摘要:

AbstractAssay of hematopoietic precursor cells in diffusion chambers (DCs) implanted intraperitoneally in experimental animals provides a powerful tool for studying stem cell kinetics in vivo. In this system, the effect of cell migration (which complicates whole animal studies) is eliminated because the membranes utilized in the construction of the chambers are impermeable for cells, while permitting free passage of molecules present in the humoral phase of the host. As judged by light microscopy, conditions in the DC cultures primarily favor macrophage and granulocyte growth. However, the use of in vitro and in vivo subculture to further analyze chamber contents has demonstrated that the system supports proliferation of early hematopoietic progenitors. Additionally, cells capable of rescuing lethally irradiated mice proliferate in DC cultures. Development of the plasma clot DC technique has revealed that most of the growth occurs in colonies which are derived from single cells (CFU‐d). Characterization of these cells indicates that they are at least as primitive as other colony‐forming cells and, also based on subculture studies, can differentiate along several hematopoietic lineages. In addition to normal CFU‐d, both embryonal and leukemic cells can give rise to granulocytes, macrophages, megakaryocytes and erythroid cells in the DC cultures. Evaluation of the effects of humoral factors on hematopoietic cell proliferation and differentiation in the system has led to the identification of both stimulators and inhibitors that may be different from the well‐characterized cytokines. Thus, the system seems to be useful for detecting molecules controlling the most primitive stages of hematopoiesis. We believe that the DC culture technique holds enormous potential in the study of stem cell proliferation and differentiation

ISSN:0737-1454    

DOI:10.1002/stem.5530070602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe clinical association of an increased incidence of acute myelogenous leukemia (AML) with previous chemoradiotherapy, the detection of specific karyotypic changes in these secondary (therapy‐induced) cases of AML and the discovery of increasing levels of oncogene‐specific RNA in leukemia cells suggest that one potential site of action of environmental agents might be the proto‐oncogenes in human hematopoietic stem cells. The location of human proto‐oncogenes at the sites of chromosome breaks and/or translocations in cells from some patients with leukemia or lymphoma is a striking observation. These data stimulated research into the mechanism of activation of specific oncogenes that change the biology of human hematopoietic cells. Recent investigations have focused upon several areas that might alter cell biology including: 1) translocation and/or inversion of chromosome fragments containing a proto‐oncogene to a location where other gene sequences can stimulate oncogene activation, 2) replication of copy number of proto‐oncogenes or increased transcriptional activity and 3) point mutation in proto‐oncogenes leading to a structurally altered protein. The third area of research has recently received significant attention with respect to the potential role of three ras genes (c‐Harvey‐rar, c‐Kirsten‐ras and N‐ras) in human leukemias and myelodysplastic syndromes. Recent studies have proposed a model for leukemogenic transformation of human hematopoietic cells by the product of a mutated ras oncogene. Mutations at codons 12, 13 or 61 of the first exon of its 4.7 Kb of DNA (for c‐Ha‐rar) have been described. Other data revealing an absence of such mutations in the ras genes of many human leukemias and the absence of detectable transcription of ras genes in many alkylating agent‐associated cases of AML, suggest that while ras mutations may be involved in some settings, there are probably multiple genetic pathways to leukemogenic transformation

ISSN:0737-1454    

DOI:10.1002/stem.5530070603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThis report presents the results of an investigation in which Gel‐Well culture chambers were evaluated for their utility as a liquid culture assay system to measure the responses of hematopoietic colony‐forming cells (CFC) to recombinant and cell‐derived growth factors. Gel‐Wells, designed for anchorage‐independent cell growth and diffusion of media components, permitted the weekly replacement of media and growth factors without removing cells from the culture chambers. In these studies, changes in cellularity and CFC content in Gel‐Well cultures of human umbilical cord blood cells induced by recombinant interleukin 3 (rIL‐3) were quantified. After one week in culture without rIL‐3, the number of erythroid burst‐forming units (BFU‐e) had decreased to 25 ± 38% of pre‐values. In contrast, addition of rIL‐3 induced an increase in the number of BFU‐e to 390 ± 135% of pre‐values. By three weeks with rIL‐3, the number of granulocyte‐macrophage colony‐forming units (CFU‐gm) had increased to 292 ± 58% of pre‐values. Also, the presence of a bone marrow stromal cell layer under the Gel‐Well helped to maintain the survival of CFC in liquid culture. These studies demonstrated that Gel‐Well culture chambers provide a useful liquid culture system for stu

ISSN:0737-1454    

DOI:10.1002/stem.5530070604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractLong‐term hemopoiesis in culture depends upon the presence of an adherent layer composed of a variety of stromal cells. A subtype of endothelial‐adipocytes from the bone marrow stroma (clone 14F1.1) was previously shown to induce long‐term myelopoiesis and renewal of pluripotent stem cells. One of a series of stromal cell lines and clones from mouse thymus stroma (STAC‐1.2) has now been found to support long‐term hemopoiesis. These marrow‐ and thymus‐derived stromal cell clones also have lymphopoietic activities: precursor T cells, or pre‐B cells accumulated in co‐cultures of thymus cells and the stromal clones, as indicated by cell surface markers, T cell receptor and immunoglobulin gene rearrangements. The predominance of a cell type in these cultures depended upon the serum used to supplement the medium. Recombinant interleuldn 2 (IL‐2) and the 14F1.1 clone synergistically promoted the proliferation of thymocytes, while a thymus hormone, THF‐Gm2, shifted the population to a relatively mature phenotype. It is proposed that one major function of stromal cells, whether from the bone marrow or thymus, is to restrain the maturation flow and preferentially support the accumulation of cells at early d

ISSN:0737-1454    

DOI:10.1002/stem.5530070605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

摘要:

AbstractThe effects of heat and the interaction between hyperthermia and alkylating agents, such as cisplatin (CDDP) and melphalan (L‐PAM) in human malignant melanoma biopsies have been investigated by a short‐term assay based upon the inhibition of H‐thymidine incorporation. Cell suspensions from 50 cutaneous and lymph nodal metastases were heated at 40.5°C or at 42°C for 1 h. There were significant antiproliferative effects due to heat in 10% of the tumors exposed to 40.5°C and 34% to 42°C. Thermal resistance was evident in 73% (at 40.5°C) and 54% (at 43°C) of tumors, and there was significant enhancement of cell growth in 17% and 12% of tumors. The combined effects of hyperthermia and drugs were studied on 36 tumors. Cell suspensions were exposed to different concentrations of CDDP or L‐PAM for 1 h at 40.5°C and 42°C. Synergy between heat and CDDP was observed in 7% of cases treated with the lowest drug dose and 38% of cases treated with the highest (40.5°C), with only a slight increase in the frequency of synergy at 42°C. Synergy between heat and L‐PAM was also observed in 12% to 44% of tumors at 42°C as a function o

ISSN:0737-1454    

DOI:10.1002/stem.5530070606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0737-1454    

DOI:10.1002/stem.5530070607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0737-1454    

DOI:10.1002/stem.5530070608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0737-1454    

DOI:10.1002/stem.5530070609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0737-1454    

DOI:10.1002/stem.5530070610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY

ISSN:0737-1454    

DOI:10.1002/stem.5530070601

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1989

数据来源: WILEY