Immature B Cell Egress from Bone Marrow Is SOCS3 Independent

Suppressor of cytokine signaling (SOCS)-3 has been suggested to regulate CXCR4 signaling in a variety of human cell lines. In mice, conditional SOCS3 inactivation in hematopoietic cells including B-lineage lymphocytes has been reported to exacerbate CXCR4-signaling and focal adhesion kinase phosphorylation, which resulted in altered immature B cell distribution in bone marrow (BM) due to sustained α4β1 integrin-mediated adhesion to the extracellular matrix. However, a recent study examining conditional SOCS3 deletion specifically in B-lineage cells failed to detect significant roles in B-lineage cell retention in BM. In this study we carefully examined the role played by SOCS3 in CXCR4 signaling in developing B cell subsets. We show that in mice conditionally deficient in SOCS3 exclusively in B cells (Socs3 ^fl/fl Mb1 ^cre/+) there was no detectable difference in B cell development in BM and in periphery. We show that SOCS3 deficient and sufficient immature B cell subsets are similarly distributed between BM parenchyma and sinusoids, and are equally competent at exiting BM into peripheral blood. Furthermore, we found no significant differences in CXCR4 desensitization upon ligand exposure in developing B lymphocyte subsets. Consequently, SOCS3-deficient and sufficient B-lineage cell migration towards CXCL12 in vitro was undistinguishable, and B-lineage cell amoeboid motility within BM parenchyma was also unaffected by SOCS3-deficiency. Thus we conclude that SOCS3 has no detectable influence on biological processes known to be controlled by CXCR4 signaling.     

Osteoclast Derivation from Mouse Bone Marrow

Osteoclasts are highly specialized cells that are derived from the monocyte/macrophage lineage of the bone marrow. Their unique ability to resorb both the organic and inorganic matrices of bone means that they play a key role in regulating skeletal remodeling. Together, osteoblasts and osteoclasts are responsible for the dynamic coupling process that involves both bone resorption and bone formation acting together to maintain the normal skeleton during health and disease.As the principal bone-resorbing cell in the body, changes in osteoclast differentiation or function can result in profound effects in the body. Diseases associated with altered osteoclast function can range in severity from lethal neonatal disease due to failure to form a marrow space for hematopoiesis, to more commonly observed pathologies such as osteoporosis, in which excessive osteoclastic bone resorption predisposes to fracture formation.An ability to isolate osteoclasts in high numbers in vitro has allowed for significant advances in the understanding of the bone remodeling cycle and has paved the way for the discovery of novel therapeutic strategies that combat these diseases. Here, we describe a protocol to isolate and cultivate osteoclasts from mouse bone marrow that will yield large numbers of osteoclasts.     

Circadian and Circannual Variations of Cell Cycle Distribution in the Mouse Bone Marrow

The cell cycle distribution of bone marrow cells from the femurs of female C3H mice has been investigated by flow cytometry according to the time of the day and month of the year. Both circadian and seasonal variations were found for the different cell cycle phases as well as the total cell numbers per femur. Both the mesor, the acrophase and the amplitude of the S, G₂ and (G₁ + G₀) phases varied significantly in some months, while in other months only insignificant rhythms were found. The relative cell cycle distribution only partly reflected variations in the total numbers of proliferating cells, since the total cell number per femur was also variable.

The total numbers of cells in DNA synthesis seem to be higher in the first part of the year, indicating increased cell proliferation during winter and spring. In this period the acrophases of DNA synthesis and G₂ were in the morning, while the second half of the year showed the peak later in the day.

In general, hemopoietic cell proliferation seems to constitute a labile equilibrium with rapidly changing activities.     

Proteinase Activated Receptor 1 Mediated Fibrosis in a Mouse Model of Liver Injury: A Role for Bone Marrow Derived Macrophages

Liver fibrosis results from the co-ordinated actions of myofibroblasts and macrophages, a proportion of which are of bone marrow origin. The functional effect of such bone marrow-derived cells on liver fibrosis is unclear. We examine whether changing bone marrow genotype can down-regulate the liver''s fibrotic response to injury and investigate mechanisms involved. Proteinase activated receptor 1 (PAR1) is up-regulated in fibrotic liver disease in humans, and deficiency of PAR1 is associated with reduced liver fibrosis in rodent models. In this study, recipient mice received bone marrow transplantation from PAR1-deficient or wild-type donors prior to carbon tetrachloride-induced liver fibrosis. Bone marrow transplantation alone from PAR1-deficient mice was able to confer significant reductions in hepatic collagen content and activated myofibroblast expansion on wild-type recipients. This effect was associated with a decrease in hepatic scar-associated macrophages and a reduction in macrophage recruitment from the bone marrow. In vitro, PAR1 signalling on bone marrow-derived macrophages directly induced their chemotaxis but did not stimulate proliferation. These data suggest that the bone marrow can modulate the fibrotic response of the liver to recurrent injury. PAR1 signalling can contribute to this response by mechanisms that include the regulation of macrophage recruitment.     

Prostaglandin E2 Production and T Cell Function in Mouse Adenovirus Type 1 Infection following Allogeneic Bone Marrow Transplantation

Adenovirus infections are important complications of bone marrow transplantation (BMT). We demonstrate delayed clearance of mouse adenovirus type 1 (MAV-1) from lungs of mice following allogeneic BMT. Virus-induced prostaglandin E₂ (PGE₂) production was greater in BMT mice than in untransplanted controls, but BMT using PGE₂-deficient donors or recipients failed to improve viral clearance, and treatment of untransplanted mice with the PGE₂ analog misoprostol did not affect virus clearance. Lymphocyte recruitment to the lungs was not significantly affected by BMT. Intracellular cytokine staining of lung lymphocytes demonstrated impaired production of INF-γ and granzyme B by cells from BMT mice, and production of IFN-γ, IL-2, IL-4, and IL-17 following ex vivo stimulation was impaired in lymphocytes obtained from lungs of BMT mice. Viral clearance was not delayed in untransplanted INF-γ-deficient mice, suggesting that delayed viral clearance in BMT mice was not a direct consequence of impaired IFN-γ production. However, lung viral loads were higher in untransplanted CD8-deficient mice than in controls, suggesting that delayed MAV-1 clearance in BMT mice is due to defective CD8 T cell function. We did not detect significant induction of IFN-β expression in lungs of BMT mice or untransplanted controls, and viral clearance was not delayed in untransplanted type I IFN-unresponsive mice. We conclude that PGE₂ overproduction in BMT mice is not directly responsible for delayed viral clearance. PGE₂-independent effects on CD8 T cell function likely contribute to the inability of BMT mice to clear MAV-1 from the lungs.     

小鼠胎肝基质细胞体外扩增骨髓来源的LTC-IC

基质细胞是胎肝造血微环境的主要成分,参与造血干/祖细胞的自我更新、增殖分化的调控。为了研究小鼠胎肝基质细胞在造血微环境中的功能,采用转染SV40大T抗原基因的方法建立了小鼠胚胎期第12.5天（Embryonic-day 12.5, E12.5d）胎肝基质细胞系A4、B3,并进一步鉴定基质细胞系的一般细胞生物学特性和造血支持功能。结果：A4、B3为细胞形态、生长行为以及表面分子表达不同细胞系,二者均可维持骨髓源长期培养启动细胞（Longterm cultureinitiating cell,LTC-IC）至少4周并且有不同程度的扩增LTC-IC能力,其中B3扩增LTC-IC的能力是A4的83倍。外源性细胞因子组合SCF+IL-3+IL6+Epo在本实验体系中不影响LTC-IC数量的维持和扩增。暗示E12.5d胎肝造血微环境中基质细胞的功能是不同的,其机制有待进一步研究。     

Autologous Bone Marrow Cell Therapy and Metabolic Intervention in Ischemia-Induced Angiogenesis in the Diabetic Mouse Hindlimb

Peripheral arterial disease (PAD) is a major health problem especially when associated to diabetes. Administration of autologous bone marrow cells (BMC) is emerging as a novel intervention to induce therapeutic angiogenesis in experimental ischemic limb models and in patients with PAD. Since tissue ischemia and diabetes are associated with an overwhelming generation of oxygen radicals and detrimental effects due to formation of glycosylation end-products, metabolic intervention with antioxidants and L-arginine can confer beneficial effects beyond those achieved by BMC alone. The effects of cotreatment with intravenous BMCs and metabolic vascular protection (1.0% vitamin E, 0.05% vitamin C, and 6% L-arginine) were examined in the ischemic hindlimb of diabetic and non diabetic mice. BMC therapy increased blood flow and capillary densities and Ki67 proliferative marker, and decreased interstitial fibrosis. This effect was amplified by metabolic cotreatment, an intervention inducing vascular protection, at least in part, through the nitric oxide pathway, reduction of systemic oxidative stress, and macrophage activation.     

Cell Interaction Molecules Utilized in Bone Marrow

Many aspects of blood cell formation can now be modeled in culture and rapid progress is being made in understanding how blood cell precursors interact with unique components of their environment. This brief review considers some cell interaction molecules that may be important for controlling the position of cells within, as well as their egress from, bone marrow.     

小鼠骨髓间充质干细胞的分离、培养及鉴定

目的建立一种从小鼠骨髓中分离培养间充质干细胞（MSCs）的高效方法。方法采取贴壁细胞分离法分离和纯化小鼠骨髓间充质干细胞（mMSCs）,检测mMSCs在不同诱导条件下向成骨细胞及脂肪细胞分化能力,用流式细胞术及显微镜分别检测mMSCs纯度和形态特征。结果mMSCs贴壁生长后形态较均一,细胞形态呈成纤维细胞样,流式细胞术检测：CD45、CD11b、CD44及CD29分别为（3.34）%、（2.41）%、（98.46）%及（99.36）%。第4代mMSCs经诱导后可向成骨细胞和脂肪细胞分化。结论通过贴壁培养可以从小鼠骨髓中分离培养出高纯度mMSCs,该方法效率高,稳定性好。     

骨髓间充质干细胞移植与肾脏病

骨髓间充质干细胞是目前广受关注的一群成体干细胞,具有取材容易,增殖能力强,生物学特性稳定,可以跨胚层分化,低免疫源性,参与受损组织修复等优点,随着组织工程的兴起和发展以及其自身所特有的生物学特性,人们逐渐认识到将骨髓间充质干细胞作为肾脏病移植治疗的种子细胞具有良好的应用前景。本文就骨髓间充质干细胞的生物学特性及其在肾脏病移植治疗中的进展做一综述。     

骨髓间充质干细胞移植与肾脏病

骨髓间充质干细胞是目前广受关注的一群成体干细胞,具有取材容易,增殖能力强,生物学特性稳定,可以跨胚层分化,低免疫源性,参与受损组织修复等优点,随着组织工程的兴起和发展以及其自身所特有的生物学特性,人们逐渐认识到将骨髓间充质干细胞作为肾脏病移植治疗的种子细胞具有良好的应用前景。本文就骨髓间充质干细胞的生物学特性及其在肾脏病移植治疗中的进展做一综述。     

Extracellular High Mobility Group Box 1 Plays a Role in the Effect of Bone Marrow Mononuclear Cell Transplantation for Heart Failure

Transplantation of unfractionated bone marrow mononuclear cells (BMCs) repairs and/or regenerates the damaged myocardium allegedly due to secretion from surviving BMCs (paracrine effect). However, donor cell survival after transplantation is known to be markedly poor. This discrepancy led us to hypothesize that dead donor BMCs might also contribute to the therapeutic benefits from BMC transplantation. High mobility group box 1 (HMGB1) is a nuclear protein that stabilizes nucleosomes, and also acts as a multi-functional cytokine when released from damaged cells. We thus studied the role of extracellular HMGB1 in the effect of BMC transplantation for heart failure. Four weeks after coronary artery ligation in female rats, syngeneic male BMCs (or PBS only as control) were intramyocardially injected with/without anti-HMGB1 antibody or control IgG. One hour after injection, ELISA showed that circulating extracellular HMGB1 levels were elevated after BMC transplantation compared to the PBS injection. Quantitative donor cell survival assessed by PCR for male-specific sry gene at days 3 and 28 was similarly poor. Echocardiography and catheterization showed enhanced cardiac function after BMC transplantation compared to PBS injection at day 28, while this effect was abolished by antibody-neutralization of HMGB1. BMC transplantation reduced post-infarction fibrosis, improved neovascularization, and increased proliferation, while all these effects in repairing the failing myocardium were eliminated by HMGB1-inhibition. Furthermore, BMC transplantation drove the macrophage polarization towards alternatively-activated, anti-inflammatory M2 macrophages in the heart at day 3, while this was abolished by HMGB1-inhibition. Quantitative RT-PCR showed that BMC transplantation upregulated expression of an anti-inflammatory cytokine IL-10 in the heart at day 3 compared to PBS injection. In contrast, neutralizing HMGB1 by antibody-treatment suppressed this anti-inflammatory expression. These data suggest that extracellular HMGB1 contributes to the effect of BMC transplantation to recover the damaged myocardium by favorably modulating innate immunity in heart failure.     

Single Cell Gene Profiling Revealed Heterogeneity of Paracrine Effects of Bone Marrow Cells in Mouse Infarcted Hearts

It is now recognized that transplantation of bone marrow cells (BMCs) into infarcted hearts has the capacity to improve the cardiac function through paracrine effects. However, detailed expression levels of paracrine factors in BMCs in infarcted hearts are poorly described. By use of laser capture microdissection combined with real-time PCR, we depicted the expression profiles of paracrine factors in infarcted hearts versus normal hearts. Consistent with the in vivo observation, a similar expression pattern was evidenced in cultured BMCs. Furthermore, BMCs displayed heterogeneity of paracrine effects in infarcted hearts as analyzed at the single cell level using single cell PCR. Interestingly, the CD45⁺ subpopulation showed higher expression levels of angiogenic factors compared to other subpopulations. Finally, most angiogenic factors were induced under the microenvironment of infarction. Our study demonstrated the heterogeneity of paracrine effects in BMCs at single cell level in infarcted hearts, highlighting preferential expression of angiogenic factors in the CD45⁺ subpopulation. These findings broaden our understanding of paracrine effects of BMCs in vivo, and offer new insights into BMCs therapy in myocardial infarction (MI).     

Differential Expression of Surface Markers in Mouse Bone Marrow Mesenchymal Stromal Cell Subpopulations with Distinct Lineage Commitment

Bone marrow mesenchymal stromal cells (BM MSCs) represent a heterogeneous population of progenitors with potential for generation of skeletal tissues. However the identity of BM MSC subpopulations is poorly defined mainly due to the absence of specific markers allowing in situ localization of those cells and isolation of pure cell types. Here, we aimed at characterization of surface markers in mouse BM MSCs and in their subsets with distinct differentiation potential. Using conditionally immortalized BM MSCs we performed a screening with 176 antibodies and high-throughput flow cytometry, and found 33 markers expressed in MSCs, and among them 3 were novel for MSCs and 13 have not been reported for MSCs from mice. Furthermore, we obtained clonally derived MSC subpopulations and identified bipotential progenitors capable for osteo- and adipogenic differentiation, as well as monopotential osteogenic and adipogenic clones, and thus confirmed heterogeneity of MSCs. We found that expression of CD200 was characteristic for the clones with osteogenic potential, whereas SSEA4 marked adipogenic progenitors lacking osteogenic capacity, and CD140a was expressed in adipogenic cells independently of their efficiency for osteogenesis. We confirmed our observations in cell sorting experiments and further investigated the expression of those markers during the course of differentiation. Thus, our findings provide to our knowledge the most comprehensive characterization of surface antigens expression in mouse BM MSCs to date, and suggest CD200, SSEA4 and CD140a as markers differentially expressed in distinct types of MSC progenitors.     

Differentiation Capacity toward Mesenchymal Cell Lineages of Bone Marrow Stromal Cells Established from Temperature-Sensitive SV40 T-Antigen Gene Transgenic Mouse

Stromal cell lines were established from bone marrow of temperature-sensitive T-antigen gene transgenic mice. These stromal cell lines consisted of fibroblasts, endothelial cells, and preadipocytes. We found that these stromal cell lines exhibited phenotypic changes depending on the inactivation of T-antigen and growth condition; one preadipocyte line was induced toward adipocytes and osteogenic cells, and several preadipocyte and endothelial cell lines were induced toward muscle cells and adipocytes. Some cell lines showed bipotential characters. These results indicated that stromal cells consisting of bone marrow hematopoietic microenvironment are derived from multipotent mesenchymal stem cells.     

Selection of Apoptotic Cell Specific Human Antibodies from Adult Bone Marrow

Autoreactive antibodies that recognize neo-determinants on apoptotic cells in mice have been proposed to have protective, homeostatic and immunoregulatory properties, although our knowledge about the equivalent antibodies in humans has been much more limited. In the current study, human monoclonal antibodies with binding specificity for apoptotic cells were isolated from the bone marrow of healthy adults using phage display technology. These antibodies were shown to recognize phosphorylcholine (PC)-associated neo-determinants. Interestingly, three of the four identified apoptotic cell-specific antibody clones were encoded by VH3 region rearrangements with germline or nearly germline configuration without evidence of somatic hypermutation. Importantly, the different identified antibody clones had diverse heavy chain CDR3 and deduced binding surfaces as suggested by structure modeling. This may suggest a potentially great heterogeneity in human antibodies recognizing PC-related epitopes on apoptotic cells. To re-construct the postulated structural format of the parental anti-PC antibody, the dominant clone was also expressed as a recombinant human polymeric IgM, which revealed a substantially increased binding reactivity, with dose-dependent and antigen-inhibitable binding of apoptotic cells. Our findings may have implication for improved prognostic testing and therapeutic interventions in human inflammatory disease.     

Rictor Is Required for Early B Cell Development in Bone Marrow

The development of early B cells, which are generated from hematopoietic stem cells (HSCs) in a series of well-characterized stages in bone marrow (BM), represents a paradigm for terminal differentiation processes. Akt is primarily regulated by phosphorylation at Thr308 by PDK1 and at Ser473 by mTORC2, and Akt signaling plays a key role in hematopoiesis. However, the role of mTORC2 in the development of early B cells remains poorly understood. In this study, we investigated the functional role of mTORC2 by specifically deleting an integral component, Rictor, in a hematopoietic system. We demonstrated that the deletion of Rictor induced an aberrant increase in the FoxO1 and Rag-1 proteins in BM B cells and that this increase was accompanied by a significant decrease in the abundance of B cells in the peripheral blood (PB) and the spleen, suggesting impaired development of early B cells in adult mouse BM. A BM transplantation assay revealed that the B cell differentiation defect induced by Rictor deletion was not affected by the BM microenvironment, thus indicating a cell-intrinsic mechanism. Furthermore, the knockdown of FoxO1 in Rictor-deleted HSCs and hematopoietic progenitor cells (HPCs) promoted the maturation of B cells in the BM of recipient mice. In addition, we revealed that treatment with rapamycin (an mTORC1 inhibitor) aggravated the deficiency in B cell development in the PB and BM. Taken together, our results provide further evidence that Rictor regulates the development of early B cells in a cell-intrinsic manner by modifying the expression of FoxO1 and Rag-1.     

Modeling Dynamics and Function of Bone Marrow Cells in Mouse Liver Regeneration

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三种有丝分裂抑制剂诱发小鼠骨髓细胞非整倍体的比较研究

以秋水仙素有丝分裂(CM)效应、微核(MN)及染色体畸变(CA)三种体内细胞遗传学指标综合评估了有丝分裂抑制剂(秋水仙素、益康唑及对苯二酚)诱发小鼠骨髓细胞非整倍体的效应。结果表明:秋水仙素是典型的多倍体及非整倍体诱发剂。益康唑对细胞有丝分裂有与秋水仙素相类似的效应,进一步分析表明其在哺乳动物体细胞内无非整倍体诱发效应。对苯二酚在哺乳动物活体实验系统中,可能具有诱发非整倍体及染色体结构畸变的多种遗传毒性。结果提示三种细胞遗传学指标能为非整倍体诱发剂的检出提供依据。