摘要:

AbstractAlthough the transfer of “therapeutic” genes into hemopoietic stem cells (HSC) offers many opportunities to treat a wide range of human disease, the low efficiency of transfer and limited expression of the transferred gene have so far largely prevented any direct beneficial effect from being obtained. However, gene marker studies in which the transferred genes are used simply to track the individual components of the infused HSC have already shown their utility. Genetic marking may be used to identify cells capable of causing relapse after autologous bone marrow transplantation and to distinguish cells in the graft capable of preventing malignant disease. Marking may also be used to analyze the consequences of ex vivo or in vivo manipulations of the HSC which are intended to accelerate engraftment or augment gene transfer efficiencies. Information obtained from these studies should therefore not only improve the outcome of HSC based therapies, but also aid in the introduction of successful gene therapy protoc

ISSN:1066-5099    

DOI:10.1002/stem.5530130502

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractInterleukin 11 (IL‐11) is a multifunctional hematopoietic cytokine which was originally identified as a factor produced by an IL‐l‐stimulated primate stromal cell line. The in vitro biological activities of recombinant human (rHu)IL‐11 result predominantly from synergistic interactions with other growth factors. In combination with other cytokines, rHuIL‐11 has been shown to support the formation of primitive hematopoietic and lymphohematopoietic progenitor colonies from bone marrow, to promote erythroid burst formation and to stimulate both early and late stages of megakaryocyte proliferation and differentiation. rHuIL‐11 is biologically active in mice, rats, dogs and primates when administered as a single agent in vivo. The predominant effect of rHuIL‐11 in naive mice was on cells of the megakaryocytic lineage, increasing the number of bone marrow megakaryocyte progenitors, stimulating megakaryocyte endoreplication and increasing peripheral platelet counts in a dose‐dependent fashion. Similar megakaryocytic stimulatory activity was seen in nonhuman primates treated with rHuIL‐11 where platelet counts were increased by as much as 300%. In several models of severe myelosuppression induced by chemotherapy and/or irradiation and in bone marrow transplant models, there were multilineage hematopoietic stimulation following rHuIL‐11 treatment. In these models, accelerated recovery of platelets was a consistent observation, while some models show enhanced neutrophil and red blood cell recovery as well. These results from preclinical studies confirm the broad spectrum of biological activities exhibited by rHuIL‐11 in vitro, and suggest that this cytokine may be an effective agent in the treatment of myelosuppression and thrombocytopenia associated with cancer chemotherapy and bone m

ISSN:1066-5099    

DOI:10.1002/stem.5530130503

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractNon‐Hodgkin lymphomas (NHL) of intermediate and high‐grade malignancy respond well to doxorubicin‐containing regimens, but long‐term survival does not exceed 30% in large studies with long‐term follow‐up. Any attempt to improve this somehow disappointing result by adding more drugs, increasing doses or shortening time intervals of chemotherapy have so far failed in randomized settings. Even autologous bone marrow transplantation (ABMT) could not improve long‐term survival when applied in first remission of the disease. Prophylactic use of hematopoietic growth factors in the chemotherapy of aggressive NHL did prevent neutropenia and positively influenced the occurrence of infectious complications, and also led to an increase of dose intensity (DI) by 15% but this did not affect survival. In contrast, a retrospective analysis of an NHL study showed that a high DI may in fact be deleterious rather than beneficial. Thus the prophylactic use of hematopoietic growth factors still has to be considered experimental in the chemotherapy of NHL and should be studied in controlled settings like the one

ISSN:1066-5099    

DOI:10.1002/stem.5530130504

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractPluripotent hematopoietic stem cells have emerged as a heterogeneous population of cells that differ in phenotype and repopulation kinetics. Stem cells in vitro and in vivo are dependent upon stromal cells for their proliferation and differentiation. Thus, stromal cells can be viewed as tools to analyze the physiological conditions that regulate stem cells. Stromal cell lines that support stem cells are infrequent, which supports the interpretation that stromal cells create distinct niches that regulate stem cell development. A model of stem cell maintenance is presented that predicts that stromal cell‐bound molecules protect stem cells from differentiation. The stroma compartment is highly adaptable and can change its function in response to external stimuli. Thus, it is tempting to speculate that the stroma acts as a translator of peripheral signals for stem cell

ISSN:1066-5099    

DOI:10.1002/stem.5530130505

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn vivo or in vitro activated human B lymphocytes can produce a wide spectrum of cytokines which are involved in the regulation of hematopoiesis and of the inflammatory and immune responses. Three major B cell subsets have been identified in peripheral lymphoid organs: the germinal center (GC), the mantle zone (MZ) and the marginal zone B lymphocytes. GC and MZ B cells can be isolated as CD39‐surface (s)IgD‐or CD39+sIgD+cells, respectively. Therefore, it is now possible to investigate the cytokine producing potential of purified GC and MZ B lymphocytes.In this article, the optimal conditions for the assessment of cytokine production by human B cells are first discussed; thereafter, the spectrum of B lymphocyte‐derived cytokines is described together with their possible physiological meaning. Next, data concerning the cytokines released in vitro by either GC or MZ B cells are presented. Some cytokines, such as granulocyte colony stimulating factor (G‐CSF) or granulocyte‐macrophage CSF (GM‐CSF), are produced only by GC or MZ B lymphocytes, respectively, whereas other cytokines, such as tumor necrosis factor‐α (TNF‐α), interleukin 6 (IL‐6) or IL‐10 are synthesized by both B cell subsets. Finally, the relationships between B cell‐derived cytokines and apoptosis of GC B lymphocytes are discussed, and a hypothetical model of the cytokine networks in secondary lymphoid follicles is presented. It is expected that these notions will help to clarify the pathophysiology of lymphoproliferative

ISSN:1066-5099    

DOI:10.1002/stem.5530130506

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractAt present, chemotherapy is not very effective against common solid cancers, especially once they have metastasized. However, laboratory experiments and studies on dose intensification in humans have indicated that some anticancer agents might be curative, but only if the dose given was very much higher than that attainable clinically. Prodrugs activated by enzymes expressed at a high level in tumors can deliver at least 50‐fold the normal dose and can cure animals with tumors normally resistant to chemotherapy. The approach is not practicable clinically because of the rarity of human tumors expressing a high level of an activating enzyme. However, new therapies have been proposed that overcome this limitation of prodrug therapy. Enzymes that activate prodrugs can be directed to human tumor xenografts by conjugating them to tumor‐associated antibodies. After allowing for the conjugate to clear from the blood a prodrug is administered which is normally inert, but which is activated by the enzyme delivered to the tumor. This procedure is referred to as ADEPT (antibody‐directed enzyme prodrug therapy). Using different combinations of antibody, enzyme and prodrug, many classes of human tumor xenograft have been shown to be very sensitive to this procedure although in most cases they are quite resistant to conventional chemotherapy. Early clinical trials are promising and indicate that ADEPT may become an effective treatment for all solid cancers for which tumor‐associated or tumor‐specific antibodies are known. Tumors have also been targeted with the genes encoding for prodrug activating enzymes. This approach has been called virus‐directed enzyme prodrug therapy (VDEPT) or more generally GDEPT (gene‐directed enzyme prodrug therapy) and has shown good results in laboratory systems. These new therapies may finally realize the potential of prodrugs in cancer

ISSN:1066-5099    

DOI:10.1002/stem.5530130507

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe elevated white cell counts (WCC) and myeloid progenitor cell levels in the blood induced by granulocyte colony‐stimulating factor (G‐CSF) treatment were studied in three settings: cancer patients previously treated with chemo/radiotherapy (n = 13), untreated cancer patients (n = 5) and normal volunteers (n = 9). The inter‐individual variations in progenitor cell mobilization responses to G‐CSF and the impact of previous chemo/radiotherapy were investigated. The absolute levels of circulating progenitor cells, but not total white cells, were reduced significantly in the pretreated cancer patients (median 961, range 289–3355 per ml blood) as compared to untreated cancer patients (median 9891, range 2219–16625 per ml blood). In each setting, wide ranges of circulating progenitor cell numbers were observed, and the variation in progenitor cell numbers was considerably greater than observed for the WCC. However, progenitor cell numbers in normal volunteers (942–25296 per ml blood) demonstrated as much variance as observed in pretreated cancer patients. This broad physiological variation in progenitor cell levels induced by G‐CSF needs to be considered when designing strategies for allogeneic peripheral blood stem cell

ISSN:1066-5099    

DOI:10.1002/stem.5530130508

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractIt is known that treatment of mice with 5‐fluorouracil (5‐FU, 150 mg/kg) confers radioprotection. To investigate this effect, we performed bone marrow transplantation (BMT) using C57BL/6‐Ly5 congenic mice treated with 5‐FU five days prior to experiments. The mononuclear cells (MNC) in 5‐FU‐treated bone marrow (BM) were 10 times more radioprotective than those in untreated BM. Moreover, the number of BM MNC expressing c‐kiton their surface from 5‐FU‐treated mice was markedly decreased relative to those from untreated controls. These results showed that the surface characteristics of cells that contributed to this radioprotective effect differ from those of stem cells as reported recently. BM MNC of mice treated with 5‐FU were separated on the basis of expression of the lineage‐specific antigens (Lin), c‐kit, and Ly6A/E. When injected into lethally irradiated mice, 1,000 Lin+and Lin‐c‐kit+Ly6A/E+cells showed radioprotective effects such that 100% and 60% survived, respectively. Flow cytometric analysis 165 days after BMT showed that 88.8% and 65.1% of peripheral blood (PB) in mice transplanted with Lin+and Lin‐c‐kit+Ly6A/E+was derived from donor mice, respectively. After six months, donor‐derived Lin‐c‐kit+Ly6A/E+cells which showed radioprotective effects on a secondary irradiated host were detected from mice transplanted with Lin+cells from 5‐FU‐treated mice. Taken together, these findings demonstrated that stem cells expressing Lin+present in the BM of mice treated with 5‐FU other than Lin‐c‐kit+Ly6A/E+cells and these Lin+cells play an impor

ISSN:1066-5099    

DOI:10.1002/stem.5530130509

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractInterest in the isolation and characterization of primitive hemopoietic cells in both the clinical and research fields has rapidly increased. In parallel, different purification systems have been developed to isolate these cells.We have compared five different methods for separation of CD34+cells from human umbilical cord blood, normal bone marrow and apheresis harvests and analyzed purity, recovery, yield and enrichment of colony forming cells (CFC) for each individual system.Our results indicate that the most reliable methods of purification for all samples were fluorescence activated cell sorting (FACS) and magnetic activated cell sorting (MACS) which consistently yielded high purities (>70%) and enrichment of CFC. In this respect the enrichment of CFC from the MACS was superior to all the other systems including FACS. Similar results (>70%) for purity were obtained using avidin affinity columns and a biotinylated antibody but neither yield nor CFC enrichment approached the values achieved with MACS. On average CFC enrichment using these affinity columns was greater than that observed for FACS while the purity was comparable.Both CELLector flasks and immunomagnetic beads coated with CD34 antibodies were less effective in our hands in separating purified populations of progenitor cells. Both purity and CFC enrichment of CD34+cells using these methods were at least 50% lower than obtained with either FACS, MACS or affinity columns.

ISSN:1066-5099    

DOI:10.1002/stem.5530130510

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY

摘要:

AbstractUmbilical cord blood (CB) has been evaluated as a potential source of hematopoietic stem cells suitable for clinical use in the transplantation setting. Previous reports have documented a significant loss of progenitor cells by any manipulation other than cryopreservation. We have evaluated the feasibility of fractionating and cryopreserving CB samples with minimal loss of progenitor cells. We have compared various separation procedures based on different density gradients in the attempt to obtain the highest depletion of red blood cells (RBC) while maintaining the highest recovery of progenitor cells. We compared three different densities of Percoll (1.069 g/ml, 1.077 g/ml, 1.084 g/ml), sedimentation over poligeline (Emagel) and sedimentation over poligeline followed by separation over Ficoll/Hypaque (F/H). Separated samples (n = 25) were analyzed for recovery of CD34+cells and progenitor cells (CFU‐GEMM, BFU‐E, CFU‐GM). Separation by sedimentation over poligeline followed by F/H allowed the highest depletion of RBC (hematocrit of the final cellular suspension 0.4 ± 0.1%) while maintaining high recovery of CD34+cells (85.3 ± 5.6%) and total recovery for CFU‐GEMM, BFU‐E and CFU‐GM. After cryopreservation, recovery of clonogenic progenitors was 82% for CFU‐GEMM, 94% for BFU‐E, 82% for CFU‐GM and 90% for colony‐forming units (CFUs) after five weeks of long‐term culture (LTC). We further evaluated the effect of stem cell factor (SCF) on the in vitro growth of hemopoietic progenitors and on replating efficiency. The presence of SCF significantly increased CFU‐GEMM (14 ± 4 versus 49 ± 5,p<0.0005) and CFU‐GM (112 ± 18 versus 178 ± 19,p<0.025), as well as the replating efficiency of CB progenitor cells (21 ± 3.5% versus 43.3 ±4.7%) and the number of CFC per replated colony (4.7 ± 3.5 versus 12.6 ± 5.3,p<0.005). In conclusion, RBC depletion of umbilical CB can be accomplished with minimal loss of committed and primitive hemopoietic progenitors. This procedure may have important implications in the large‐scale banking of CB as well as ex

ISSN:1066-5099    

DOI:10.1002/stem.5530130511

出版商:John Wiley&Sons, Ltd.    

年代:1995

数据来源: WILEY