Derivation and immunological characterization of mesenchymal stromal cells from human embryonic stem cells

OBJECTIVE: We have previously shown the simultaneous generation of CD73(+) mesenchymal stromal cells (MSCs) along with CD34(+) hematopoietic cells from human embryonic stem cells (ESCs) when they are cocultured with OP9 murine stromal cells. We investigated whether MSCs can be derived from human ESCs without coculturing with OP9 cells, and if such cells exhibit immunological properties similar to MSCs derived from adult human bone marrow (BM). MATERIALS AND METHODS: Our starting populations were undifferentiated human ESCs cultured on Matrigel-coated plates without feeder cells. The differentiated fibroblast-looking cells were tested for expression of MSC markers and their potential for multilineage differentiation. We investigated surface expression of human leukocyte antigen (HLA) molecules on these MSCs before and after treatment with interferon-gamma (IFN-gamma). We also tested the proliferative response of T-lymphocytes toward MSCs and the effects of MSCs in mixed lymphocyte reaction (MLR) assays. RESULTS: We derived populations of MSCs from human ESCs with morphology, cell surface marker characteristics, and differentiation potential similar to adult BM-derived MSCs. Similar to BM-derived MSCs, human ESC-derived MSCs express cell surface HLA class I (HLA-ABC) but not HLA class II (HLA-DR) molecules. However, stimulation with IFN-gamma induced the expression of HLD-DR molecules. Human ESC-derived MSCs did not induce proliferation of T-lymphocytes when cocultured with peripheral blood mononuclear cells. Furthermore, ESC-derived MSCs suppressed proliferation of responder T-lymphocytes in MLR assays. CONCLUSIONS: MSCs can be derived from human ESCs without feeder cells. These human ESC-derived MSCs have cell surface markers, differentiation potentials, and immunological properties in vitro that are similar to adult BM-derived MSCs.     

Plasticity of marrow-derived stem cells

Bone marrow (BM) contains hematopoietic stem cells (HSCs), which differentiate into every type of mature blood cell; endothelial cell progenitors; and marrow stromal cells, also called mesenchymal stem cells (MSCs), which can differentiate into mature cells of multiple mesenchymal tissues including fat, bone, and cartilage. Recent findings indicate that adult BM also contains cells that can differentiate into additional mature, nonhematopoietic cells of multiple tissues including epithelial cells of the liver, kidney, lung, skin, gastrointestinal (GI) tract, and myocytes of heart and skeletal muscle. Experimental results obtained in vitro and in vivo are the subject of this review. The emphasis is on how these experiments were performed and under what conditions differentiation from bone marrow to epithelial and neural cells occurs. Questions arise regarding whether tissue injury is necessary for this differentiation and the mechanisms by which it occurs. We also consider which bone marrow subpopulations are capable of this differentiation. Only after we have a better understanding of the mechanisms involved and of the cells required for this differentiation will we be able to fully harness adult stem cell plasticity for clinical purposes.     

Bone marrow-derived circulating endothelial precursors do not contribute to vascular endothelium and are not needed for tumor growth

The mechanisms by which bone marrow (BM)-derived stem cells might contribute to angiogenesis and the origin of neovascular endothelial cells (ECs) are controversial. Neovascular ECs have been proposed to originate from VEGF receptor 2-expressing (VEGFR-2+) stem cells mobilized from the BM by VEGF or tumors, and it is thought that angiogenesis and tumor growth may depend on such endothelial precursors or progenitors. We studied the mobilization of BM cells to circulation by inoculating mice with VEGF polypeptides, adenoviral vectors expressing VEGF, or tumors. We induced angiogenesis by syngeneic melanomas, APCmin adenomas, adenoviral VEGF delivery, or matrigel plugs in four different genetically tagged universal or endothelial cell-specific chimeric mouse models, and subsequently analyzed the contribution of BM-derived cells to endothelium in a wide range of time points. To study the existence of circulating ECs in a nonmyeloablative setting, pairs of genetically marked parabiotic mice with a shared anastomosed circulatory system were created. We did not observe specific mobilization of VEGFR-2+ cells to circulation by VEGF or tumors. During angiogenesis, abundant BM-derived perivascular cells were recruited close to blood vessel wall ECs but did not form part of the endothelium. No circulation-derived vascular ECs were observed in the parabiosis experiments. Our results show that no BM-derived VEGFR-2+ or other EC precursors contribute to vascular endothelium and that cancer growth does not require BM-derived endothelial progenitors. Endothelial differentiation is not a typical in vivo function of normal BM-derived stem cells in adults, and it has to be an extremely rare event if it occurs at all.     

Bone marrow-derived cells: roles in solid tumor. Minireview

The role of cancer stem cells has been demonstrated for some cancers. Recently, research indicated that solid tumors may originate from bone marrow stem cells. Bone marrow-derived cells have recently been shown to contribute to stromal formation, especially angiogenesis and lymphvasculogenesis. Moreover, the interaction and the cell fusion between cancer cells and bone mesenchymal stem cells could enhance the aggregative ability of cancer cells. Bone marrow derived cells home to tumor-specific pre-metastatic sites to provide a permissive niche for incoming tumor cells. Since bone marrow-derived cells play an important role in carcinogenesis, angiogenesis and metastasis, bone marrow-derived cells are not only the tool for cancer therapy, but also the targets for cancer therapy.     

Abnormal tumor vasculatures and bone marrow-derived pro-angiogenic cells in cancer

Tumor-derived factors affect the stroma of cancer tissue by activating pro-angiogenic signals. One of the key components of this response is the mobilization of the pro-angiogenic cells from bone marrow (BM), which contribute to the development of abnormal tumor vasculature. Evidence is accumulating that the pro-angiogenic cells derived from BM are involved in the physiological processes of tissue repair and wound healing. However, vascular structure in cancer tissue is impaired, resulting in the formation of chaotic neo-vessels and hypoxic microenvironments. Ultimately, these structural and functional abnormalities result in the limited delivery of chemotherapeutic agents and create regions of metabolic derangement, both of which enhance resistance to chemotherapy. In spite of recent advances in targeted therapy using anti-vascular agents, clinical results from studies using individual agents have unsatisfactory, necessitating the combinatorial use of anti-cancer drugs and a targeting agent. We suggest the possibility of a new therapeutic approach in which aberrant tumor vessels are normalized by BM-derived pro-angiogenic cells, and the delivery of anti-cancer drugs is maximized. In this review, we focus on the current understanding of the structure and function of tumor vessels, and an alternative approach to the repair of abnormal tumor vasculature by the use of BM-derived pro-angiogenic cells. This approach may improve both the delivery and the efficacy of anti-cancer drugs by restoring aberrant tumor vascularization and hypoxia.     

Sonic hedgehog and retinoic acid synergistically promote sensory fate specification from bone marrow-derived pluripotent stem cells

Recent studies demonstrated that stromal cells isolated from adult bone marrow have the competence of differentiating into neuronal cells in vitro and in vivo. However, the capacity of marrow stromal cells or mesenchymal stem cells (MSCs) to differentiate into diverse neuronal cell populations and the identity of molecular factors that confer marrow stromal cells with the competence of a neuronal subtype have yet to be elucidated. Here, we show that Sonic hedgehog (Shh) and retinoic acid (RA), signaling molecules secreted from tissues in the vicinity of peripheral sensory ganglia during embryogenesis, exert synergistic effects on neural-competent MSCs to express a comprehensive set of glutamatergic sensory neuron markers. Application of Shh or RA alone had little or no effect on the expression of these neuronal subtype markers. In addition, incubation of MSCs with embryonic hindbrain/somite/otocyst conditioned medium or prenatal cochlea explants promoted up-regulation of additional sensory neuron markers and process outgrowth. These results identify Shh and RA as sensory competence factors for adult pluripotent cells and establish the importance of interactions between adult pluripotent cells and the host microenvironment in neuronal subtype specification.     

Role of bone marrow-derived cells in colon cancer: lessons from mouse model studies

The role of the tumor stroma in carcinogenesis and cancer progression have been documented for a long time. However, the molecules and mechanisms involved have not been understood precisely. Recently, various mediators involved in the communication between the tumor epithelium and stroma and their roles have been revealed by utilizing new technology such as array analysis, laser capture sampling, and genetically altered mice. Moreover, accumulating evidence indicates that some cells in the tumor stroma are derived from the bone marrow (BM). While some of these BM-derived cells are well-known players in inflammation, as exemplified by macrophages, other types of BM-derived cells have been described only recently and are still poorly characterized. In this review, I focus on the latter class of BM-derived cells in colon carcinogenesis, with reference to similar cells in other types of cancer as well. Studies of these myeloid cells should help us understand the inflammation and immune response from a broader perspective as the body’s reaction to pathogenic insults.     

Contextual niche signals towards colorectal tumor progression by mesenchymal stem cell in the mouse xenograft model

Background

The role of mesenchymal stem/stromal cells (MSCs) in tumorigenesis remains controversial. This study aimed to determine whether heterotypic interactions between MSCs and colon cancer cells can supply contextual signals towards tumor progression.

Methods

Xenografts consisting of co-implanted human colorectal cancer cells with rat MSCs in immunodeficient mice were evaluated by tumor progression, angiogenic profiles, and MSC fate. Furthermore, we investigated how MSCs function as a cancer cell niche by co-culture experiments in vitro.

Results

Tumor growth progressed in two ways, either independent of or dependent on MSCs. Such cell line-specific dependency could not be explained by host immune competency. COLO 320 xenograft angiogenesis was MSC-dependent, but less dependent on vascular endothelial growth factor (VEGF), whereas HT-29 angiogenesis was not MSC-dependent, but was VEGF-dependent. MSCs and COLO 320 cells established a functional positive feedback loop that triggered formation of a cancer cell niche, leading to AKT activation. Subsequently, MSCs differentiated into pericytes that enhanced angiogenesis as a perivascular niche. In contrast, the MSC niche conferred an anti-proliferative property to HT-29 cells, through mesenchymal–epithelial transition resulting in p38 activation.

Conclusions

In conclusion, MSCs demonstrate pleiotropic capabilities as a cancer cell or perivascular niche to modulate colorectal cancer cell fate in a cell line-dependent manner in a xenogeneic context.

     

Emerging roles for multipotent, bone marrow-derived stromal cells in host defense

Multipotent, bone marrow-derived stromal cells (BMSCs, also known as mesenchymal stem cells [MSCs]), are culture-expanded, nonhematopoietic cells with immunomodulatory effects currently being investigated as novel cellular therapy to prevent and to treat clinical disease associated with aberrant immune response. Emerging preclinical studies suggest that BMSCs may protect against infectious challenge either by direct effects on the pathogen or through indirect effects on the host. BMSCs may reduce pathogen burden by inhibiting growth through soluble factors or by enhancing immune cell antimicrobial function. In the host, BMSCs may attenuate pro-inflammatory cytokine and chemokine induction, reduce pro-inflammatory cell migration into sites of injury and infection, and induce immunoregulatory soluble and cellular factors to preserve organ function. These preclinical studies provide provocative hints into the direction MSC therapeutics may take in the future. Notably, BMSCs appear to function as a critical fulcrum, providing balance by promoting pathogen clearance during the initial inflammatory response while suppressing inflammation to preserve host integrity and facilitate tissue repair. Such exquisite balance in BMSC function appears intrinsically linked to Toll-like receptor signaling and immune crosstalk.     

Bone marrow-derived cells can acquire renal stem cells properties and ameliorate ischemia-reperfusion induced acute renal injury

ABSTRACT: BACKGROUND: Bone marrow (BM) stem cells have been reported to contribute to tissue repair after kidney injury model. However, there is no direct evidence so far that BM cells can trans-differentiate into renal stem cells. METHODS: To investigate whether BM stem cells contribute to repopulate the renal stem cell pool, we transplanted BM cells from transgenic mice, expressing enhanced green fluorescent protein (EGFP) into wild-type irradiated recipients. Following hematological reconstitution and ischemia-reperfusion (I/R), Sca-1 and c-Kit positive renal stem cells in kidney were evaluated by immunostaining and flow cytometry analysis. Moreover, granulocyte colony stimulating factor (G-CSF) was administrated to further explore if G-CSF can mobilize BM cells and enhance trans-differentiation efficiency of BM cells into renal stem cells. RESULTS: BM-derived cells can contribute to the Sca-1+ or c-Kit+ renal progenitor cells population, although most renal stem cells came from indigenous cells. Furthermore, G-CSF administration nearly doubled the frequency of Sca-1+ BM-derived renal stem cells and increased capillary density of I/R injured kidneys. CONCLUSIONS: These findings indicate that BM derived stem cells can give rise to cells that share properties of renal resident stem cell. Moreover, G-CSF mobilization can enhance this effect.     

Stem cells in tumor angiogenesis

Contribution from diverse tissue-specific stem cell types is required to create the cell populations necessary for the activation of angiogenesis and neovascular growth in cancer. Bone marrow (BM)-derived circulating endothelial progenitors (EPCs) that would differentiate to bona fide endothelial cells (ECs) were previously believed to be necessary for tumor angiogenesis. However, numerous recent studies demonstrate that EPCs are not needed for tumor angiogenesis and indicate EPCs to be artifactual rather than physiological. It is evident that tumor infiltrating hematopoietic cells produced by BM-residing hematopoietic stem cells (HSCs) may contribute to tumor angiogenesis in a paracrine manner by stimulating ECs or by remodeling the extracellular matrix. Therefore, identification of the various hematopoietic cell subpopulations that are critical for tumor angiogenesis and better understanding of their proangiogenic functions and mechanisms of action have potential therapeutic significance. Stem and progenitor cell subsets for also other vascular or perivascular cell types such as pericytes or mesenchymal/stromal cells may provide critical contributions to the growing neovasculature. Furthermore, we hypothesize that the existence of a yet undiscovered—and largely unsearched—tissue-specific adult vascular endothelial stem cell (VESC) would provide completely novel targeted approaches to block pathological angiogenesis and cancer growth. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".     

Cancer gene therapy using mesenchymal stem cells

Cellular and gene therapies represent promising treatment strategies at the frontier of medicine. Hematopoietic stem cells, lymphocytes, and mesenchymal stem cells (MSCs) can all serve as sources of cells for use in such therapies. Strategies for gene therapy are often based on those of cell therapy, and it is anticipated that some examples will be put to practical use in the near future. Given their ability to support hematopoiesis, MSCs may be useful for the enhancement of stem cell engraftment, and the acceleration of hematopoietic reconstitution. Furthermore, MSCs may advance the treatment of severe graft-versus-host disease, based on their immunosuppressive ability. This application is also based on the homing behavior of MSCs to sites of injury and inflammation. Interestingly, MSCs possess tumor-homing ability, opening up the possibility of applications in the targeted delivery of anti-cancer genes to tumors. Many reports have indicated that MSCs can be utilized to target tumors and to deliver anti-cancer molecules locally, as tumors are recognized as non-healing wounds with inflammatory tissue. Here, we review both the potential of MSCs as cellular vehicles for targeted cancer therapy and the molecular mechanisms underlying MSC accumulation at tumor sites.     

Human mesenchymal stem cells isolated from bone marrow and lymphoid organs support tumor B-cell growth: role of stromal cells in follicular lymphoma pathogenesis

Accumulating evidence indicates that the cellular microenvironment plays a key role in follicular lymphoma (FL) pathogenesis, both within tumor lymph nodes (LNs) and in infiltrated bone marrow where ectopic LN-like reticular cells are integrated within malignant B-cell nodular aggregates. In normal secondary lymphoid organs, specific stromal cell subsets provide a highly specialized microenvironment that supports immune response. In particular, fibroblastic reticular cells (FRCs) mediate immune cell migration, adhesion, and reciprocal interactions. The role of FRCs and their postulated progenitors, that is, bone marrow mesenchymal stem cells (MSCs), in FL remains unexplored. In this study, we investigated the relationships between FRCs and MSCs and their capacity to sustain malignant B-cell growth. Our findings strongly suggest that secondary lymphoid organs contain MSCs able to give rise to adipocytes, chondrocytes, osteoblasts, as well as fully functional B-cell supportive FRCs. In vitro, bone marrow-derived MSCs acquire a complete FRC phenotype in response to a combination of tumor necrosis factor-alpha and lymphotoxin-alpha1beta2. Moreover, MSCs recruit primary FL cells that, in turn, trigger their differentiation into FRCs, making them able to support malignant B-cell survival. Altogether, these new insights into the cross talk between lymphoma cells and their microenvironment could offer original therapeutic strategies.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.     

骨髓基质细胞治疗脑梗死的研究现状

目前,治疗脑梗死的药物虽然很多,但均未取得满意疗效.骨髓基质细胞(mesenchymalstromal cell,MSC)具有多向分化潜能和自我更新能力,可分化为神经细胞.通过分泌营养因子和生长因子、促进血管发生等机制,移植的MSC能改善梗死后神经功能缺损,促进神经功能恢复,从而降低脑梗死的致残率.利用MSC进行细胞移植很可能成为治疗脑梗死的一种理想手段.