Characterization of nonexpanded mesenchymal progenitor cells from normal adult human bone marrow

OBJECTIVE: Adult bone marrow (BM) mesenchymal stem/progenitor cells (MS/PC) are a potentially useful tool for cell therapy and tissue repair. However, the identification of cell subsets rich in MS/PC from fresh BM has not been described. We have developed a means of identifying such subsets from untouched bone marrow. MATERIAL AND METHODS: First, MS/PC were enriched by short-time adherence (D(1-3)) before any cell division to evaluate the efficiency of CD73, CD105, CDw90, and CD49a antigens to select highly purified CD45(-)CD14(-) fluorescence-activated sorted subsets enriched in clonogenic mesenchymal cells. Then, we adapted this method to unmanipulated BM mononuclear cells (MNC). RESULTS: Short-time (D(1-3)) adherent CD45(-)CD14(-) cells expressing CD73 or CD49a antigens contained all the CFU-F, even though the CD105(+) and CDw90(+) subsets comprised less than half the total. In fresh unmanipulated BM MNC, CD73 and CD49a were also highly discriminative and allowed up to a 3 log enrichment of CFU-F when compared to BM MNC. Normal culture conditions upregulated most of the tested antigens. CONCLUSION: The CD45(-)CD14(-)/CD73(+) and CD45(-)CD14(-)/CD49a(+) phenotypes identified subsets containing all the CFU-F and sufficiently enriched to detect them in fresh BM, enabling evaluation of mesenchymal content of BM collections for cell therapy.     

Intronic splicing of hyaluronan synthase 1 (HAS1): a biologically relevant indicator of poor outcome in multiple myeloma

In this study, we show that the hyaluronan synthase 1 (HAS1) gene undergoes aberrant intronic splicing in multiple myeloma (MM). In addition to HAS1 full length (HAS1(FL)), we identify 3 novel splice variants of HAS1, HAS1Va, HAS1Vb, and HAS1Vc, detected in patients with MM or monoclonal gammopathy of undetermined significance (MGUS). HAS1Vb and HAS1Vc undergo intronic splicing with creation of a premature stop codon. MM cells expressing one or more HAS1 variants synthesize extracellular and/or intracellular hyaluronan (HA). Expression of the HAS1Vb splice variant was significantly correlated with reduced survival (P = .001). Together, alternative HAS1 gene splicing, the correlations between HAS1 splicing and HA synthesis, and the correlations between HAS1 splicing and reduced survival of MM patients support the hypothesis that the family of HAS1 protein plays a significant role in disease progression. Further, expression of HAS1Vb, in conjunction with HAS1(FL) and/or other HAS1 variants, may lead to accumulation of intracellular HA molecules and an impact on receptor for HA-mediated motility (RHAMM)-mediated mitotic abnormalities in MM. This study highlights the potential importance of HAS1 and its alternative splicing in pathophysiology of MGUS and MM.     

Prospective identification and isolation of murine bone marrow derived multipotent mesenchymal progenitor cells

Enormous confusion still exists in the scientific community regarding the in vivo identity of putative bone marrow (BM) multipotent mesenchymal progenitor cells (MPCs). There is still lack of consensus between laboratories on this issue but recent advancements in this field have shed light on the identity of these cells in humans. However, in mice there are limited and reproducible data available that convincingly define prospectively these cells in vivo. In this review we will critically address: 1) important considerations on how to interpret MPC nomenclature, heterogeneity and differentiation abilities; 2) potential surface antigens that could aid in the isolation of MPC from mouse BM; 3) and their topography and prospective cellular relationship with pericytes, adventitial reticulocytes (ARCs) and vascular smooth muscle cells (VSMCs).     

Endothelial cells in the bone marrow of patients with multiple myeloma

Endothelial cells (EC) were extracted through a lectin-based method from bone marrow of 57 patients with active multiple myeloma (MM) and compared with their healthy quiescent counterpart, human umbilical vein EC (HUVEC). MMECs exhibit specific antigens that indicate ongoing angiogenesis and embryo vasculogenesis; solid intercellular connections, hence stability of MM neovessels; and frequent interactions with plasma cells, hence tumor dissemination. They show heterogeneous antigen expression, hence existence of subsets. Their main genetic markers are indicative of a vascular phase. They show intrinsic angiogenic ability, because they rapidly form a capillary network in vitro, and extrinsic ability, because they generate numerous new vessels in vivo. They vividly secrete growth and invasive factors for plasma cells. They signal through kinases mandatory for development of neovascularization. Ultrastructurally, they are abnormal and show metabolic activation, like tumor ECs. Thalidomide heavily interferes with their functions. Vasculogenesis and angiogenesis might contribute to the MM vascular tree and progression, in the form of growth, invasion, and dissemination. In view of the heterogeneity of the antigenic phenotype of MMECs, a mixture (or a sequence) of antiangiogenic agents coupled with thalidomide would seem plausible for the biologic management of MM.     

Production of cytokines by bone marrow cells obtained from patients with multiple myeloma

Previous work with continuously cultured multiple myeloma lines suggested that cytokine production by tumor cells may mediate some of the medical complications of this disease. To further investigate this issue, we assayed freshly obtained bone marrow (BM) cells from myeloma patients for the in vitro production of cytokines and the presence of cytokine RNA. Production of cytokine protein was assessed by bioassays with the aid of specific neutralizing anticytokine antibodies. These assays detected interleukin-1 (IL-1) and tumor necrosis factor (TNF) secretion by myeloma BM cells, which was significantly greater than secretion from similarly processed BM cells of control individuals. In contrast, lymphotoxin and interleukin-2 (IL-2) production could not be detected. The levels of IL-1 and TNF produced in vitro peaked at 24 hours of culture and correlated with stage and the presence (or absence) of extensive osteolytic bone disease. Northern blot analysis demonstrated the presence of IL-1 beta and TNF RNA in uncultured myeloma BM cells but no detectable IL-1 alpha or lymphotoxin RNA. In addition, the amount of cytokine RNA correlated with protein production, being significantly greater in patients' BM cells than in control marrow. These data suggest a role for IL-1 beta and/or TNF in the pathophysiology of multiple myeloma and argue against a role for lymphotoxin or IL-2.     

Isolation and characterization of bone marrow multipotential mesenchymal progenitor cells

OBJECTIVE: There is an increased interest in rheumatology in mesenchymal progenitor/stem cells (MPCs) and their roles in rheumatic diseases, but little is known about the phenotype of these cells in vivo. The aim of this study was to isolate and characterize human bone marrow (BM) MPCs. METHODS: Fluorescence microscopy was used to identify putative MPCs among adherent BM cells. To purify them, a positive selection with antifibroblast microbeads was used, combined with fluorescence-activated cell sorting (FACS) for microbead+,CD45(low) cells. A more detailed phenotype of these cells was determined using 4-color flow cytometry, and standard chondrogenic, osteogenic, and adipogenic assays were used to investigate their differentiation potentials. RESULTS: Putative MPCs microscopically identified as large, fibroblast-like, D7-FIB+ cells were purified using positive selection with D7-FIB-conjugated (antifibroblast) microbeads followed by FACS for specifically bound microbead+,CD45(low) cells. These cells represented 0.01% of mononuclear cells in the BM. They were uniformly positive for CD105, LNGFR, HLA-DR, CD10, CD13, CD90, STRO-1, and bone morphogenetic protein receptor type IA (BMPRIA) and were negative for CD14, CD34, CD117, and CD133. Only cells with this phenotype could proliferate and produce adherent cell monolayers capable of chondrogenic, osteogenic, and adipogenic differentiation. D7-FIB- cells in the BM lacked any MPC activity. Uncultured skin fibroblasts had a phenotype similar to that of BM MPCs, but were negative for LNGFR, STRO-1, HLA-DR, and BMPRIA. CONCLUSION: This study shows the distinct phenotype, morphology, and method of isolation of BM MPCs. The findings may have implications for defining the physiologic roles of MPCs in arthritis, bone diseases, and joint regeneration.     

Inherited and acquired variations in the hyaluronan synthase 1 (HAS1) gene may contribute to disease progression in multiple myeloma and Waldenstrom macroglobulinemia

To characterize genetic contributions toward aberrant splicing of the hyaluronan synthase 1 (HAS1) gene in multiple myeloma (MM) and Waldenstrom macroglobulinemia (WM), we sequenced 3616 bp in HAS1 exons and introns involved in aberrant splicing, from 17 patients. We identified a total of 197 HAS1 genetic variations (GVs), a range of 3 to 24 GVs/patient, including 87 somatic GVs acquired in splicing regions of HAS1. Nearly all newly identified inherited and somatic GVs in MM and/or WM were absent from B chronic lymphocytic leukemia, nonmalignant disease, and healthy donors. Somatic HAS1 GVs recurred in all hematopoietic cells tested, including normal CD34(+) hematopoietic progenitor cells and T cells, or as tumor-specific GVs restricted to malignant B and plasma cells. An in vitro splicing assay confirmed that HAS1 GVs direct aberrant HAS1 intronic splicing. Recurrent somatic GVs may be enriched by strong mutational selection leading to MM and/or WM.     

Hematopoietic cells and osteoblasts are derived from a common marrow progenitor after bone marrow transplantation

Bone and bone marrow are closely aligned physiologic compartments, suggesting that these tissues may represent a single functional unit with a common bone marrow progenitor that gives rise to both osteoblasts and hematopoietic cells. Although reports of multilineage engraftment by a single marrow-derived stem cell support this idea, more recent evidence has challenged claims of stem cell transdifferentiation and therefore the existence of a multipotent hematopoietic/osteogenic progenitor cell. Using a repopulation assay in mice, we show here that gene-marked, transplantable marrow cells from the plastic-nonadherent population can generate both functional osteoblasts/osteocytes and hematopoietic cells. Fluorescent in situ hybridization for the X and Y chromosomes and karyotype analysis of cultured osteoblasts confirmed the donor origin of these cells and excluded their generation by a fusion process. Molecular analysis demonstrated a common retroviral integration site in clonogenic hematopoietic cells and osteoprogenitors from each of seven animals studied, establishing a shared clonal origin for these ostensibly independent cell types. Our findings indicate that the bone marrow contains a primitive cell able to generate both the hematopoietic and osteocytic lineages. Its isolation and characterization may suggest novel treatments for genetic bone diseases and bone injuries.     

Hepatocyte transplantation: potential of hepatocyte progenitor cells and bone marrow derived stem cells

The liver has a large regenerative capacity in response to injury. However, in severe cases of liver injury, its regenerative capacity may prove insufficent and the liver injury may progress to liver failure, and in such situations liver transplantation is the only treatment option. An alternative, less invasive approach may be transplantation of hepatocytes or hepatocyte precursor cells. In the adult liver two candidate progenitor cells have been identified: oval cells and small hepatocytes. The former are induced by liver injury under conditions preventing cell division of mature hepatocytes, while the latter are present in small numbers in normal liver. Both cell types have the capacity to expand and differentiate into hepatocytes. In recent years evidence has been presented that bone-marrow derived stem cells can also be expanded and differentiated into hepatocyte progenitor cells. Such cells may be a source for hepatocyte transplantation and hence have the potential to offer a novel therapy for liver failure.     

Increased expression of vascular endothelial growth factor in bone marrow of multiple myeloma patients

Background: Angiogenesis (neovascularization) is a multistep process in which new blood vessels grow from existing vessels. Angiogenesis is associated with the growth, dissemination, and metastasis of solid tumors. There is increasing evidence that neovascularization may be important in hematological malignancies. Several studies suggest that vascular endothelial growth factor (VEGF) is one of the most important cytokines responsible for the development, maintenance, and progression of multiple myeloma (MM) by promoting bone marrow angiogenesis. A high serum concentration of VEGF has been reported in MM patients. The aim of this study was to evaluate the expression of VEGF in the bone marrow of MM patients. Methods: Eighteen paraffin-embedded bone marrow core biopsy specimens from newly diagnosed patients with MM were evaluated. In addition, 10 bone marrow core biopsy specimens from adult patients without evidence of malignancy were used as controls. Bone marrow sections were stained immunohistochemically for VEGF. Results: Our data show that multiple myeloma is associated with an increased expression of VEGF in the bone marrow. Conclusions: Our observation supports previous studies suggesting that angiogenesis may play a role in the pathophysiology of hematopoietic malignancies. The clinical significance of this phenomenon needs further investigation. However, this study provides rationale for the use of angiogenesis inhibitors in MM therapy.     

Characterization of bone marrow mesenchymal stromal cells in aplastic anaemia

In aplastic anaemia (AA), haemopoietic activity is significantly reduced and generally attributed to failure of haemopoietic stem cells (HSC) within the bone marrow (BM). The regulation of haemopoiesis depends on the interaction between HSC and various cells of the BM microenvironment, including mesenchymal stromal cells (MSC). MSC involvement in the functional restriction of HSC in AA is largely unknown and therefore, the physical and functional properties of AA MSC were studied in vitro. MSC were characterized by their phenotype and ability to form adherent stromal layers. The functional properties of AA MSC were assessed through proliferative, clonogenic and cross‐over culture assays. Results indicate that although AA MSC presented typical morphology and distinctive mesenchymal markers, stromal formation was reduced, with 50% of BM samples failing to produce adherent layers. Furthermore, their proliferative and clonogenic capacity was markedly decreased (P = 0·03 and P = 0·04 respectively) and the ability to sustain haemopoiesis was significantly reduced, as assessed by total cell proliferation (P = 0·032 and P = 0·019 at Week 5 and 6, respectively) and clonogenic potential of HSC (P = 0·02 at Week 6). It was concluded that the biological characteristics of AA MSC are different from those of control MSC and their in vitro haemopoiesis‐supporting ability is significantly reduced.     

小鼠内皮祖细胞的分离、培养与定向诱导分化

目的 建立一种稳定、高效,从小鼠骨髓中分离培养与定向诱导分化内皮祖细胞(EPCs)的方法。方法 从小鼠骨髓中密度梯度离心法分离单个核细胞,经差速贴壁结合特殊培养基扩增并向内皮细胞定向诱导分化EPCs。应用免疫荧光和流式细胞技术鉴定内皮细胞系列标志:CD34、CD31、Flk-1和祖细胞标志CD133。并通过检测其对FITC标记的UEA-1的吸附和内吞DiI-ac-LDL来进行细胞功能学的鉴定。对分化细胞行vWF、CD31 免疫组化染色鉴定,并与血管内皮细胞合成前列腺素能力进行比较。结果 经过梯度密度离心和贴壁法选择的细胞表达内皮细胞特异性抗原CD34、CD31、Flk-1,部分表达CD133。分离所得细胞经EBM-2专用培养基培养后,第4天可见集落形成,培养第9天流式细胞仪检测其CD34、CD133、CD31、Flk-1阳性率分别为(44±4)%、(18±3)%、(49±4)%和(79±6)%,细胞能特异性吸附FITC标记的荆豆凝集素并内吞DiI-ac-LDL,约3周左右可融合近80%,形成铺路石样内皮细胞特有形态。传代后vWF、CD31免疫组化染色阳性率分别为(66±5)%和(56±5)%。诱导后的内皮祖细胞的合成前列腺素能力与血管内皮细胞之间无显著差异。结论 从小鼠骨髓中分离培养与定向诱导分化EPCs的方法,效率高,稳定性和重复性好。     

Dendritic cells derived from multiple myeloma patients efficiently internalize different classes of myeloma protein

Myeloma protein is a unique tumor antigen that can be used to devise tumor-specific vaccination strategies. As dendritic cells (DCs) are extremely potent at inducing T-cell responses, clinical protocols have been designed using myeloma protein-pulsed DCs to elicit anti-tumor cell responses in vivo. To optimize antigen pulsing of DCs, we investigated mechanisms of antigen uptake and evaluated various laboratory parameters including class of myeloma protein, antigen exposure time, and DC maturational stage.DCs were generated by culturing peripheral blood stem cells from myeloma patients in granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4). Myeloma proteins were labeled with fluorescein isothiocyanate (FITC) and internalization of protein by DCs was measured by flow cytometry.IgG, IgA, and free-kappa light chain myeloma proteins were all rapidly internalized by DCs in a time-dependent fashion. Maturation of DCs with tumor necrosis factor-alpha (TNF-alpha) resulted in diminished uptake. Endocytosis of myeloma protein by DCs was primarily mediated by fluid-phase macropinocytosis based on morphology, nonsaturable uptake kinetics, and sensitivity to drugs that inhibit membrane ruffling. Pulse-chase experiments revealed that the majority of internalized myeloma protein disappeared within 4 hours but was retained in the presence of chloroquine, indicating antigen processing had occurred.Cultured DCs from myeloma patients are functional and can efficiently endocytose different classes of myeloma protein by the mechanism of macropinocytosis. This demonstrates the feasibility of using all classes of myeloma protein for producing DC vaccines, and defines culture conditions for optimizing antigen loading of DCs for induction of anti-myeloma responses.     

The prognostic significance of polyclonal bone marrow plasma cells in patients with relapsing multiple myeloma

Prior studies have revealed that the presence of increasing number of polyclonal plasma cells (pPCs) in the bone marrow (BM) are associated with better outcomes in newly diagnosed multiple myeloma (MM) patients. This effect has not been studied in patients with MM at the time of disease relapse. We determined the prognostic value of depletion of pPCs in the BM by 7‐color multiparameter flow cytometry in a series of 174 relapsing MM patients. The time to next therapy (TTNT) in those with <5% pPCs was 9.4 months versus 13.9 months in those with ≥5% pPCs (P = .0091). The median overall survival (OS) in those with <5% pPCs was 21.4 months, while the median OS was not reached in those patients with ≥5% pPCs (P = .019). Of the 109 patients with standard risk cytogenetics, the median OS of those with <5% pPCs was 28.4 months, while the median OS was not reached in those with ≥5% pPCs (P = .033). As such, <5% pPCs in the BM appears to have prognostic utility in identifying a subset of relapsing MM patients, even with standard‐risk cytogenetics, who have a particularly adverse outcome.     

Repair of articular cartilage defects in rabbits using CDMP1 gene-transfected autologous mesenchymal cells derived from bone marrow

OBJECTIVE: Cartilage-derived morphogenetic protein 1 (CDMP1), which is a member of the transforming growth factor-beta superfamily, is an essential molecule for the aggregation of mesenchymal cells and acceleration of chondrocyte differentiation. In this study, we investigated whether CDMP1-transfected autologous bone marrow-derived mesenchymal cells (BMMCs) enhance in vivo cartilage repair in a rabbit model. METHODS: BMMCs, which had a fibroblastic morphology and pluripotency for differentiation, were isolated from bone marrow of the tibia of rabbits, grown in monolayer culture, and transfected with the CDMP1 gene or a control gene (GFP) by the lipofection method. The autologous cells were then implanted into full-thickness articular cartilage defects in the knee joints of each rabbit. RESULTS: During in vivo repair of full-thickness articular cartilage defects, cartilage regeneration was enhanced by the implantation of CDMP1-transfected autologous BMMCs. The defects were filled by hyaline cartilage and the deeper zone showed remodelling to subchondral bone over time. The repair and reconstitution of zones of hyaline articular cartilage was superior to simple BMMC implantation. The histological score of the CDMP1-transfected BMMC group was significantly better than those of the control BMMC group and the empty control group. CONCLUSION: Modulation of BMMCs by factors such as CDMP1 allows enhanced repair and remodelling compatible with hyaline articular cartilage.     

Amyloid in bone marrow smears of patients affected by multiple myeloma

Systemic AL amyloidosis is associated with nearly 15% of cases of multiple myeloma, but data on the frequency and significance of amyloid deposits in the bone marrow of patients affected by multiple myeloma without clinical signs of systemic amyloidosis are scanty. Bone marrow smears of 166 unselected patients affected by multiple myeloma (126 at diagnosis and 40 after treatment) were stained with Congo red and studied by transmission and birefringence microscopy. Both focal and diffuse storages were considered positive. Overall, 67 patients were positive and 99 were negative to Congo red and apple-green birefringence. In particular, 51 of the 126 patients studied at diagnosis and 16 of the 40 patients with advanced disease were positive. Seventeen patients were reassessed after a mean follow-up of 32 months (range: 6–91): disappearance of amyloid deposits was verified in three cases, all responsive to bortezomib-based regimens. The preliminary data available suggest that amyloid deposition in the marrow of myeloma patients is frequent, as it can be traced in nearly 40% of cases. We failed to find correlations between bone marrow amyloid deposits and immunoglobulin type, disease stage, plasma cells percentage, hemoglobin, calcium, creatinine, albumin, or β₂microglobulin. Significantly higher incidence of moderate/severe peripheral neuropathy was found in patients with marrow amyloid exposed to potentially neurotoxic antineoplastic agents. Further studies and prolonged follow-up are needed to validate our findings and to define possible prognostic aspects.