影响外周血CD34+细胞纯化的相关因素

背景:造血干细胞具有良好的自我复制和更新的能力,CD34+细胞具备有造血干细胞的标志.目的:分析影响外周血CD34+细胞纯化的因素.方法:90例患者,经粒细胞集落刺激因子5 μg/(kg·d)动员1～3 d后,应用COBE血细胞分离机采集外周血单个核细胞液80～100 mL,经Clini MACS免疫磁珠分选技术纯化CD34+细胞.结果与结论:90例CD34+细胞平均数为(1.73±1.15)×107,经流式细胞仪分析,CD34+细胞阳性率大于80%.COBE血细胞分离机单次收集的循环血量在980～1 100 mL时,利于CD34+细胞收集(P=0.005);动员后白细胞浓度在(16～21)×109 L-1时,利于CD34+细胞收集(P < 0.05);中间细胞和淋巴细胞总比例超11%时,利于CD34+细胞收集(P < 0.05);单个核细胞液血小板小于2 100×109 L-1时,利于CD34+细胞的收集(P < 0.05);年龄小于16岁,CD34+细胞数高(P=0.003);CD34+细胞抗体的温度、磁性标记及细胞处理时离心力的大小,均有影响.结果提示,经Clini MACS免疫磁珠细胞分选技术纯化的CD34+细胞能满足临床需要,实验稳定性好,重复性好;注重相关因素的影响,可提高纯化的CD34+细胞数量.     

The number of CD34(+) cells in peripheral blood as a predictor of the CD34(+) yield in patients going to autologous stem cell transplantation

The number of CD34(+) cells in peripheral blood (PB) is a guide to the optimal timing to harvest peripheral blood progenitor cells (PBPC). The objective was to determine the number of CD34(+) cells in PB that allows achieving a final apheresis product containing > or =1.5 x 10(6) CD34(+) cells/kg, performing up to three aphereses. Between March 1999 and August 2003, patients with hematological and solid malignancies who underwent leukapheresis for autologous bone marrow transplantation were prospectively evaluated. Seventy-two aphereses in 48 patients were performed (mean 1.45 per patient; range 1-3). PBPC were mobilized with cyclophosphamide plus recombinant human granulocyte-colony stimulating factor (G-CSF) (n = 40), other chemotherapy drugs plus G-CSF (n = 7), or G-CSF alone (n = 1). We found a strong correlation between the CD34(+) cells count in peripheral blood and the CD34(+) cells yielded (r = 0.903; P < 0.0001). Using receiver-operating characteristic (ROC) curves, the minimum number of CD34(+) cells in PB to obtain > or =1.5 x 10(6)/kg in the first apheresis was 16.48 cells/microL (sensitivity 100%; specificity 95%). The best cut-off point necessary to obtain the same target in the final harvest was 15.48 cells/microL, performing up to three aphereses (sensitivity 89%; specificity 100%). In our experience, > or =15 CD34(+) cells/microL is the best predictor to begin the apheresis procedure. Based on this threshold level, it is possible to achieve at least 1.5 x 10(6)/kg CD34(+) cells in the graft with < or =3 collections.     

Mobilization and transduction of CD34(+) peripheral blood stem cells in patients with X-linked chronic granulomatous disease

As a single-gene defect in phagocytes, the X-linked form of chronic granulomatous disease (X-CGD) is a disorder potentially amenable to gene therapy by transfer of a functional copy of the gp91(phox) gene into hematopoietic stem cells (HSC). Although antimicrobial agents and interferon-gamma (IFN-gamma) have significantly improved its prognosis, CGD is still associated with high morbidity and mortality. The disease can be cured by bone marrow transplantation (BMT); however, BMT in CGD has been associated with unacceptably high rates of morbidity, mortality, and graft failure, except in very selected cases in which an HLA-identical donor is available. Prerequisites for a clinical gene therapy of CGD are an efficient mobilization of peripheral blood stem cells (PBSC) as well as the preservation of their viability and hematopoietic potential following transduction and ex vivo culture. We show that (i) mobilization and collection of CD34(+) cells after a 4-week IFN-gamma-free period by G-CSF results in sufficient numbers of cells for transplantation; (ii) the quality of collected stem cells is not altered in comparison to cells obtained from healthy volunteers as assessed by long-term culture initiating cells (LTC-IC) and progenitor cell expansion; (iii) retroviral transfer of the gp91(phox) gene under defined, serum-free conditions leads to high and stable reconstitution of the respiratory burst activity in X-CGD neutrophils derived from transduced CD34(+) progenitor and LTC-IC. Withdrawal of IFN-gamma in CGD patients may improve mobilization of CD34(+) stem cells by G-CSF. The gene transfer conditions established here are applicable to a clinical approach for gene therapy of X-CGD.     

Nonmyeloablative stem cell transplantation with CD8-depleted or CD34-selected peripheral blood stem cells

To decrease the incidence of graft-versus-host disease (GVHD) observed after nonmyeloablative stem cell transplantation (NMSCT), we studied the feasibility of CD8-depleted or CD34-selected NMSCT followed by CD8-depleted preemptive donor lymphocyte infusion (DLI) given in incremental doses on days 40 and 80. Fourteen patients with high-risk malignancies and an HLA-identical sibling (n = 8) or alternative donor (n = 6) but ineligible for a conventional transplant were included. Nonmyeloablative conditioning regimen consisted in 2 Gy total body irradiation (TBI) alone, 2 Gy TBI and fludarabine (previously untreated patients) or cyclophosphamide and fludarabine (patients who had previously received > or =12 Gy TBI). Patients 1-4 (controls) received unmanipulated peripheral blood stem cells (PBSC) and DLI and patients 5-14 CD8-depleted or CD34-selected PBSC followed by CD8-depleted DLI. Post-transplant immunosuppression was carried out with cyclosporine A (CsA) and mycophenolate mofetil (MMF). Initial engraftment was seen in all patients, but 1 patient (7%) later rejected her graft. The actuarial 180-day incidence of grades II-IV acute GVHD was 75% for patients 1-4 versus 0% for patients 5-14 (p = 0.0019). Five of 14 patients were in complete remission (CR) 180 days after the transplant and 6/14 had partial responses. The 1-year survival rate was 69%, and nonrelapse and relapse mortality rates were 16 and 18%, respectively. We conclude that CD8-depleted or CD34-selected NMSCT followed by CD8-depleted DLI is feasible and considerably decreases the incidence of acute GVHD while preserving engraftment and apparently also the graft-versus-leukemia (GVL) effect. Further studies are needed to confirm this encouraging preliminary report.     

Kinetic study of CD34+ cells during peripheral blood stem cell collections

The impact of the separated volume on the yield of CD34+ cells during peripheral blood stem cell collections (PBSCC) remains controversial. We therefore studied the CD34+ cell concentration in the peripheral blood of patients (pts) during PBSCC as well as the total amount of CD34+ cells collected after each blood volume (BV) processed and engraftment data for each cycle of high dose chemotherapy (HD Ctx). A total of 21 PBSCC from 20 patients with different malignancies were analyzed. Stem cells were mobilized by chemotherapy and G-CSF (14 pts) or GM-CSF (6 pts). Samples from the pts peripheral blood and the collection bag were taken after each BV processed and analyzed for CD34+ cells, WBC, platelets (plt), and hemoglobin (Hb). The total volume processed was two to five times the pts calculated BV (mean value 17.4 L, range 9.0–24.0 L). Sixteen pts could be evaluated for engraftment. The mean peripheral blood CD34+ cell count was 116±103.5/μl at the start of PBSCC and decreased to 57±61.6/μl after processing of four times the pts BV. The mean number of CD34+ cells collected after each BV was 2.3±2.4, 5.8±5.2, 8.5±7.2, and 11.8±10.3×10⁶ per kg body weight, respectively. The mean plt count decreased by 53±40.2/nl, Hb by 1.±0.5 g/dl and WBC by 0.±6.1/nl after separation of 4 BV. All but two pts reached the target value of 1.5 × 10⁶ CD34+ cells/kg body weight and planned cycle of HD Ctx with 1 PBSCC. All pts engrafted and reached neutrophils>500/μl and plt>20,000/μl at a median of 11 and 13 days, respectively. We could demonstrate, that the yield of CD34+ cells during PBSCC increased continuously with the volume of the separated BV and that up to 5× the patients' BV could be processed safely without serious side effects. Most pts had to undergo only 1 PBSCC to collect sufficient numbers of CD34+ cells to support sequential courses of HD Ctx without delayed engraftment. J. Clin. Apheresis 14:18–25, 1999. © 1999 Wiley-Liss, Inc.     

CD34定量分析外周血干细胞的研究

目的定量检测外周血干细胞(PBSC).方法以藻红蛋白(PE)标记的CD34单克隆抗体,用流式细胞术(FCM)对34例白血病患者与33例健康成人外周血表达CD34抗原(CD34+)的细胞进行定量分析,并以普通光学显微镜(LM)、透射电子显微镜(TEM)、激光扫描共聚焦显微镜(LSCM)分别对CD34+/CD34-细胞进行观察.结果经LSCM证实,FCM定量检测CD34+细胞特异性强,CD34+细胞在0%～16.1%范围内线性良好(r=0.9947),当CD34+细胞为91.0%、38.3%时,CV＜3%.CD34+/CDD34-细胞在LM、TEM下形态与结构相似,但CD34+细胞在LSCM下显示圆环状橙红色荧光.结论FCM检测外周血干细胞灵敏、特异、快速,但其方法学待进一步标准化.     

免疫磁珠分离及流式细胞仪分选纯化外周血CD34+/CD90+干细胞

目的　建立人外周血CD34 细胞及其亚群的纯化分离方法。方法　用干细胞采集仪收集了 3例病人的外周血干细胞 ,应用免疫磁珠分离柱快速分离其中的CD34 细胞 ,随后采用分选型EPICSElite流式细胞仪进一步分选出CD34 /CD90 双阳性早期造血干细胞。结果　免疫磁珠分离纯化后CD34 干细胞的纯度可达 83%～ 95 % ,回收率 5 4 %～ 71% ,活细胞率 >95 %。流式细胞仪分选后的CD34 /CD90 细胞纯度可达 90 %以上 ,回收率在 4 0 %～ 5 0 % ,生存率 >95 %。起始标本中CD34 细胞含量越高 ,纯化所得到的干细胞纯度和回收率越高。两种纯化后的干细胞在形态学上有明显的不同。结论　联合应用免疫磁珠分离和流式细胞仪分选 ,可以较高的回收率快速纯化高纯度的CD34 细胞及其亚群     

Hematopoietic recovery in cancer patients after transplantation of autologous peripheral blood CD34+ cells or unmanipulated peripheral blood stem and progenitor cells

BACKGROUND: A study of CD34+ cell selection and transplantation was carried out with particular emphasis on characteristics of short- and long-term hematopoietic recovery. STUDY DESIGN AND METHODS: Peripheral blood stem and progenitor cells (PBPCs) were collected from 32 patients, and 17 CD34+ cell-selection procedures were carried out in 15 of the 32. One patient in whom two procedures failed to provide 1 × 10(6) CD34+ cells per kg was excluded from further analysis. After conditioning, patients received CD34+ cells (n = 10, CD34 group) or unmanipulated (n = 17, PBPC group) PBPCs containing equivalent amounts of CD34+ cells or progenitors. RESULTS: The yield of CD34+ cells was 53 percent (18–100) with a purity of 63 percent (49–82). The CD34+ fraction contained 66 percent of colony-forming units-granulocyte- macrophage (CFU-GM) and 58 percent of CFU of mixed lineages, but only 33 percent of burst-forming units-erythroid (BFU-E) (p < 0.05). Early recovery of neutrophils and reticulocytes was identical in the two groups, although a slight delay in platelet recovery may be seen with CD34+ cell selection. Late hematopoietic reconstitution, up to 1.5 years after transplant, was also similar. The two groups were thus combined for analyses of dose effects. A dose of 40 × 10(4) CFU-GM per kg ensured recovery of neutrophils to a level of 1 × 10(9) per L within 11 days, 15 × 10(4) CFU of mixed lineages per kg was associated with platelet independence within 11 days, and 100 × 10(4) BFU-E per kg predicted red cell independence within 13 days. However, a continuous effect of cell dose well beyond these thresholds was apparent, at least for neutrophil recovery. CONCLUSION: CD34+ cell selection, despite lower efficiency in collecting BFU-E, provides a suitable graft with hematopoietic capacity comparable to that of unmanipulated PBPCs. In both groups, all patients will eventually show hematopoietic recovery of all three lineages with 1 × 10(6) CD34+ cells per kg or 5 × 10(4) CFU-GM per kg, but a dose of 5 × 10(6) CD34+ cells or 40 × 10(4) CFU-GM per kg is critical to ensure rapid recovery.     

Successful autologous peripheral blood stem cell collection using large volume leukapheresis in patients with very low or undetectable peripheral blood CD34+ progenitor cells

Autologous stem cell transplantation provides some patients with hematolymphoid and solid organ malignancies an opportunity for cure. Management of peripheral hematopoietic stem cell (HSC) collections differs among institutions, especially if a very low pre-procedure peripheral blood CD34+ cell count (PBCD34) is demonstrated. This study retrospectively analyzed results of large-volume peripheral HSC collections in 91 patients over approximately two years. Fifteen patients with PBCD34 < 10 × 10e6/l (eleven with undetectable PBCD34) were compared to 76 patients with higher counts on the first collection day (adequate mobilizers). The poor mobilizer group had significantly lower pre-collection WBC and platelet counts as well as collection yields. However, most patients with PBCD34 < 10 × 10e6/l (80 %) collected the minimum target for HSC transplant (2.0 × 10e6 CD34+ cells/kg) in <5 consecutive days of collection, and those who did collect the minimum successfully underwent autologous transplantation, with hematopoietic engraftment and long-term survival comparable to the adequate mobilizers. Successful HSC collection may often be achieved regardless of d 1 PBCD34 counts.     

自体外周血干细胞动员中测定CD34^＋Thy—1＋细胞的意义

目的：确切评估动员后外周血干细胞（ＰＢＳＣ）水平的变化，及时指导临床选择最佳采血时机。方法：用流式细胞术测定化疗和粒细胞集落刺激因子（Ｇ－ＣＳＦ）联合动员时外周血ＣＤ３４＋Ｔｈｙ－１＋细胞含量的变化，同时用体外集落培养方法评价外周血祖细胞（ＰＢＰＣｓ）的克隆形成能力。结果：动员后循环血中ＣＤ３４＋Ｔｈｙ－１＋细胞、ＣＤ３４＋细胞和克隆形成细胞（ＣＦＣ）含量分别增高４８．６倍、５０．０倍和５３．１倍，高峰时间在化疗后第１２～１４天（注射Ｇ－ＣＳＦ的第６～８天）；外周血单个核细胞中ＣＤ３４＋Ｔｈｙ－１＋细胞、ＣＤ３４＋细胞的比例分别增高１３．８倍和１０．５倍；动员的早期阶段，ＣＤ３４＋细胞中Ｔｈｙ－１＋细胞比例最高。结论：联合应用化疗和Ｇ－ＣＳＦ对ＰＢＰＣｓ，尤其对早期干／祖细胞具有显著动员作用；用流式细胞术检测ＣＤ３４＋Ｔｈｙ－１＋细胞可及时指导临床准时采集ＰＢＳＣ。     

Enumeration of viable CD34+ cells in cord blood using a novel stem cell enumeration kit

ObjectiveTo assess the detection performance of the hematopoietic stem cell enumeration kit developed by BD Biosciences.MethodsCord blood samples were prepared using a hematopoietic stem cell enumeration kit developed by BD Biosciences and Stem-Kit reagents from Beckman Coulter. CD34+ cells were enumerated using a BD FACSCanto instrument and FACSDiva software.ResultsA total of 519 samples were analyzed in this study. The hematopoietic stem cell enumeration kit developed by BD Biosciences yielded absolute counts of CD34-positive cells that were on average 8.7% lower than Beckman Coulter Stem-Kit reagents (range: −5.7% to−14.7%). The BD Biosciences kit yielded relative counts that were on average 9.9% higher compared with Beckman Coulter Stem-Kit reagents (range: −2.1% to +13.8%). The intraclass correlation coefficients for absolute and relative counts of CD34-positive cells were 0.9967 (95% confidence interval [CI]: 0.9961–0.9972) and 0.9512 (95% CI: 0.9423–0.9587) for the BD Biosciences and Beckman Coulter kits, respectively.ConclusionsThe hematopoietic stem cell enumeration kit developed by BD Biosciences can be used to enumerate CD34-positive stem cells from cord blood samples.     

Factors affecting mobilization of CD34+ cells in normal donors treated with filgrastim

BACKGROUND: Multiple days of apheresis are required for some normal peripheral blood progenitor cell (PBPC) donors, to ensure a sufficient collection of CD34+ cells for allografting. It would be of practical value to be able to identify the patients with poor mobilization on the basis of simple pretreatment clinical or hematologic variables. STUDY DESIGN AND METHODS: Clinical characteristics and laboratory data for 119 normal PBPC donors who underwent apheresis on Days 4 to 6 of treatment with granulocyte-colony-stimulating factor (filgrastim) were analyzed for correlations with CD34+ cell yield from the first day of apheresis. RESULTS: The CD34+ cell yield was significantly lower in donors who were more than 55 years of age, who underwent apheresis on Day 4 of filgrastim therapy, or who were not obese. There were weak direct correlations between CD34+ cell yield and the baseline white cell count, preapheresis white cell count, and preapheresis mononuclear cell count, and there was a weak inverse correlation with age. Twenty- one donors (18%) were considered to have poor mobilization (< 20 × 10(6) CD34+ cells/L blood processed). In the multivariate analysis, the only significant factor was age greater than 55 years, which conferred a 3.8 times greater risk (95% CI, 1.1-13.7) of poor mobilization (p = 0.04). However, poor mobilization occurred in all age groups, so the predictive value of the model was low. CONCLUSION: Donor variables correlated with CD34+ cell yield only weakly, so no particular clinical characteristic can be used to exclude an individual as a PBPC donor if he or she is otherwise suitable for the apheresis procedure.     

Second mobilization and collection of peripheral blood progenitor cells in healthy donors is associated with lower CD34(+) cell yields

We have retrospectively evaluated the results of two cycles of mobilization and collection of peripheral blood progenitor cells (PBPC) from 46 healthy donors included in the Spanish National Donor Registry. Mobilization involved the administration of granulocyte colony-stimulating factor (G-CSF) at a median dose of 10 microg/kg per day, and apheresis was begun after the fourth dose of G-CSF in both cycles. The median interval between both mobilizations was 187 days (range, 7-1428 days). The incidence and types of side-effects were similar after both donations, with 25 and 26 donors developing some toxicity after the first and second donations, respectively. The median number of CD34(+) cells collected was higher after the first mobilization than after the second (5.15 versus 3.16 x 10(6)/kg, respectively; p = 0.05), and 29 donors yielded fewer CD34(+) cells after the second mobilization (p = 0.018). A lower proportion of donors yielded CD34(+) cell counts >4 x 10(6)/kg after the second cycle than after the first (52% versus 76%, respectively; p = 0.057). Our study shows that second rounds of PBPC collection from normal donors are well tolerated but are associated with a significantly reduced number of CD34(+) cells collected when the same mobilization scheme is used.     

脐血CD34^＋细胞和外周血单核细胞两种来源的树突状细胞特性？…

目的 体外大量扩增和纯化具有典型表型、形态和功能的树突状细胞（ＤＣ）、以进行相关基础研究和临床应用。方法 采用免疫磁珠江分离脐血ＣＤ３４＾＋细胞及外周血去Ｂ、去Ｔ淋巴细胞的单个核细胞（单核细胞）,然后以ＧＭ－ＣＳＦ、ＩＬ－４、ＴＮＦα、Ｆｌｔ３配基（ＦＬ）、ＳＣＦ等不同的细胞因子配伍分别诱生ＤＣ,通过流式细胞仪、电镜、光镜分析其特性,同时检测其刺激同种Ｔ细胞增殖的能力。结果 脐民外周血诱生ＤＣ的方     

Differential increase of CD34, KDR/CD34, CD133/CD34 and CD117/CD34 positive cells in peripheral blood of patients with acute myocardial infarction

Objective Circulating progenitor cells (CPC) may contribute to cardiac regeneration and neovascularization after acute myocardial infarction (AMI). For potential therapeutic use, understanding the endogenous mechanisms after ischemia is inevitable. We investigated the absolute number, but also the subset composition of CD34+ CPC after AMI. Methods CD34+, KDR+/ CD34+, CD133+/CD34+ and CD117+/CD34+ CPC were analyzed by FACS in peripheral blood of 10 patients with acute MI (59±5 yrs, m/f=8/2) at day of AMI (day 0) and days 1–5. For comparison patients with stable coronary artery disease (CAD, n=12, 66±2 yrs, m/f=10/2) and young healthy volunteers (n=7, 26±2 yrs, m/f=3/4) were studied. Results CD34 and KDR/CD34, CD133/CD34, CD117/CD34 were increased day 3 and 4 after AMI. KDR+ fraction within CD34+ population remained unchanged (58.3±7.8% vs 55.3±10.6%), whereas CD133+ (64.9±3.1% vs 43.5±5.9%, P=0.006) and CD117+ fractions (71.7±5.6% vs 50.1±5.5%, P=0.02) were elevated. In CAD, all CPC and fractions were similar as AMI day 0. Healthy volunteers had more CD34+ than CAD and AMI day 0. Double positive CPC were also higher, but fractions were unchanged vs CAD with more KDR/CD34 in trend (72.8±10.6% vs 50.5±5.6%, P=0.058). After AMI both absolute numbers of CD34+ and their subset composition change, suggesting selective mobilization of CPC. Increased CPC after AMI never reach numbers of young healthy volunteers.     

CD133+CD34+ and CD133+CD38+ blood progenitor cells as predictors of platelet engraftment in patients undergoing autologous peripheral blood stem cell transplantation

BackgroundHematopoietic stem cells (HSC) have been characterized by CD34+ expression and an adequate dose of CD34+ cells is associated with a complete engraftment. CD133 is a more specific marker of HSC.Materials and methodsWe studied the relationship between graft content of CD34+, CD133+, and CD38+ cells and trilineage engraftment after autologous stem cell transplantation in patients with different hematological disorders. Blood samples were obtained before and after mobilization with recombinant granulocyte-colony stimulating factor (G-CSF, 16 μg/kg), from apheresis collections, and after transplantation.ResultsCell subsets were quantified by flow cytometry, and the dose of each population infused was correlated with success of engraftment. G-CSF induced mobilization of CD133+CD38+ cells (12.6-fold) and CD133+CD34+ cells (14.7-fold). A correlation was observed between the infused dose of CD133+CD34+ and CD133+CD38+ cells and platelet engraftment.ConclusionCD133+CD34+ and CD133+CD38+ cells were mobilized with G-CSF and these cell subsets were correlated with platelet engraftment.     

Identification and functional characterization of human CD4(+)CD25(+) T cells with regulatory properties isolated from peripheral blood

A subpopulation of peripheral human CD4(+)CD25(+) T cells that expresses CD45RO, histocompatibility leukocyte antigen DR, and intracellular cytotoxic T lymphocyte-associated antigen (CTLA) 4 does not expand after stimulation and markedly suppresses the expansion of conventional T cells in a contact-dependent manner. After activation, CD4(+)CD25(+) T cells express CTLA-4 on the surface detectable for several weeks. These cells show a G1/G0 cell cycle arrest and no production of interleukin (IL)-2, IL-4, or interferon (IFN)-gamma on either protein or mRNA levels. The anergic state of CD4(+)CD25(+) T cells is not reversible by the addition of anti-CD28, anti-CTLA-4, anti-transforming growth factor beta, or anti-IL-10 antibody. However, the refractory state of CD4(+)CD25(+) T cells was partially reversible by the addition of IL-2 or IL-4. These data demonstrate that human blood contains a resident T cell population with potent regulatory properties.     

Mesenchymal stem cells from CD34− human umbilical cord blood

Umbilical cord blood (UCB) is well known to be a rich source of stem cells especially for haematopoietic stem cells (HSCs). Recently, mesenchymal stem cells (MSCs) have also been shown to exist in cord blood. Although MSCs have been described by a subset of surface antigens after expansion, little is known about the cell surface phenotype of undifferentiated MSCs. The aim of this study therefore was to clarify whether undifferentiated MSCs are resident among CD34^? UCB cells. CD34⁺ cells were separated from UCB mononuclear cells (MNCs) by magnetic sorting and the CD34^? cell fractions were cultured in Dulbecco's modified Eagle's medium (DMEM) with 10% foetal calf serum (FCS) and basic‐fibroblast growth factor. Isolated CD34⁺ cells were also cultured in the same medium. Adherent fibroblast‐like cells at passage 3–4 were analyzed by fluorescence‐activated cell sorting (FACS) for MSC marker expression , and standard adipogenic, osteogenic and chondrogenic assays were used to investigate their differentiation potentials. After 4–5 weeks in culture, the cells from the CD34^? fraction became confluent with flat and fibroblast‐like morphology. These cells were positively stained for the mesenchymal cell markers CD29, CD73 and CD105. In adipogenic differentiation, the cells showed oil red O positive and expressed FABP4, adipsin and proliferation‐activated receptor γ‐2 (PPARγ2 genes) associated with adipogenesis. In osteogenic differentiation, calcium accumulation and osteocalcin were detected. The cells grown in chondrogenic conditions were positively stained for human aggrecan and expressed collagen type II and Sox‐9 genes. In contrast, cells from the CD34⁺ fraction failed to generate any cells with MSC morphology under the same culture conditions. Our results showed that UCB contained MSCs which are only resident in the CD34^? fraction. The MSCs could be induced to differentiate into at least three lineage cell types, adipocytes, osteoblasts and chondrocytes.     

Isolation of CD34+ progenitor cells from peripheral blood by use of an automated immunomagnetic selection system: factors affecting the results

BACKGROUND: The isolation of CD34+ cells from mobilized peripheral blood is being increasingly used in the setting of allogeneic or autologous hematopoietic cell transplantation. Investigation of variables that may influence the effectiveness of CD34+ cell selection is of interest. STUDY DESIGN AND METHODS: Fifty-one CD34+ cell selections from peripheral blood progenitor cells (PBPCs) (39 allogeneic and 12 autologous) were performed using a magnetic cell separator (Isolex 300i, Baxter), including version 2.0 software. The results obtained were analyzed for different processing variables. The feasibility of transplanting these isolated CD34+ cells was also analyzed. RESULTS: The isolated CD34+ cell fraction had a median purity of 88.9 percent (range, 47.8-98.3). The median recovery of CD34+ cells was 45.1 percent (13.8-76.2), and the median colony-forming unit- granulocyte-macrophage (CFU-GM) content was 17. 2 percent (0.8-58.6). Logarithms of T- and B-cell depletion had median values of 3.7 and 2.8, respectively. The version 2.0 software of the Isolex 300i gave a higher CD34+ cell recovery in the enriched cell fraction (median 57.8%) than did version 1.11 (39.4%) or 1.12 (44.4%) (p = 0.01). The use of recombinant human deoxyribonuclease I during cell processing yielded more CD34+ cells (53% vs. 41%, p = 0. 01) and higher purity (92.8% vs. 87%, p = 0.03). There was a correlation between the percentage of CD34+ cells labeled with the monoclonal antibody 8G12 clone and the percentage of CD34+ cells labeled with the monoclonal antibody used during the processing technique (9C5 clone) in the initial, enriched, and depleted CD34+ cell fractions (R(2) = 0.95; 0.92; 0.78, p< 0.005, respectively). Median times for recovering >0.5 x 10(9) per L of granulocytes and >20 x 10(9) per L of platelets were 13 and 16 days in the allograft patients and 13 and 14 days in the autograft patients. CONCLUSION: CD34+ cells can be highly and effectively isolated from allogeneic and autologous grafts by use of this automated technique, with a high grade of T- and B-cell depletion. These purified CD34+ cell components can engraft normally.