Blood Fibrocytes Research Articles

Mesenchymal Cells and Fibrocytes in Peripheral Blood. Culture Conditions

The fibrocytes, the mesenchymal cells and the colony forming units are included in the concept fibroblast-like, peripheral-blood circulating stem cells. The aim of this work was to establish the culture conditions.Peripheral blood mononuclear cells were isolated from 25 samples collected from the cephalic vein. These were cultured in McCoy's 5A enriched with 20% of foetal bovine serum. The culture was read at 7, 14 and 21 days, evaluating the proliferation, confluence and the round cell/spindle cell ratio. Moreover the 21st day surface markers and phagocytic activity testing was carried out.Growth was achieved in all the cases but only in two dishes were confluence areas retrieved. Spindle cells were 36 ± 3.71% (mean ± SD). All the cells showed intense signal against vimentin, CD34 marker and the NBT test were positives.Clear CD34 expression, positivity against a connective tissue marker such as vimentin and positivity in a phagocytic assay like the NBT-test, support that stem cells, monocytes and fibroblasts share common characteristics.

Circulating peripheral blood fibrocytes in human fibrotic interstitial lung disease

Fibrotic interstitial lung diseases are illnesses of unknown cause characterized by progressive decline in lung function. Fibrocytes are bone marrow-derived, circulating progenitor cells capable of differentiating into diverse mesenchymal cell types. Prior work has shown fibrocytes to traffic to the lung via the CXCL12-CXCR4 chemokine axis in an animal model of pulmonary fibrosis. We therefore assessed the relevance of fibrocytes in patients with fibrotic interstitial lung disease. We found enhanced expression of CXCL12 in both the lungs and plasma of patients with lung fibrosis. CXCL12 levels were associated with an order of magnitude higher number of circulating fibrocytes in the peripheral blood of these patients. Most of the circulating fibrocytes in patients with interstitial lung diseases were negative for the myofibroblast marker alpha-smooth muscle actin, suggesting a relatively undifferentiated phenotype. Taken together, these data suggest that fibrocytes are involved in the pathogenesis of human lung fibrosis.

Peripheral blood fibrocytes contribute to the formation of the avian spleen

Chick-quail chimeric studies were made to determine the origin of the cells of splenic ellipsoid. The ellipsoid is formed by supporting and phagocytic cells, which are embedded in a well-organized extracellular matrix. Splenic and bursal anlage of 6- to 6.5-day-old quail embryos were transplanted into the coelomic cavity of 3-day-old chick embryos and further incubated for 17 days. CD45+ chicken hemopoietic cells colonized both organs. They formed the cells of the ellipsoid and the periellipsoidal white pulp of the transplanted quail spleen. Chicken-specific collagen III was produced only in the donor quail spleen, but not in the bursa of Fabricius. The CD45+/collagen I+/collagen III+ cells are probably identical with the mammalian peripheral blood fibrocytes and contribute to the formation of supporting cells, whereas the CD45+/74.2+ ellipsoid-associated macrophages are of monocytic origin. We provide, for the first time, experimental evidence that peripheral blood fibrocytes exist in the avian species; they are present in the circulation of the chicken embryo and contribute to the organogenesis of the spleen.

Hematopoietic Origin of Fibroblasts and Their Precursors.

Recent studies indicate that hematopoietic stem cells (HSCs) are capable of reconstituting a number of non-hematopoietic organs and tissues. To define the potential of the HSC precisely, we initiated transplantation studies of a clonal population of cells derived from a single HSC. We used the bone marrow (BM) of transgenic enhanced green fluorescent protein (EGFP) mice as the source of donor HSCs. We demonstrated the HSC origin of glomerular mesangial cells (Masuya et al, Blood 101: 2215, 2003) and brain microglial cells and pericyte-like perivascular cells (Hess et al, Exp Neurol 186: 134, 2004). These observations and the fact that glomerular mesangial cells and pericytes are considered myofibroblasts suggested that fibroblasts are also derived from HSCs. In this abstract, we present evidence for HSC origin of fibroblasts and their precursors, BM fibroblast colony-forming units (CFU-F) and peripheral blood (PB) fibrocytes. Lin−Sca-1+c-Kit+CD34− cells from the BM of adult EGFP mice were individually sorted into 96 well Corning plates and cultured for 7 days in the presence of Steel factor and IL-11 or Steel factor and G-CSF. Viable clones consisting of fewer than 20 cells were individually transplanted into lethally irradiated mice. EGFP+ mononuclear cells were sorted from the BM cells of recipients showing high-level, multilineage hematopoietic reconstitution and assayed for CFU-F in Retronectin-treated tissue culture plates. Colonies consisting of more than 50 adherent cells were all EGFP+. The majority of the cells comprising the colonies were fibroblast-like, exhibited spindle-shaped or polygonal cytoplasm and had clear, ovoid nuclei. Flow cytometric analyses revealed that these cells expressed collagen-1 and discoidin domain receptor 2 (DDR2) and exhibited a decreased intensity of CD45. RT-PCR analysis of these cells revealed the presence of mRNA for procollagen 1 alpha-1, vimentin, fibronectin and DDR2. Next we analyzed the PB for donor origin fibrocytes, a fibroblast-like cell type that expresses both fibroblastic and hematopoietic phenotypes in culture. When nucleated PB cells from clonally engrafted mice were cultured on fibronectin-coated dishes, proliferation of EGFP+ fibroblast-like cells was detected. Only one-third of the EGFP+ cells expressed CD45 and most of the EGFP+ cells expressed both collagen-I and DDR2. Similar results were obtained with EGFP+ cells from mice transplanted with 100 uncultured Lin−Sca-1+c-Kit+CD34− cells or 1x106 BM nucleated cells. These studies excluded the effects of short-term culture on HSC differentiation and established the HSC origin of CFU-F and fibrocytes. Classic studies of CFU-F by Friedenstein and others have led to the general belief that mesenchymal stem cells (MSCs), rather than HSCs, generate a number of tissues including adipocytes, osteoblasts, chondrocytes, myocytes and vascular endothelial cells. Here we unequivocally demonstrated that CFU-F are of HSC origin, warranting a re-evaluation of the relationship between HSCs and MSCs.

A role for the peripheral blood fibrocyte in leishmaniasis?

A role for the peripheral blood fibrocyte in leishmaniasis?

A novel polymorphic CAAT/enhancer-binding protein beta element in the FasL gene promoter alters Fas ligand expression: a candidate background gene in African American systemic lupus erythematosus patients.

A single-nucleotide polymorphism (SNP), identified at nucleotide position -844 in the 5' promoter of the FasL gene, lies within a putative binding motif for CAAT/enhancer-binding protein beta (C/EBPbeta). Electrophoretic mobility shift and supershift assays confirmed that this element binds specifically to C/EBPbeta and demonstrated that the two alleles of this element have different affinities for C/EBPbeta. In luciferase reporter assays, the -844C genotype had twice the basal activity of the -844T construct, and basal expression of Fas ligand (FasL) on peripheral blood fibrocytes was also significantly higher in -844C than in -844T homozygous donors. FasL is located on human chromosome 1q23, a region that shows linkage to the systemic lupus autoimmune phenotype. Analysis of 211 African American systemic lupus erythematosus patients revealed enrichment of the -844C homozygous genotype in these systemic lupus erythematosus patients compared with 150 ethnically matched normal controls (p = 0.024). The -844C homozygous genotype may lead to the increased expression of FasL, to altered FasL-mediated signaling in lymphocytes, and to enhanced risk for autoimmunity. This functionally significant SNP demonstrates the potential importance of SNPs in regulatory regions and suggests that differences in the regulation of FasL expression may contribute to the development of the autoimmune phenotype.

Peripheral Blood Fibrocytes from Burn Patients: Identification and Quantification of Fibrocytes in Adherent Cells Cultured from Peripheral Blood Mononuclear Cells

Peripheral blood fibrocytes are a newly identified leukocyte subpopulation that displays fibroblast-like properties. These blood-borne cells can rapidly enter the site of injury at the same time as circulating inflammatory cells. We hypothesize that circulating fibrocytes represent an important source of fibroblasts for healing of extensive burn wounds where it may be difficult for fibroblasts to migrate from the edges of uninjured tissue. In this study we identified and quantified fibrocytes among the adherent cells cultured from human peripheral blood mononuclear cells (PBMC) obtained from 18 burn patients and 12 normal individuals, based on their ability to express type I collagen. Our results showed that adherent cells cultured from PBMC of burn patients differentiated to fibrocytes more efficiently than did those from normal individuals. The percentage of type I collagen-positive fibrocytes was significantly higher for patients than for controls (89.7 ± 7.9% versus 69.9 ± 14.7%, p < 0.001). This percentage was consistently higher for patients with a ≥30% total body surface area burn until 1 year, with the highest percentage appearing within 3 weeks of injury. A positive correlation was found between the levels of serum transforming growth factor-β1 (TGF-β1) and the percentage of fibrocytes developing in the cultures of PBMC derived from these patients. We also demonstrated that fibrocytes were derived from CD14+ cells but not CD14− cells. Conditioned medium from CD14− cells was, however, required for fibrocyte differentiation, whereas direct contact between CD14− and CD14+ cells was not necessary. Treatment of the cell cultures with TGF-β1 enhanced the development of collagen-positive cells, whereas the inclusion of neutralizing anti-TGF-β1 antibodies in the CD14− conditioned medium suppressed fibrocyte differentiation. These data suggest that the development of fibrocytes is up-regulated systemically in burn patients. Increased TGF-β in serum stimulates the differentiation of the CD14+ cell population in PBMC into collagen-producing cells that may be important in wound healing and scarring.

A role for peripheral blood fibrocytes in Lyme disease?

It is proposed that peripheral blood fibrocytes will be a new and important player in the pathogenesis of Lyme disease. Peripheral blood fibrocytes are a circulating leukocyte subpopulation that: (a) express collagen; (b) are an abundant source of cytokines, chemoattractants and growth factors; and (c) are able to recruit and activate naive T-cells and memory T-cells. We predict that peripheral blood fibrocytes will represent a new and important antigen-presenting cell which will play an important role in directing the immune response from the pathogenic Th1 to the protective Th2 response cell in Borrelia infections.

Peripheral blood fibrocytes: differentiation pathway and migration to wound sites.

Fibrocytes are a distinct population of blood-borne cells that display a unique cell surface phenotype (collagen I+/CD11b+/CD13+/CD34+/CD45RO+/MHC class II+/CD86+) and exhibit potent immunostimulatory activities. Circulating fibrocytes rapidly enter sites of tissue injury, suggesting an important role for these cells in wound repair. However, the regulatory processes that govern the differentiation of blood-borne fibrocytes and the mechanisms that underlie the migration of these cells to wound sites are currently not known. We report herein that ex vivo cultured fibrocytes can differentiate from a CD14+-enriched mononuclear cell population and that this process requires contact with T cells. Furthermore, we demonstrate that TGF-beta1 (1-10 ng/ml), an important fibrogenic and growth-regulating cytokine involved in wound healing, increases the differentiation and functional activity of cultured fibrocytes. Because fibrocytes home to sites of tissue injury, we examined the role of chemokine/chemokine receptor interactions in fibrocyte trafficking. We show that secondary lymphoid chemokine, a ligand of the CCR7 chemokine receptor, acts as a potent stimulus for fibrocyte chemotaxis in vitro and for the homing of injected fibrocytes to sites of cutaneous tissue injury in vivo. Finally, we demonstrate that differentiated, cultured fibrocytes express alpha smooth muscle actin and contract collagen gels in vitro, two characteristic features of wound-healing myofibroblasts. These data provide important insight into the control of fibrocyte differentiation and trafficking during tissue repair and significantly expand their potential role during wound healing.

Peripheral blood fibrocytes: mesenchymal precursor cells and the pathogenesis of fibrosis.

Peripheral blood fibrocytes are a novel population of cells that rapidly enter sites of tissue injury and contribute to connective scar formation. Fibrocytes display a distinct cell surface phenotype (CD34+/CD45+/collagen I+), and are an abundant source of cytokines and growth factors that function to attract and activate inflammatory and connective tissue cells. Fibrocytes also are specialized to activate naïve T cells against foreign antigen, and may play a critical role in the initiation of cognate immunity during the earliest phases of tissue injury. Recently, immunohistochemical studies of fibrotic tissues have shown that fibrocytes co-localize to areas of connective tissue matrix deposition. Peripheral blood fibrocytes thus may participate in the generation of excessive fibroses associated with various autoimmune disorders involving a persistent T-cell activation, as occurs in scleroderma.

Interaction of Borrelia burgdorferi with Peripheral Blood Fibrocytes, Antigen-Presenting Cells with the Potential for Connective Tissue Targeting

Borrelia Burgdorferi has a predilection for collagenous tissue and can interact with fibronectin and cellular collagens. While the molecular mechanisms of how B. burgdorferi targets connective tissues and causes arthritis are not understood, the spirochetes can bind to a number of different cell types, including fibroblasts. A novel circulating fibroblast-like cell called the peripheral blood fibrocyte has recently been described. Fibrocytes express collagen types I and III as well as fibronectin. Besides playing a role in wound healing, fibrocytes have the potential to target to connective tissue and the functional capacity to recruit, activate, and present antigen to CD4(+) T cells. Rhesus monkey fibrocytes were isolated and characterized by flow cytometry. B. burgdorferi were incubated with human or monkey fibrocyte cultures in vitro and the cellular interactions analyzed by light and electron microscopy. The two strains of B. burgdorferi studied included JD1, which is highly pathogenic for monkeys, and M297, which lacks the cell surface OspA and OspB proteins. In this study, we demonstrate that B. burgdorferi binds to both human and monkey (rhesus) fibrocytes in vitro. This process does not require OspA or OspB. In addition, the spirochetes are not phagocytosed but are taken into deep recesses of the cell membrane, a process that may protect them from the immune system. This interaction between B. burgdorferi and peripheral blood fibrocytes provides a potential explanation for the targeting of spirochetes to joint connective tissue and may contribute to the inflammatory process in Lyme arthritis.

Regulated Production of Type I Collagen and Inflammatory Cytokines by Peripheral Blood Fibrocytes

We recently described a novel population of blood-borne cells, termed fibrocytes, that display a distinct cell surface phenotype (collagen+/CD13+/CD34+/CD45+), rapidly enter sites of tissue injury, and contribute to scar formation. To further characterize the role of these cells in vivo, we examined the expression of type I collagen and cytokine mRNAs by cells isolated from wound chambers implanted into mice. Five days after chamber implantation, CD34+ fibrocytes but not CD14+ monocytes or CD90+ T cells expressed mRNA for type I collagen. Fibrocytes purified from wound chambers also were found to express mRNA for IL-1beta, IL-10, TNF-alpha, JE/MCP, MIP-1alpha, MIP-1beta, MIP-2, PDGF-A, TGF-beta1, and M-CSF. The addition of IL-1beta (1-100 ng/ml), a critical mediator in wound healing, to fibrocytes isolated from human peripheral blood induced the secretion of chemokines (MIP-1alpha, MIP-1beta, MCP-1, IL-8, and GRO alpha), hemopoietic growth factors (IL-6, IL-10, and macrophage-CSF), and the fibrogenic cytokine TNF-alpha. By contrast, IL-1beta decreased the constitutive secretion of type I collagen as measured by ELISA. Additional evidence for a role for fibrocytes in collagen production in vivo was obtained in studies of livers obtained from Schistosoma japonicum-infected mice. Mouse fibrocytes localized to areas of granuloma formation and connective matrix deposition. We conclude that fibrocytes are an important source of cytokines and type I collagen during both the inflammatory and the repair phase of the wound healing response. Furthermore, IL-1beta may act on fibrocytes to effect a phenotypic transition between a repair/remodeling and a proinflammatory mode.

The peripheral blood fibrocyte is a potent antigen-presenting cell capable of priming naive T cellsin situ

Recent studies have identified a novel population of blood-borne cells, termed fibrocytes, that have a distinct cell surface phenotype (collagen+/CD13(+)/CD34(+)/CD45(+)), rapidly enter sites of tissue injury, and synthesize connective tissue matrix molecules. We found by flow cytometry that purified human fibrocytes express each of the known surface components that are required for antigen presentation, including class II major histocompatability complex molecules (HLA-DP, -DQ, and -DR), the costimulatory molecules CD80 and CD86, and the adhesion molecules CD11a, CD54, and CD58. Human fibrocytes induced antigen-presenting cell-dependent T cell proliferation when cultured with specific antigen and this proliferative activity was significantly higher than that induced by monocytes and nearly as high as that induced by purified dendritic cells. Mouse fibrocytes also were found to express the surface components required for antigen presentation and to function as potent APCs in vitro. Mouse fibrocytes pulsed in vitro with the HIV-proteins p24 or gp120 and delivered to a site of cutaneous injury were found to migrate to proximal lymph nodes and to specifically prime naive T cells. These data suggest that fibrocytes play an early and important role in the initiation of antigen-specific immunity.

Peripheral blood fibrocytes: novel fibroblast-like cells that present antigen and mediate tissue repair.

Conference Article| May 01 1997 Peripheral blood fibrocytes: novel fibroblast-like cells that present antigen and mediate tissue repair J. Chesney; J. Chesney 1The Picower Institute for Medical Research, Laboratory of Medical Biochemistry, Manhasset, NY 11030, U.S.A. Search for other works by this author on: This Site PubMed Google Scholar R. Bucala R. Bucala * *To whom correspondence should be addressed. Search for other works by this author on: This Site PubMed Google Scholar Biochem Soc Trans (1997) 25 (2): 520–524. https://doi.org/10.1042/bst0250520 Article history Received: November 04 1996 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation J. Chesney, R. Bucala; Peripheral blood fibrocytes: novel fibroblast-like cells that present antigen and mediate tissue repair. Biochem Soc Trans 1 May 1997; 25 (2): 520–524. doi: https://doi.org/10.1042/bst0250520 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Society Transactions Search Advanced Search Keywords: APC, antigen-presenting cell, TGF-β1, transforming growth factor β1, M-CSF, macrophage colony-stimulating factor, MIP, macro-phage-inflammatory protein, IL, interleukin, TNF-α, tumour necrosis factor α This content is only available as a PDF. © 1997 Biochemical Society1997 Article PDF first page preview Close Modal You do not currently have access to this content.