5-Azacytidine-treated human mesenchymal stem/progenitor cells derived from umbilical cord, cord blood and bone marrow do not generate cardiomyocytes in vitro at high frequencies

Background and Objectives   Mesenchymal stem/progenitor cells (MSCs) are multipotent progenitors that differentiate into such lineages as bone, fat, cartilage and stromal cells that support haemopoiesis. Bone marrow MSCs can also contribute to cardiac repair, although the mechanism for this is unclear. Here, we examine the potential of MSCs from different sources to generate cardiomyocytes in vitro , as a means for predicting their therapeutic potential after myocardial infarction.
Materials and Methods   Mesenchymal stem/progenitor cells were isolated from the perivascular tissue and Wharton's jelly of the umbilical cord and from cord blood. Their immunophenotype and differentiation potential to generate osteoblasts, chondrocytes, adipocytes and cardiomyoxcytes in vitro was compared with those of bone marrow MSCs.
Results   Mesenchymal stem/progenitor cells isolated from umbilical cord and cord blood were phenotypically similar to bone marrow MSCs, the exception being in the expression of CD106, which was absent on umbilical cord MSCs, and CD146 that was highly expressed in cord blood MSCs. They have variable abilities to give rise to osteoblasts, chondrocytes and adipocytes, with bone marrow MSCs being the most robust. While a small proportion (~0·07%) of bone marrow MSCs could generate cardiomyocyte-like cells in vitro, those from umbilical cord and cord blood did not express cardiac markers either spontaneously or after treatment with 5-azacytidine.
Conclusion   Although MSCs may be useful for such clinical applications as bone or cartilage repair, the results presented here indicate that such cells do not generate cardiomyocytes frequently enough for cardiac repair. Their efficacy in heart repair is likely to be due to paracrine mechanisms.     

亲缘供者脐血加异基因骨髓混合移植治疗骨髓增生异常综合征

目的探讨亲缘供者脐血加异基因骨髓混合移植治疗骨髓增生异常综合征(MDS)的可行性方案和疗效。方法采用有亲缘关系的胞妹脐血加异基因骨髓混合移植治疗MDS女性患儿1例。预处理方案为环磷酰胺、马利兰、抗淋巴细胞球蛋白,以短疗程CD25单抗、环孢菌素A和霉酚酸酯预防移植物抗宿主病(GVHD)。结果 18d中性粒细胞升至0.5×109/L, 28d白细胞升至4.2×109/L, 42d血小板升至34×109/L。 30、 90d经STR-PCR检测均为完全供者型。无GVHD发生。现患儿移植后健康生存时间达1a4个月。结论有亲缘关系的HLA相合的脐血加异基因骨髓的混合移植治疗MDS是可行的。     

脐血造血干细胞向巨核细胞诱导分化的研究

目的:建立脐血CD34+造血干细胞向巨核细胞诱导分化的体系,探讨最佳的扩增方法。方法:免疫磁珠法分离获得CD34+细胞培养在无血清无基质培养液中,采用TPO加SCF加IL-3加IL-6、TPO加SCF加IL-3、TPO加SCF3种不同因子组合对其诱导分化及扩增。收集3、7、10、14d的扩增产物,运用荧光显微镜检测巨核细胞的表面标志;流式细胞术(FCM)检测巨核细胞的凋亡;并对巨核细胞形成单位(CFU-MK)及DNA含量进行检测。结果:分离获得的CD34+细胞在体外可以有效扩增,随培养时间的延长CD34+/CD41+细胞数第7天达最高值,之后逐渐下降;而CD41+、CD42b+、CD61+细胞随培养时间的延长表达量逐渐增高。加入IL-3和IL-6后,Annexin Ⅴ阳性细胞由(8.26±2.49)%降至(3.51±1.24)%。CFU-MK的数量在第10天时最高,且8倍体及8倍体以上的巨核细胞所占的的百分比增加,即成熟产板型巨核细胞增加。结论:脐血CD34+造血干细胞在体外可向巨核细胞诱导分化及有效扩增。3种因子组合中TPO加SCF加IL-3加IL-6组扩增效率最高。     

Growth of macroscopic human megakaryocyte colonies from cord blood in culture with recombinant human thrombopoietin (c-mpl ligand) and the effects of gestational age on frequency of colonies

We investigated the effects of recombinant human thrombopoietin (rhTPO) on the growth of megakaryocytic (MK) colony derived MK progenitors from human cord blood (CB) in vitro and the effects of gestational age on the number of MK colonies. The results demonstrated that rhTPO alone supports the growth of MK colonies and induces not only proliferation but also differentiation of MK progenitors. CB shows a high frequency of MK colonies; most of which are very large and equivalent to high proliferative potential colony-forming unit-megakaryocyte. The colonies could be macroscopically observed as white spots in the culture dish. Preterm neonates showed greater numbers of MK progenitors than term neonates and there was an inverse correlation between gestational age and concentration of MK progenitors of CB. The effects of gestational age was an important factor on the proliferative capacity of MK progenitors and on the response to rhTPO.     

Flt3L induces the ex-vivo amplification of umbilical cord blood committed progenitors and early stem cells in short-term cultures

Umbilical cord blood (UCB) has been successfully used for haemopoietic stem cell transplantation, although its use has been cautiously limited to paediatric patients because of the reduced volume produced. The clinical results have confirmed that either engraftment or survival significantly correlate with cell dose infused. We have standardized a culture method providing in a short time a significant amplification of both committed progenitors and primitive stem cells for clinical use. Eight-day culture of UCB cells with flt3L/SCF/PIXY 321 induced a 10-fold amplification of CD34+ cells and the expansion of multipotent (CFU-GEMM) and committed (CFU-GM, BFU-E) progenitors respectively of 5-, 7- and 9-fold over input cells. As to the early stem cell pool, the primitive CD34+Thy-1+ cell fraction increased 6-fold and the LTC-IC were amplified 17-fold. Furthermore, the in vitro proliferation was detected by the gradual loss of fluorescence of the CD34+ cells tracked at day 0 with the dye PKH26. After 8 d of amplification >6% of the CD34+ cells remained intensely fluorescent. This subpopulation represents a deeply quiescent cell fraction unresponsive to cytokines and very enriched of primitive stem cells. These cells are most likely to be responsible for long-term reconstitution after transplant.     

Lymphocyte subset reconstitution after unrelated cord blood or bone marrow transplantation in children

We report the post‐transplant lymphocyte subset recovery of 226 children treated with Unrelated Cord Blood transplant (UCBT) (n = 112) or Unrelated Bone Marrow Transplant (UBMT) (n = 114) for malignant or non‐malignant diseases. Absolute numbers of natural killer (NK), B and T cells were monitored by flow cytometry up to 5 years post‐transplant. Immunological endpoints were: time to achieve a CD3⁺ cell count >0·5 and 1·5 × 10⁹/l, CD4⁺ > 0·2 and 0·5 × 10⁹/l, CD8⁺ > 0·25 × 10⁹/l, CD19⁺ > 0·2 × 10⁹/l, NK > 0·1 × 10⁹/l. These endpoints were analysed through the use of cumulative incidence curves in the context of competing risks. CD8⁺ T cell recovery was delayed after UCBT with a median time to reach CD8⁺ T cells > 0·25 × 10⁹/l of 7·7 months whereas it was 2·8 months in UBMT (P < 0·001). B cell recovery was better in UCBT, with a median time to reach CD19⁺ cells > 0·2 × 10⁹/l of 3·2 months in UCBT and 6·4 months in UBMT (P = 0·03). Median time for CD4⁺ T cell and NK cell recovery was similar in UCBT and UBMT. CD4⁺ T cells recovery was negatively correlated to age (better reconstitution in younger patients, P = 0·002). CD8⁺ T cells recovery was shorter in recipients with a positive cytomegalovirus serology (P = 0·001).     

早产胎儿脐血和脐带间充质干细胞分离培养的比较

目的对比早产胎儿脐血和脐带间充质于细胞（MSCs）的培养成功率,探讨早产胎儿MSCs获取的最佳途径。方法无菌条件下采集早产胎儿（不足37周）脐血,密度梯度离心法分离单个核细胞,采用贴壁培养法获得脐血MSCs;将脐带剪成1mm^3大小组织块,采用组织块贴壁法获得脐带MSCs;分别观察脐血和脐带MSCs的生物学特性,免疫荧光法检测MSCs表面标记物的表达情况。结果采用Mesencult^TM培养基,早产胎儿脐血MSCs培养成功率为100％,脐带MSCs培养成功率为67％,明显低于脐血MSCs;早产胎儿脐血和脐带MSCs均表达CD29、CD44和CD90不表达造血干细胞表面标志CD34。结论早产胎儿脐血中较易获得MSCs,为临床移植治疗提供了理想的细胞来源。     

经肝动脉自体骨髓或脐带血干细胞移植治疗失代偿期肝硬化患者的安全性和近期疗效比较

比较经肝动脉途径注入自体骨髓干细胞或脐带血干细胞治疗失代偿期肝硬化患者的安全性,以及对患者肝功能和凝血酶原活动度的近期改善作用。方法选择失代偿期肝硬化患者65例,随机分为骨髓组33例和脐血组32例;骨髓组患者经股动脉插管至肝固有动脉注入自体骨髓干细胞移植治疗,脐血组经同样途径注入脐带血干细胞治疗;治疗后8周检测血清谷丙转氨酶、总胆红素、凝血酶原活动度、白蛋白和甲胎蛋白水平变化,同时观察临床症状的改善情况及术后的不良反应。结果治疗后第3天两组患者乏力、纳差症状均有改善,两组间差异无显著性。治疗后8w,骨髓组和脐血组白蛋白水平分别由（31.0±4.6） g/L 上升至（34.6±7.1）g/L和由（34.6±7.1） g/L上升至（37.8±8.3） g/L,凝血酶原活动度上升由（48.8±13.4）%上升至（55.5±11.2）%和由（47.5±12.5）上升至（58.9±14.0）%,但两组间改善程度的差异无显著性;在治疗8w末血清谷丙转氨酶、总胆红素和甲胎蛋白在骨髓组分别为（45.6±12.3） IU/L、（28.1±13.5）μmol/L和（11.3±4.1）μg/L,在脐血组分别为（47.2±11.8） IU/L、（30.7±14.8）μmol/L和（9.8±3.5）μg/L,两组间与基础水平相比改善程度的差异也无显著性。结论自体骨髓干细胞或脐带血干细胞经肝动脉途径移植治疗失代偿期肝硬化患者的近期疗效及安全性均良好,但两种细胞治疗的改善水平无显著差异。     

Human leucocyte antigen-Cw-specific cytotoxic T lymphocytes generated from naive cord blood used for cord blood stem cell transplantation

Human leucocyte antigen (HLA)-Cw-reactive cytotoxic T lymphocytes (CTL) were generated from cord blood (CB) lymphocytes of two cases used for cord blood stem cell transplantation (CBSCT). In both cases, the CTL were cytotoxic against the patient's leukaemic cells, as well as the patient's Epstein-Barr virus (EBV)-lymphoblastoid cell line (EBV-LCL) and phytohaemagglutinin blasts, and the cytotoxicity was blocked by anti-HLA-class I monoclonal antibodies. In the first case, the CTL recognized Cw 3 (Cw 9 and Cw 10)-positive EBV-LCL, while in the second case, the CTL recognized Cw1 and/or Cw7. These cases suggest that CB T cells may be competent enough for generating CTL to induce a graft-versus-leukaemia effect and/or graft-versus-host disease in patients with CBSCT and that the mismatching of Cw antigens between patient and CB may be related to the outcome of CBSCT.     

T-lymphoid differentiation potential measured in vitro is higher in CD34+CD38-/lo hematopoietic stem cells from umbilical cord blood than from bone marrow and is an intrinsic property of the cells

Background

Human bone marrow and umbilical cord blood are sources of allogeneic hematopoietic stem cells for transplantation, which is a life-saving treatment in a variety of diseases but is burdened by delayed T-cell reconstitution. Observational studies evaluating T-cell reconstitution in post-transplant recipients suggest that cord blood hematopoietic stem cells have a more effective capacity for T-cell reconstitution. This study focuses on the comparison of the capacity of cord blood and bone marrow hematopoietic stem cells to generate T cells in vitro.

Design and Methods

Hematopoietic stem cells were cultured in OP9-delta-like-1 and OP9-green fluorescent protein co-cultures to estimate T and myeloid generation capacity, respectively. Phenotypic markers of T-lineage or myeloid differentiation were measured by flow cytometry and used to analyze their kinetics as a function of culture time. Hematopoietic stem cells were labeled with carboxyfluorescein diacetate succinamidyl ester and analyzed after culture to track their phenotypic progression in consecutive generations. Mixed OP9-delta-like-1 co-cultures were done with either carboxyfluorescein diacetate succinamidyl ester-labeled bone marrow and unlabeled cord blood hematopoietic stem cells, or vice versa, to evaluate their mutual influence on T-lineage differentiation. The T-cell potential of hematopoietic stem cells was addressed quantitatively by limiting dilution analysis.

Results

Bulk cultures showed faster and more extensive T-cell differentiation by cord blood hematopoietic stem cells. Furthermore, the T-lymphoid differentiation capacity of cord blood and bone marrow hematopoietic stem cells can be discriminated very early based on the coordinated expression of CD34 and CD7. Mixing experiments with cord blood hematopoietic stem cells and bone marrow hematopoietic stem cells showed that these differences are cell intrinsic. Quantitative clonal analyses demonstrated that CD34⁺CD38^−/lo hematopoietic stem cells from cord blood contained a two-fold higher T-lineage generation capacity than CD34⁺CD38^−/lo bone marrow hematopoietic stem cells, whereas the myeloid differentiation was similar.

Conclusions

Our data shows that cord blood hematopoietic stem cells have higher T-lymphoid differentiation potential than bone marrow hematopoietic stem cells and that this property is cell autonomous.     

脐血、外周血内皮祖细胞分化成内皮细胞的实验研究

目的探讨人的脐血、外周血内皮祖细胞（endothelialprogenitorcells,EPCs）体外分离、纯化、诱导扩增和分化为内皮细胞的可行性,并检测其表型和功能。方法新鲜脐血和健康成年人的外周血,使用Ficoll密度梯度离心法得单个核细胞,在M199培养基中体外培养,3d后去除悬浮细胞,继续培养,诱导EPCs增殖和分化。流式细胞仪检测EPCs标志CD34和内皮细胞特异性标志CD31表型,RTPCR检测ecNOS,flk1/KDR基因水平表达,免疫组化验证蛋白水平表达,并进一步通过NO活性的变化检测内皮细胞的功能。结果流式细胞仪检测,外周血单个核细胞（peripheralbloodmononuclearcells,PBMC）刚分离时,CD34阳性表达率为（1.1±0.8）%,培养3d后为（16.9±6.2）%。细胞形态观察发现,刚分离的单个核细胞呈圆形,形态小,3d后有明显集落形成,7d后梭形细胞线样排列,随培养时间增加,细胞形态逐渐变大,呈现出典型铺路石样改变。脐血单个核细胞（umbilicalcordbloodmononuclearcells,CBMC）和PBMC培养10d后,CD31阳性表达率分别为（76±17）%和（82±9）%。RTPCR检测有内皮细胞特异性成分ecNOS,flk1/KDR的表达。免疫组化染色,细胞膜和细胞浆中有弥漫性棕色出现,呈阳性反应,证实了蛋白水平的表达。培养10d的贴壁细胞随着VEGF浓度增加,NO生成增加,具有内皮细胞的功能。结论脐血,外周血EPCs体外分离,纯化,诱导培养后的贴壁细胞表型检测,大部分细胞具有内皮系标志物,并具有产生NO功能。     

Effects of thrombopoietin on the proliferation and differentiation of primitive and mature haemopoietic progenitor cells in cord blood

Thrombopoietin (TPO) is considered to be the primary growth factor for regulating megakaryopoiesis and thrombopoiesis. In this study we investigated the in vitro effect of TPO on relatively immature and mature CD34⁺ progenitor cells in cord blood. Cells were cultured in both liquid and semi-solid cultures containing 50 ng/ml TPO. The CD34⁺/CD45RA⁻ and CD34⁺/CD38⁻ subfractions in cord blood were both enriched for megakaryocyte progenitors as determined in a semisolid CFU-meg assay. Progenitor cells derived from the CD34⁺/CD45RA⁻ and CD34⁺/CD38⁻ subfractions showed high proliferative capacity in liquid cultures. We observed a mean 19-fold expansion of the total CD34⁺ cell fraction, whereas in the CD34⁺/CD45RA⁻ and CD34⁺/CD38⁻ subfractions the mean expansion was 23- and 50-fold respectively. The expansion of the immature progenitor cell subfractions resulted in a highly purified megakaryocyte suspension containing > 80% megakaryocytes after 14 d in culture. However, these expanded megakaryocytes remained in a diploid (2N) and tetraploid (4N) state. Maturation could not be further induced by low concentration of TPO (0.1 ng/ml). The majority of the cells were 2N (80%) and 4N (15%) and only 5% of the cells had a ploidy of more than 4N. These results indicate that megakaryocyte progenitor cells in cord blood residing in the immature stem cell fraction exhibit a high proliferative capacity when cultured in the presence of TPO as the single growth factor, without maturation to hyperploid megakaryocytes.     

Probability of progenitor renewal (PPR) and production of clonogenic progeny (CFU-GM) by primitive adherent progenitor cells in adult human bone marrow and umbilical cord blood

Summary. Human haemopoietic tissues contain primitive plastic-adherent progenitor cells (PΔ cells) that can be detected by measurement of their granulocyte-macrophage colony-forming cell (CFU-GM) progeny. Limiting dilution analysis and Poisson statistics are necessary for determining the frequency of PΔ cells because each of them produces several CFU-GM. Limiting dilution also permits measurement of the abilities of individual PΔ progenitors to produce CFU-GM. Here we report that the frequencies of PΔ progenitors in cord blood and adult marrow are similar (5.6 and 7.8/10⁵ mononuclear cells respectively) and individual cord blood PΔ progenitors produce fewer CFU-GM than adult PΔ progenitors. To test the possibility that the lower production of differentiated progeny by cord blood cells was the result of a higher rate of self-renewal, we devised a two-stage limiting dilution assay relying on the relative production of CFU-GM after two consecutive weeks of incubation. The probability of progenitor renewal (PPR) was derived from the number of wells (progenitors) that produced CFU-GM on both occasions compared with the number that produced CFU-GM on the first occasion only. The total number of CFU-GM produced on the second occasion compared with the number produced on the first occasion provided an index of the overall change in the size of the PΔ cell population. The data indicate that PΔ cells in cord blood have a higher PPR (0.59) than those in adult marrow (036). Also, the relative numbers of CFU-GM produced in the second and first weeks were greater for cord blood (1.2) than for adult marrow (0.36). Therefore PΔ cells in cord blood have a greater capacity for self-maintenance and possibly for expansion than PΔ cells in adult marrow.     

Growth factor receptor profile of CD34 cells in normal bone marrow, cord blood and mobilized peripheral blood

Growth factors regulate the proliferation and differentiation of hemopoietic cells. Their effect on hemopoietic precursors differs according to the ontogenic source of the cells. Cord blood and mobilized blood CD34(+) cells have a higher sensitivity for growth factors than bone marrow CD34(+) cells. This could be due to a higher expression of growth factor receptors. Therefore, we examined the expression of receptors for stem cell factor (SCF), interleukin-6 (IL-6), IL-3, granulocyte colony-stimulating factor (G-CSF) and IL-7 on the CD34(+) cells of cord blood, mobilized peripheral blood and bone marrow. The receptors were detected with monoclonal antibodies and flow cytometry. The majority of the CD34(+) cells in bone marrow clearly expressed SCFR; they showed a moderate positivity for IL-3Ralpha and a weak staining for G-CSFR and IL-6 Ralpha. Less than 10% of the cells were IL-7R positive. Cord blood CD34(+) cells showed a higher expression of SCFR and a lower positivity for G-CSFR and IL-6Ralpha. Mobilized blood CD34(+) cells showed a lower expression of SCFR and G-CSFR, and a higher positivity for IL-3Ralpha. This was not solely due to the presence of more myeloid precursors in mobilized blood, as the growth factor receptor profile did not correspond to that of early or late myeloid CD34(+) precursors in normal bone marrow. Changes induced by the mobilization procedure occurred as well. In conclusion, the higher sensitivity for growth factors of hemopoietic precursors in cord blood and mobilized blood cannot be explained by a general increase of the growth factor receptor expression on the CD34(+) cells.     

Four phases of checks for exclusion of umbilical cord blood donors

Aim

The aim of this study was to analyse umbilical cord blood (UCB) collection over 1 year between October 2008 and September 2009, seeking ways to improve the number of suitable banked UCB units. Four phases of the process were investigated, from the consent form to the banking procedure, paying attention to the discarded UCB units.

Material and methods

We recruited couples at 35 weeks of gestation and took an accurate history, focusing on genetic, immunological and infectious diseases. We collected UCB from pregnant women who delivered vaginally or by Caesarean section between the 37–41⁺⁶ weeks of gestation. Some units were discarded on the basis of the patients'' history, obstetric events or biological criteria. In utero collection was the preferred method of collection.

Results

During the study period, between October 2008 and September 2009, there were 1,477 deliveries in our unit. The number of couples interested in UCB donation was 595 (40.2%-595/1,477). We collected 393 UBC units. We excluded 122 patients at the phase of the history taking, counselling and informed consent (first phase check). Of the 393 units collected, 162 (41.3%) were banked whereas 231 (58.7%) were discarded because they did not fulfil biological criteria (third phase check). The volume of UCB units collected after Caesarean section was greater than the volume of units collected after vaginal delivery (95.4 mL versus 85.0 mL, respectively; p <0.01). The UCB units collected after vaginal delivery contained a higher number of total nucleated cells compared to the units collected after Caesarean section (970x10⁶ cells versus 874x10⁶ cells, respectively; p=0.037). None of the banked UCB units was discarded at the clinical check 6 months after delivery (fourth phase check).

Conclusions

Our study shows that strict observance of each of the checks and the collection strategy is important to guarantee the safety of the UCB units and to maximise the cost-benefit ratio. After the appropriate checks we banked UCB units from only 27.2% (162/595) of the couples who gave consent to the procedure and from only 11% (162/1,477) of all the deliveries in the 12 month study period, as 59.8% of couples were not properly informed about UCB donation.     

Plasma thrombopoietin levels in thrombocytopenic states: implication for a regulatory role of bone marrow megakaryocytes

To evaluate the diagnostic value of thrombopoietin (TPO, c-mpl ligand) measurements, and clarify the regulatory mechanisms of TPO in normal and in thrombocytopenic conditions, the plasma TPO concentration was determined in normal individuals (n = 20), umbilical cord blood (n = 40), chronic idiopathic thrombocytopenic purpura (ITP; n = 16), in severe aplastic anaemia (SAA; n = 3), chemotherapy-induced bone marrow hypoplasia (n = 10), myelodysplastic syndrome (MDS; n = 11), and sequentially during peripheral blood progenitor cell transplantation (n = 7). A commercially available ELISA and EDTA-plasma samples were used for the analysis. The plasma TPO concentration in the normals and umbilical cord blood were 52 ± 12 pg/ml and 66 ± 12 pg/ml, respectively. The corresponding values in patients with SAA and chemotherapy-induced bone marrow hypoplasia were 1514 ± 336 pg/ml and 1950 ± 1684 pg/ml, respectively, and the TPO concentration, measured sequentially after myeloablative chemotherapy and peripheral blood progenitor cell transplantation, was inversely related to the platelet count. In contrast, the plasma TPO recorded in patients with ITP (64 ± 20 pg/ml) and MDS (68 ± 23 pg/ml) were only slightly higher than normal levels. In conclusion, TPO levels were significantly elevated in patients in which bone marrow megakaryocytes and platelets in circulation were markedly reduced, whereas TPO levels were normal in ITP patients, and only slightly increased in the MDS patients. These latter patients displayed a preserved number of megakaryocytes in bone marrow biopsies. Our data support the suggestion that megakaryocyte mass affects the plasma TPO concentration. In thrombocytopenic patients a substantially increased plasma TPO implies deficient megakaryocyte numbers. However, TPO measurements do not distinguish between ITP and thrombocytopenia due to dysmegakaryopoiesis, as seen in MDS patients.     

Human neonatal blood: stem cell content, kinetics of CD34+ cell decline and ex vivo expansion capacity

Haemopoietic stem cells are present in fetal blood but their levels decline rapidly in the peripheral circulation of the infant after birth. We previously reported a case of stem cell transplant in a beta-thalassaemia boy using a combination of the cord blood (CB) and neonatal blood (NB) of his sister. This transplant resulted in a successful engraftment. To investigate the possibility of using NB to supplement CB for related transplants, we further characterized stem and progenitor cells and lymphocyte subsets in 20 NB samples, comparing the findings with those in 20 CB samples. Our data showed that NB contained substantial levels of CD34+ cells, CD34+CD38- cells, colony-forming units-granulocyte macrophage (CFU-GM), colony forming units-erythroid (CFU-E), burst forming units-erythroid (BFU-E) and long-term culture initiating cells (LTCIC). NB was similar to CB in the levels of T lymphocytes, but the amounts of B lymphocytes and natural killer cells were higher in CB (P = 0.033, P= 0.001, respectively). The kinetics of CD34+ cells in NB was investigated in serial blood samples obtained from 10 full-term infants at 2, 4, 6, 8, 24 and 48h after birth. CD34+ cells decreased rapidly after birth, declining to only 30% of the 2h level at 48h (P<0012). The rate of decline was greatest in the first 4 h of life. NB from four infants was expanded by culturing the blood samples in the presence of thrombopoietin (Tpo), interleukin 1beta (IL1beta), IL-3, IL-6, flt-3 ligand and stem cell factor (SCF) for 7 d. This resulted in the increase of CD34+ cells, CFU-GM and CFU-MK by 271+/-179, 556+/-385 and 113+/-75 fold respectively. Three of the five samples expanded for 7 d contained LTCIC. These findings suggest that NB might be a supplementary or alternative source of stem cells to CB for transplant. The ethics and practicality of this approach deserve further exploration.     

Adult bone marrow is a rich source of human mesenchymal 'stem' cells but umbilical cord and mobilized adult blood are not

In postnatal life, mesenchymal stem cells (MSC) self-replicate, proliferate and differentiate into mesenchymal tissues, including bone, fat, tendon, muscle and bone marrow (BM) stroma. Possible clinical applications for MSC in stem cell transplantation have been proposed. We have evaluated the frequency, phenotype and differentiation potential of MSC in adult BM, cord blood (CB) and peripheral blood stem cell collections (PBSC). During culture, BM MSC proliferated to confluence in 10-14 d, maintaining a stable non-haemopoietic phenotype, HLA class-1+, CD29+, CD44+, CD90+, CD45-, CD34- and CD14 through subsequent passages. Using the colony forming unit fibroblasts assay, the estimated frequency of MSC in the BM nucleated cell population was 1 in 3.4 x 10(4) cells. Both adipogenic and osteogenic differentiation of BM MSC was demonstrated. In contrast, CB and PBSC mononuclear cells cultured in MSC conditions for two passages produced a population of adherent, non-confluent fibroblast-like cells with a haemopoietic phenotype, CD45+, CD14+, CD34-, CD44-, CD90- and CD29-. In paired experiments, cultured BM MSC and mature BM stroma were seeded with CB cells enriched for CD34+. Similar numbers of colony-forming units of granulocytes-macrophages were produced by MSC-based and standard stroma cultures over 10 weeks. We conclude that adult BM is a reliable source of functional cultured MSC, but CB and PBSC are not.     

CFU-C proliferation and granulopoiesis in suspension cultures of bone marrow,cord blood and adult blood

Summary. Normal bone marrow, cord blood and adult blood cells were separated on ficoll-hypaque density gradients and cultured in MCoy 5A medium with 15% human serum in 25 cm² flasks for up to 14 days to characterize their growth. The system permits the study of granulopoiesis from the generation in culture of new CFU-C to the emergence of neutrophils and monocyte-macrophage cells at the end of the culture period. Bone marrow, cord blood and adult blood, showed 2-3-fold increases in CFU-C, but characteristically only small numbers of CFU-C were detected in adult blood, and only small numbers of granulocytes were produced. The total nucleated cell count only rose consistently in bone marrow cultures. Adherent cell layers formed in all cultures with confluent or near confluent growth of macrophages after 14 days. Some macrophages were multinucleated giant cells; these cells were found most commonly in adult blood cultures. Exclusively in bone marrow cultures macroscopic fibroblast colonies and smaller fibroblast clusters of about 20-50 cells occurred. CFU-C did not proliferate if they were deprived of adherent cells, but some growth did occur when bone marrow depleted of adherent cells was cultured on preformed marrow or fibroblast-free peripheral blood adherent layers. These allogeneic adherent cells were, however, less stimulatory than the autologous cells. It is concluded that CFU-C progenitors are detectable in blood and bone marrow, while fibroblast colony forming cells do not circulate. It appears that macrophages in the absence of fibroblasts will support some CFU-C generation and granulopoiesis in suspension culture. This system is a useful model for examining the cellular and humoral regulation of granulopoiesis in vitro and further studies are in progress.