Preferential expansion of human umbilical cord blood-derived CD34-positive cells on major histocompatibility complex-matched amnion-derived mesenchymal stem cells

Background

We previously found in a murine hematopoietic system that hematopoietic stem cells show high differentiation and proliferation capacity on bone marrow-derived mesenchymal stem cells/stromal cells (microenvironment) with “self” major histocompatibility complex (MHC).

Design and Methods

We examined whether amnion-derived adherent cells have the characteristics of mesenchymal stem cells, and whether these adherent cells can support the proliferation of umbilical cord blood-derived lineage-negative and CD34-positive cells (Lin^–CD34⁺ cells) obtained from the same fetus to a greater extent than those derived from other fetuses.

Results

Culture-expanded amnion-derived adherent cells expressed mesenchymal stem cell markers and HLA-ABC molecules and could differentiate into osteoblasts, adipocytes and chondrocyte-like cells, indicating that the cells have the characteristics of mesenchymal stem cells. The Lin^–CD34⁺ cells purified from the frozen umbilical cord blood were strongly positive for HLA-ABC, and contained a large number of hematopoietic stem cells. When the Lin^–CD34⁺ cells were cultured on the autologous (MHC-matched) or MHC-mismatched amnion-derived adherent cells in short-term assays (hematopoietic stem cell-proliferation) and long-term culture-initiating cell assays, greater expansion of the Lin^–CD34⁺ cells was observed in the MHC-matched combination than in MHC-mismatched combinations. The concentration of granulocyte-macrophage colony-stimulating factor in the culture supernatants of the long-term culture-initiating cell assays was significantly higher in the MHC-matched combination than in MHC-mismatched combinations.

Conclusions

It is likely that a MHC restriction exists between hematopoietic stem cells and mesenchymal stem cells/stromal cells in the human hematopoietic system and that granulocute-macropage colony-stimulating factor contributes to some extent to the preferential hematopoiesis-supporting ability of the MHC-matched amnion-derived adherent cells.     

CD34+ Hematopoietic Stem Cells Mobilization, Paralleled with Multiple Cytokines Elevated in Patients with HBV-Related Acute-on-Chronic Liver Failure

Background

Recent studies indicate that bone marrow (BM)-derived stem cells contribute to liver regeneration. But limited information is available on the dynamic and mechanisms of mobilization of BM-derived hematopoietic stem cells (HSCs) after acute-on-chronic liver failure (ACLF).

Aims

The purpose of this study was to assess the mobilization of BM-derived CD34+ HSCs in ACLF patients, and elucidate the association of stress-induced cytokines in HSCs mobilization and/or liver repair in ACLF patients.

Methods

Thirty patients with HBV-related ACLF, 30 patients undergoing chronic hepatitis B, and 20 healthy controls were enrolled. The percentages of peripheral blood CD34+ cells were determined by two-color flow cytometry. The hepatic commitment of mobilized CD34+ cells was investigated by RT-PCR. The serum levels of stress-induced cytokines were determined by enzyme-linked immunosorbent assays.

Results

A significant increase of circulating CD34+ cells was observed in ACLF patients. RT-PCR analyses showed that the mobilized CD34+ cells expressed both CD34 mRNA and liver-specific markers including cytokeratin 19 and α-fetoprotein. In parallel with mobilization of BM-derived CD34+ cells, elevated serum levels of hepatocyte growth factor, interleukin-6, stem cell factor, granulocyte colony-stimulating factor and matrix metalloproteinase 9 were observed in ACLF patients.

Conclusion

We demonstrated that ACLF led to mobilization of CD34+ cells, which had a hepatic differentiation potential.     

Mouse mesenchymal stem cells can support human hematopoiesis both in vitro and in vivo: the crucial role of neural cell adhesion molecule

Background

We previously established a mesenchymal stem cell line (FMS/PA6-P) from the bone marrow adherent cells of fetal mice. The cell line expresses a higher level of neural cell adhesion molecule and shows greater hematopoiesis-supporting capacity in mice than other murine stromal cell lines.

Design and Methods

Since there is 94% homology between human and murine neural cell adhesion molecule, we examined whether FMS/PA6-P cells support human hematopoiesis and whether neural cell adhesion molecules expressed on FMS/PA6-P cells contribute greatly to the human hematopoiesis-supporting ability of the cell line.

Results

When lineage-negative cord blood mononuclear cells were co-cultured on the FMS/PA6-P cells, a significantly greater hematopoietic stem cell-enriched population (CD34⁺CD38⁻ cells) was obtained than in the culture without the FMS/PA6-P cells. Moreover, when lineage-negative cord blood mononuclear cells were cultured on FMS/PA6-P cells and transplanted into SCID mice, a significantly larger proportion of human CD45⁺ cells and CD34⁺CD38⁻ cells were detected in the bone marrow of SCID mice than in the bone marrow of SCID mice that had received lineage-negative cord blood mononuclear cells cultured without FMS/PA6-P cells. Furthermore, we found that direct cell-to-cell contact between the lineage-negative cord blood mononuclear cells and the FMS/PA6-P cells was essential for the maximum expansion of the mononuclear cells. The addition of anti-mouse neural cell adhesion molecule antibody to the culture significantly inhibited their contact and the proliferation of lineage-negative cord blood mononuclear cells.

Conclusions

These findings suggest that neural cell adhesion molecules expressed on FMS/PA6-P cells play a crucial role in the human hematopoiesis-supporting ability of the cell line.     

Adoptive Transfer of Human Gingiva‐Derived Mesenchymal Stem Cells Ameliorates Collagen‐Induced Arthritis via Suppression of Th1 and Th17 Cells and Enhancement of Regulatory T Cell Differentiation

Objective

Current approaches offer no cures for rheumatoid arthritis (RA). Accumulating evidence has revealed that manipulation of bone marrow–derived mesenchymal stem cells (BM‐MSCs) may have the potential to control or even prevent RA, but BM‐MSC–based therapy faces many challenges, such as limited cell availability and reduced clinical feasibility. This study in mice with established collagen‐induced arthritis (CIA) was undertaken to determine whether substitution of human gingiva‐derived mesenchymal stem cells (G‐MSCs) would significantly improve the therapeutic effects.

Methods

CIA was induced in DBA/1J mice by immunization with type II collagen and Freund's complete adjuvant. G‐MSCs were injected intravenously into the mice on day 14 after immunization. In some experiments, intraperitoneal injection of PC61 (anti‐CD25 antibody) was used to deplete Treg cells in arthritic mice.

Results

Infusion of G‐MSCs in DBA/1J mice with CIA significantly reduced the severity of arthritis, decreased the histopathology scores, and down‐regulated the production of inflammatory cytokines (interferon‐γ and interleukin‐17A). Infusion of G‐MSCs also resulted in increased levels of CD4+CD39+FoxP3+ cells in arthritic mice. These increases were noted early after infusion in the spleens and lymph nodes, and later after infusion in the synovial fluid. The FoxP3+ Treg cells that were increased in frequency mainly consisted of Helios‐negative cells. When Treg cells were depleted, infusion of G‐MSCs partially interfered with the progression of CIA. Pretreatment of G‐MSCs with a CD39 or CD73 inhibitor significantly reversed the protective effect of G‐MSCs on CIA.

Conclusion

The role of G‐MSCs in controlling the development and severity of CIA mostly depends on CD39/CD73 signals and partially depends on the induction of CD4+CD39+FoxP3+ Treg cells. G‐MSCs provide a promising approach for the treatment of autoimmune diseases.

     

Gastritis Promotes an Activated Bone Marrow-Derived Mesenchymal Stem Cell with a Phenotype Reminiscent of a Cancer-Promoting Cell

Background

Bone marrow-derived mesenchymal stem cells (BM-MSCs) promote gastric cancer in response to gastritis. In culture, BM-MSCs are prone to mutation with continued passage but it is unknown whether a similar process occurs in vivo in response to gastritis.

Aim

The purpose of this study was to identify the role of chronic gastritis in the transformation of BM-MSCs leading to an activated cancer-promoting phenotype.

Methods

Age matched C57BL/6 (BL/6) and gastrin deficient (GKO) mice were used for isolation of stomach, serum and mesenchymal stem cells (MSCs) at 3 and 6 months of age. MSC activation was assessed by growth curve analysis, fluorescence-activated cell sorting and xenograft assays. To allow for the isolation of bone marrow-derived stromal cells and assay in response to chronic gastritis, IRG/Vav-1^Cre mice that expressed both enhanced green fluorescent protein-expressing hematopoietic cells and red fluorescent protein-expressing stromal cells were generated. In a parabiosis experiment, IRG/Vav-1^Cre mice were paired to either an uninfected Vav-1^Cre littermate or a BL/6 mouse inoculated with Helicobacter pylori.

Results

GKO mice displayed severe atrophic gastritis accompanied by elevated gastric tissue and circulating transforming growth factor beta (TGFβ) by 3 months of age. Compared to BM-MSCs isolated from uninflamed BL/6 mice, BM-MSCs isolated from GKO mice displayed an increased proliferative rate and elevated phosphorylated-Smad3 suggesting active TGFβ signaling. In xenograft assays, mice injected with BM-MSCs from 6-month-old GKO animals displayed tumor growth. RFP+ stromal cells were rapidly recruited to the gastric mucosa of H. pylori parabionts and exhibited changes in gene expression.

Conclusions

Gastritis promotes the in vivo activation of BM-MSCs to a phenotype reminiscent of a cancer-promoting cell.     

Increased expression of CD40 on bone marrow CD34+ hematopoietic progenitor cells in patients with systemic lupus erythematosus: Contribution to Fas‐mediated apoptosis

Objective

Patients with systemic lupus erythematosus (SLE) display increased apoptosis of bone marrow (BM) CD34+ hematopoietic progenitor cells. This study was undertaken to evaluate the expression of CD40 and CD40L in the BM of SLE patients, and to explore the possible involvement of these molecules in apoptosis of CD34+ cells.

Methods

The proportion and survival characteristics of CD40+ cells within the BM CD34+ fraction from SLE patients and healthy controls were evaluated by flow cytometry. The production of CD40L by BM stromal cells was assessed using long‐term BM cultures, and the effect of CD40L on the survival characteristics and clonogenic potential of CD34+ cells was evaluated ex vivo by flow cytometry and clonogenic assays.

Results

SLE patients displayed an increased proportion of CD40+ cells within the CD34+ fraction as compared with controls. The CD34+CD40+ subpopulation contained an increased proportion of apoptotic cells compared with the CD34+CD40− fraction in patients and controls, suggesting that CD40 is involved in the apoptosis of CD34+ cells. Stimulation of patients' CD34+ cells with CD40L increased the proportion of apoptotic cells and decreased the proportion of colony‐forming cells as compared with untreated cultures. The CD40L‐mediated effects were amplified following treatment with recombinant Fas ligand, suggesting that the effects of these ligands are synergistic. CD40L levels were significantly increased in long‐term BM culture supernatants and adherent layers of BM cells from SLE patients as compared with controls.

Conclusion

These data reveal a novel role for the CD40/CD40L dyad in SLE by demonstrating that up‐regulation and induction of CD40 on BM CD34+ cells from patients with SLE contribute to the amplification of Fas‐mediated apoptosis of progenitor cells.

     

Mimicking the functional hematopoietic stem cell niche in vitro: recapitulation of marrow physiology by hydrogel-based three-dimensional cultures of mesenchymal stromal cells

Background

A culture system that closely recapitulates marrow physiology is essential to study the niche-mediated regulation of hematopoietic stem cell fate at a molecular level. We investigated the key features that play a crucial role in the formation of a functional niche in vitro.

Design and Methods

Hydrogel-based cultures of human placenta-derived mesenchymal stromal cells were established to recapitulate the fibrous three-dimensional architecture of the marrow. Plastic-adherent mesenchymal stromal cells were used as controls. Human bone marrow-derived CD34⁺ cells were co-cultured with them. The output hematopoietic cells were characterized by various stem cell-specific phenotypic and functional parameters.

Results

The hydrogel-cultures harbored a large pool of primitive hematopoietic stem cells with superior phenotypic and functional attributes. Most importantly, like the situation in vivo, a significant fraction of these cells remained quiescent in the face of a robust multi-lineage hematopoiesis. The retention of a high percentage of primitive stem cells by the hydrogel-cultures was attributed to the presence of CXCR4-SDF1α axis and integrin beta1-mediated adhesive interactions. The hydrogel-grown mesenchymal stromal cells expressed high levels of several molecules that are known to support the maintenance of hematopoietic stem cells. Yet another physiologically relevant property exhibited by the hydrogel cultures was the formation of hypoxia-gradient. Destruction of hypoxia-gradient by incubating these cultures in a hypoxia chamber destroyed their specialized niche properties.

Conclusions

Our data show that hydrogel-based cultures of mesenchymal stromal cells form a functional in vitro niche by mimicking key features of marrow physiology.     

Human gastric cancer organizes neighboring lymphatic vessels via recruitment of bone marrow-derived lymphatic endothelial progenitor cells

Background

Lymphatic metastasis is a critical determinant of prognosis in human gastrointestinal cancers. Studies suggest that lymphatic metastasis has been linked to lymphangiogenesis, the growth of lymphatic vessels, while the mechanisms of tumor lymphangiogenesis remain poorly characterized.

Methods

Human gastric cancer cells, MKN45, were implanted under the gastric submucosa of nude mice receiving green fluorescent protein-positive bone marrow (BM) transplants. In addition, MKN45 cells were subcutaneously injected into the back of each mouse as a model of human tumor xenografts. The tumor tissue was analyzed 3?weeks after implantation.

Results

The mice with MKN45 cells represent recruitment and incorporation of BM-derived lymphatic endothelial progenitor cells (LEPC) into gastric lymphatics. Moreover, in a xenograft model, MKN45 cells induced lymphangiogenesis as well as recruitment of BM-derived LEPC in tumor lymphatics in a xenograft model.

Conclusions

These findings of this study suggest that human gastric adenocarcinoma induces tumor lymphangiogenesis via recruitment of LEPC from BM.     

Prolonged ex vivo culture of human bone marrow mesenchymal stem cells influences their supportive activity toward NOD/SCID-repopulating cells and committed progenitor cells of B lymphoid and myeloid lineages

Background

Bone marrow mesenchymal stem cells support proliferation and differentiation of hematopoietic progenitor cells in vitro. Since these cells constitute a rare subset of bone marrow cells, mesenchymal stem cell preparations for clinical purposes require a preparative step of ex vivo multiplication. The aim of our study was to analyze the influence of culture duration on mesenchymal stem cell supportive activity.

Design and Methods

Mesenchymal stem cells were expanded for up to ten passages. These cells and CD34+ cells were seeded in cytokine-free co-cultures after which the phenotype, clonogenic capacity and in vivo repopulating activity of harvested hematopoietic cells were assessed.

Results

Early passage mesenchymal stem cells supported hematopoietic progenitor cell expansion and differentiation toward both B lymphoid and myeloid lineages. Late passage mesenchymal stem cells did not support hematopoietic progenitor cell and myeloid cell outgrowth but maintained B-cell supportive ability. In vitro maintenance of NOD/SCID mouse repopulating cells cultured for 1 week in contact with mesenchymal stem cells was effective until the fourth passage of the mesenchymal cells and declined thereafter. The levels of engraftment of CD34⁺ cells in NOD/SCID mice was higher when these cells were co-injected with early passage mesenchymal stem cells; however mesenchymal cells expanded beyond nine passages were ineffective in promoting CD34⁺ cell engraftment. Non-contact cultures indicated that mesenchymal stem cell supportive activity involved diffusible factors. Among these, interleukins 6 and 8 contributed to the supportive activity of early passage mesenchymal stem cells but not to those of late passage cells. The phenotype, as well as fat, bone and cartilage differentiation capacity, of mesenchymal stem cells did not change during their culture.

Conclusions

Extended culture of mesenchymal stem cells alters the ability of these cells to support hematopoietic progenitor cells without causing concomitant changes in their phenotype or differentiation capacity.     

Long-term type 1 diabetes influences haematopoietic stem cells by reducing vascular repair potential and increasing inflammatory monocyte generation in a murine model

Aims/hypothesis

We sought to determine the impact of long-standing type 1 diabetes on haematopoietic stem/progenitor cell (HSC) number and function and to examine the impact of modulating glycoprotein (GP)130 receptor in these cells.

Methods

Wild-type, gp130 ^?/? and GFP chimeric mice were treated with streptozotocin to induce type 1 diabetes. Bone marrow (BM)-derived cells were used for colony-formation assay, quantification of side population (SP) cells, examination of gene expression, nitric oxide measurement and migration studies. Endothelial progenitor cells (EPCs), a population of vascular precursors derived from HSCs, were compared in diabetic and control mice. Cytokines were measured in BM supernatant fractions by ELISA and protein array. Flow cytometry was performed on enzymatically dissociated retina from gfp ⁺ chimeric mice and used to assess BM cell recruitment to the retina, kidney and blood.

Results

BM cells from the 12-month-diabetic mice showed reduced colony-forming ability, depletion of SP-HSCs with a proportional increase in SP-HSCs residing in hypoxic regions of BM, decreased EPC numbers, and reduced eNos (also known as Nos3) but increased iNos (also known as Nos2) and oxidative stress-related genes. BM supernatant fraction showed increased cytokines, GP130 ligands and monocyte/macrophage stimulating factor. Retina, kidney and peripheral blood showed increased numbers of CD11b⁺/CD45^hi/ CCR2⁺/Ly6C^hi inflammatory monocytes. Diabetic gp130 ^?/? mice were protected from development of diabetes-induced changes in their HSCs.

Conclusions/interpretation

The BM microenvironment of type 1 diabetic mice can lead to changes in haematopoiesis, with generation of more monocytes and fewer EPCs contributing to development of microvascular complications. Inhibition of GP130 activation may serve as a therapeutic strategy to improve the key aspects of this dysfunction.     

Cathepsin X is secreted by human osteoblasts, digests CXCL-12 and impairs adhesion of hematopoietic stem and progenitor cells to osteoblasts

Background

Hematopoietic stem cells are retained within discrete bone marrow niches through the effects of cell adhesion molecules and chemokine gradients. However, a small proportion of hematopoietic stem cells can also be found trafficking in the peripheral blood. During induced stem cell mobilization a proteolytic microenvironment is generated, but whether proteases are also involved in physiological trafficking of hematopoietic stem cells is not known. In the present study we examined the expression, secretion and function of the cysteine protease cathepsin X by cells of the human bone marrow.

Design and Methods

Human osteoblasts, bone marrow stromal cells and hematopoietic stem and progenitor cells were analyzed for the secretion of cathepsin X by western blotting, active site labeling, immunofluorescence staining and activity assays. A possible involvement of cathepsin X in cell adhesion and CXCL-12-mediated cell migration was studied in functional assays. Matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) analysis revealed the digestion mechanism of CXCL-12 by cathepsin X.

Results

Osteoblasts and stromal cells secrete cathepsin X, whereas hematopoietic stem and progenitor cells do not. Using a cathepsin X-selective substrate, we detected the catalytic activity of cathepsin X in cell culture supernatants of osteoblasts. Activated cathepsin X is able to reduce cellular adhesive interactions between CD34⁺ hematopoietic stem and progenitor cells and adherent osteoblasts. The chemokine CXCL-12, a highly potent chemoattractant for hematopoietic stem cells secreted by osteoblasts, is readily digested by cathepsin X.

Conclusions

The exo-peptidase cathepsin X has been identified as a new member of the group of CXCL-12-degrading enzymes secreted by non-hematopoietic bone marrow cells. Functional data indicate that cathepsin X can influence hematopoietic stem and progenitor cell trafficking in the bone marrow.     

MicroRNA126 contributes to granulocyte colony-stimulating factor-induced hematopoietic progenitor cell mobilization by reducing the expression of vascular cell adhesion molecule 1

Background

Mobilization of hematopoietic stem/progenitor cells from the bone marrow to the peripheral blood by granulocyte colony-stimulating factor is the primary means to acquire stem cell grafts for hematopoietic cell transplantation. Since hematopoietic stem/progenitor cells represent a minority of all blood cells mobilized by granulocyte colony-stimulating factor, the underlying mechanisms need to be understood in order to develop selective drugs.

Design and Methods

We analyzed phenotypic, biochemical and genetic changes in bone marrow cell populations from granulocyte colony-stimulating factor-mobilized and control mice, and linked such changes to effective mobilization of hematopoietic stem/progenitor cells.

Results

We show that granulocyte colony-stimulating factor indirectly reduces expression of surface vascular cell adhesion molecule 1 on bone marrow hematopoietic stem/progenitor cells, stromal cells and endothelial cells by promoting the accumulation of microRNA-126 (miR126)-containing microvescicles in the bone marrow extracellular compartment. We found that hematopoietic stem/progenitor cells, stromal cells and endothelial cells readily incorporate these miR126-loaded microvescicles, and that miR126 represses vascular cell adhesion molecule 1 expression on bone marrow hematopoietic stem/progenitor cells, stromal cells and endothelial cells. In line with this, miR126-null mice displayed a reduced mobilization response to granulocyte colony-stimulating factor.

Conclusions

Our results implicate miR126 in the regulation of hematopoietic stem/progenitor cell trafficking between the bone marrow and peripheral sites, clarify the role of vascular cell adhesion molecule 1 in granulocyte colony-stimulating factor-mediated mobilization, and have important implications for improved approaches to selective mobilization of hematopoietic stem/progenitor cells.     

Vascular endothelial growth factor receptor 1 signaling facilitates gastric ulcer healing and angiogenesis through the upregulation of epidermal growth factor expression on VEGFR1+CXCR4+ cells recruited from bone marrow

Background

Angiogenesis is essential for gastric ulcer healing. Recent results suggest that vascular endothelial growth factor receptor 1 (VEGFR1), which binds to VEGF, promotes angiogenesis. In the present study, we investigated the role of VEGFR1 signaling in gastric ulcer healing and angiogenesis.

Methods

Gastric ulcers were induced by serosal application of 100 % acetic acid in wild-type (WT) and tyrosine kinase-deficient VEGFR1 mice (VEGFR1 TK^?/?). Bone marrow transplantation into irradiated WT mice was carried out using bone marrow cells isolated from WT and VEGFR1 TK^?/? mice.

Results

Ulcer healing was delayed in VEGFR1 TK^?/? mice compared to WT mice and this was accompanied by decreased angiogenesis, as evidenced by reduced mRNA levels of CD31 and decreased microvessel density. Recruitment of cells expressing VEGFR1 and C-X-C chemokine receptor type 4 (CXCR4) was suppressed and epidermal growth factor (EGF) expression in ulcer granulation tissue was attenuated. Treatment of WT mice with neutralizing antibodies against VEGF or CXCR4 also delayed ulcer healing. In WT mice transplanted with bone marrow cells from VEGFR1 TK^?/? mice, ulcer healing and angiogenesis were suppressed, and this was associated with reduced recruitment of bone marrow cells to ulcer granulation tissue. VEGFR1 TK^?/? bone marrow chimeras also exhibited downregulation of EGF expression on CXCR4⁺VEGFR1⁺ cells recruited from the bone marrow into ulcer lesions.

Conclusion

VEGFR1-mediated signaling plays a critical role in gastric ulcer healing and angiogenesis through enhanced EGF expression on VEGFR1⁺CXCR4⁺ cells recruited from the bone marrow into ulcer granulation tissue.     

Bone marrow mesenchymal stromal cells non-selectively protect chronic myeloid leukemia cells from imatinib-induced apoptosis via the CXCR4/CXCL12 axis

Background

Residual chronic myeloid leukemia disease following imatinib treatment has been attributed to the presence of quiescent leukemic stem cells intrinsically resistant to imatinib. Mesenchymal stromal cells in the bone marrow may favor the persistence and progression of leukemia by preserving the proliferation and self-renewal capacities of the malignant progenitor cells.

Design and Methods

BV173 or primary chronic myeloid leukemia cells were co-cultured with human mesenchymal stromal cells and imatinib-induced cell death was then measured. The roles of pro-and anti-apoptotic proteins and chemokine CXCL12 in this context were evaluated. We also studied the ability of BV173 cells to repopulate NOD/SCID mice following in vitro exposure to imatinib and mesenchymal stromal cells.

Results

Whilst imatinib induced dose-dependent apoptosis of BV173 cells and primary chronic myeloid leukemia cells, co-culture with mesenchymal stromal cells protected both types of chronic myeloid leukemia cells. Molecular analysis indicated that mesenchymal stromal cells reduced caspase-3 activation and modulated the expression of the anti-apoptotic protein Bcl-XL. Furthermore, chronic myeloid leukemia cells exposed to imatinib in the presence of mesenchymal stromal cells retained the ability to engraft into NOD/SCID mice. We observed that chronic myeloid leukemia cells and mesenchymal stromal cells express functional levels of CXCR4 and CXCL12, respectively. Finally, the CXCR4 antagonist, AMD3100 restored apoptosis by imatinib and the susceptibility of the SCID leukemia repopulating cells to the tyrosine kinase inhibitor.

Conclusions

Human mesenchymal stromal cells mediate protection of chronic myeloid leukemia cells from imatinib-induced apoptosis. Disruption of the CXCL12/CXCR4 axis restores, at least in part, the leukemic cells’ sensitivity to imatinib. The combination of anti-CXCR4 antagonists with tyrosine kinase inhibitors may represent a powerful approach to the treatment of chronic myeloid leukemia.     

Low number of invariant NKT cells is associated with poor survival in acute myeloid leukemia

Background

T lymphocytes play an important role in the immunosurveillance of patients with hematologic malignancies. No study has so far examined the association between the number of lymphocyte subsets at diagnosis and overall survival (OS). We examined this relationship in adult patients with de novo acute myeloid leukemia (AML).

Methods

A longitudinal prospective study was conducted on 28 AML patients. Peripheral blood (PB) and bone marrow (BM) were obtained before chemotherapy to quantify the number of CD4+?and CD8+?T cells, natural killer (NK), invariant NKT (iNKT), and type-1 and type-2 dendritic cells. The Kaplan–Meier and Cox proportional hazard model were used to determine significant association between the number of each cell subtype and survival.

Results

BM counts of CD4+?lymphocytes?>506.11/μL and CD8+?T lymphocytes?>556.02/μL and a PB count of iNKT cells?<0.2/μL were associated with poor OS by univariate analysis (P?=?0.015, P?=?0.009, P?=?0.033 respectively). Multivariate analysis showed that an iNKT count?<0.2 cells/μL is an independent prognostic factor for OS.

Conclusion

An iNKT cell number of?<0.2/μL confers a poor prognosis in de novo AML patients.     

Inflammation is preceded by tumor necrosis factor‐dependent infiltration of mesenchymal cells in experimental arthritis

Objective

To determine the involvement of mesenchymal progenitor cells in the induction of collagen‐induced arthritis (CIA).

Methods

DBA/1 mice were immunized with type II collagen in adjuvant or adjuvant alone, and the presence of mesenchymal cells in the joints of prearthritic mice was studied by immunohistochemistry.

Results

An analysis of the joints on day 10 postimmunization (at least 10 days before the onset of arthritis) revealed synovial hyperplasia without leukocytic infiltration. Large, round cells expressing bone morphogenetic protein receptors (BMPRs), which serve as markers for primitive mesenchymal cells, were present in increased numbers in the bone marrow adjacent to the joint, in the synovium itself, and within enlarged bone canals that connect the bone marrow to the synovium. Similar changes were observed in mice given adjuvant without collagen. Adjuvant‐induced infiltration of BMPR⁺ cells and enlargement of bone canals were abrogated by anti‐tumor necrosis factor (anti‐TNF) treatment and were absent in TNFR p55/p75^−/− mice. Increased numbers of bone marrow cells and enlarged bone canals were observed in nonimmunized TNF transgenic mice (which spontaneously develop arthritis).

Conclusion

These findings suggest that in CIA, there is an antigen‐independent (innate) prearthritic phase that prepares the joint for the subsequent immune‐mediated arthritis. The induction phase involves marrow‐derived mesenchymal cells and requires the presence of TNF.

     

Isolation and characterization of spheroid cells from the HT29 colon cancer cell line

Background

Colorectal cancer stem cells (Cr-CSCs) are involved in the growth of colon cancer, but their specific role in tumor biology, including metastasis, is still unclear. Currently, methods for sorting Cr-CSCs are based on the expression of surface markers (e.g., CD133⁺, CD44⁺, and aldehyde dehydrogenase 1 (ALDH1⁺)); however, the specificity of these markers for Cr-CSCs is uncertain.

Purpose

This study aimed to develop more effective ways of isolating and purifying Cr-CSCs.

Methods

Suspension culture was used for isolation of Cr-CSCs. And spheroid cells were performed by side population technology, and the putative molecular marker analysis of colorectal cancer stem cell. Migration assay and chemoresistance experiment were conducted between the adherent cells and spheroid cells.

Results

HT29 colon cancer cells grew well in suspension culture. The percentage of CD44⁺ cancer cell of spheroid cells was 68 times higher than that of adherent cells (89.5% vs. 1.3%), but there was no obvious difference in the percentage of CD133⁺ cells (6.25% vs. 5.6%). Moreover, it is worth noting that the percent of CD133 ⁺/CD44⁺ cells remarkably rose (from 0.6% to 5.4%). The expression of ALDH1 was markedly increased (7.5% vs. 20.5%) for the spheroid cells than the adherent cells. The side population within the spheroid population dramatically increased from 0.2% to 6.3%. The resistance of spheroid cells to 5-FU was higher than that of adherent cells, as was their ability to migrate in the presence of SDF-1??.

Conclusion

Suspension culture is an effective approach for enriching Cr-CSCs and can provide an inexhaustible supply of genetically stable colon cancer stem cells for targeted Cr-CSC studies. Spheroid cell models also enable the study of colon cancer chemoresistance and metastasis and may help to elucidate the role of cancer stem cells in colon cancer.     

Role of FK506 binding protein 5 (FKBP5) in osteoclast differentiation

Objectives

We previously disclosed the enhanced expression of FK506 binding protein 5 (FKBP5) messenger RNA (mRNA) in bone marrow (BM) CD34⁺ cells in rheumatoid arthritis (RA), in which systemic osteoporosis takes place. Since BM CD34⁺ cells are precursors of osteoclasts, it is possible that FKBP5 overexpression might lead to osteoporosis by affecting osteoclastogenesis. We therefore explore the influences of FKBP5 in osteoclast differentiation.

Methods

Stable transfectants of RAW264.7 overexpressing murine FKBP5 gene were established. Osteoclast differentiation was induced by receptor activator of nuclear factor kappa B (NF-κB) ligand and was evaluated by tartrate-resistant acid phosphatase (TRAP) staining and pit formation assay.

Results

FKBP5 transfectants of RAW264.7 generated higher numbers of TRAP-positive multinucleated cells with increased activity of pit formation on calcium phosphate-coated culture slides than mock transfectants. The enhancement of osteoclast differentiation of FKBP5 transfectants was only partially inhibited by N-acetyl l-cysteine. Finally, glucocorticoid enhanced FKBP5 mRNA expression as well as osteoclast differentiation of RAW264.7 cells in a dose-dependent manner.

Conclusions

These results indicate that FKBP5 promotes osteoclast differentiation by a mechanism distinct from NF-κB activation. Moreover, the data suggest that FKBP5 might play a role in bone destruction and development of osteoporosis in RA as well as in glucocorticoid-induced osteoporosis.     

Oxygen tension plays a critical role in the hematopoietic microenvironment in vitro

Background

In the bone marrow mesenchymal stromal cells and osteoblasts form functional niches for hematopoietic stem and progenitor cells. This microenvironment can be partially mimicked using in vitro co-culture systems. In this study, we examined the oxygen tension in three distinct compartments in a co-culture system of purified CD34⁺ cells and mesenchymal stromal cells with regard to different spatial localizations.

Design and Methods

Hypoxic cells in the co-culture were visualized by pimonidazole staining. Hematopoietic cell distribution, and functional and phenotypic characteristics were analyzed by flow cytometry. The secretion of vascular endothelial growth factor and stromal-derived factor-1 by mesenchymal stromal cells in low oxygen co-cultures was determined by an enzyme-linked immunosorbent assay. The effect of co-culture medium on the hematopoietic cell migration potential was tested in a transwell assay.

Results

In co-cultures under atmospheric oxygen tension, regions of low oxygen tension could be detected beneath the feeder layer in which a reservoir of phenotypically more primitive hematopoietic cells is located in vitro. In low oxygen co-culture, the adhesion of hematopoietic cells to the feeder layer was decreased, whereas hematopoietic cell transmigration beneath mesenchymal stromal cells was favored. Increased vascular endothelial growth factor-A secretion by mesenchymal stromal cells under low oxygen conditions, which increased the permeability of the monolayer, was responsible for this effect. Furthermore, vascular endothelial growth factor-A expression in low oxygen mesenchymal stromal cells was induced via hypoxia-inducible factor signaling. However, stromal cell-derived factor-1 secretion by mesenchymal stromal cells was down-regulated under low oxygen conditions in a hypoxia-inducible factor-independent manner.

Conclusions

We demonstrate for the first time that differences in oxygen tension cause selective modification of hematopoietic cell and mesenchymal stromal cell interactions in a co-culture system, thus confirming that oxygen tension plays a critical role in the interaction between hematopoietic cells and the niche environment.     

Systems biology approach to identify alterations in the stem cell reservoir of subcutaneous adipose tissue in a rat model of diabetes: effects on differentiation potential and function

Aims/hypothesis

Autologous progenitor cells represent a promising option for regenerative cell-based therapies. Nevertheless, it has been shown that ageing and cardiovascular risk factors such as diabetes affect circulating endothelial and bone marrow-derived progenitor cells, limiting their therapeutic potential. However, their impact on other stem cell populations remains unclear. We therefore investigated the effects of diabetes on adipose-derived stem cells (ASCs) and whether these effects might limit the therapeutic potential of autologous ASCs.

Methods

A systems biology approach was used to analyse the expression of genes related to stem cell identification in subcutaneous adipose tissue (SAT), the stromal vascular fraction and isolated ASCs from Zucker diabetic fatty rats and their non-diabetic controls. An additional model of type 2 diabetes without obesity was also investigated. Bioinformatic approaches were used to investigate the biological significance of these changes. In addition, functional studies on cell viability and differentiation potential were performed.

Results

Widespread downregulation of mesenchymal stem cell markers was observed in SAT of diabetic rats. Gene expression and in silico analysis revealed a significant effect on molecules involved in the maintenance of pluripotency and self-renewal, and on the alteration of main signalling pathways important for stem cell maintenance. The viability and differentiation potential of ASCs from diabetic rats was impaired in in vitro models and in in vivo angiogenesis.

Conclusions/interpretation

The impact of type 2 diabetes on ASCs might compromise the efficiency of spontaneous self-repair and direct autologous stem cell therapy.