Establishment and characterization of a new murine cell line (SR-4987) derived from marrow stromal cells

A new murine cell line designated as SR-4987 was established by treating a long-term bone marrow culture with the supernatant from Y-1 cells which actively produce viral C-particles (MuLV). The line showed a fibrolbast-like morphology and its mesodermal origin was confirmed by immunocytochemical staining. Flow cytometric analysis of DNA index evidenced a tetraploid number of chromosomes whereas cell cycle analysis showed 34.8% of cells in S phase and 60.7% in G1.In vitro growth studies demonstrated a population doubling time of 14.7h, a good plating efficiency (52.3%) and a very poor agar clonogenic capacity (0.6%). SR-4987 was tumorigenic only in syngeneic mice in which sarcomas were induced. The line produced M-CSF in the culture supermatant whereas G-CSF, IL-3 and GM-CSF were not detected. Studies are in progress to assess the production of other cytokines and to verify if same autocrine growth factor is involved in the control of SR-4987 proliferation. Our line provides a further model of stromal cells for studying the interaction between hemopoietic progenitors and their micro-environment, as well as to study factors produced by stromal cells acting as modulators of proliferation and differentiation of related cell populations.     

Rescue of myeloid lineage-committed preprogenitor cells from cytomegalovirus-infected bone marrow stroma.

The effect of murine cytomegalovirus on myelopoiesis was studied in long-term bone marrow culture to find an in vitro correlate for the lethal virus interference with bone marrow reconstitution (W. Mutter, M. J. Reddehase, F. W. Busch, H.-J. Bühring, and U. H. Koszinowski, J. Exp. Med. 167:1645-1658, 1988). The in vitro generation of granulocyte-monocyte progenitors (CFU-GM) discontinued after infection of the stromal cell layer, whereas the proliferation and differentiation of CFU-GM to granulocyte-monocyte colonies remained unaffected. A protocol was established to probe the functional integrity of earlier hematopoietic cells. Pre-CFU-GM (the progenitors of the CFU-GM) could be recovered from an infected bone marrow donor culture by transfer onto an inductive recipient stromal cell layer. Thus, at least in vitro, infection of bone marrow stroma appears to be the only cause of the defect in myelopoiesis.     

A mesenchymal stromal cell line resistant to paclitaxel that spontaneously differentiates into osteoblast-like cells

The mesenchymal stromal cell line SR-4987 has been established in our laboratory from the bone marrow of BDF/1 mice. Recent information on mesenchymal stem cells biology and the need to deal with well-characterized cell lines suggest to critically consider the existent data on this cell line by updating them with new investigations on growth parameters, in vitro plasticity, and drug sensitivity to anti-cancer, anti-inflammatory, and a histone deacetylase inhibitor. SR-4987 cells show a population doubling time of 24.5 ± 5.4 h, a plating efficiency of 2.87 ± 1.19%, and under stimulation maintain only in part their multipotency by differentiating towards chondro-osteogenic lineages but not into adipogenic. Surprisingly, these mesenchymal stromal cells differentiate spontaneously into osteoblast-like cells and this is significantly stimulated by valproic acid. SR-4987 cells show a dramatic resistance to paclitaxel (PTX) with a resistance index of 39.6 times (evaluated versus MOLT-4 leukemia) and of 68.2 (versus HT-29 colorectal carcinoma). SR-4987 resistance is reversed by verapamil and correlates with high expression of P-glycoprotein that is down-modulated by PTX. Taken together, our results indicated that SR-4987 line is a very interesting cell model useful to investigate both drug sensitivity resistance and physiopathological aspects related to mesenchymal cell function.     

小鼠胎肝基质细胞造血刺激因子体外生物活性研究

本实验对基质细胞造血刺激因子－１（ＳＨＦ－１）的体外生物活性进行了研究。结果表明,ＳＨＦ－１可刺激小鼠骨髓ＣＦＵ－Ｅ、ＢＦＵ－Ｅ、ＣＦＵ－ＧＭ、ＣＦＵ－Ｍｉｘ集落的形成,它产生的这些广泛造血刺激作用是其自身所具活性的直接影响。正常小鼠骨髓细胞与ＳＨＦ－１在体外孵育４ｈ,其中ＣＦＵ－Ｓ的自杀率可提高约１０％,显示它对造血干细胞也有诱导增殖作用。     

Thy-1 is a differentiation antigen that characterizes immature murine erythroid and myeloid hematopoietic progenitors

To determine the role of Thy-1 antigen in murine hematopoietic differentiation, bone marrow was treated with anti-Thy-1.2 antibody and complement or complement alone. Growth of immature hematopoietic progenitors, erythroid burst-forming units (BFU-E), and granulocyte/macrophage colony-forming units (CFU-GM) was greatly reduced following antibody and complement treatment and was not restored by mitogen-stimulated spleen cell supernatants. In contrast, more mature erythroid and myeloid progenitors, the erythroid colony-forming unit (CFU-E) and the macrophage progenitor stimulated by L-cell-conditioned media (LCM), were spared by anti-Thy-1.2 antibody and complement treatment. Here, to separate the effects of anti-Thy-1.2 antibody treatment on accessory cells from those on progenitors, splenic T cells and thymocytes were added to treated marrow at ratios of up to 200%. Growth of BFU-E and CFU-GM was not restored. To more precisely replace required accessory cells, male complement-treated marrow was cocultured with female anti-Thy-1.2 antibody and complement-treated marrow. Even marrow cells failed to restore female BFU-E and CFU-GM growth. Fluorescent-activated cell sorting (FACS) and immune sheep red cell rosetting with anti-Thy-1.2-labeled marrow were then performed to determine if immature hematopoietic progenitors bear Thy-1.2. These techniques revealed enrichment of BFU-E and CFU-GM in the Thy-1.2-positive fraction, demonstrating the presence of Thy-1.2 on early murine hematopoietic progenitors. CFU-E and CFU-M were present in the Thy-1.2-negative fraction following FACS separation. These data demonstrate that Thy-1.2 is a differentiation antigen, present on at least some murine BFU-E and CFU-GM and lost as they mature to CFU-E and CFU-M.     

Multipotent marrow stromal cell line is able to induce hematopoiesis in vivo.

Several murine marrow stromal cells were established from murine bone marrow cultures. Stromal cell lines transfected with a tumor-inducing polyoma virus middle T antigen (MTAg) were inoculated into nude mice subcutaneously. KUSA-MTAg cells, one of these cell lines, led to the rapid local development of bone marrow consisting of trilineage hematopoietic cells and bone; other cell lines produced spindle cell sarcoma or hemangiosarcoma. These results suggested that a single stromal cell line, KUSA-MTAg cells, may induce hematopoietic stem cells or early progenitors of three lineages of hematopoietic cells in vivo. Interestingly, untransfected KUSA cells expressed three new mesenchymal phenotypes, osteocytes, adipocytes, and myotubes, after treatment with 5-azacytidine.     

In vitro inhibition of murine hematopoietic progenitors and stromal cells by vinorelbine

Hematopoietic progenitor colony assays were used to establish the effects of the vinca alkaloid vinorelbine (VRB) on murine bone marrow. The in vitro growth of colony-forming units–granulocyte/macrophage (CFU-GM), burst forming units–erythroid (BFU-E) and colony-forming units–mix (CFU-mix) was dose-dependently inhibited by VRB. The highest dose assayed (0.02 μg/ml) suppressed all of the different progenitor cells by 100%. A comparison of the dose–response curves showed that CFU-GM, BFU-E, and CFU-mix exhibited similar patterns of sensitivity to the cytotoxic action of VRB. Long-term bone marrow cultures have provided a valuable in vitro model for studying the role of the microenvironment of bone marrow. Cellularity of stromal layers was reduced with increasing doses of VRB. The appearence of these layers was altered minimally with the lowest dose used; a gradual loss of cellularity was seen in cultures exposed to 0.05 and 0.075 μg/ml; and a marked loss at the dose of 0.1 μg/ml. Our results show that VRB has an important effect on hematopoietic progenitors at the highest dose tested, while the stromal cells were not affected at a similar dose (0.025 μg/ml), suggesting that the stroma is more resistant to this drug. This revised version was published online in July 2006 with corrections to the Cover Date.     

Systematic analysis of the ability of stromal cell lines derived from different murine adult tissues to support maintenance of hematopoietic stem cells in vitro.

Hematopoietic stem cells interact with a complex microenvironment both in vivo and in vitro. In association with this microenvironment, murine stem cells are maintained in vitro for several months. Fibroblast-like stromal cells appear to be important components of the microenvironment, since several laboratories have demonstrated that cloned stromal cell lines support hematopoiesis in vitro. The importance of the tissue of origin of such cell lines remains unknown, since systematic generation of stromal cell lines from adult tissues has never been accomplished. In addition, the capacity of stromal cell lines to support reconstituting stem cell has not been examined. We have previously described an efficient and rapid method for the immortalization of primary bone marrow stromal cell lines (Williams et al., Mol. Cell. Biol. 8:3864-3871, 1988) which can be used to systematically derive cell lines from multiple tissues of the adult mouse. Here we report the immortalization of primary murine lung, kidney, skin, and bone marrow stromal cells using a recombinant retrovirus vector (U19-5) containing the simian virus large T antigen (SV40 LT) and the neophosphotransferase gene. The interaction of these stromal cells with factor-dependent cells Patterson-Mix (FDCP-Mix), colony forming units-spleen (CFU-S), and reconstituting hematopoietic stem cells was studied in order to analyze the ability of such lines to support multipotent stem cells in vitro. These studies revealed that stromal cell lines from these diverse tissues were morphologically and phenotypically similar and that they quantitatively bound CFU-S and FDCP-Mix cells equally well. However, only those cell lines derived from bone marrow-supported maintenance of day 12 CFU-S in vitro. One lung-derived stromal cell line, ULU-3, supported the survival of day 8 CFU-S, but not the more primitive CFU-S12. A bone marrow-derived stromal cell line, U2, supported the survival of long-term reconstituting stem cells for up to 3 weeks in vitro as assayed by reconstitution 1 year post-transplant. These studies suggest that adherence of HSC to stromal cells is necessary but not sufficient for maintenance of these stem cell populations and that bone marrow provides specific signals relating to hematopoietic stem cell survival and proliferation.     

Generation of murine stromal cell lines supporting hematopoietic stem cell proliferation by use of recombinant retrovirus vectors encoding simian virus 40 large T antigen.

The bone marrow is a complex microenvironment made up of multiple cell types which appears to play an important role in the maintenance of hematopoietic stem cell self-renewal and proliferation. We used murine long-term marrow cultures and a defective recombinant retrovirus vector containing the simian virus 40 large T antigen to immortalize marrow stromal cells which can support hematopoiesis in vitro for up to 5 weeks. Such cloned cell lines differentially supported stem cells which, when transplanted, allowed survival of lethally irradiated mice, formed hematopoietic spleen colonies in vivo, and stimulated lymphocyte proliferation in vitro. Molecular and functional analyses of these cell lines did not demonstrate the production of any growth factors known to support the proliferation of primitive hematopoietic stem cells. All cell lines examined produced macrophage colony-stimulating factor. The use of immortalizing retrovirus vectors may allow determination of unique cellular proteins important in hematopoietic stem cell proliferation by the systematic comparison of stromal cells derived from a variety of murine tissues.     

Bone marrow stromal cells selectively stimulate the rapid expansion of lineage-restricted myeloid progenitors

Bone marrow stromal cells serve hematopoietic microenvironments where different blood cells are controlled in their growth and differentiation. To characterize functions of stromal cells, 33 bone marrow stromal cells including preadipocytes, endothelial cells, and fibroblasts were established from transgenic mice harboring temperature-sensitive SV40 T-antigen gene and their selective stimulatory abilities to support large colony formation of lineage-specific hematopoietic progenitor cells (erythroid, monocyte/macrophage, granulocyte, and monocyte-granulocyte) were examined. Among established stromal cells, 27 clones showed erythropoietic stimulatory activity in the presence of erythropoietin. On myeloid progenitors, the stromal cells showed lineage-restricted stimulatory activity and a reciprocal relationship was observed between granulocyte formation and macrophage formation, but these activities were not dependent on the amount of produced colony-stimulating factors (CSFs). Our present study with many stromal cells established from bone marrow indicated that each stromal cell in the bone marrow may provide the preferable microenvironment for a rapid expansion of the lineage-restricted progenitor cells in combination with CSFs. © 1995 Wiley-Liss, Inc.     

Demonstration of a protector effect of interleukin-1 against hematologic toxicity of azidothymidine (AZT)]

3'-azido-3'-deoxythymidine (Azidothymidine or AZT) has attained wide critical utility in the treatment of acquired immunodeficiency syndrome (AIDS). Unfortunately, treatment with AZT is associated with the development of severe hematopoietic toxicity. The AZT sensitivity of marrow progenitors was different with an IC 50 of 10(-8) M and 10(-6) M for respectively BFU-E and CFU-GM/GEMM. Data reported here show that recombinant human interleukin-1 alpha (IL-1 alpha), a pleiotropic cytokine, was demonstrated to be efficient to protect normal human as well as murine hematopoietic progenitors (CFU-GM, CFU-GEMM and BFU-E) from the toxic effect of AZT. The maximal effect was observed with 30 U/ml (Human cells) or 100 U/ml (murine cells) IL-1 alpha for BFU-E and CFU-GM/GEMM, with a marked effect at 1 U/ml. The results demonstrate that marrow progenitors respond differently to AZT and point out the potential efficacy of IL-1 alpha to enhance the proliferation of hematopoietic stem cells treated with growth factors (IL-3, erythropoietin) and to minimize the hematopoietic toxicity associated with AZT treatment.     

Large-scale production of murine bone marrow cells in an airlift packed bed bioreactor

Large-scale cultivation of murine bone marrow cells was accomplished in an airlift packed bed bioreactor system designed to mimic the in vivo bone marrow environment. The attachment-dependent stromal cell population, which provides the necessary microenvironment, including growth factors for subsequent hematopoietic activity, was first established within the bioreactor. This attachment-dependent cell growth occurred on the fiber-glass matrix packed in the annular region of the bioreactor. Once the stromal cell layer was established, fresh bone marrow cells were inoculated to initiate hematopoiesis. However, traditional culture medium was found to be inadequate for the initiation of hematopoiesis, but the use of stromal cell "conditioned" medium (with no exogenously added growth factors) yielded sustained cell production. The extent of stromal cell subculturing prior to inoculation into the bioreactor and the inoculation density were also important factors for the successful initiation of hematopoietic activity. A 500-mL perfusion culture experiment resulted in the production and harvest of 3.6 x 10(8) suspended bone marrow cells over the course of 11 weeks. (c) 1996 John Wiley & Sons, Inc.     

Vascular cell adhesion molecule-1 expression and hematopoietic supportive capacity of immortalized murine stromal cell lines derived from fetal liver and adult bone marrow

Ontogeny-specific differences in hematopoietic behavior may be influenced by unique adhesive interactions between hematopoietic cells and the microenvironment, such as that mediated by vascular cell adhesion molecule-1 (VCAM-1, CD 106). Although VCAM-1 is variably expressed during vertebrate development, we hypothesized that VCAM-1 expression might be linked to the enhanced capacity of the fetal liver microenvironment to support hematopoiesis. To test this we used immortalized murine stromal cell lines derived from midgestation fetal liver and adult bone marrow to compare the functional expression of VCAM-1. Molecular analysis of VCAM-1 expression was performed on stromal cell lines using Northern blot analysis, immunoprecipitation studies, and solid-phase enzyme-linked immunosorbent assay. Hematopoietic studies were performed by coculturing fetal liver cells with stromal cell lines, and the functional readout was determined by high-proliferative potential colony-forming cell (HPP-CFC) adherence assays. In contrast to our initial hypothesis, we observed greater expression of VCAM-1 messenger ribonucleic acid and protein on an adult marrow stromal cell line. In functional studies, anti-VCAM-1 antibody inhibited the binding of nearly half of the HPP-CFCs to adult marrow stroma but had a minimal effect on their binding to fetal liver stroma, despite the greater adherence of HPP-CFCs to fetal stroma. We conclude that VCAM-1 influences the hematopoietic supportive capacity of immortalized murine stroma derived from adult bone marrow. Our studies suggest that cellular interactions other than those mediated by VCAM-1 are involved in the increased adhesive capacity of immortalized murine stroma derived from fetal liver.     

Use of in vitro assays to assess hematotoxic effects of environmental compounds

The number of chemicals being introduced into the environment increases and many of these substances may pose a health risk to exposed individuals. Many environmental toxicants with a potential toxicity to the hematopoietic system have been identified by animal experiments. Owing to the risks of severe chronic hematopoietic disorders, it is important to screen chemicals for their hematotoxicity. The aim of this work was to identify, through the use ofin vitro techniques, targets for hematotoxic effects. Our study focused on myeloid and erythroid hematopoietic progenitors and stromal stem cells as possible targets. Thein vitro assays showed that various hematotoxic compounds exert different effects on these cell populations. In vitro exposure of murine bone marrow cells to various inorganic (cadmium, lead) and organic (benzene metabolites, lindane, benzo-[a]-pyrene (BaP), PCB (polychlorinated biphenyl) congeners) environmental chemicals indicated that hematopoietic or stromal bone marrow cells were targets for most of the chemicals. Stromal cells were more affected by lead, cadmium, and BaP compared to myeloid cells. Benzene and phenol gave no response, but the metabolites catechol and hydroquinone were equally toxic to the stromal and the myeloid progenitor cells. Among the PCBs tested, PCB126 was most toxic. Human progenitor cells derived from cord blood were exposedin vitro to catechol, hydroquinone, lead nitrate, and PCBs. Human hematopoietic cells were sensitive to the tested compounds. Human erythroid progenitors are more susceptible to lead exposure than are myeloid progenitors. Based on thein vitro tests, humans are more sensitive to lead, catechol, and PCB126 than are mice. In contrast to the murine data, humans responded with individual differences to lead and PCB126. This revised version was published online in July 2006 with corrections to the Cover Date.     

Self-renewing osteoprogenitors in bone marrow sinusoids can organize a hematopoietic microenvironment

The identity of cells that establish the hematopoietic microenvironment (HME) in human bone marrow (BM), and of clonogenic skeletal progenitors found in BM stroma, has long remained elusive. We show that MCAM/CD146-expressing, subendothelial cells in human BM stroma are capable of transferring, upon transplantation, the HME to heterotopic sites, coincident with the establishment of identical subendothelial cells within a miniature bone organ. Establishment of subendothelial stromal cells in developing heterotopic BM in vivo occurs via specific, dynamic interactions with developing sinusoids. Subendothelial stromal cells residing on the sinusoidal wall are major producers of Angiopoietin-1 (a pivotal molecule of the HSC "niche" involved in vascular remodeling). Our data reveal the functional relationships between establishment of the HME in vivo, establishment of skeletal progenitors in BM sinusoids, and angiogenesis.     

Microenvironmental Scenario of the Bone Marrow of Inorganic Arsenic-Exposed Experimental Mice

Exposure to arsenic on a regular basis, mainly through drinking water, agricultural pesticide, and sometimes therapeutic dose, results in various diseases of different tissues including the bone marrow hematopoietic system. Hematopoiesis is a dynamic process by which bone marrow (BM) hematopoietic stem/progenitor cells (HSPCs) generate a relatively constant pool of functionally mature blood cells by the support of microenvironmental components. The present study has been aimed to understand stem cell microenvironmental status during arsenic toxicity and the consequent reflection of dysregulation involving the hematopoietic machinery in experimental mice. Swiss albino mice were experimentally exposed to 10 μg arsenic trioxide/g body weight through oral gavage and 5 μg arsenic trioxide/g body weight intraperitoneally for a period of 30 days. Altered hemogram values in peripheral blood reflected the impaired hematopoiesis which was further validated by the reduced BM cellularity along with the deviated BM cell morphology as observed by scanning electron microscopy post arsenic exposure. The stromal cells were unable to establish a healthy matrix and the sustainability of hematopoietic progenitors was drastically affected in arsenic-exposed mouse groups, as observed in in vitro explant culture. The inability of stromal cells to establish supportive matrix was also explained by the decreased adherent colony formation in treated animals. Furthermore, the flow cytometric characterization of CXCR4⁺ and Sca-1⁺ CD44⁺ receptor expressions confirmed the dysregulation in the hematopoietic microenvironment. Thus, considering the importance of microenvironment in the maintenance of HSPC, it can be concluded that arsenic toxicity causes microenvironmental damage, leading to niche derangement and impaired hematopoiesis.     

Protection of 3'-azido-3'-deoxythymidine induced toxicity to murine hematopoietic progenitors (CFU-GM, BFU-E and CFU-MEG) with interleukin-1

3'-Azido-3'-deoxythymidine (AZT) has attained wide clinical utility in the treatment of acquired immunodeficiency syndrome (AIDS). Unfortunately, associated with AZT use, is the development of severe hematopoietic toxicity as manifested by anemia, neutropenia and overall bone marrow suppression. Interleukin-1 (IL-1), a cytokine, primarily produced by activated macrophages, has been involved in the control of hematopoiesis by acting synergistically with other hematopoietic growth factors, and has been demonstrated to be an effective agent in reducing the myelosuppression associated with the therapy for malignant disease. We report here the ability of recombinant human IL-1 alpha to protect normal murine hematopoietic progenitors (CFU-GM, BFU-E, and CFU-Meg) from the toxic effects of AZT. Following the determination of the LD50 dose for each progenitor, IL-1 was added in co-culture studies (10-1000 units; 0.001-1.0 micrograms/ml protein) with adherent cell depleted marrow. Marrow progenitors expressed differences in AZT sensitivity, e.g., BFU-E, LD50 5 x 10(-9)M; CFU-Meg, LD50 10(-7) M; CFU-GM, 5 x 10(-5) M respectively. IL-1 inhibited AZT induced toxicity. The maximum IL-1 dose effect was observed for CFU-GM and CFU-Meg at 300 units, 0.3 micrograms protein; however BFU-E required a dose of 600 units, 0.6 micrograms/ml protein to reverse the effects of AZT. These results demonstrate marrow progenitors respond differently to AZT and identifies the potential efficacy of IL-1 to minimize the hematopoietic toxicity associated with AZT treatment.     

Mesenchymal stromal cells primed with paclitaxel provide a new approach for cancer therapy

Background

Mesenchymal stromal cells may represent an ideal candidate to deliver anti-cancer drugs. In a previous study, we demonstrated that exposure of mouse bone marrow derived stromal cells to Doxorubicin led them to acquire anti-proliferative potential towards co-cultured haematopoietic stem cells (HSCs). We thus hypothesized whether freshly isolated human bone marrow Mesenchymal stem cells (hMSCs) and mature murine stromal cells (SR4987 line) primed in vitro with anti-cancer drugs and then localized near cancer cells, could inhibit proliferation.

Methods and Principal Findings

Paclitaxel (PTX) was used to prime culture of hMSCs and SR4987. Incorporation of PTX into hMSCs was studied by using FICT-labelled-PTX and analyzed by FACS and confocal microscopy. Release of PTX in culture medium by PTX primed hMSCs (hMSCsPTX) was investigated by HPLC. Culture of Endothelial cells (ECs) and aorta ring assay were used to test the anti-angiogenic activity of hMSCsPTX and PTX primed SR4987(SR4987PTX), while anti-tumor activity was tested in vitro on the proliferation of different tumor cell lines and in vivo by co-transplanting hMSCsPTX and SR4987PTX with cancer cells in mice. Nevertheless, despite a loss of cells due to chemo-induced apoptosis, both hMSCs and SR4987 were able to rapidly incorporate PTX and could slowly release PTX in the culture medium in a time dependent manner. PTX primed cells acquired a potent anti-tumor and anti-angiogenic activity in vitro that was dose dependent, and demonstrable by using their conditioned medium or by co-culture assay. Finally, hMSCsPTX and SR4987PTX co-injected with human cancer cells (DU145 and U87MG) and mouse melanoma cells (B16) in immunodeficient and in syngenic mice significantly delayed tumor takes and reduced tumor growth.

Conclusions

These data demonstrate, for the first time, that without any genetic manipulation, mesenchymal stromal cells can uptake and subsequently slowly release PTX. This may lead to potential new tools to increase efficacy of cancer therapy.     

人参总皂甙对人GM-CSF和GM-CSFR表达的调控

为探讨人参调控粒细胞发生的生物学机制,采用造血祖细胞和骨髓基质细胞体外培养、造血生长因子生物学活性检测、免疫细胞化学、核酸分子原位杂交、免疫沉淀和蛋白印迹等现代生物学技术,研究人参总皂甙(total saponins of Panax ginaeng,TSPG)对人粒-巨噬细胞集落刺激因子(granulocyte-macrophage colony-stimulating factor,GM-CSF)和粒-巨噬细胞集落刺激因子受体α(GM-CSFRα)表达的影响。结果：(1)经TSPG(50μg／m1)诱导制备的骨髓基质细胞、胸腺细胞、脾细胞、血管内皮细胞和单核细胞条件培养液可显著提高粒单系造血祖细胞(CFU-GM)的集落产率;(2)经TSPG(50μg/ml)诱导后,上述细胞的GM-CSF蛋白(诱导24h)和mRNA(诱导12h)表达显著提高;(3)经TSPG(50μg/ml)诱导24h骨髓造血细胞的GM-CSFRα蛋白表达增强;(4)经TSPG(50μg/ml)刺激后2min,GM-CSFRα和Shc发生酪氨酸磷酸化,5min时达高峰,随后去磷酸化。上述结果表明,TSPG可能通过直接和／或间接途径促进淋巴细胞与骨髓基质细胞合成与分泌GM-CSF,诱导骨髓造血细胞表达GM-CSFRα,并刺激GM-CSFRα和Shc的酪氨酸可逆磷酸化,从而通过调控GM-CSF的信号转导过程,促进CFU-GM的增殖。