病理变化。结果 照后10 d起,rTMP-GH处理组各时相的外周血血小板数明显高于rhGH处理组和生理盐水对照组,尤其是血小板的最低值显著升高( P <0.01),照后22 d已升至正常水平的80%,对照组仅为30%。骨髓病理观察显示,rTMP-GH处理组骨髓造血重建明显,并见大量不同时期巨核细胞;rTMP-GH处理组骨髓组织切片每个视野下的巨核细胞平均数(3.07±0.32)明显高于rhGH处理组(2.20±0.22, P <0.05)和生理盐水对照组(0.87±0.19, P <0.01)。结论 rTMP-GH能快速、有效地促进放射损伤小鼠骨髓巨核细胞增生和血小板生成。     

Does thrombopoiesis in multiple myeloma patients depend on the stage of the disease?

PurposeInfiltration of the bone marrow by neoplastic plasmocytes in multiple myeloma (MM) patients might impair megakaryocytopoiesis. The aim of the study was to evaluate stage-dependent platelet count (PLT) and thrombopoietin (TPO) concentration in comparison to the control group. We also wanted to establish whether TPO might be recognized as a marker of the stage of the disease.Material/methodsThe study group consisted of 41 patients (mean age 67.7) with newly diagnosed MM prior to treatment and categorized according to the Durie and Salmon diagnostic classification. The control group consisted of 30 healthy subjects (mean age 65.5). PLT, WBC, RBC and Hb were measured with the use of the haematological analyser. TPO was assayed with the use of ELISA and albumin with the use of the immunonephelometry method. The number of plasma cells in the bone marrow was evaluated in bone marrow smears under light microscopy.ResultsPLT was not statistically different as compared the control groups, but was stage-dependent. Thrombocytopenia was observed in the III stage of MM. TPO median was significantly higher in study group than in healthy subjects and it was increasing considerably with the stage of the disease. TPO concentration was negatively correlated with albumin and PLT. AUC for TPO was 0.9764. The number of plasma cells in the bone marrow was considerably increasing with the stage of the disease.ConclusionsPLT and TPO in MM patients were stage-dependent. Elevated TPO concentration in MM patients might be an unfavourable marker of the stage of the disease.