Cryopreservation of Pluripotent and Committed Hemopoietic Progenitor Cells from Human Bone Marrow and Cord Blood

As one of the studies on autologous bone marrow transplantation for childhood cancer, the viabilities of several kinds of hemopoietic progenitor cells after cryopreservation was assayed using bone marrow and cord blood samples. The mean recovery rates of granulocyte-macrophage colony forming units (CFU-GM), erythroid burst forming units (BFU-E) and erythroid colony forming units (CFU-E) from bone marrow cells were 47.9%, 31.3% and 10.5%, respectively. The mean recovery rates of CFU-GM, BFU-E and CFU-E from cord blood cells were 46.7%, 39.1% and 22.4%, respectively. The ratio of primitive to mature BFU-E did not change after cryopreservation. The mean recovery rate of mixed colony forming units (CFU-mix) from marrow cells was 30.2%, and that from cord blood cells was 58.9%, demonstrating their sufficient proliferative activity after cryopreservation. These results demonstrate that CFU-mix, primitive BFU-E as well as CFU-GM, mature BFU-E can be well cryopreserved, supporting the usefulness of autologous marrow transplantation for the rescue of the ruined hemopoiesis after intensive cancer therapy.     

Modulation of neonatal myelopoiesis in newborn rats after 7 days' administration of either granulocyte-monocyte colony stimulating factor or interleukin-3

Single-pulse administration of either recombinant human granulocyte-monocyte colony stimulating factor or recombinant human granulocyte colony stimulating factor to newborn rats has previously been demonstrated to increase the peripheral neutrophil count and modulate bone marrow (BM) neutrophil pools. In our present study, we investigated the effects of 7 d of either recombinant murine granulocyte-monocyte colony stimulating factor (rmGM-CSF) (75 micrograms/kg/d) or recombinant murine IL-3 (rm IL-3) (10 micrograms/kg/d) on newborn rat myelopoiesis. Sprague Dawley newborn rats (greater than or equal to 24 h) were injected (intraperitoneally) daily for 7 d with either rmGM-CSF, rmIL-3, or PBS/BSA. rmGM-CSF induced a significant increase in the peripheral neutrophil count on d 3 (p less than 0.03) and d 7 (p less than 0.001) (75% increase). Additionally, rmGM-CSF induced a 50% increase in the BM neutrophil storage pool (p less than 0.025). rmIL-3 increased the BM colony forming unit-granulocyte monocyte pool (p less than 0.001); however, it failed to increase the peripheral neutrophil count or BM neutrophil storage pool. Neither CSF increased the BM neutrophil proliferative pool or BM colony forming unit-granulocyte monocyte proliferative rate. Additionally, 7 d of rmGM-CSF with or without antibiotics did not synergistically alter the mortality rate after group B streptococcol inoculation. This study suggests that rmIL-3 appears to stimulate more neonatal myeloid committed progenitor cell activity compared with rmGM-CSF. Optimal modulation of neonatal myelopoiesis may require the use of a sequential combination of hematopoietic CSF, namely an early-acting CSF followed by a more lineage myeloid-specific CSF.     

人类巨细胞病毒感染对脐血造血祖细胞增殖的影响(英文)

目的：探讨人类巨细胞病毒(HCMV)感染对脐血造血祖细胞(CFU-GM、CFU-E、BFU-E、CFU-Mix及CFU-Mk)体外增殖的抑制作用及其机制。方法：20例脐血标本收集于正常足月顺产新生儿。实验共分5组:(1)3个HCMV感染组,每个感染组分别加入0.1 mL的103、104及105空斑形成单位(PFU)HCMV-AD169病毒液于培养体系中;(2)灭活对照组,加入同体积灭活HCMV病毒液;(3)空白对照组,不加HCMV病毒液,代之以同体积的IMDM。采用造血祖细胞体外半固体培养技术,培养、观察、计数HCMV-AD169株对脐血CFU-GM、CFU-E、BFU-E、CFU-Mix及CFU-Mk集落数、抑制率和集落维持时间;并用聚合酶链反应(PCR)技术检测集落细胞内HCMV-DNA。结果：(1)在造血祖细胞培养体系中加入不同滴度的HCMV-AD169后,104和105PFU滴度感染对CFU-GM、CFU-E、BFU-E、CFU-Mix及CFU-Mk集落形成均有显著的抑制作用,103PFU滴度感染对CFU-Mix及CFU-Mk集落形成有显著的抑制作用,与空白对照组和灭活对照组比较,差异有显著性(P<0.05)。病毒滴度越高,抑制程度越明显(P<0.05)。(2)104和105PFU滴度感染组CFU-GM、CFU-E、BFU-E、CFU-Mix及CFU-Mk集落维持时间较对照组明显缩短(P<0.01),103PFU滴度感染组CFU-Mix和CFU-Mk集落维持时间较对照组明显缩短(P<0.01)。(3)PCR显示3个感染组的CFU-GM、CFU-E、CFU-Mix及CFU-Mk集落细胞内均有HCMV-AD169DNA存在。结论：HCMV-AD169能直接感染CFU-GM、CFU-E、BFU-E、CFU-Mix及CFU-Mk造血祖细胞,并抑制造血祖细胞的增殖,这可能与HCMV感染患儿出现粒细胞减少、血小板减少和贫血等造血功能紊乱有关。     

人巨细胞病毒感染对脐血巨核系祖细胞体外增殖的影响

目的　探讨人巨细胞病毒 (HCMV)对脐血巨核系祖细胞 (CFU Mk)体外增殖的影响及其机制。方法　采用造血祖细胞体外培养技术 ,观察、计数HCMV AD169感染的CFU Mk集落产率、抑制率、集落峰值及维持时间 ;并采用聚合酶链反应 (PCR)技术检测集落细胞内HCMV AD169DNA。结果　 1.HCMV AD169感染组集落产率较对照组明显减少 ,HCMV对CFU Mk集落的抑制程度与病毒滴度有关 ,集落产率随病毒感染滴度增高而减少 ,抑制率随病毒感染滴度增高而渐增加 ;各组集落峰值出现时间无明显差异 (P均 >0 .0 5 ) ,但各感染组集落维持时间明显短于对照组 (P <0 .0 1) ;2 .用PCR在集落细胞内检测到HCMV AD169DNA。结论　CFU Mk是HCMV的宿主细胞之一 ,HCMV能直接感染CFU Mk ;在体外HCMV AD169对CFU Mk的增殖和集落形成有明显抑制作用 ,此作用可能与临床HCMV感染后患者血小板减少有关     

Agranulocytosis following infectious mononucleosis

A girl developed acute agranulocytosis (45/mm³), 37 days after the onset of infectious mononucleosis. The bone marrow showed myeloid hyperplasia with maturation arrest and erythroid hypoplasia. A normal amount of colony forming units of granulocytes and macrophages (CFU-GM) colonies with a relative high number of clusters was observed. Neither anti-neutrophil antibodies nor circulating inhibitors of colony growth were found in serum. Granulocyte and macrophage colony stimulating factor (GM-CSF) activity in the patient's serum rose at this time. The agranulocytosis lasted 5 days and her clinical state soon improved. These results suggested that agranulocytosis was presumably not due to serum factors, including auto-antibodies and/or suppressive substances, and that Epstein-Barr virus (EBV) had some direct or indirect effect on the marrow cells of the myeloid series.     

Defective in-vitro colony formation of haematopoietic progenitors in patients with cartilage-hair hypoplasia and history of anaemia

Cartilage-hair hypoplasia (CHH) is a metaphyseal chondrodysplasia with short-limbed short stature. The CHH gene has been recently mapped to chromosome 9, and a generalized defect in cellular proliferation has been suggested. Immunological and haematological abnormalities are common findings in CHH. In the present study erythroid, megakaryocyte, and granulocyte-macrophage colony formation in vitro by progenitors from bone marrow and blood was investigated in eight patients with CHH. All patients showed decreased erythroid and megakaryocyte colony formation. Only one patient had a normal granulocyte-macrophage growth, while the others showed decreased numbers of colonies. The defect in colony formation did not correlate with the haemoglobin concentration, platelet count or neutrophil count. The impaired growth was not caused by a decreased number of progenitors as shown by erythroid cultures. The erythroid progenitors were incapable of colony formation in culture conditions sufficient for colony formation by normal progenitors. In a more effectively stimulated culture assay the number of erythroid progenitors was normal or increased.Conclusion The present study shows defective in vitro colony formation in all myeloid lineages in patients with CHH, which is in accordance with the suggestion of a common cell proliferation defect in CHH.     

MEGADOSE METHYLPREDNISOLONE FOR KASABACH-MERRITT SYNDROME

We report two girls with primary erythrocytosis in whom extensive diagnostic studies revealed no underlying cause. Normal growth of colonies derived from erythroid burst forming units (BFU-E) was observed, and serum erythropoietin concentrations were within or below the normal range. The absence of a rise in serum erythropoietin levels after isovolemic phlebotomy implicated the erythroid marrow as the site of the pathophysiologic abnormality in both patients. Spontaneous resolution of erythrocytosis occurred during the second decade of life. Our experience suggests that primary erythrocytosis may be self-limited in some children. In these cases, the proliferative abnormality may be sufficiently subtle as to not be detected by standard in vitro culture systems, which support the growth of colonies derived from erythroid progenitors.     

Effects of cytokines on hematopoietic progenitor cells in cord blood,in bone marrow,and in peripheral blood mobilized by chemotherapy and G-CSF

We compared the effects of various combinations of cytokines (stem cell factor [SCF], interleukin [IL] ?3, IL-6, granulocyte-colony stimulating factor [G-CSF], erythropoietin [EPO]) among the growth of human hematopoietic progenitor cells from cord blood (CB), bone marrow (BM), and peripheral blood mononuclear cells (MNC) mobilized by chemotherapy and G-CSF (PB) in a semi-solid medium. Macroscopic colonies, that were visible to the naked eye, were formed from PB-MNC within 1 week even without cytokines. They consisted of blasts containing macrophage-like cells with immature nuclei on Wright stain, and were strongly accelerated by IL-3. Macroscopic colonies were also formed from CB-MNC. However, they appeared after 1–3 weeks and synergistic effects of SCF with other cytokines, especially EPO, were prominent. Macroscopic colonies were not formed from BM-MNC. Granulocyte-colony stimulating factor was effective in increasing colony forming units of granulocyte macrophage from BM-MNC and they appeared between 1 and 2 weeks. These results suggested that the quality of hematopoietic progenitor cells was different among blood sources. This might lead to different bone marrow recovery patterns after transplantation of each blood source. The appropriate cytokines should be added to evaluate their exact potential.     

Erythropoiesis is distinct at each stage of ontogeny.

In vitro erythropoiesis from fetuses, newborn infants, and adults was compared in methyl cellulose cultures. Fetal and newborn blood erythroid colony formation tended to be more sensitive to erythropoietin than adult. The day of maximal colony formation was earlier in fetal than in newborn or adult cultures. The number of colonies/100,000 mononuclear cells on d 13 of culture and on the day of peak growth was highest in fetal, intermediate in newborn, and lowest in adult cultures. Burst forming units-erythroid/mL of blood on culture d 13 and the day of peak growth were similar in fetuses and newborns, and both were significantly greater than in adults. The proportional synthesis of gamma-globin in fetal colonies was 2-fold greater than in newborn colonies, and 6-fold greater than in adult colonies. Thus, fetal, newborn, and adult erythroid progenitor cultures are each unique with regard to erythropoietin sensitivity, growth time course, number of erythroid colonies, and the proportion of gamma-globin synthesis.     

Long-lasting partial remission by Interferon-alpha treatment in a child with essential thrombocythemia

Essential thrombocythemia (ET) is a clonal myeloproliferative disorder characterized by sustained thrombocytosis, isolated hyperplasia of megakaryocytic lineage, and association with thrombotic or bleeding episodes. It is extremely rare in childhood and frequently presents without evident clinical signs. We describe a 3-year-old girl with severe headache and dizziness suffering from ET, who was treated with Interferon-alpha-2a (IFN) based on the potent effect of this agent to inhibit myeloid colonies induced by phytohemagglutinin A stimulated leukocyte conditioned medium (PHA-LCM). Bone-marrow-derived mononuclear cells of this patient did not exhibit spontaneous colony formation but responded to recombinant human (rh) erythropoietin (EPO), rh granulocyte-colony stimulating factor (G-CSF), granulocyte-macrophage (GM)-CSF, and stem-cell factor in addition to PHA-LCM. After 65 months of in vivo IFN treatment, the patient experienced a sustained partial remission with platelet counts varying between 400 and 600 x 10(3)/microl.     

In vitro megakaryocytopoiesis in children with acute idiopathic thrombocytopenic purpura

Idiopathic thrombocytopenic purpura (ITP) of childhood is a disorder characterized by a history of previous viral illness followed by acute onset of low circulating platelet count with present or increased megakaryocytes in the bone marrow. The majority of children recover a normal platelet count within 6 months to 1 year after onset of the disease. To better understand the regulation of megakaryocytopoiesis in this disorder, we studied nine patients with childhood ITP with the plasma clot colony assay in vitro for megakaryocyte colony forming units (CFU-Mk). Mononuclear bone marrow cells from some of the patients with ITP contained greater numbers of CFU-Mk and greater numbers of cells per colony than mononuclear bone marrow cells from healthy adult volunteers (p less than 0.026) when the cultures contained no added megakaryocyte colony-stimulating activity (Mk-CSA). The serum from patients with ITP did not stimulate in vitro megakaryocytopoiesis from healthy adult volunteers' bone marrow mononuclear cells above baseline values. These findings are consistent with the hypothesis that a decrease in bone marrow megakaryocytes is needed for Mk-CSA production. Alternatively, Mk-CSA is consumed by active megakaryocytopoiesis in the bone marrow.     

Spontaneous Resolution of Primary Erythrocytosis in Two Girls

We report two girls with primary erythrocytosis in whom extensive diagnostic studies revealed no underlying cause. Normal growth of colonies derived from erythroid burst forming units (BFU-E) was observed, and serum erythropoietin concentrations were within or below the normal range. The absence of a rise in serum erythropoietin levels after isovolemic phlebotomy implicated the erythroid marrow as the site of the pathophysiologic abnormality in both patients. Spontaneous resolution of erythrocytosis occurred during the second decade of life. Our experience suggests that primary erythrocytosis may be self-limited in some children. In these cases, the proliferative abnormality may be sufficiently subtle as to not be detected by standard in vitro culture systems, which support the growth of colonies derived from erythroid progenitors.     

Thrombocytopenia with absent radii: frequency of marrow megakaryocyte progenitors, proliferative characteristics, and megakaryocyte growth and development factor responsiveness

Congenital thrombocytopenia with absent radii (TAR syndrome) is characterized by defective thrombopoiesis and bleeding in early infancy. To determine the frequency and responsiveness to cytokines of megakaryocyte progenitors (CFU-Meg) in TAR syndrome, the authors studied marrow samples from 3 patients and 6 normal controls, using optimally standardized megakaryocyte growth media incorporating interleukin-3, interleukin-6, stem cell factor, and granulocyte-monocyte colony-stimulating factor, with and without pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF). CFU-Meg was identified with a specific staining system utilizing monoclonal antibodies to glycoprotein IIb/IIIa. Growth of small CFU-Meg colonies (3-20 cells/colony) was observed in all patients in cultures without PEG-rHuMGDF, with a mean frequency of 8 (range 5-12) per 2.25x10⁵ mononuclear cells plated (control mean 23; range 2-70). Identical cultures of marrow cells from patients and controls with added PEG-rHuMGDF produced more colonies per dish (mean 17, range 8-23; control mean 30, range 6-62). Except for 1 case, however, patients' colonies in response to PEG-rHuMGDF remained smaller than those of controls. Two patients tested had higher plasma thrombopoietin levels than 6 normal subjects. The findings demonstrate proliferative and PEG-rHuMGDF-responsive megakaryocytic progenitors in TAR syndrome. The modest reduction in frequency of megakaryocyte progenitors and the suboptimal size of colonies in response to PEG-rHuMGDF are compatible with the reported defective signal transduction in the c-mpl pathway in TAR syndrome.     

Fatal Aplastic Anemia in a Child with Down's Syndrome

ABSTRACT. An infant with Down's syndrome developed severe persistent neutropenia at the age of 9 months and fluctuating anemia and thrombocytopenia at one year of age which terminated as full-blown aplastic anemia at 26 months of age. Immunological evaluation revealed increased peripheral and bone marrow lymphocytes and impaired blood OKT4: OKT8 ratio. Bone marrow granulocyte-macrophage colony forming cells (GM-CFC) were markedly increased, while peripheral blood mononuclear cells (PBMN) produced normal numbers of colonies. The patient's PBMN and serum were both somewhat inhibitory to normal bone marrow derived GM-CFC, suggesting the existence of a suppressor activity both in his serum and PBMN. This unusual course of aplastic anemia and the abnormalities in T-cells and hematopoiesis in Down's syndrome are discussed.     

三种重组人细胞因子对急性粒细胞白血病和非白血病骨髓细胞增殖的影响

应用重组人粒单细胞集落刺激因子（ｒｈＧＭＣＳＦ）、白细胞介素３（ｒｈＩＬ－３）和白细胞介素６（ｒｈＩＬ－６）作为刺激因子，通过集落形成和细胞周期动力学变化，观察急性粒细胞白血病和非白血病骨髓细胞增殖影响，以及它们之间的关系。结果表明：ｒｈＩＬ－３促成ＣＦＵ－ＧＭ形成率高于ｒｈＧＭ－ＣＳＦ和ｒｈＩＬ－６的作用，ＩＬ－３＋ＩＬ－６配伍时ＣＦＵ－ＧＭ产率大于任何一种因子单独应用组和其它两因子配伍组；ｒｈＩＬ－６与ｒｈＧＭＣＳＦ或ｒｈＩＬ－６与ｒｈＩＬ－３配伍在非白血病骨髓和白血病骨髓动力学方面影响不一致。在集落形成和动力学之间存在一定关系。     

In vitro effect of dexamethasone phosphate on hematopoietic progenitor cells in preterm infants

The in vitro effect of dexamethasone on the clonal growth of haematopoietic progenitors in preterm infants was investigated. Concentrations of 10⁶M to 10⁹M were associated with a dose dependent inhibition of colony formation, with the most clinically important effects seen on the earliest erythroid and granulocyte-macrophage colonies. Because of the potential clinical implications of these observations, studies are needed to determine the effects of dexamethasone on haematopoiesis in preterm infants.

     

Megakaryocyte growth and development factor is a potent growth factor for primitive hematopoietic progenitors in the human fetus

Megakaryocyte growth and development factor (MGDF), or thrombopoietin, has received considerable attention as a therapeutic agent for treating thrombocytopenia or for its use in the ex vivo culture of hematopoietic stem cells. MGDF is known to support the growth of a broad spectrum of hematopoietic precursors obtained from adult or neonatal tissues, but its effects on the growth of fetal progenitors and stem cells has not been studied. Human CD38(+)CD34(2+) progenitors and CD38(-)CD34(2+) cells, a population that contains stem cells, were isolated from midgestation liver and grown under defined conditions with MGDF and various cytokines known to support the growth of primitive hematopoietic precursors. In clonal assays of colony-forming cells (CFCs), MGDF supported the growth of 15-25% of candidate stem cells when combined with granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor (GM-CSF), flk-2/flt3 ligand, or stem cell factor. MGDF was observed to strongly support the early stages of hematopoiesis and expansion of high proliferative potential CFCs. More mature progenitors were expanded nearly 78-fold in 1 wk of culture with MGDF+SCF+GM-CSF. MGDF alone was also found to support the short-term (2 d) survival of CD38(-)CD34(2+) high proliferative potential CFCs. The effects of MGDF were more modest on CD38(+)CD34(2+) progenitors with only additive increases in colony formation being observed. These findings suggest that MGDF administration in fetuses and neonates may strongly affect the growth and mobilization of primitive hematopoietic progenitors and that MGDF may find use in the ex vivo growth and expansion of fetal stem cells.     

更昔洛韦和黄芪对巨细胞病毒感染所致造血祖细胞增殖抑制的影响

目的　探讨更昔洛韦 (GCV)和黄芪对巨细胞病毒 (CMV)感染所致脐血粒 巨噬系祖细胞 (CFU GM)、红系早、晚期祖细胞 (CFU E、BFU E)、多向造血祖细胞 (CFU Mix)及巨核系祖细胞(CFU Mk)体外增殖抑制的影响。方法　采用造血祖细胞培养技术 ,培养、观察、计数巨细胞病毒AD169株 (CMV AD169)感染CFU GM、CFU E、BFU E、CFU Mix和CFU Mk后各祖细胞集落、峰期及维持时间 ;用聚合酶链反应 (PCR)检测集落细胞内CMV DNA ;根据细胞毒性实验结果 ,将GCV和黄芪作用于CMV感染的CFU GM、CFU E、BFU E、CFU Mix及CFU Mk祖细胞 ,再分别计数集落、峰期及维持时间。结果 ( 1)CMV感染组CFU GM、CFU E、BFU E、CFU Mix及CFU Mk集落数较对照组明显减少 (P <0 0 1) ;集落维持时间CMV感染组较对照组明显缩短 ;( 2 )用PCR在感染组集落细胞内检测到CMV DNA的存在 ;( 3)黄芪和 (或 )GCV作用于CMV感染的祖细胞后 ,与病毒组比较集落维持时间明显延长 ,集落数和集落增殖率明显提高 (P <0 0 1) ,黄芪组集落增殖率分别为 2 7 2 %、4 5 2 %、4 9 1%、39 0 %、11 9% ;GCV组分别为 37 4 %、74 2 %、71 7%、6 7 4 %、38 9% ;GCV 黄芪组分别为 5 3 6 %、83 8%、88 7%、87 8%、6 1 5 %。结论　CMV AD169在体外能明显抑制CFU GM、CFU E、BFU     

In vitro CFU-E and BFU-E responses to androgen in bone marrow from children with primary hypoproliferative anaemia: a possible therapeutic assay

The effects of natural and synthetic androgens on erythroid colony formation in children's bone marrow cultures were studied using a methylcellulose microculture assay. In an attempt to predict the clinical response to androgens in two children with Fanconi anaemia (FA) and two children with Diamond-Blackfan syndrome (DB), we tested the hormonal stimulation of testosterone, nortestosterone and etiocholanolone on CFU-E, BFU-E and uroporphyrinogen I synthase activity (UROS). We observed that colony formation and UROS activity were reduced when compared to values obtained with normal children's bone marrow cultures. The addition of steroids to the cultures significantly enhanced the numbers of CFU-E and BFU-E derived colonies and their UROS activity in marrow from patients with FA and one patient with DB. The strong depletion of marrow progenitor cells in the unresponsive marrow from child 4 with DB could explain the absence of hormonal response. Whereas the responsiveness to steroids varied according to the individual, the in vitro testing of erythroid differentiation in the presence of androgens theoretically may lead to an effective prediction of response to therapy in children with hypoplastic anaemia.Abbreviations FA Fanconi anaemia - DB Diamond-Blackfan syndrome - BFU-E burst forming unit-erythroid - CFU-E colony forming unit-erythroid - UROS uroporphyrinogen I synthase - EPO erythropoietin     

脐血巨核细胞体外扩增及其功能的研究

目的研究扩增后脐血巨核细胞的生物学特性和功能,为脐血巨核细胞的扩增和临床应用提供依据。方法收集足月妊娠健康新生儿的脐带血,免疫磁珠法分离出其中的CD34^＋细胞。采用血小板生长因子（thrombopoietin,TPO）＋干细胞因子（stem cell factor,SCF）＋白细胞介素3（interleukin-3,IL-3）＋IL-6和TPO＋SCF两种细胞因子组合,将富集的脐血CD34^＋接种于无血清无基质细胞的悬浮培养体系中,分别在3、7、10、14d收集扩增产物。运用流式细胞术检测巨核细胞的表型;血浆块法检测巨核细胞集落（colony forming unit-megakaryocyte,CFU-MK）的形成;对巨核细胞进行DNA含量检测以评价其成熟程度;血小板体外活化实验及SCID小鼠体内移植实验评价扩增后巨核细胞的功能。结果不同细胞因子组合和培养时间扩增后,巨核细胞的数量和生物学特性不同。随着培养时间的延长,巨核细胞（CD41^＋）的数量逐渐增加,但培养至14d时增势减缓。因子组合TPO＋SCF＋IL-3＋IL-6各时间段的扩增能力（分别扩增5．2、40．7、121．2、149．7倍）均比因子组合TPO＋SCF（分别扩增3．8、27．4、85．9、106．5倍）强,但因子组合TPO＋SCF的扩增能力仍能满足临床的需要。巨核祖细胞（CD34^＋CD41^＋）的数量在第7天时最多（分别增加43．4和36．2倍）,这也被CFU-Mk所证实。DNA含量检测发现,随着培养天数的增加,多倍体细胞所占的百分比增加。体外血小板活化实验证实,扩增的巨核细胞在体外可产生血小板,有正常巨核细胞功能。移植后两组小鼠的骨髓中均检测到人CD45^＋和CD41^＋细胞。小鼠外周血中人血小板在移植后3d就可测到,5d就可达到高水平（分别为20．7％和17．9％）,维持20d以后才逐渐下降。结论通过对扩增后巨核细胞的生物学特性的研究,有助于寻找有效、简便、易于植入受者体内的扩增方法。体外扩增的脐血巨核细胞可植入骨髓并产生功能正常的血小板。