Biomedical subjects

E D Ball

Publications and source records attributed to E D Ball.

At least 37 records · Page 2Linked to original sources

PubMed1998

Comparison of methods for retroviral mediated transfer of glucocerebrosidase gene to CD34+ hematopoietic progenitor cells.

Gaucher disease is an excellent candidate for gene therapy by transduction of hematopoitic stem cells. In this study, we compared methods which allow an increase in transfer of the glucocerebrosidase gene to human hematopoietic progenitor cells. Several techniques were employed, including the use of cytokines, bone marrow stroma, fibronectin, centrifugal enhancement and in vitro long-term culture. The effect of prestimulation with cytokines interleukin-3 (IL-3), interleukin-6 (IL-6) and stem cell factor (SCF) on transduction of cord blood CD34+ cells was examined. The results suggest that 16-h prestimulation was sufficient for efficient transduction. We examined the effect of bone marrow stroma and fibronectin, both of which increased transduction efficiency up to 36% and 44%, respectively, as measured by PCR for the integrated GC-cDNA in clonogenic cells (9% without any support). Transduction efficiency of 83% was obtained using 2-h centrifugation. Combining centrifugation and in vitro culture in long-term bone marrow culture media containing cytokines (IL-3/IL-6/SCF), CD34+ cells from cord blood and peripheral blood of 3 Gaucher patients were transduced weekly for 21 d. The results of 6 separate experiments consistently demonstrated transduction efficiency of 100% after 7-d in vitro culture. This transduction protocol combining centrifugation and in vitro long-term culture is an attractive method and can be applied to clinical trials.

Antigens, CD34↗

PubMed1997

An allelic association implicates myeloperoxidase in the etiology of acute promyelocytic leukemia.

Myeloperoxidase (MPO) catalyzes a reaction between chloride and hydrogen peroxide to generate hypochlorous acid and other reactive compounds that have been linked to DNA damage. The MPO gene is expressed at high levels in normal myeloid precursors and in acute myeloid leukemias (AMLs) which are clonal derivatives of myeloid precursors that have lost the ability to differentiate into mature blood cells. Two MPO alleles differ at -463 G/A within a cluster of nuclear receptor binding sites in an Alu element. The -463 G creates a stronger SP1 binding site and retinoic acid (RA) response element (RARE) in the allele termed Sp. In this study, we investigate potential links between MPO genotype, MPO expression level, and myeloid leukemia. The SpSp MPO genotype is shown to correlate with increased MPO mRNA levels in primary myeloid leukemia cells. This higher-expressing SpSp genotype is further shown to be overrepresented in acute promyelocytic leukemia-M3 (APL-M3) and AML-M4, suggesting that higher levels of MPO are associated with an increased risk for this subset of leukemias.

Alleles↗

PubMed1997

Thy-1 expression on blast cells from adult patients with acute myeloid leukemia.

Bone marrow and peripheral blood from 28 adult patients with acute myeloid leukemia (AML) were analyzed for the surface expression of the Thy-1 antigen by dual-colour flow cytometry. The Thy-1 antigen was expressed on greater than 5% of cells from seven patients with the proportions of Thy-1 positive cells ranging from 8.1% to 85.0%. The CD34+ Thy-1+ phenotype was present in all seven cases. The expression of Thy-1 on leukemia cells from patients with AML may need to be considered in the development of methods of normal stem cell isolation from these patients.

Acute Disease↗

PubMed1997

Purging autologous bone marrow with monoclonal antibodies for transplantation in acute myelogenous leukemia.

Myeloablative chemotherapy followed by allogeneic bone marrow rescue is considered curative therapy and offers an alternative approach to consolidate patients with acute myelogenous leukemia who achieve a first complete remission after standard induction chemotherapy. In patients transplanted during second or third complete remission, allogeneic transplantation can also be curative, although there is lower relapse-free survival. Despite the success of this treatment modality, only 10-20% of patients will be eligible to receive an allogeneic transplantation due to advanced age or lack of an HLA-matched donor. In this situation, autologous bone marrow transplantation allows therapy of comparable intensity to be administered with less morbidity and mortality due to the lack of graft-versus-host disease. In contrast to allografts, remission autografts may harbor residual occult malignant cells unable to be grossly detected. The infusion of these malignant cells following myeloablative therapy can contribute to leukemia relapse. Various in vitro approaches to 'purge' occult malignant leukemia cells from remission marrows have been developed. The two techniques that have been studied in preclinical and clinical trials include pharmacological and monoclonal antibody-mediated methods. The efficacy of using the latter to purge autografts compared with the use of unpurged autografts in patients with acute myelogenous leukemia undergoing autologous bone marrow transplantation is currently the focus of a prospective multicenter trial.

Antibodies, Monoclonal↗

PubMed1997

Relationship of CD34+ cell dose to early and late hematopoiesis following autologous peripheral blood stem cell transplantation.

We evaluated early and late hematopoietic reconstitution in 27 patients with advanced lymphoma, Hodgkin's disease, and breast or ovarian cancer after treatment using high-dose/myeloablative conditioning regimens and autologous peripheral blood stem cell PBSC) transplantation. Eighteen patients (67%) received G-CSF 5 micrograms/kg/day following chemotherapy and nine (33%) were mobilized using G-CSF alone. Each patient had 7 x 10(8) mononuclear cells (MNC) per kg collected. G-CSF was administered post-PBSC infusion. While all patients showed prompt granulocyte recovery by day 14, platelet recovery failed to occur in our (15%) heavily pretreated patients with non-Hodgkin's lymphoma. Retrospective analysis in 17 patients revealed that the infused number of CD34 surface antigen-positive cells correlated with time to granulocyte (r = 0.59, P = 0.012) and platelet (r = 0.58, P = 0.021) recovery. Patients receiving the higher numbers of CD34+ cells had consistently better hematologic parameters at 11 times examined. At 180 days post-transplant, the median Hb level was 124 g/l vs 88 g/l (P = 0.004); platelet count was 202 x 10(9)/l vs 25 x 10(9)/l (P = 0.004); and neutrophil count was 3100 x 10(6)/l vs 1400 x 10(6)/l (P = 0.15). Hemoglobin strongly correlated with the CD34+ cell dose at 360 days (r = 0.90, P = 0.01). We conclude that graft CD34+ cell content appears to be an indicator of the quality of late as well as early hematopoietic function.

Adult↗

PubMed1997

Allogeneic peripheral blood stem cell transplant for myelodysplasia after chemotherapy for post-transplant lymphoma in a cardiac transplant recipient at 10 years.

A 32-year-old male received an allogeneic peripheral blood stem cell transplant (alloPBSCT) for myelodysplasia from his one HLA-A antigen mismatched brother. He is alive with trilineage engraftment and without active GVHD 200 days after transplant. In July 1986 he underwent orthotopic cardiac transplantation for viral cardiomyopathy and has received continuous immunosuppressive therapy. A post-transplant lymphoproliferative disorder with Hodgkin-like histopathology was diagnosed in August 1993 and was successfully treated with four cycles of MOPP chemotherapy. Due to persistent pancytopenia he underwent a bone marrow aspiration and biopsy in May 1996 which revealed monosomy 7 and morphologic changes compatible with myelodysplasia. This is the first report of a cardiac transplant recipient receiving an allogeneic hematopoietic stem cell transplant.

Adult↗

PubMed1997

Purging marrow or peripheral blood stem cells for autografting.

Myeloablative therapy followed by autologous bone marrow or peripheral blood stem cell rescue is an alternative therapeutic option for patients who are not candidates for allogeneic transplantation due to the lack of an appropriate HLA-matched donor or to advanced age. It allows therapy to be administered that is of comparable intensity to that used for allogeneic transplantation, and offers an alternative approach to achieving long-term disease-free survival. Although autologous transplantation obviates the risk of graft-versus-host disease, with its increased morbidity and mortality, it may also increase the rate of disease relapse due to the lack of an immune-mediated graft-versus-leukemia effect, as occurs in the allogeneic transplantation setting. The possibility that residual occult neoplastic cells, reinfused with the remission autografts following myeloablative therapy, can potentiate disease relapse has also been a concern in patients who undergo autologous bone marrow transplantation. This review discusses recent data concerning various strategies that are being used to "purge" autografts in patients undergoing autologous bone marrow transplantation in an effort to decrease the relapse rates and improve the disease-free and overall survival.

Antineoplastic Agents↗

PubMed1996

Granulocyte colony-stimulating factor activation of Stat3 alpha and Stat3 beta in immature normal and leukemic human myeloid cells.

Granulocyte colony-stimulating factor (G-CSF) is the cytokine critical for directing neutrophilic granulocyte differentiation. Acute myelogenous leukemia (AML) cells, which frequently arise from this lineage, respond aberrantly to G-CSF by proliferating without differentiating. The basis for this abnormal responses is unknown. In the present study, we investigated whether G-CSF signaling in immature normal and leukemic human myeloid cells diverges at the level of activation of signal transducers and activators of transcription (STAT) proteins. We compared the profile of STAT proteins activated in G-CSF-stimulated immature normal and leukemic human myeloid cells. G-CSF activated Stat3 alpha in all AML cell lines examined except HL60 and in three of six uncultured AML patient samples. In normal human CD34+ bone marrow cells and HL60 cells, both reported to differentiate in response to G-CSF, G-CSF did not activate Stat3 alpha; rather, it activated only an 83 kD form of Stat3 that proved to be the human homologue of a short form of Stat3, Stat3 beta. Because the transcriptional activity of Stat3 beta is distinct from Stat3 alpha, these results suggest that the balance of the two Stat3 isoforms in myeloid cells may influence the cellular pattern of gene activation and consequently the ability of these cells to differentiate in response to G-CSF.

Acute Disease↗

PubMed1996

Persistence of the AML1/ETO fusion transcript in patients treated with allogeneic bone marrow transplantation for t(8;21) leukemia.

The AML1/ETO fusion transcript is expressed in virtually all patients with t(8;21) (q22;q22) acute myeloid leukemia (AML). The fusion transcript can be detected by reverse transcription-polymerase chain reaction (RT-PCR) in most of these patients in long-term complete remission (CR) following conventional chemotherapy or autologous bone marrow transplantation (BMT). However, AML1/ETO expression has not been analyzed in a series of patients following allogeneic BMT. We examined CR bone marrow (BM) samples and, in some cases, blood samples from 10 patients with t(8;21) leukemia who underwent allogeneic BMT in either first or second remission or first or second relapse. A variety of myeloablative regimens were used. Eight patients received non-T-cell depleted BM from matched sibling donors, one patient received a T-cell depleted haploidentical BM, and one patient received a non-T-cell depleted BM from a matched unrelated donor (MUD). Five patients developed acute and/ or chronic graft versus host disease (GVHD). The furthest time points analyzed for the AML1/ETO transcript in the 10 patients in CR following allogeneic BMT ranged from 7.5 to 83.0 months. Sufficient RNA was extracted from the most recent BM or BM and blood samples from nine patients to assay for presence or absence of the AML1/ETO fusion transcript by RT-PCR. The fusion transcript was detected by RT-PCR in all nine of these patient samples; eight were positive in BM and one was negative in BM, but positive in blood. The fusion transcript could not be detected in a BM sample from the tenth patient obtained 7.5 months after BMT, but the amount of RNA available was suboptimal. Hematopoietic chimerism could be demonstrated in sorted CD34+ BM cells from two of four patient CR BM samples with RT-PCR evidence of the fusion transcript. Additionally, in one of the two cases with chimerism, we demonstrated an abnormal clonal population of recipient cells in the CR BM sample by fluorescence in situ hybridization. One patient died of complications from GVHD, while the other nine patients remain alive without evidence of relapse, with a median follow-up time of 27 (range, 7.5 to 87) months post-BMT. These data suggest that allogeneic BMT, like conventional chemotherapy and autologous BMT, is not sufficient to eradicate cells expressing AML1/ETO, and that a positive RT-PCR for the fusion transcript post allogeneic BMT is compatible with continued CR.

Adult↗

PubMed1996

Human dendritic cells genetically engineered to express high levels of the human epithelial tumor antigen mucin (MUC-1).

We have achieved stable high-level expression of a human tumor antigen, epithelial cell mucin (MUC-1), on human dendritic cells (DCs) by retroviral transduction of CD34+ progenitor cells and their subsequent cytokine-induced differentiation into DCs. The process of retroviral transduction did not alter the growth or differentiation of DCs from CD34+ progenitor cells. Immunofluorescence and electron microscopy studies revealed that the expression of mucin was limited to the body of the DCs and was excluded from the cytoplasmic veils of the DCs. Furthermore, the expression of mucin on DCs was similar, if not identical, to the nonpolarized expression of mucin found on carcinoma cells. In functional studies, the MUC-1(+)-transduced DCs were potent stimulators of allogeneic CD4+ T cells and, in fact, were superior to MUC-1- DCs. Thus, MUC-1+ DCs are expected to be a valuable tool in the immunotherapeutic treatment of patients with tumors that express MUC-1.

Antigens, CD34↗

PubMed1996

Evaluation of monoclonal antibody-mediated anti-acute myeloid leukemia immunotherapy in a SCID/hu model.

The therapeutic potential of the IgM complement-fixing murine monoclonal antibody (mAb) PM-81 (anti-CD15) against acute myeloid leukemia (AML) was assessed in a SCID/hu leukemia model. Intraperitoneal (i.p.) injection of NB4 leukemia cells resulted in aggressive growth of leukemia cells in the peritoneal cavity of irradiated SCID/CB-17 mice. Flow cytometric analysis of human CD15, 33 and 45 expression, as well as cytologic examination, revealed that leukemia cells disseminated into the peripheral blood and multiple tissues of the mice. The approximately linear relationship between the injected leukemia cells and the subsequent leukemia cell proliferation provided a reliable model for monitoring the therapeutic effects of immunotherapy. Intraperitoneal injection of the mAb PM-81 markedly suppressed leukemia cell growth in this SCID/leukemia model. Most of the untreated mice died within 35-50 days of leukemia cell inoculation. Four weeks after inoculation of NB4 cells, five of nine mAb PM-81 treated mice had no solid tumor growth and six of nine had no detectable peritoneal exudate leukemia cells as determined by flow cytometry. In contrast, 100% of the mice in the untreated or control mAb groups were found to have both solid and peritoneal leukemia growth. In further experiments designed to evaluate the effects of therapy on survival, 50% (4/8) of PM-81 treated mice survived to 150 days, and had no detectable solid or suspension leukemia cells detectable at necropsy. In contrast, the median survival of untreated or negative control antibody-treated mice was 40 days (comparison to PM-81 treated; p = 0.006 and p = 0.03, respectively). The mechanism of leukemia cell suppression is not likely due to complement fixation since we could not demonstrate in vitro any cytotoxicity mediated by SCID mouse plasma. Further study is required to understand the mechanism of the antileukemia effect of PM-81 in this model.

Animals↗

PubMed1996

Generation of activated natural killer (A-NK) cells in patients with chronic myelogenous leukaemia and their role in the in vitro disappearance of BCR/abl-positive targets.

Activated natural killer (A-NK) cells, a subset of CD56(dim)CD3- lymphocytes, are obtained from PBMC of normal donors by adherence to plastic and culture in the presence of IL2. In this study we tested the feasibility of generating A-NK cells in patients with Ph+ chronic myeloid leukaemia (CML). Cultures obtained from patients with early chronic phase (ECP; n=7) contained a mean (+/-SD) of83 +/- 7% of CD3- cells, and those from patients with advanced chronic phase (ACP; n=7) contained 27+/-33% CD56+CD3- cells. In three patients with leukaemia in a blastic phase (BP) it was only possible to obtain one culture enriched in CD56+CD3- cells (81%). Cellular aggregates of myeloid cells and large granular lymphocytes were observed in early A-NK cell cultures. Paired freshly-adherent and cultured A-NK cells were tested for the presence of BCR/abl mRNA by RT-PCR. The BCR/abl+ cells were detected in all 12 preparations of the freshly adherent A-NK cells tested. In 6/12 the BCR/abl+ cells were no longer detectable by RT-PCR on day 14 of culture. Both proliferation and antileukaemic cytotoxicity were significantly higher (P=0.002 and P=0.029, respectively) in the BCR/abl- cultures than those in the six BCR/abl+ cultures. 5/6 BCR/abl- cultures were highly enriched in A-NK cells on day 14, and 1/6 contained predominantly CD56+CD3+ cells. Only 2/6 BCR/abl + cultures were enriched in A-NK cells on day 14, but they had poor cytotoxicity and a low proliferative index. Myeloid cells (CD33+) were more frequently detected in the BCR/abl+ than BCR/abl- A-NK cell cultures (P=0.028). These observations suggest that: (1) populations of benign A-NK cells can be generated from the peripheral blood of CML patients; (2) the ability to generate A-NK cells is impaired in patients with advanced CML; and (3) the ability to generate A-NK cells with antileukaemic activity correlates with the disappearance of BCR/abl+ cells from these cultures.

Antigens, CD↗

PubMed1996

A combination of CD34 selection and complement-mediated immunopurging (anti-CD15 monoclonal antibody) eliminates tumor cells while sparing normal progenitor cells.

Autologous bone marrow transplantation (ABMT) for acute myeloid leukemia (AML) in first complete remission (CR) results in a prolonged disease-free survival (DFS) of 34%-57%. Relapse of the underlying disease is the major cause for failure of ABMT. Relapse can result fom tumor cells either surviving in the patient or reinfused in the autograft. Genetic marking of autografted cells has demonstrated that transplanted cells contribute to relapse. This finding supports the use of purged autografts. Several purging techniques have been used. Immunologic purging using the monoclonal antibody (mAb) PM-81 (anti-CD15) has been used by our center with a long-term DFS in 50% of AML patients. PM-81 reacts with 90% of AML patients, and we have used it for over 10 years. We have investigated a two-stage purging technique involving initial selection for CD34+ cells followed by mAb purging in bone marrow (BM) and peripheral blood stem cell (PBSC) harvests. This method achieved up to a 7 log diminution in leukemic cells and 1-4 log reduction in CD15+ cells, without a significant loss of hematopoietic progenitor cells. This double-purging technique has the advantages of cytoreduction, elimination of CD34- leukemic cells, and possible improvement in the clinical efficacy of purging by concentrating for CD34+ cells. Cytoreduction by CD34 enrichment followed by purging may facilitate the use of PBSC transplants in AML.

Antibodies, Monoclonal↗

PubMed1996

High-dose cyclophosphamide, carboplatin, and etoposide with autologous stem cell rescue in patients with breast cancer.

This study was designed to establish the toxicity and response rates o observed with a combination of high-dose cyclophosphamide, carboplatin, and etoposide with stem cell rescue in patients with breast carcinoma. Eligibility criteria included metastatic or locally advanced breast carcinoma ; aged < or equal to 60 years; performance status Eastern Cooperative Oncology Group (ECOG) 0-1; and creatinine clearance > or equal to 65 ml/min. Chemotherapy consisted of cyclophosphamide 25 mg/kg i.v. X 4 days, etoposide 400 mg/m(2) i.v. X 4 days, and carboplatin 375 mg/m(2) X 4 days. Bone marrow or peripheral blood stem cells were reinfused 48 h after completion of chemotherapy. Seventeen patients were treated in this study. The major toxicity was gastrointestinal (grades I and II). Fevers associated with neutropenia were observed in all the patients, but no episodes of bacteremia were documented. Hematopoietic toxicities were acceptable. No toxic deaths were observed. Six patients had chemotherapy-sensitive disease at time of transplant, nine had refractory disease, and two were untested. A response rate of 62% with 18% complete response (CR) was achieved. Two patients are free of disease at +7 and +9 months after transplantation. The combination of high-dose cyclophosphamide, carboplatin, and etoposide is well tolerated with a response rate comparable to previously reported high-dose chemotherapy regimens. However, in a poor prognostic risk group, namely patients with chemoinsensitive disease, this therapeutic approach seems to be of no advantage over standard chemotherapy.

Adult↗

PubMed1996

Toxicity of busulfan and cyclophosphamide (BU/CY2) in patients with hematologic malignancies.

Between July 1991 and January 1994, 52 patients with hematologic malignancies underwent BMT using BU/CY2 as conditioning regimen. Median patient age was 38 years. Eleven patients underwent autologous BMT, 22 HLA-identical allogeneic BMT, and 19 patients underwent a MUD or an allogeneic mismatched BMT. GVHD prophylaxis was with cyclosporine/methylprednisone in 26 patients; T cell depletion was used in 15 patients. VOD was observed in 7.5% of patients, IP in 12%, seizures in 4%. The overall incidence of grade II-IV acute GVHD was 35%. Delayed platelet engraftment was observed in seven of 11 patients who underwent autologous BMT. Graft failure was seen in seven of 19 (37%) patients who underwent MUD or allogeneic mismatched BMT. Six of the seven patients received T cell depletion as GVHD prophylaxis. BU/CY2 transplantation from an unrelated or family-mismatched donor with T cell depletion is associated with a high incidence of graft failure.

Adolescent↗

PubMed1995

Hematopoietic progenitor cell content of vertebral body marrow used for combined solid organ and bone marrow transplantation.

While cadaveric vertebral bodies (VB) have long been proposed as a suitable source of bone marrow (BM) for transplantation (BMT), they have rarely been used for this purpose. We have infused VB BM immediately following whole organ (WO) transplantation to augment donor cell chimerism. We quantified the hematopoietic progenitor cell (HPC) content of VB BM as well as BM obtained from the iliac crests (IC) of normal allogenic donors (ALLO) and from patients with malignancy undergoing autologous marrow harvest (AUTO). Patients undergoing WO/BM transplantation also had AUTO BM harvested in the event that subsequent lymphohematopoietic reconstitution was required. Twenty-four VB BM, 24 IC BM-ALLO, 31 IC AUTO, and 24 IC WO-AUTO were harvested. VB BM was tested 12 to 72 hr after procurement and infused after completion of WO grafting. IC BM was tested and then used or cryopreserved immediately. HPC were quantified by clonal assay measuring CFU-GM, BFU-E, and CFU-GEMM, and by flow cytometry for CD34+ progenitor cells. On an average, 9 VB were processed during each harvest, and despite an extended processing time the number of viable nucleated cells obtained was significantly higher than that from IC. Furthermore, by HPC content, VB BM was equivalent to IC BM, which is routinely used for BMT. We conclude that VB BM is a clinically valuable source of BM for allogeneic transplantation.

Animals↗

PubMed1995

Morphologic characteristics of erythroleukemia (acute myeloid leukemia; FAB-M6): a CALGB study.

We have reviewed the clinical, morphologic, immunophenotypic, and cytogenetic features of 52 patients with erythroleukemia (FAB Cooperative Group; AML-M6) studied by the Cancer and Leukemia Group B (CALGB). The purpose of this study was to correlate morphology with the clinical features, immunophenotypes, and karyotypes of neoplastic cells, and with the response to therapy of patients with AML-M6. Thirty-three patients (63%) were male, median age 59 (range 16-81) years, 47 patients (90%) were white, and 42 patients (81%) had a performance status of < 2. Myelodysplastic changes were observed in at least 1 cell lineage in all cases, and in 2 cell lineages in 45 of 52 (86%) cases. Fifty percent or more of cases studied were positive for CD11b, CD13, CD15, CD33, glycophorin-A, and HLA-DR markers. Fourteen of 27 cases (52%) in whom karyotypic analyses were conducted had cytogenetic abnormalities. Five (19%) were simple (< 3 karyotypic abnormalities), while 9 (33%) were complex (> or = 3 abnormalities). We observed either a complete or partial loss of chromosomes 5, 7, or 12p, or the presence of trisomy 8, in 11 of 27 (41%) patients. Cases of AML-M6 were divided into group 1 (14 patients with bone marrow proerythroblasts and basophilic erythroblasts > 25% of all erythroblasts) and group 2 (38 patients with proerythroblasts and basophilic erythroblasts < or = 25% of all erythroblasts). We observed no significant differences between groups 1 and 2 in regard to sex, age, race, performance status, percentage of blood erythroblasts or myeloblasts, percentage of bone marrow erythroblasts, and periodic acid-Schiff (PAS) or myelodysplasia scores. Six of 6 (100%) patients of group 1, and 7 of 21 (33%) patients of group 2, had normal karyotypes (P = .006). Nine of 13 (69%) patients of group 1 and 15 of 33 (45%) patients of group 2 had a complete remission (CR) (P = .2). Eight of 11 (73%) cytogenetically normal patients achieved CR: 5 of 6 (83%) in group 1, and 3 of 5 (60%) in group 2. Five of 12 (42%) cytogenetically abnormal patients achieved CR. No difference in duration of survival (group 1, median = 4.6 months vs. group 2, median = 10.2 months; P = .93) was observed between the 2 groups. We conclude that AML-M6 is typified by multilineage involvement of hematopoietic cells. The morphology of erythroblasts in patients with AML-M6 may correlate with cytogenetic abnormalities and rate of CR.

Adolescent↗

PubMed1995

A unique population of CD34+ cells in cord blood.

Human umbilical cord blood (CB) is a rich source of hematopoietic stem cells for both research and stem cell transplantation. In clinical studies, it appears that recovery from myeloablative therapy using CB requires significantly fewer cells than a typical allogeneic marrow transplant. This suggests that CB may be enriched for early hematopoietic progenitors. The present studies were undertaken to determine the presence of CD34+ cells in CB with the phenotypic characteristics of multipotential stem cells. In 22 CB harvests, the average percentage of CD34+ cells was 1.33 +/- 0.21% (SE), a value similar to that in adult normal bone marrows (BM). However, the distribution of CD34+ cells was distinctly different from either BM or granulocyte colony-stimulating factor (G-CSF) mobilized peripheral blood stem cell harvests. CB contained a defined population of brightly staining CD34+ cells with low side scatter. These CD34 (bright) cells comprised a mean of 14.5 +/- 2.5% of the CB CD34+ cells, whereas < 1% of BM CD34+ cells has been shown to be CD34- bright. Eighty-five to ninety percent were negative for three antigens expressed at an early stage of stem cell maturation: CD38, HLA-DR and LFA-1. Fifty-five percent of these CD34 (bright) cells did not express the CD45RA isoform, an additional marker of immaturity. The antigen-bright cells also lacked lineage-specific antigens including CD33, CD56, CD19, CD10 and CD7 as well as CD71. Approximately 46% were Thy-1+, and 40% expressed c-kit receptors. These data suggest that, by phenotypic criteria, CB may be a particularly enriched source of primitive hematopoietic precursors.

Antigens, CD↗