Tissue-specific differences in cultured human diploid fibroblasts

NIH/3T3 Fibroblasts Selectively Activate T Cells Specific for Posttranslationally Modified Collagen Type II

It has been shown that synovial fibroblasts (SF) play a key role in the initiation of inflammation and joint destruction, leading to arthritis progression. Fibroblasts may express major histocompatibility complex class II region (MHCII) molecules, and thus, they could be able to process and present antigens to immunocompetent cells. Here we examine whether different types of fibroblasts (synovial, dermal, and thymic murine fibroblasts, destructive LS48 fibroblasts, and noninvasive NIH/3T3 fibroblasts) may be involved in the initiation of rheumatoid arthritis (RA) pathogenesis and can process and present type II collagen (COL2)-an autoantigen associated with RA. Using a panel of MHCII/Aq-restricted T-cell hybridoma lines that specifically recognize an immunodominant COL2 epitope (COL2_259-273), we found that NIH/3T3 fibroblasts activate several T-cell clones that recognize the posttranslationally glycosylated or hydroxylated COL2_259-273 epitope. The HCQ.3 hybridoma, which is specific for the glycosylated immunodominant COL2 epitope 259-273 (Gal264), showed the strongest response. Interestingly, NIH/3T3 cells, but not destructive LS48 fibroblasts, synovial, dermal, or thymic fibroblasts, were able to stimulate the HCQ.3 hybridoma and other COL2-specific T-cell hybridomas. Our experiments revealed that NIH/3T3 fibroblasts are able to activate COL2-specific T-cell hybridomas even in the absence of COL2 or a posttranslationally modified COL2 peptide. The mechanism of this unusual activation is contact-dependent and involves the T-cell receptor (TCR) complex.

Targeting the tumour stroma to improve cancer therapy

Cancers are not composed merely of cancer cells alone; instead, they are complex 'ecosystems' comprising many different cell types and noncellular factors. The tumour stroma is a critical component of the tumour microenvironment, where it has crucial roles in tumour initiation, progression, and metastasis. Most anticancer therapies target cancer cells specifically, but the tumour stroma can promote the resistance of cancer cells to such therapies, eventually resulting in fatal disease. Therefore, novel treatment strategies should combine anticancer and antistromal agents. Herein, we provide an overview of the advances in understanding the complex cancer cell-tumour stroma interactions and discuss how this knowledge can result in more effective therapeutic strategies, which might ultimately improve patient outcomes.

Senescence-associated β-galactosidase activity marks the visceral endoderm of mouse embryos but is not indicative of senescence

Senescence-associated β-galactosidase (SA-β-gal) activity is widely used as a marker of cellular senescence and as an indicator of organismal aging. Here, we report that SA-β-gal activity is present in the visceral endoderm layer of early postimplantation mouse embryos in predictable patterns that vary as the embryo progresses in development. However, determination of the mitotic index and analysis of the expression of Cdkn1a (p21), a marker of senescent cells, do not indicate cellular senescence. Instead, analysis of embryos in culture revealed the presence of SA-β-gal activity in apical vacuoles of visceral endoderm cells likely a reflection of acidic β-galactosidase function in these organelles. SA-β-gal serves as a practical marker of the dynamics of the visceral endoderm that can be applied to developmental as well as functional studies of early mammalian embryos.

Deep dermal fibroblasts contribute to hypertrophic scarring

Hypertrophic scar (HTS) following thermal injury is a dermal fibroproliferative disorder that leads to considerable morbidity. The development of HTS involves numerous cell types and cytokines with dermal fibroblasts being a key cell. We have previously reported that the phenotype of fibroblasts isolated from HTS was altered compared to fibroblasts from normal skin. In this study, normal skin was horizontally sectioned into five layers using a dermatome from which fibroblasts were isolated and cultured. Cells from the deeper layers were observed to proliferate at a slow rate, but were morphologically larger. In ELISA and FACS assays, cells from the deeper layers produced more TGF-beta1 and TGF-beta1 producing cells were higher. In quantitative RT-PCR, the cells from the deeper layers had higher CTGF and HSP47 mRNA levels compared to those from superficial layers. In western blot, FACS and collagen gel assays, fibroblasts from the deeper layers produced more alpha-smooth muscle actin (alpha-SMA), had higher alpha-SMA positive cells and contracted collagen gels more. Fibroblasts from the deeper layers were also found to produce more collagen, but less collagenase by mass spectrometry and collagenase assay. Interestingly, cells from the deeper layers also produced more of the proteoglycan, versican, but less decorin. Taken together, these data strongly demonstrate that fibroblasts from the deeper layers of the dermis resemble HTS fibroblasts, suggesting that the deeper layer fibroblasts may be critical in the formation of HTS.

In contrast to lung fibroblasts--no signs of senescence in skin fibroblasts of patients with emphysema

Smoking is known to be linked to skin ageing and there is evidence for premature senescence of parenchymal lung fibroblasts in emphysema. To reveal whether the emphysema-related changes in cellular phenotype extend beyond the lung, we compared the proliferation characteristics of lung and skin fibroblasts between patients with and without emphysema. Parenchymal lung fibroblasts and skin fibroblasts from the upper torso (thus limiting sun exposure bias) were obtained from patients without, or with mild, or with moderate to severe emphysema undergoing lung surgery. We analysed proliferation rate, population doublings (PD), staining for senescence-associated beta-galactosidase (beta-gal) and gene expression of IGFBP-3 and IGFBP-rP1. Population doubling time of lung fibroblasts differed between control, mild, and moderate to severe emphysema (median (IQR) 29.7(10.0), 33.4(6.1), 44.4(21.2) h; p=0.012) and staining for beta-gal was elevated in moderate to severe emphysema. Compared to control subjects, skin fibroblasts from patients with emphysema did not differ with respect to proliferation rate, PD and beta-gal staining, and showed a lower abundance of mRNA for IGFBP-3 and -rP1 (p<0.05, each). These results suggest that the induction of a senescent fibroblast phenotype by cigarette smoke, as observed in emphysema, primarily occurs in the lung.

[Role of fibroblasts in physiologic, reparative and pathologic processes]

Fibroblast is counted as one of the important cell of the connective tissue. At the present time many phenotypes are known taking part in normal, repair and pathological processes, meanwhile cellular and molecular events occur, where fibroblasts play essential role. Among molecular factors, first of all integrins, growth factors, cytokines and matrix molecules are discussed. The aim of this work is to summarize the morphological, biochemical and functional role of fibroblasts in addition to the physiological process, wound repair and in such pathological processes as Dupuytren's disease, rheumatoid arthritis, Graves' ophthalmopathy and carcinogenesis. It becomes known that fibroblasts participate in dynamic interplay with other cells and with the extracellular matrix. The results of the new investigations clarify better the physiological and pathological processes of the tissue, at the same time give potential help to the therapy of some illnesses. The authors summarise the important data of the subject on the basis of international literature and of their own investigations.

Insights into the role of fibroblasts in human autoimmune diseases

Traditional wisdom has considered fibroblasts as contributing to the structural integrity of tissues rather than playing a dynamic role in physiological or pathological processes. It is only recently that they have been recognized as comprising diverse populations of cells exhibiting complex patterns of biosynthetic activity. They represent determinants that react to stimuli and help define tissue remodelling through the expression of molecules imposing constraints on their cellular neighbourhood. Moreover, fibroblasts can initiate the earliest molecular events leading to inflammatory responses. Thus they must now be viewed as active participants in tissue reactivity. In this short review, I will provide an overview of contemporary thought about the contribution of fibroblasts to the pathogenesis of autoimmune processes through their expression of, and responses to, mediators of inflammation and tissue remodelling.

Enhanced Dupuytren's disease fibroblast populated collagen lattice contraction is independent of endogenous active TGF-beta2

Background

Dupuytren's disease (DD) is a debilitating fibro-proliferative disorder of the hand characterized by the appearance of fibrotic lesions (nodules and cords) leading to flexion contractures of the fingers and loss of hand function. Although the molecular mechanism of DD is unknown, it has been suggested that transforming growth factor-β₂ (TGF-β₂) may play an important role in the underlying patho-physiology of the disease. The purpose of this study was to further explore this hypothesis by examining the effects of TGF-β₂ on primary cell cultures derived from patient-matched disease and normal palmar fascia tissue using a three-dimensional collagen contraction assay.

Methods

Fibroblast-populated collagen lattice (FPCL) contraction assays using primary cell cultures derived from diseased and control fascia of the same DD patients were studied in response to exogenous TGF-β₂ and neutralizing anti-TGF-β₂ antibodies.

Results

Contraction of the FPCLs occurred significantly faster and to a greater extent in disease cells compared to control cells. The addition of TGF-β₂ enhanced the rate and degree of collagen contraction in a dose-dependent fashion for both control and diseased cells. Neutralizing anti-TGF-β₂ antibodies abolished exogenous TGF-β₂ stimulated collagen contraction, but did not inhibit the enhanced basal collagen contraction activity of disease FPCL cultures.

Conclusions

Although exogenous TGF-β₂ stimulated both disease and control FPCL contraction, neutralizing anti-TGF-β₂ antibodies did not affect the elevated basal collagen contraction activity of disease FPCLs, suggesting that the differences in the collagen contraction activity of control and disease FPCL cultures are not due to differences in the levels of endogenous TGF-β₂ activity.

Thy-1 expression in human fibroblast subsets defines myofibroblastic or lipofibroblastic phenotypes

Fibroblasts represent a dynamic population of cells, exhibiting functional heterogeneity within and among tissues. Fibroblast heterogeneity also results from phenotypic differences and may arise from activation or differentiation processes taking place in the cells. We previously reported that human fibroblasts were heterogeneous with respect to surface Thy-1 expression and that separation into Thy-1(+) and Thy-1(-) subsets resulted in functionally distinct subpopulations, leading to the concept of fibroblast subset specialization. In this report we investigated whether Thy-1(+) and/or Thy-1(-) fibroblasts were capable of differentiating into myofibroblasts or lipofibroblasts. Fibroblast subsets were used from human myometrium and orbit to test this hypothesis. Only Thy-1(+) human myometrial and orbital fibroblasts were capable of myofibroblast differentiation after treatment with TGFbeta or platelet concentrate supernatant, assessed by alpha smooth muscle actin expression. Interestingly, only Thy-1(-), but not Thy-1(+) subsets differentiated to lipofibroblasts, as determined by the accumulation of cytoplasmic lipid droplets after treatment with 15-deoxy-Delta(12, 14)-PGJ(2) or ciglitazone. We propose that fibroblast Thy-1 display pre-determines lineage to a contractile or lipid-like phenotype in the human myometrium and orbit. This additional distinction between Thy-1(+) and Thy-1(-) human fibroblast subtypes has important consequences in normal tissue homeostasis and in pathogenesis of orbital and myometrial diseases characterized by persistent myofibroblasts or fat accumulation, such as occurs in Graves' ophthalmopathy, tissue fibrosis, abnormal wound healing, and scarring.

Elevated expression of hepatocyte and keratinocyte growth factor in cultured buccal-mucosa-derived fibroblasts compared with normal-skin-derived fibroblasts

Oral mucosa heals faster with less scar formation than skin and a hypertrophic scar is very rare in the oral cavity, but its mechanism has not been elucidated enough. To elucidate whether or not there are differences in growth factor expression between fibroblasts derived from buccal mucosal and normal skin, we investigated the expression of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF) and stem cell factor (SCF) by cultured fibroblasts. The semiquantitative RT-PCR revealed that the expression of HGF and KGF transcripts by buccal mucosal fibroblasts was significantly elevated compared with that by dermal fibroblasts. In parallel, ELISA revealed the significant increase of HGF production by buccal mucosal fibroblasts. The level of production of SCF protein did not differ significantly. Our study suggests that increased expression of HGF and KGF by buccal mucosal fibroblasts may partly be responsible for the faster wound healing with less scar formation in the oral cavity compared with normal skin.

Accumulation of oxidative DNA damage, 8-oxo-2'-deoxyguanosine, and change of repair systems during in vitro cellular aging of cultured human skin fibroblasts

Effects of in vitro cellular aging on the content of 8-oxo-2'-deoxyguanosine, a typical oxidation product of DNA bases, were examined in cultured human skin fibroblasts. The 8-oxo-2'-deoxyguanosine content in the DNA of TIG-3S cells established from skin tissues of a fetal donor increased immediately before the cessation of proliferation. TIG-114 and TIG-104 cells established from skin tissues of adult and aged donors, respectively, showed similar changes in 8-oxo-2'-deoxyguanosine content during in vitro cellular aging. The accumulation of 8-oxo-2'-deoxyguanosine in late-passage cells was dependent on the number of cell divisions, and not on the cultivation time. Increases in the activities of superoxide dismutase and glutathione peroxidase were observed prior to the increase in 8-oxo-2'-deoxyguanosine content, while the catalase activity decreased gradually during in vitro cellular aging at late-passage. Furthermore, the activities of 8-oxo-2'-deoxyguanosine endonuclease and DNA polymerases decreased with the progression of proliferation. These results indicate that defense systems against oxidative stress in late-passage cells remain sufficiently active before the cessation of cell division, but that repair systems against oxidative damage decay at late-passage. Oxidative stress beyond the antioxidant capacity and/or repair activity seems to result in an accumulation of 8-oxo-2'-deoxyguanosine in late-passage cells.

Fibroblast heterogeneity: existence of functionally distinct Thy 1(+) and Thy 1(-) human female reproductive tract fibroblasts

Little is known about fibroblasts from the female reproductive tract, much less whether or not functional subsets exist. Fibroblasts are key as sentinel cells for recruiting white blood cells and for wound healing. The purpose of this research was to evaluate the possibility that functional subsets of fibroblasts exist in the human female reproductive tract. The strategy used was to define fibroblast subpopulations based on their surface expression of the Thy 1 antigen. In situ staining of human myometrium and endometrium showed heterogeneous staining for Thy 1. Freshly derived strains of fibroblasts from the myometrium and endometrium also demonstrated heterogeneous Thy 1 expression. For the first time, using magnetic beading and fluorescence-activated cell sorting, human myometrial fibroblasts were successfully separated into functionally unique Thy 1(+) and Thy 1(-) subsets. Both subsets produced the proinflammatory cytokines interleukin (IL)-6 and IL-8 after IL-1beta stimulation, but only the Thy 1(+) subset produced MCP-1. Furthermore, only Thy 1(+) fibroblasts up-regulated CD40 surface expression with IL-1beta or interferon-gamma treatment. Engagement of CD40 in the Thy 1(+) subpopulation induced IL-6, IL-8, and MCP-1. The discovery of functional subsets of reproductive tract fibroblasts now permits assessment of their roles in the normal functions of the reproductive tract and in disease states such as adhesions and menorrhagia.

Differences between fibroblasts cultured from oral mucosa and normal skin: implication to wound healing

It is generally agreed that oral mucosa heals faster with less scar than skin does, and hypertrophic scar or keloid is very rare in the oral cavity. Fibroblasts are thought to play an important role in wound healing and scar formation, whose control is mediated by growth factors. We have studied whether there are any differences in the cellular behavior of fibroblasts between oral mucosa and skin, and in their response to growth factors. Oral mucosal fibroblasts proliferated slightly more than dermal fibroblasts on average. Dermal fibroblasts in collagen gel possessed greater contraction potency than oral mucosa fibroblasts, irrespective of the presence of growth factors; however, oral mucosa fibroblasts showed an earlier collagen gel contraction with or without TGF-beta1. There were no differences in basal collagen synthetic rate between dermal and oral mucosal fibroblasts, while the latter synthesized more collagen than dermal fibroblasts when they were stimulated with TGF-beta1. Our study showed that oral mucosal fibroblasts and dermal fibroblasts had selective differences in cellular behavior and in their responses to growth factors, which seems to contribute to the differences in wound healing.

Is fibroblast heterogeneity relevant to the health, diseases, and treatments of periodontal tissues?

There are wide variations of gene expression and strikingly different responses to extracellular signals among different fibroblast populations. This has prompted a large number of in vitro studies which suggest that fibroblasts are not homogeneous but instead comprise multiple subpopulations with extensive site-to-site and intra-site variations. Conceivably, either fibroblasts are not all created equal, or, alternatively, discrete subpopulations may emerge in development, inflammatory lesions, or wound healing. While the heterogeneous nature of cultured fibroblasts has been known for some time, are these variations relevant to our understanding of the biology of oral tissues, their involvement in disease, and their response to therapy? Since fibroblasts are the predominant cell type in soft connective tissue matrices, the regulation of their proliferative, synthetic, and degradative behavior is likely to be important in tissue physiology and pathology. In this review, we use the current literature to assess whether fibroblast subpopulations really make a difference in the health and disease of periodontal tissues. We address the following questions: (1) Is fibroblast heterogeneity a real in vivo phenomenon? (2) How can we advance our knowledge of phenotypic variations and the regulation of fibroblast differentiation? (3) Could a knowledge of fibroblast heterogeneity have an impact on the development of new approaches to pathogenesis and the treatment of periodontal tissues?

In vitro radiation sensitivity of mouse lung fibroblasts isolated by flow cytometry

PURPOSE

Recently, we have isolated two major fibroblast cells (Thy-1+, Thy-1-) from mouse LAF1 lung tissue using the anti-Thy-1 antibody expression and fluorescence activated cell sorter. To examine the possibility that x- or gamma-ray-induced pulmonary fibrosis at the late stage of injury could arise from radioresistant cell subpopulations, the radiation sensitivities of Thy-1+ and Thy-1- cells were evaluated by the colony forming assay.

METHODS AND MATERIALS

Cell survival curves, repair of potentially lethal damage (PLD) and sublethal damage (SLD), and cell-age response curves were obtained after Cs-137 gamma-ray irradiation.

RESULTS

The cell survival curves measured after 0-10 Gy gamma-ray showed that Thy-1+ cells were slightly more radioresistant than Thy-1- cells. The D0, n, alpha, and beta values measured from the survival curves also confirmed this observation. After a single dose of 10 Gy, a small amount of PLD repair was observed in Thy-1- cells, while no PLD repair was found in Thy-1+ cells. Although the initial cell survival level of Thy-1- cells was lower, the final survival levels of Thy-1+ and Thy-1- cells became identical at 8 h after irradiation due to the PLD repair. After split-dose irradiation of 4 Gy followed by 4 Gy, a similar extent and rate of SLD repair was found in Thy-1+ and Thy-1- cells. Cell-age response curves were obtained from irradiated G0/G1, S, and G2M cells separated by centrifugal elutriation and irradiated with 8 Gy gamma-ray. The results indicated that Thy-1+ and Thy-1- cells had a similar S resistant, and G1, G2M-sensitive radiation cell-age response curve.

CONCLUSIONS

This study suggests that the selection of radioresistant lung fibroblast may not be responsible for the development of lung fibrosis in irradiated LAF1 mouse.

Corticosteroids induce proliferation but do not influence TNF- or IL-1 beta-induced ICAM-1 expression of human dermal microvascular endothelial cells in vitro

The effects of hydrocortisone, dexamethasone, betamethasone 17-valerate and clobetasol propionate at concentrations of 10(-5)-10(-12) M on the proliferation of human dermal microvascular endothelial cells (HDMEC) were studied in vitro. In addition, confluent HDMEC were treated with TNF (1000 U/ml) or IL-1 beta (1000 U/ml) alone or in combination with the corticosteroids (10(-5) M, 10(-6) M) for 24 h, and cytokine-induced expression of intercellular adhesion molecule-1 (ICAM-1) was assessed by immunocytochemistry. Controls were treated either with growth medium or with the corticosteroids alone. All tested corticosteroids stimulated HDMEC growth after 4 and 6 days of treatment in a dose-dependent manner, as assessed by 3H-thymidine incorporation and the 4-methyl-umbelliferyl heptanoate (MUH) assay. The minimal effective concentration was 10(-9) M for hydrocortisone, 10(-10) M for dexamethasone and betamethasone, and 10(-12) M for clobetasol. In untreated and in corticosteroid-treated cultures, less than 5% of the cells expressed ICAM-1. TNF and IL-1 beta were strong inducers of ICAM-1 expression on 74% and 82% of the cells, respectively. None of the tested corticosteroids significantly influenced cytokine-induced ICAM-1 expression, suggesting that the anti-inflammatory effects of corticosteroids are not related to ICAM-1 modulation on HDMEC.

Proliferative characteristics of fibroblast lines derived from open lung biopsy specimens of patients with IPF (UIP)

We compared the doubling time of fibroblasts derived from idiopathic pulmonary fibrosis (usual interstitial pneumonia) (IPF [UIP]) lung tissues and control fibroblasts, cultured in usual growth medium, and examined the response of these fibroblasts to platelet-derived growth factor (PDGF) and prostaglandin E2 (PGE2). Ten fibroblast lines from open lung biopsy specimens of patients with IPF (UIP) and ten control fibroblast lines from surgically resected lung tissue of patients with limited lung diseases were established. The average doubling time of fibroblast lines was 32.0 +/- 6.0 h (mean +/- SD) in UIP and 33.2 +/- 10.4 h in controls, showing no difference between the two groups. To examine the responses of fibroblasts to PDGF and PGE2 and the differences between fibroblasts derived from fibrotic tissues with different intensity of fibrosis, lung specimens from five patients with IPF were subdivided into two groups, higher-intensity fibrotic lesions (H) and lower-intensity fibrotic lesions (L). The fibroblast lines were established separately. 3H-thymidine uptake with or without PDGF or PGE2 was examined. Results were expressed as the index of thymidine incorporation into the fibroblasts. There were no differences in the doubling times and the responses to PDGF and PGE2 between H and L. There were no differences between control and H regarding their response to PDGF. In response to PGE2, the growth inhibition for H was significantly decreased compared with the control (p less than 0.05). There was no difference in growth inhibition between H and L. The finding that PGE2 inhibits fibroblast proliferation less in UIP lung tissue suggests that fibroblasts from UIP were functionally altered cells or, to some extent, out of normal regulation. These results suggest an abnormal proliferation of fibroblasts observed in IPF (UIP).

The biochemistry of mammalian senescence

Senescence is a process which, until quite recently, has been the subject of little scientific investigation. Even the word "senescence" is difficult to define, and complex methodological pitfalls have impeded progress. In the past few years, there have been exciting advances in understanding the physiological, cell biological, biochemical, and molecular biological nature of senescence. Changes in membrane function, protein synthesis, DNA structure (including glycosylation, altered tertiary structure, free-radical effects, and loss of telomeric DNA), and changes in gene regulation with age are reviewed. Recent work on changes in responses to transcriptional regulatory proteins and cellular senescence factors, some of which have been identified, is particularly promising and leads to the conclusion that senescence, at least in part, is a programmed process. Despite these advances, the fundamental cause of senescence remains elusive but might, as in the case of other biological processes which are phylogenetically widespread, turn out to be quite simple, and perhaps, even modifiable.

Differential expression of the fibronectin isoform containing the ED-B oncofetal domain in normal human fibroblast cell lines originating from different tissues

Fibronectin (FN) polymorphism is due both to alternative splicing of three sequences (ED-A, ED-B, and IIICS) of the primary transcript and to post-translational modifications. The FN isoform containing the ED-B sequence (B-FN), while having an extremely restricted distribution in normal adult tissues, has a high expression in fetal and tumor tissues. On a panel of non-fetal skin, fetal skin, and fetal lung fibroblast cell lines we have studied, through S1-nuclease protection analysis, the expression of the ED-B containing FN mRNA as well as the expression of the ED-B containing FN isoform through immunoblotting and immunofluorescence techniques, using domain specific monoclonal antibodies. The results show that the expression of B-FN in the different fibroblast cell lines has an extremely great variability depending on the developmental stage of the donor and on the tissue of origin. Moreover, we found that SV-40-transformed fibroblasts present a higher expression of B-FN mRNA with respect to their normal counterparts. An increase in the relative amount of the B-FN isoform in normal human fibroblasts was also obtained by treatment with transforming growth factor-beta.

Changes in lectin-binding pattern in the digestive tract of Xenopus laevis during metamorphosis. II. Small intestine

The binding of seven lectins (concanavalin A, Con A; Dolichos biflorus agglutinin, DBA; peanut agglutinin, PNA; Ricinus communis agglutinin I, RCA-I; soybean agglutinin, SBA; Ulex europeus agglutinin, UEA-I; and wheat germ agglutinin, WGA) to the small intestine in metamorphosing Xenopus laevis was studied by the avidin-biotin-peroxidase (ABC) method. The staining pattern of the epithelium with all lectins except for UEA-I and Con A changed gradually during metamorphic climax; the main component of the epithelium, absorptive cells, gradually became positive for DBA, PNA, and SBA and the scattered goblet cells for RCA-I and WGA. On the other hand, the change of the staining pattern in the connective tissue occurred only for Con A, RCA-I, and WGA, and this change took place rapidly at the beginning of climax (stage 60). Increased staining for Con A and WGA at stage 60 was observed only in a group of connective tissue cells close to the epithelium and in the basement membrane. As metamorphosis progressed, this localization of the staining intensity became less clear. At the completion of metamorphosis (stage 66), the absorptive cells were stained with all lectins except for UEA-I, whereas the goblet cells stained only with RCA-I and WGA. These results indicate that lectin histochemistry can distinguish between larval and adult cells of both two epithelial types (absorptive and goblet cells). The technique may also identify a group of connective tissue cells, close to the epithelium, that possibly induce the metamorphic epithelial changes.

Proliferation of rat and human lung fibroblasts following exposure to prostaglandin E2

Numerous investigators have reported that exogenous prostaglandin E2 (PGE2) can inhibit human lung fibroblast proliferation in vitro. Yet various lines of evidence derived from clinical and experimental studies suggest that PGE2 may not be of major importance in inhibiting fibroblast proliferation in vivo. We examined the effects of exogenously-supplied PGE2 on the in vitro proliferation of HFL-1 human lung fibroblasts and rat lung fibroblasts derived from Fischer 344 rats using a multisample assay system that provided a detailed kinetic picture of PGE2 effects on fibroblast proliferation. Exogenously supplied PGE2 (5-5000 ng/ml) had no effect on the proliferation of actively cycling or initially quiescent subconfluent populations of rat lung fibroblasts. In contrast, initially quiescent subconfluent or confluent cultures of HFL-1 cells that were treated with 50-5000 ng/ml PGE2 exhibited a dose-dependent, transitory inhibition of division when stimulated to return to a state of active proliferation. Once division resumed, the cells divided at the rate of the PGE2-free control condition, even in the continued presence of the prostaglandin. This initial postinhibitory resumption of division was not attributable to the emergence of a PGE2-resistant subpopulation. Thus, although exogenously supplied PGE2 indeed inhibits proliferation of human pulmonary fibroblasts in vitro, the duration of the inhibition appears to be much shorter than previously suspected.

Characterization of two major populations of lung fibroblasts: distinguishing morphology and discordant display of Thy 1 and class II MHC

We have determined that murine lung fibroblasts are divisible into two major subpopulations based on expression of Thy 1. Twenty-four to fifty-three percent of freshly isolated lung cells displayed Thy 1 and were separated using FACS into Thy 1+ and Thy 1- fractions for morphologic examination. Analysis by electron microscopy revealed that both the Thy 1+ and Thy 1- fractions contained fibroblasts. Freshly isolated lung cells cultured for 2 wk consisted of greater than 95% fibroblasts, with 28 to 49% displaying Thy 1. These cells were sorted by FACS into Thy 1+ and Thy 1- lines that maintained a stable phenotype over many weeks and that were used as a source to obtain stable fibroblast clones. Adherent pulmonary fibroblasts are not phagocytic and lack the markers of macrophages, dendritic cells, B lymphocytes, and T lymphocytes (with the exception of Thy 1). Interestingly, the Thy 1- fibroblasts spread more and contained a more extensive microfilament and microtubule network than did the spindly and often lipid-containing Thy 1+ population. Both populations of fibroblasts synthesized collagen. Class I MHC expression was very low on Thy 1+ and Thy 1- fibroblasts, but high levels were displayed after gamma-IFN treatment. Most exciting was the unexpected finding that only the Thy 1- lines and clones displayed class II MHC (Ia) in response to treatment with gamma-IFN. Moreover, only the Thy 1- fraction (gamma-IFN-treated) presented antigen to T lymphocyte clones, an observation that suggests that this subset of cells may be involved primarily in promoting chronic lung inflammation, which is associated with developing fibrosis. Thus, two populations of pulmonary fibroblasts exist, defined by the expression of Thy 1, distinguishing morphology, inducibility for Ia expression, and antigen-presenting function. It should now be possible, using these characteristics, to ascertain the role of pulmonary fibroblast subpopulations in developing fibrosis.

Genetic control of variation in human gingival fibroblast proliferation rate

Logarithmic proliferation rate (Days 1 to 6) of gingival fibroblasts derived from 15 pairs of monozygotic (MZ) and 9 pairs of dizygotic (DZ) human twins was compared under optimal and suboptimal growth conditions. Cell proliferation rates exhibited considerable variability among strains. For Caucasian donors (13 MZ, 6 DZ pairs) DZ twins demonstrated significantly greater (P less than 0.01) within-pair variance in cell proliferation rate compared to MZ twins when evaluated under optimal growth conditions. Heritability analysis indicated strong genetic control of proliferation rate of human gingival fibroblasts (HGF) under optimal growth conditions (1.0 +/- 0.67), whereas proliferation rate of HGF under suboptimal growth conditions revealed less genetic control (0.42 +/- 0.61). These findings emphasize the importance of carefully matching control and test HGF in assays dependent on cellular proliferation.

Effect of histamine on proliferation of normal human adult lung fibroblasts

Fibrotic lung tissue shows increased connective tissue deposition and fibroblast proliferation and in addition a substantial increase in mast cell numbers in and around the fibrotic area. To elucidate the question of whether products of mast cells affect the proliferative behaviour of structural cells in the lung and thereby contribute to fibrogenesis, the effect of histamine, a prominent mast cell derived mediator, on the in vitro proliferation of primary cultures of normal adult human lung fibroblasts was studied. Histamine enhanced fibroblast proliferation in a dose dependent manner, with an optimum effect at a physiological concentration of 10(-7) mol/l. This effect occurred when cells were exposed to histamine at restricted times during cell growth and was shown to depend in part on the stage of the cell cycle reached by the fibroblasts. The histamine induced proliferation was mediated through an H2 histamine receptor on the fibroblast, being inhibited by cimetidine, an H2 antagonist, and not by pyrilamine maleate, an antagonist of the H1 receptor. Mast cell products such as histamine may interact with and promote the increased fibroblast proliferation found in pulmonary fibrosis.

Isolation and growth characteristics of adult human tendon fibroblasts

An explant method for the isolation of fibroblasts from adult human tendon is described. Cells were successfully isolated from 22 out of 27 common biceps tendons obtained from cadaveric donors (age range 11-83 years). The fibroblasts could be maintained in culture using standard methods and morphologically resembled those of synovial rather than dermal origin. Growth characteristics of 12 cell lines were assessed by deoxyribose nucleic acid (DNA) synthesis using [3H]thymidine incorporation in response to stimulation by fetal calf serum. Cells obtained separately from superficial and deep parts of the tendons produced almost identical responses. No significant reduction in growth response with increasing age was found when related to the age of the donor. Therefore this study did not show any age related defect in the short term tendon fibroblast replicative responses to serum.

Cellular senescence revisited: a review

The field of cellular senescence (cytogerontology) is reviewed. The historical precedence for investigation in this field is summarized, and placed in the context of more recent studies of the regulation of cellular proliferation and differentiation. The now-classical embryonic lung fibroblast model is compared to models utilizing other cell types as well as cells from donors of different ages and phenotypes. Modulation of cellular senescence by growth factors, hormones, and genetic manipulation is contrasted, but newer studies in oncogene involvement are omitted. A current consensus would include the view that the life span of normal diploid cells in culture is limited, is under genetic control, and is capable of being modified. Finally, embryonic cells aging in vitro share certain characteristics with early passage cells derived from donors of increasing age.

Free radical scavenging systems and the effect of peroxide damage in aged human skin fibroblasts

One prominent theory of aging postulates an accumulation of cell damage resulting from nonenzymatic chemical reactions between important cellular components and free radicals. Fibroblast lines derived from skin biopsies of psychiatric patients ranging in age from 22 to 70 were evaluated soon after adaptation to culture. No significant correlation was found between donor age and the detoxification enzyme activities of superoxide dismutase (SOD) or aryl hydrocarbon hydroxylase (AHH) or susceptibility to damage by oxygen metabolites as measured by cell viability or lactate dehydrogenase (LDH) leakage.

Hydrocortisone modulates RA-induced growth inhibition of normal and transformed human embryonic lung fibroblasts

All-trans retinoic acid (10(-5) M) added at seeding reduces the growth rate and saturation density of normal human embryonic lung fibroblasts of two lines (WI-38 and IMR-90) and similarly inhibits growth of SV40-transformed WI-38 cells (VA13A). The growth inhibitory effects of retinoic acid do not show serum dependency, and the viability of treated cells is 95-99% of controls. Old populations of WI-38 cells (cells at high population doubling levels) are more sensitive to the effects of retinoic acid than are young populations (cells at low population doubling levels), and population life span is reduced by continuous exposure to retinoic acid. When retinoic acid is combined with the glucocorticoid hydrocortisone, inhibition of VA13A cell growth is increased, whereas the retinoic acid-induced inhibition of normal cells is decreased. VA13A cells treated with retinoic acid alone, or in combination with hydrocortisone, exhibit a reversion to a more elongated, fibroblast-like appearance. This paper discusses the clinical implications of the relationship between retinoic acid and hydrocortisone.

The heterogeneity of human fibroblasts as determined from the effects of hydrocortisone on cell growth and specific dexamethasone binding

To elucidate the heterogeneity of human fibroblasts from lung and skin, the effects of hydrocortisone on cell proliferation and the specific dexamethasone binding to cells were studied. Hydrocortisone at physiological concentrations stimulated the proliferation in three strains of human fetal lung fibroblasts and inhibited it in two strains. There are two kinds of fibroblasts in the human fetal lung in addition to the human skin fibroblasts reported previously. Dexamethasone-binding experiments showed that human fibroblasts may be classified into two groups with respect to the dissociation constant (Kd) of the binding reaction. The heterogeneity of human fibroblasts shown by Kd could not be correlated to classification on the basis of the effects of hydrocortisone on cell proliferation. The differences in Kd for the binding reactions suggest differences in donor tissues from which human fibroblasts are derived.

Use of cultured human cells for biochemical analysis

The use of cultured human cells for biochemical analysis is increasing. This reflects the many advantages of such cells over tissue samples: independence of the measurements from the biological milieu of the donor, better control of experimental variables and the possibility of immortalizing the patient via his cells. Concomitant with these advantages, however, are certain new experimental variables which, if not properly controlled, can yield spurious results. This paper describes the types of cultured human cells that are generally available and the basic steps involved in their culture, as well as a discussion of the sources of variability in biochemical measurements which can be attributed to cell culture.

The current state of research with peripheral tissues in Huntington disease

Huntington disease is a neurological autosomal dominant disease of unknown origin and the search for a suitable diagnostic marker has been extended to the peripheral tissues. It is generally believed that a membrane defect exists in Huntington disease although the evidence is controversial. It is the aim of this review to examine the validity of these claims for each of the peripheral tissues and techniques involved, and it is not intended to include all other aspects of research into Huntington disease.

Characterization of a new human diploid cell line--IMR-91

A human diploid fibroblast cell line has been established from the lung tissue of a male fetus. This has been characterized and frozen away in large quantity. A smaller quantity of fibroblastlike cells from skin has also been established, partially characterized, and placed in frozen storage from the same fetus. This project is in support of the National Institute on Aging research in general cell biology. The present lines designated IMR-91 lung and IMR-91 skin complement the previous human diploid fibroblast culture (IMR-90) established from a female fetus. The lack of random inactivation of one of the two X chromosomes in the present male line reduces the genetic heterogeneity inherent in the female line.

Effects of various steroids on in vitro lifespan and cell growth of human fetal lung fibroblasts (WI-38)

Human fetal lung fibroblasts, WI-38, were cultivated in a medium containing various steroids. A dose-response curve constructed by counting the number of cells on day 16, or at regular intervals, showed that glucocorticoids (hydrocortisone and cortisone) and mineralocorticoids (aldosterone and deoxycorticosterone) caused an increase in cell density when added at physiological concentrations or higher. On the other hand, androgens (testosterone, dihydrotestosterone, and dehydroepiandrosterone), estrogen (17 beta-estradiol), and progesterone caused a decrease in cell density at higher concentrations (5 micrograms/ml, or more) although these had no effect on cell density at concentrations lower than 0.5 micrograms/ml. With cells grown from population doubling 31 in a medium containing steroids, it was shown that hydrocortisone extended the in vitro lifespan of WI-38 cells at concentrations of both 5 micrograms/ml and 0.5 micrograms/ml, while dehydroepiandrosterone, 17 beta-estradiol, and progesterone caused a shortening in lifespan at only 5 micrograms/ml. These results suggest that there is a direct relationship between the effects of steroids on cell growth and the lifespan of human fetal lung fibroblasts.

Human fetal lung fibroblasts: observations on origin and stability in culture

The loosely associated lung mesenchymal cell found between the ducts of the 3-to 4-month fetus is considered to be the probable progenitor of lung fibroblast cultures and of alveolar interstitial cells. A possible stage- and tissue-specific property of this cell type, the reduction of cortisone to cortisol, is defined and its activity studied in a variety of cell lines. Fibroblast lines derived from both fetal and adult lung had about ten times the cortisone-reducing activity of corresponding skin fibroblast lines. This relatively high activity was also characteristic of cell lines established by cloning the initial fetal lung digest. Lines established from developmentally related esophagus and from trachea had less activity than corresponding lung fibroblasts. A high level of cortisone-reducing activity was maintained in four serially passaged lung fibroblast lines for at least 85% of the proliferative life span and a second cell property, the enhancement of this activity by pretreatment with cortisol, was also maintained in three of the four lines.

Attachment and extracellular matrix differences between tendon and synovial fibroblastic cells

Fibroblasts of the synovium of sheathed tendons were isolated, and their biochemical properties were compared with those of the fibroblasts of the remaining tendon. The synovial cells had a lower attachment efficiency than did the tendon cells. On the day of cell isolation the synovial cells synthesized collagen as 10% of their total protein, whereas the tendon cells synthesized 30% collagen. After growth in fetal bovine serum (FBS), the percentage of collagen synthesized by both populations decreased; however, the synovial cells still made less collagen than did the tendon cells (5 versus 11%). On the basis of cyanogen bromide peptide analysis, the synovial cells were found to synthesize Types I and III collagen in primary culture, whereas the tendon cells synthesized only Type I. The synovial cells also synthesized two to three times less sulfated glycosaminoglycans in culture than did the tendon cells. Thus, the two cell populations differed in attachment efficiency and in their biosynthesis of collagen and sulfated glycosaminoglycans. These differences reflect extracellular matrix differences that have been observed in the tendon in vivo. In addition, the results augment existing data showing that not all fibroblasts have identical phenotypes.

Kinetics of chick embryo cell types in culture

The growth kinetics and population doubling limits of chick embryonic fibroblasts, chondroblasts, and retinal pigment cells were compared. Chondroblasts were found to have a cumulative population doubling level (37 +/- 3 PDL) similar (p = 0.05) to that of control fibroblasts (42 +/- 2 PDL), in individual and pooled clones. While both cell types have similar doubling potential, the proportion of tritium-labeled nuclei decreases, and differs significantly as doubling level increases. This age-associated decline is due to an extension in the population doubling time. Direct cell-cycle analysis shows this increase to occur in the G1 phase. Furthermore, cartilage colonies maintain their phenotypic expression (metachromasia) throughout their lifespan under conditions of subcloning at sparse density. When fibroblasts derived from 15 day chick embryos are compared with fibroblasts from 10 day embryos (41 +/- 2 PDL) there is no significant difference (p = 0.05) in cumulative PDL or percent labeled nuclei, indicating that fibroblasts of different embryonic age have similar potential. The addition of hydrocortisone and insulin to the medium significantly shortens (25 +/- 2 PDL) the lifespan of 10 day chick fibroblasts. Kinetics of retinal pigment cells show a population doubling potential (29 +/- 1 PDL) different from fibroblasts and chondroblasts, suggesting that different cell types may not have similar limits on doubling potential when first determined in embryogenesis. Hydrocortisone and insulin have no effect on the growth kinetics or lifespan of retinal pigment cells in culture.

Selective inhibition of fibroblasts by spermine in primary cultures of normal human skin epithelial cells

Overgrowth with fibroblasts has been a major problem in the cultivation of normal human skin epithelium. In the present study it is shown that the addition of spermine to the culture medium in micromolar concentrations has a differential cytotoxic effect on fibroblasts allowing the cultivation of human skin epithelial cells in primary culture without fibroblastic overgrowth. Putrescine, another polyamine, is shown to be equally cytotoxic to fibroblasts and epithelial cells when added in millimolar concentrations; below this concentration range no cytotoxic effect could be demonstrated. This difference in cytotoxicity between spermine and putrescine is suggested to depend on the conversion of spermine, but not putrescine, and to highly cytotoxic products by an amine oxidase present in fetal bovine serum.

Fibroblast heterogeneity in glucocorticoid regulation of collagen metabolism: genetic or epigenetic?

Cultured fibroblasts derived from normal human dermis show a consistent 62% inhibition of collagen synthesis by hydrocortisone, whereas cultures derived from keloids average only 30% inhibition and show a much larger strain to strain variation ranging from 75% inhibition to 49% stimulation. Examination of fibroblast clones indicates that this high variation among keloid strains is not due to differences in the proportion of normal and keloid cells in the mass culture populations. Small but significant differences in the effect of hydrocortisone on collagen deposition are also seen among these clonal populations, but are not related to the type of tissue from which cultures were derived. Two to three-fold differences among clones derived from a single individual were observed, possibly suggesting functional heterogeneity of dermal fibroblasts with regard to collagen metabolism under control conditions and in response to hydrocortisone. However, this variation among clones may simply reflect differences in clonal growth, inasmuch as both collagen synthesis and deposition, and the effect of hydrocortisone on these processes, are strongly affected by population density.

Fibrodysplasia ossificans progressiva: a distinctive bone-forming lesion of the soft tissue

A 3-month-old white female presented with a bone-forming lesion of the soft tissue of the left cheek. Skeletal survey revealed numerous associated radiographic abnormalities, predominantly involving the phalanges. Mineral metabolism and endocrine function were within normal limits. Multiple operations were performed over a 17-year period for palliation of sequelae arising from inability to open the mouth due to ankylosis of the temporomandibular joint by the progressively ossifying lesion. Histologically, the pathologic material had features resembling those of periosteal grafts, with all stages of membranous bone formation and a tendency for more mature lesions later in the course. .The clinico-pathologic features are those of fibrodysplasia ossificans progressiva (FOP). The differential diagnosis of this rare condition from other bone-forming lesions of the soft tissue such as myositis ossificans, extra-skeletal osteosarcoma and osseous metaplasia is discussed.

Evidence for a relationship between longevity of mammalian species and life spans of normal fibroblasts in vitro and erythrocytes in vivo

The replicative life spans of mammalian fibroblasts in vitro were studied in a number of cell cultures representing eight species. Emphasis was placed on determining the population doubling level at which phase III (a period of decrease in the rate of proliferation) and chromosomal alterations occur. All the cell cultures studied went through a growth crisis, a period of apparent growth cessation lasting for at least 2 weeks. In most cultures, the crisis represented the end of their replicative capacities, but in some cultures cell proliferation was resumed after the crisis. A predominantly diploid chromosome constitution (more than 75%) was demonstrated prior to the growth crisis. In cultures in which cell proliferation was resumed after the crisis, a nondiploid constitution prevailed in all cases except the rat (with 90% or more diploid cells all the time). The growth crisis occurred at population doubling levels that were characteristic for the species and was shown to be related to the species' maximal life span by a strict power law, being proportional to the square root of the maximal life span. Based on data in the literature, the same relationship was also valid for the lifespans of circulating mammalian erythrocytes in vivo. These results may indicate the prevalence of a common functional basis regulating the life span of fibroblasts and erythrocytes and thus operating in replicative as well as postmitotic cells in vitro and in vivo.

Estrogen induces different responses in dermal and lung fibroblasts: special reference to collagen

Fibroblast-like cells derived from dorsal skin and lung of AKR strain mouse embryos were cultured with estrogen for 4 days. The labeled hydroxyproline content was measured as newly synthesized collagenous protein in the cell layer and media. Although collagen synthesis by both cell lines was increased in both fractions under the influence of beta-estradiol-3-benzoate, at physiological concentrations of 10(-3)-10(-1) microgram/ml, the rate of increase differed. Fibroblasts derived from skin showed increased collagen synthesis of approximately 76%, while those from lung showed an increase of approximately 25%. Total protein synthesis by both cell lines also increased. In lung fibroblast cultures the synthesis of total protein was increased more than the synthesis of collagens; on the other hand in skin fibroblast cultures the synthesis of collagen was increased more than the synthesis of total protein. DNA synthesis by both cell lines was not affected by estrogen at the concentrations used. These findings suggest that fibroblasts develop in a different manner in each organ.