Decline of fibroblast chemotaxis with age of donor and cell passage number

Factors Influencing Elastographically Determined Remodeling of Venous Thrombi

OBJECTIVES

To verify whether elastographically determined remodeling of venous obliterating material formed during sclerotherapy is influenced by patient-specific factors.

METHODS

The study included 60 patients who underwent sclerotherapy for venous insufficiency. Elastographic parameters of obliterating material, including relative vascular cross sections (percent) with the highest (red), intermediate (green), and lowest elasticity (blue), determined 7 ± 1, 14 ± 2, and 21 ± 2 days after sclerotherapy, were analyzed against the patients' ages, sexes, physical activity levels, and pain severities.

RESULTS

The patients included 45 women and 15 men with a mean age ± SD of 51.2 ± 14.7 years. A significant correlation was observed between the age of the patients and the relative area of the vessel highlighted in red during the third control visit (R = 0.289; P = .025). The proportion of men in whom the elastographic structure of venous obliterating material during the second visit was classified as mixed was higher than that of women (66.7% versus 28.9%; P = .032). During the third visit, the proportion of patients with low physical activity in whom the elastographic structure of venous obliterating material was classified as fibrous turned out to be lower than the respective percentages of patients with moderate and high activity levels (12.0% versus 35.0% versus 46.7%; P = .045). However, none of these effects was observed systematically throughout the whole follow-up period.

CONCLUSIONS

The time to complete organization of venous obliterating material may be longer in older patients, women, and patients with lower levels of physical activity, but these factors seem to influence the thrombus structure solely at specific time points in its evolution. Nevertheless, they should be considered during elastographic assessments of thrombus age.

Extracellular Matrix Invasion in Metastases and Angiogenesis: Commentary on the Matrigel "Chemoinvasion Assay"

Invasive and metastatic cells must cross the basement membrane's extracellular matrix to disseminate to distant sites. Although in the eighties the concept was well established, no easy in vitro functional assay was available. Working in Hynda Kleinman's and George Martin's laboratory at NIH (Bethesda, MD), where the reconstituted basement membrane Matrigel was discovered, I had the intuition that Matrigel coating of migration filters could represent a valid tool to mimic in vitro biological matrix barriers. The "chemoinvasion assay" using Matrigel in Boyden blind-well chambers was developed in 1985-1986 and published in Cancer Research in 1987. It was a rapid and easy tool for studying invasion, a crucial step in cancer metastasis. Since its conception, the assay has been employed for studies on the metastatic process, angiogenesis, and for the screening of drugs that are potentially able to decrease cell invasion. It was adapted to be easily employed as a routine assay and commercialized. In that historical article, we also described the use of thick layers of Matrigel for the study of morphogenesis of invasive cells, a simple and visual assay, adaptable to reproduce collective cell migration in vitro To date, in its diverse optimized variants, the chemoinvasion assay is still widely used, contributing to novel data production. In the era of precision medicine and next-generation sequencing, the cheap, fast, and reproducible chemoinvasion assay may have further developments, including possible applications in the investigations on cancer stem cells, immunity and immune modulators, applications with siRNA silencing, selection of aggressive cell populations, and phenotypes and genetic evaluations. Cancer Res; 76(16); 4595-7. ©2016 AACR.See related article by Albini A et al., Cancer Res 1987;47:3239-45Visit the Cancer Research 75(th) Anniversary timeline.

Wound healing and the role of fibroblasts

Fibroblasts are critical in supporting normal wound healing, involved in key processes such as breaking down the fibrin clot, creating new extra cellular matrix (ECM) and collagen structures to support the other cells associated with effective wound healing, as well as contracting the wound. This article explores and summarises the research evidence on the role of fibroblasts, their origins and activation, and how they navigate the wound bed, as well as how their activity leads to wound contraction. This article also explores the local conditions at the wound site, which activate, regulate and ultimately reduce the fibroblast activity as the skin's integrity returns on healing.

Maggots and wound healing: an investigation of the effects of secretions from Lucilia sericata larvae upon the migration of human dermal fibroblasts over a fibronectin-coated surface

Lucilia sericata larvae, or greenbottle fly maggots, placed within chronic wounds have been observed to remove necrotic tissue and infection. They are also believed to actively promote granulation tissue formation. Interactions between fibroblasts and the surrounding extracellular matrix play a crucial role in tissue formation, influencing fibroblast proliferation, migration, and tissue remodeling. For example, the strength of cell adhesion to surfaces coated with extracellular matrix influences cell motility. L. sericata larval excretory/secretory products having previously been shown to modify fibroblast adhesion to collagen and particularly fibronectin, it was hypothesized that these products would alter fibroblast migration. This was investigated using a two-dimensional in vitro wound assay, time-lapse digital photography, enzyme class-specific substrates and inhibitors, and gel electrophoresis. Results showed that L. sericata excretory/secretory products promoted fibroblast migration upon a fibronectin-coated surface. This was related to the degradation of fibronectin by serine proteinases within maggot excretion/secretions. The presence of a metalloproteinase activity may also have played a role. Thus, a possible mechanism by which maggots enhance tissue formation within wounds may be via the promotion of fibroblast motility, providing for a wider distribution of viable fibroblasts.

Motogenic substrata and chemokinetic growth factors for human skin cells

Extracellular matrix remodelling and accurate spatio-temporal coordination of growth factor expression are two factors that are believed to regulate mitoses and cell migration in developing and regenerating tissues. The present quantitative videomicroscopical study examined the influence of some of the principal components of extracellular matrix and several growth factors that are known to be expressed in dermal wounds on three important facets of human skin cell behaviour in culture. Keratinocytes, melanocytes and dermal fibroblasts (and myofibroblast controls) exhibited varying degrees of substrate adhesion, division and migration depending on the composition of the culture substrate. Substrates that are recognized components of transitional matrices generally accentuated cell adhesion and proliferation, and were motogenic, when compared with serum-treated control surfaces, whereas components of more stable structures such as basement membrane had less influence. Platelet-derived growth factor (PDGF), epidermal growth factor (EGF) and alpha fibroblastic growth factor (alphaFGF) all promoted cell proliferation and were chemokinetic to dermal fibroblasts, but not keratinocyte growth factor (KGF) or transforming growth factor beta (TGFbeta). PDGF, EGF and KGF, but not TGFbeta or alphaFGF, all enhanced proliferation of dermal keratinocytes. The same growth factors, and in addition KGF, all stimulated motility in keratinocytes, but TGFbeta and alphaFGF again had no effect. Developing a better understanding of the interdependency of factors that control crucial cell behaviour may assist those who are interested in the regulation of histogenesis and also inform the development of rational therapeutic strategies for the management of chronic and poorly healed wounds.

Expression of fibronectin and TGF-beta1 mRNA and protein suggest altered regulation of extracellular matrix in degenerated disc tissue

We studied the distribution of fibronectin (a marker for "active" reparative connective tissue processes) and TGF-beta1 (a cytokine controlling the connective tissue metabolism) in intervertebral disc tissue from individuals of different age and various histomorphological evidence for tissue degeneration. The protein deposition was determined by immunohistochemistry on 30 complete cross-sections of lumbar spine obtained at autopsy (0-86 years) and 12 surgically removed disc samples. The mRNA expression was detected by non-radioactive in situ hybridization in the surgical material. All control experiments (blank and isotype controls in immunohistochemistry/sense controls in in situ hybridization) were negative. Immunohistochemically, we detected enhanced staining for fibronectin in both nuclear and anular tissues in areas with histological signs of mild-to-severe tissue degeneration (e.g., cleft formation and cell clustering) beginning with 16 years of age. Anular tissue showed less fibronectin staining than did nuclear areas. Fibronectin mRNA was detected mainly in nuclear cells by in situ hybridization corresponding to the protein staining indicating de novo synthesis. In parallel, TGF-beta1 was expressed by nuclear and occasional anular cells spatially associated with the fibronectin synthesizing cells. This was seen by both immunohistochemistry and in situ hybridization. This preliminary study provides evidence for a significant ongoing rearrangement of the extracellular matrix during disc degeneration, as monitored by enhanced fibronectin deposition that is produced by local disc cells. These cells also synthesize TGF-beta1, as shown by protein and mRNA expression. Since it is known that TGF-beta1 induces matrix alterations (by auto and paracrine stimulation of matrix synthesis), these observations suggest that the recently described disturbance of the matrix during disc degeneration may be induced by TGF-beta. This may offer new approaches to interfere with disc matrix alterations.

LPS-mediated NFκB activation varies between activated human hepatic stellate cells from different donors

The activation of hepatic stellate cells (HSC) is recognized as the key event of hepatic fibrosis [Virchows Arch. 430 (1997) 195; Semin. Liver Dis. 21 (2001) 437; Front. Biosci. 7 (2002) d808]. NFkappaB has been associated with the development of the activated phenotype, the expression of proinflammatory genes, and with promoting survival of activated HSC. High levels of circulating endotoxin are observed in liver fibrosis and several lines of evidence indicate that LPS plays an important role in chronic liver disease. Here, we investigated the LPS-induced NFkappaB activation in activated HSC from different human donors. HSC were isolated from liver specimens obtained during surgical liver resection and were activated by culturing on plastic. LPS-induced NFkappaB activity and IL-8 expression revealed a significant correlation but differed significantly comparing HSC from individual donors. These variations seen in LPS mediated NFkappaB activation and chemokine secretion between HSC from different donors in vitro may contribute to differences seen in vivo between patients in the progression of fibrosis and the degree of inflammation during chronic liver disease.

The effects of age-related skin changes on wound healing rates

The evidence that wound healing is adversely affected by age-related changes is inconclusive. Some studies report that ageing skin loses its ability to regenerate, whereas others have found that ageing processes can have beneficial effects.

Autocrine fibronectin-induced migration of human colonic fibroblasts

OBJECTIVES

A central event during wound repair is the migration of activated fibroblasts to the wound area. Thus far, the mechanisms inducing migration of colonic lamina propria fibroblasts (CLPF) have not been studied in detail. Previously, we have shown that CLPF secrete factors that are essential to their ability to migrate in response to different growth factors.

METHODS

Primary human CLPF were obtained from endoscopic biopsies or surgical specimens taken from normal mucosa areas of patients undergoing surveillance colonoscopy or surgery for colorectal carcinoma. Migration assays of CLPF were performed in the modified 48-well Boyden chamber.

RESULTS

Conditioned medium of CLPF collected after 24-h stimulated migration of CLPF (22 +/- 2 cells/ hpf). Filtration of conditioned medium through a 300-kDa filter reduced the migration-inducing potential in subsequent migration assays to 2 +/- 1 cells/hpf, filtration through a 100-kDa filter abolished migration of CLPF completely, indicating that large molecules such as extracellular matrix components could be responsible for the induction of CLPF migration. Enzyme-linked immunosorbent assays revealed the presence of fibronectin in conditioned medium (17.3 microg/ml). Immunoprecipitation of fibronectin in conditioned medium of CLPF reduced the migration-inducing potential by 63%. Addition of fibronectin to fibronectin-depleted conditioned medium reconstituted the migration. Dose-response assays with fibronectin (1-100 microg/ml) diluted in nonconditioned medium induced migration of CLPF in a dose-dependent manner. Maximum migration was induced with 25 microg/ml fibronectin (37 +/- 5 cells/hpf).

CONCLUSION

Fibronectin is an autocrine and paracrine factor essential for intestinal fibroblast migration. Fibronectin induces migration of intestinal fibroblasts and is essential for their ability to migrate in response to different growth factors. A detailed understanding of the regulation of the migration of intestinal fibroblasts is necessary to gain further insights in the pathophysiology of stricture and fistula formation.

Reduced migration of fibroblasts in inflammatory bowel disease: role of inflammatory mediators and focal adhesion kinase

BACKGROUND & AIMS

Crohn's disease (CD) and ulcerative colitis (UC) are associated with chronic tissue damage and continuous tissue repair. A central, but not well-characterized, event during this process is the migration of activated fibroblasts to the wound.

METHODS

Human colonic lamina propria fibroblasts (CLPF) were isolated from patients with CD and UC and from healthy controls and were characterized by immunocytochemistry. Migration assays of CLPF were performed in the modified 48-well Boyden chamber. Focal adhesion kinase (FAK) and FAK autophosphorylation in migrating CLPF were determined by Western blotting. FAK mRNA expression was investigated by Northern blotting.

RESULTS

The migration of CD-CLPF and UC-CLPF was significantly reduced when compared with control-CLPF. This was correlated with a decrease in FAK phosphorylation, whereas, in migrating control-CLPF, an increase was found. Similarly, the presence of the inflammatory mediators interferon (IFN)-gamma (50 ng/mL) or tumor necrosis factor (TNF) (30 ng/mL) in conditioned medium significantly reduced the migration of control-CLPF to 41% +/- 4% or 30% +/- 7%, respectively. Preincubation of control-CLPF with TNF (20 ng/mL) and IFN-gamma (10 ng/mL) for 3 days reduced their migratory response to 10% of control (P < 0.001), which also was correlated with a decrease in FAK phosphorylation. Culture of IFN-gamma/TNF-treated CLPF for a further 7 days without cytokines did not restore the migratory potential and FAK phosphorylation, indicating a persistent functional change.

CONCLUSIONS

CD- and UC-CLPF have a reduced migratory potential compared with normal CLPF. That may be caused by contact with IFN-gamma and TNF. This loss of migratory potential was correlated with diminished FAK phosphorylation.

Arresting cell cycles and the effect on wound healing

Wounds that contain a significant number of fibroblasts that are arrested because of senescence, damaged DNA, or enduring quiescence do not heal. As the arrested population of cells decreases and more cells that divide and contribute to wound repair populate the wound, the wound is more likely to achieve closure. Having an understanding of the regulatory mechanisms within the cell cycle is important to wound repair, particularly chronic wounds. The theory of cellular senescence in chronic wounds is new and has never been tested. Studies seem to show that senescent cells in chronic wounds are a significant part of the wounding process. Senescence is irreversible, and senescent cells are refractory to growth factor therapy. Future growth factor therapies or genetic transfections that are capable of repairing the short circuit in cycling cells or overriding the senescent condition will be important partners in the successful treatment of chronic wound patients.

Migration of mesenchymal stem cells to heart allografts during chronic rejection

BACKGROUND

Mesenchymal stem cells (MSC) are pluripotent progenitors for a variety of cell types, including fibroblasts and muscle cells. Their involvement in the tissue repair of allografts during the development of chronic rejection has been hypothesized, but not yet substantiated, by experimental evidence.

METHODS

Rat MSC were isolated from circulation using an aortic pouch allograft as a trapping device. The plasticity of these cells was examined in differentiation cultures. One of the resulting MSC lines was immortalized and transduced to express a marker gene. The -labeled cells were then transferred to F344 rats bearing Lewis (LEW) cardiac allografts to measure their localization and contribution to graft tissue repair.

RESULTS

The MSC isolated from circulation exhibited multipotential for differentiation in culture, developing into various lineages including osteoblasts, lipocytes, chondrocytes, myotubes, and fibroblasts. Intravenous engraftment of the -labeled cells into recipients of heart transplant resulted in migration of the beta-gal+ cells into the lesions of chronic rejection in the cardiac grafts and homing of the cells to the bone marrow. The majority of beta-gal+ cells present in the allografts exhibited fibroblast phenotypes, and a small number of the cells expressed desmin, indicative of myocyte differentiation.

CONCLUSION

MSC vigorously migrated into the site of allograft rejection. This data suggests that they may be attracted to this site to actively participate in tissue repair during chronic rejection. In addition, given the robust migration, the inhibition of MSC differentiation toward fibroblast progeny and induction toward the myocyte lineage may serve as a new strategy for treatment of chronic rejection and allograft tissue repair.

Effect of age and hypoxia on TGFbeta1 receptor expression and signal transduction in human dermal fibroblasts: impact on cell migration

Wound healing is critically affected by age, ischemia, and growth factors such as TGFbeta1. The combined effect of these factors on fibroblast migration, an essential component of wound healing, is poorly understood. To address this deficiency, we examined expression of TGFbeta receptor type I and II (TGFbetaRI and RII) under normoxia or hypoxia (1% O(2)) in cultured human dermal fibroblasts (HDFs) from young (ages 24-33) and aged (ages 61-73) adults. TGFbetaRI and RII expression was similar in both groups under normoxia. Hypoxia did not alter receptor levels in young HDFs but significantly decreased TGFbetaRI in aged cells (12 and 43%, respectively). Additionally, young cells displayed a 50% increase in activation of p42/p44 mitogen-activated kinase by TGFbeta1 (2-200 pg/ml) under hypoxia while aged cell levels of active p42/p44 decreased up to 24%. To determine functional outcomes of these findings, we measured the migratory capacity of the cells on type I collagen using a gold salt migration assay. Hypoxia increased the migratory index (MI) of young HDFs over normoxia by 30% but had no effect on aged cells. Under normoxia, TGFbeta1 (1-1000 pg/ml) increased young HDF migration in a concentration-dependent manner up to 109% over controls but minimally increased aged HDF migration (37%). Under hypoxia, TGFbeta1 significantly increased young cell MI at all concentrations but was without effect on the aged HDF response. These data demonstrate that aged fibroblasts have an impaired migratory capacity with complete loss of responsiveness to hypoxia and deficits in the migratory and signal transduction responsiveness to TGFbeta1 that may partly explain diminished healing capabilities often observed in aged patients.

Impaired migration, integrin function, and actin cytoskeletal organization in dermal fibroblasts from a subset of aged human donors

Deficits in the motility of fibroblasts contribute to age-related impairment of wound healing. We analyzed 'young' fibroblasts from four healthy donors 22-30 years old and 'aged' fibroblasts from six healthy donors 81-92 years old for migratory ability on type I collagen, secretion of matrix metalloproteases (MMPs), attachment to matrices and, expression and function of integrin alpha2beta1. Cells from each donor were analyzed separately in each experiment. Whereas migration of young fibroblasts was uniformly robust, three aged lines migrated well and three migrated poorly. Synthesis of MMP1 and TIMP1, but not MMP2 or MMP9, was increased in the aged fibroblasts relative to the young fibroblast lines irrespective of their motility. All lines of young and aged fibroblasts attached to plastic or collagen with similar efficiency. Although young and aged fibroblasts expressed comparable levels of the alpha2 integrin; the lines of aged fibroblasts that were poor migrators exhibited a significant reduction in alpha2beta1 function relative to fibroblasts with normal migratory capacities. Moreover, the lines of aged fibroblasts that exhibited poor migration demonstrated a disordered actin cytoskeleton and a reduced ability to contract collagen gels. In conclusion, aged fibroblasts, unlike young fibroblasts, displayed variable migratory capacities. Deficient migration by specific lines of aged fibroblasts was not related to the capacity to attach, express alpha2 integrin, or secrete MMPs and TIMP1, but was characterized by disorganized cytoskeletal actin and reduced alpha2beta1 function.

Inhibitory effects of human serum on human fetal skin fibroblast migration: migration-inhibitory activity and substances in serum, and its age-related changes

In order to clarify the environmental factors modulating cell migration, we investigated the effects of human serum on cell migration, and found that serum from adult donors strongly (by 48%) suppressed the migration of human fetal skin fibroblasts into a denuded area in a cell monolayer. Human serum from old donors inhibited cell migration more strongly than that from adult donors. Next, we investigated the properties of migration-inhibitory activity of human serum and serum proteins in order to identify migration-inhibitory substances. Human serum from adult donors strongly suppressed the migration of human fetal skin fibroblasts, although it stimulated cell proliferation more strongly than fetal bovine serum (FBS), indicating that the inhibitory effects of human serum on cell migration was not due to its toxic effects. The inhibition of cell migration by human serum was concentration dependent. It was demonstrated that the inhibition did not depend on the inhibitory effects of human serum on collagen synthesis. The migration-inhibitory activity was seen in fractions over 100 kDa, as determined by an ultrafiltration membrane, and no inhibitory activity was observed in fractions under 100 kDa. On the other hand, it was not detected either in fractions over 100 kDa or under 100 kDa in FBS. Among the over 100 kDa human serum proteins examined, gamma-globulin, alpha2-macroglobulin, and low density lipoprotein (LDL) suppressed fibroblast migration in a concentration-dependent manner. However, among the three, cell migration-inhibiting activity of gamma-globulin almost disappeared when cell migration was conducted in 10% FBS-supplemented medium. These results indicated that alplha2-macroglobulin and LDL were candidate substances for cell migration-inhibiting activity in human serum.

Chemotactic response of periodontal ligament cells decreases with donor age: association with reduced expression of c-fos

OBJECTIVE

To understand the effects of aging on cellular motility of human periodontal ligament (PDL) cells, and to determine the possible link between cell proliferation and migration in relation to cellular aging.

MATERIALS AND METHODS

The chemotactic response of PDL cells from three juvenile and four older donors were compared. Then, migrated or unmigrated cells were examined for their cell cycle by morphological and immunocytochemical procedures. Finally, migrated or unmigrated cells were examined for the expression of c-fos and c-myc by in situhybridization.

RESULTS

PDL cells from older donors showed lower chemotaxis compared with the cells from juvenile donors (P < 0.05). Cells undergoing migration were found not to be in the S- or M-phase of the cell cycle. However, all migrated cells were found to express c-fos, while many of the cells which did not migrate were found not to express c-fos.

CONCLUSIONS

Cellular motility of PDL cells decreases with donor age as well as cell proliferation. Since the cells reaching senescence fail to express c-fos, the mechanisms linked to cellular senescence may be a possible underlying mechanism for low migration seen in the older cells.

Differential collagen I gene expression in fetal fibroblasts

PURPOSE

Fetal wound healing is characterized by the regeneration of normal dermis and the absence of scar. Transforming growth factor beta-1 (TGF-beta1) is a ubiquitous cytokine with potent fibrogenic effects in both postnatal and fetal wounds. Supplementing fetal wounds with TGF-beta1 results in increased fibrosis consisting primarily of collagen I. We hypothesized that the lack of scar formation in fetal wounds may be caused by differential collagen I gene (COL1A1) expression. The authors examined basal collagen Ia gene expression in human fetal, newborn, and adult dermal fibroblasts after stimulation with exogenous TGF-beta1.

METHODS

Subconfluent human dermal fibroblasts from fetal, newborn, and adult cell lines were incubated for 24 hours, then stimulated by incubation for 4 hours with 1 ng/mL of human recombinant TGF-beta1, or with media alone for basal collagen gene expression, and then placed in guanidium isothyocyanate buffer. To quantitate COL1A1 gene expression, total cellular RNA was extracted and subjected to northern and slot blot hybridization analysis with Dig-labeled COL1A1 probes. The membrane was exposed to x-ray film for 15 minutes and developed.

RESULTS

Scant COL1A1 gene transcript was detected in control fetal fibroblasts. Brief stimulation with of TGF-beta1 upregulated the COL1A1 gene transcription in fetal fibroblasts. Gene expression for COL1A1 in both postnatal cell lines appeared similar in treated and untreated cells. Housekeeping control (GAPDH) confirmed no difference in total amount of RNA at the start or end of the experiment.

CONCLUSION

COL1A1 gene expression is notably absent in unstimulated fetal fibroblasts, but is upregulated by TGF-beta1. In contrast, postnatal fibroblasts demonstrate significant constitutive COL1A1 gene expression at baseline and unchanged after TGF-beta1 stimulation. This differential regulation may contribute to the ability of fetal wounds to regenerate without scar and explain the effect of exogenous TGF-beta1 to increase fibroplasia in fetal dermal incisional wounds.

Readers' Questions

TOPICAL ANALGESICS IN LEG ULCER PATIENTS.

Ageing and wounds. Part 2: Healing in old age

The second part of this review outlines the physiology of wound healing in old age and how it differs from normal adult healing.

Interferon-beta, an autocrine cytokine, suppresses human fetal skin fibroblast migration into a denuded area in a cell monolayer but is not involved in the age-related decline of cell migration

The migration of human skin fibroblasts into a denuded area in a cell monolayer declined during in vitro and in vivo aging. We carried out a study to determine whether this age-related decline in cell migration was mediated by the autocrine cytokine interferon-beta (IFN-beta), which has been reported to suppress the proliferation, chemotaxis and collagen synthesis of human fibroblasts. Actually, IFN-beta specifically suppressed the migration of TIG-3S human fetal skin fibroblasts into a denuded area in a cell monolayer, as shown by the dose response experiments of IFN-beta and neutralizing anti-IFN-beta antibody. IFN-beta also inhibited their collagen synthesis but the addition of type I collagen could not reverse IFN-beta-induced inhibition of cell migration. Double strand RNA, which has been generally known to induce IFN-beta in human skin fibroblasts, suppressed the migration of TIG-3S cells. Next, a study was done to determine whether IFN-beta and double strand RNA suppressed the migration of TIG-3S cells in late passages as well as early passages, or whether neutralizing anti-IFN-beta antibody stimulated the migration of TIG-3S cells in late and middle passages. IFN-beta and double strand RNA suppressed the migration of TIG-3S cells in middle (PD45) and late (PD55) passages as well as in early passages (PD23-28). Neutralizing anti-IFN-beta antibodies could not reverse the low migratory activity of middle and late passage cells to the high migratory activity of early passage cells. These results indicated that the autocrine cytokine IFN-beta did not seem to be involved in the age-dependent decline of fibroblast migration.

Analysis of the age-related composition of human skin collagen and collagens synthesized by fibroblast culture

Age-related differences in the composition and the post-translational modifications of human skin collagens were examined in the present study. The data were compared with results of collagen synthesis from in vivo-aged fibroblasts in culture. Skin extracts and newly synthesized collagen from fibroblast cultures derived from both old and young donor groups showed the same ratio of collagen III to collagen I. Furthermore, no difference was noted in the degree of prolyl and lysyl hydroxylation of collagen I and collagen III Young and old fibroblasts synthesized a similar quantity of collagen in vitro. The data suggest that fibroblasts maintain a uniform level of collagen production, composition and modification independent of the age of the donor.

Inter- and intra-site heterogeneity in the expression of fetal-like phenotypic characteristics by gingival fibroblasts: potential significance for wound healing

We have previously reported that fetal and adult skin fibroblasts display distinctive migratory phenotypes on 3-D collagen substrata and that these behavioural characteristics may be quantified by a function defined as the cell density migration index (CDMI). Subsequent work indicated that this difference in migratory phenotype was due to the production by fetal fibroblasts of a migration stimulating factor (MSF) that is not produced by normal adult skin fibroblasts. We now present data indicating that: (a) unselected fibroblasts obtained from 14/14 (100%) of adult gingival explants expressed fetal-like CDMI values compared to only 1/10 (10%) of similarly explanted paired skin cells; (b) 12/12 (100%) of these gingival fibroblast lines also produced detectable quantities of MSF compared to 0/9 (0%) of the tested skin cells; (c) by microdissection studies, gingival fibroblasts obtained from different anatomical microdomains consisted of behaviourally distinct subpopulations, with cells derived from the papillary tips (PAP fibroblasts) displaying fetal-like CDMI values and persistent MSF production, whilst cells obtained from the deeper reticular tissue (RET fibroblasts) were adult-like with respect to these two criteria; (d) PAP fibroblasts were also smaller and achieved higher saturation cell densities compared to paired RET cells; (e) PAP fibroblasts passaged in vitro underwent a fetal-to-adult phenotypic transition characterized by the adoption of various RET cell characteristics, including the acquisition of CDMI values falling within the adult range and cessation in MSF production; and (f) early passage PAP fibroblasts incubated in the presence of an affinity-purified anti-MSF rabbit polyclonal antibody were induced to alter their migratory phenotype and exhibited CDMI values falling within the adult range. Statistical analysis indicated a highly significant correlation between the expression of a fetal-like CDMI and production of MSF (P &lt; 0.00001, using the Fisher exact contingency test). Taken together, these observations suggest that the production of MSF by PAP fibroblasts is responsible for their characteristically fetal-like migratory behaviour. The existence of such inter- and intra-site phenotypic heterogeneity in populations of skin and gingival fibroblasts is discussed in the context of fibroblast lineage relationships and the possible contribution of persistently fetal-like fibroblast subpopulations to connective tissue function in wound healing.

Cytokine control of cell motility: modulation and mediation by the extracellular matrix

Cytokines are multifunctional regulators of cell behaviour affecting such diverse activities as cell proliferation, gene expression and motility. Matrix macromolecules influence a similarly wide range of cell functions. A review of the available literature suggests that cytokines may affect cell motility by (a) directly influencing the motility apparatus, and (b) indirectly as a consequence of the altered expression of genes coding for matrix macromolecules, their respective cell surface receptors and matrix degrading enzymes and their inhibitors. Conversely, the composition and supramolecular organisation of the matrix plays a central role in defining cellular response to potentially multifunctional cytokines. Such complex and reciprocal interactions between cytokines and the matrix elicit both positive and negative reiterative feedback loops which must be taken into account when interpreting the results of migration assays in vitro and extrapolating them to in vivo processes.

Familial co-segregation of the elastin phenotype in skin fibroblasts from Hutchinson-Gilford progeria

Elastin and type IV collagen production are markedly elevated in fibroblasts derived from the skin of patients with Hutchinson-Gilford progeria (HGP). Fibroblasts from three affected children and their parents were compared to normal human skin fibroblasts with respect to elastin production as a function of different concentrations of calf serum and the cytokines, transforming growth factor-beta and basic fibroblast growth factor (TGF-beta 1, bFGF). In cultured fibroblasts from the parents of probands that were very high elastin producers (> 10(5) molecular equivalents/cell per h), at least one parent (mother) presented the same phenotype. Overproduction of elastin in culture could have been due to increased sensitivity of HGP strains to stimuli present in serum; however, relative stimulation of elastin production by calf serum in cell strains from HGP elastin over-producers was less than half the control strain. In most of the cultures examined, the responsiveness of elastin production to TGF-beta 1 was almost absent when compared to the response of normal fibroblasts. HGP strains with high elastin production modified conditioned medium to enhance elastin production in normal cells. These results suggest the presence, in HGP skin fibroblasts, of inheritance of high elastin production that is associated with accelerated aging.

Similar, but not identical, modulation of expression of extracellular matrix components during in vitro and in vivo aging of human skin fibroblasts

Regulation of the synthesis of procollagen and other extracellular matrix components was examined in human skin fibroblasts obtained from donors of various ages, from fetal to 80 years old (in vivo aged), and in fetal fibroblasts at varying passage levels (in vitro aged). Growth rates and saturation densities of fibroblasts decreased with increasing age of the donor and after passage 20 of fetal fibroblasts. The rates of collagen and proteoglycan synthesis also decreased during both types of aging to about 10-25% of the rate in early passage fetal fibroblasts, whereas the synthesis of total noncollagenous proteins was not greatly affected. Decreased collagen synthesis in both types of aging was correlated with lower steady-state levels of mRNAs for the two subunits of type I procollagen mRNA, although their regulation was not coordinate. Type III collagen mRNA levels also declined in both types of aging. The concentration of fibronectin mRNA also decreased during in vitro aging but more rapidly than the collagen mRNAs, whereas in fibroblasts from 51-80-year-old donors, it was similar to or higher than in early passage fetal fibroblasts. This study suggests that the decreased synthesis of procollagen and proteoglycans in in vivo aged fibroblasts represents changes that are responsible for intrinsic degenerative changes that occur in human skin during aging. Furthermore, although in vitro and in vivo aging were similar in many respects, they were not equivalent, as evidenced by the differences in regulation of fibronectin expression.

Changes in the migratory ability of human lung and skin fibroblasts during in vitro aging and in vivo cellular senescence

The migration of human lung and skin fibroblasts was determined during in vitro aging and in vivo cellular senescence by measuring their migration from the edge of a denuded area of a monolayer. The migration of human fetal lung fibroblasts (TIG-1 and TIG-3) decreased only very slightly with increasing passage, whereas the migration of human fetal skin fibroblasts (TIG-3S) declined gradually: the difference in cell migratory ability between early and late passages was significant (P less than 0.05). The migratory patterns of skin fibroblasts from adult and elderly donors were also similar to that of fetal skin fibroblasts. Next, the migratory abilities of fibroblast lines from adult and elderly donor groups were compared, using relatively early passaged cells. The migratory ability of the elderly-donor skin fibroblast lines was significantly lower (P less than 0.05) than that of the adult-donor skin fibroblast lines. Addition of suramin and monensin suppressed the migration of fibroblasts from fetal, adult and elderly donors, which implies that fibroblast migration is regulated by growth factors and matrix substances. The relationships between the age-dependent decline of migratory ability, growth factors and the extracellular matrix are discussed.

Characterization of the subtypes of cell motility in ageing human skin fibroblasts

Previous studies have noted alterations in cell migration during wound healing with age. Both intracellular and extracellular factors alter cell migration. In an effort to clarify the relationship between ageing and cell motility we have utilized time-lapse videomicroscopy to quantitatively and qualitatively study the various subtypes of cell motility including membrane ruffling, lamellapodal extension and cell translocation of ageing human fibroblasts in culture. We demonstrate a global decline in all types of cell motility of human fibroblasts with increasing donor age. Furthermore, we demonstrate that this decrease in cell motility with ageing is independent of chemotactic gradients.

Correlations between age and rat dermis modifications. Ultrastructural-morphometric evaluations and lysyl oxidase activity

The extracellular matrix is a complex, integrated macromolecular system which plays a crucial role in the economy of each organ. In this study we focused our attention on the correlations between age and rat skin dermis. The latter was chosen as a model of the connective tissue, and was analyzed by means of electron microscopy and by measurement of the activity of lysyl oxidase, the enzyme involved in collagen and elastin crosslink formation. Ultrastructural and morphometric evaluations associated to body weight growth, showed a progressive increase in the amounts of extracellular components and a progressive reduction in the cell density. Skin from adult animals appeared characterized by a well organized matrix; by contrast, in old rats, we observed several degenerative features such as the disorganization of collagen bundles, the vacuolization of elastic fibers, and the atrophy of the mesenchimal cells. Morphometric evaluations in old animals showed a slight but significant reduction in the percentage of the total collagen measured, a fair stability in the area occupied by the elastin fibers, and an increase of the apparently non-structured matrix. The fact that lysyl oxidase activity was diminished in old rats does not corroborate the observation by several authors that increased collagen insolubility is a consequence of higher intra- and intermolecular crosslinking. This would suggest that other chemical modifications, such as crosslink oxidation or non enzymatic glycosylation, might be involved during the aging of connective tissue. The qualitative and quantitative modifications observed at all ages illustrate the correlation between connective tissue modifications and structural and/or functional properties of the skin.

Effects of serum from human subjects of different ages on migration in vitro of human fibroblasts

A study was carried out to determine whether human serum from older subjects inhibited cell migration. Sera of both sexes from subjects in their 60s (60-64 years) tended to be more inhibitory (8-14%) to the migration of human fetal lung fibroblasts, TIG-1, than serum from subjects in their 20s (20-29 years). In the case of females, the effects of serum on cell migration were significantly (P less than 0.05) different between the younger and older groups. Next, cell migration-stimulatory activity of serum was measured using human skin fibroblasts from young adult (age 21) and elderly (age 65) donors. The results were similar to those obtained with TIG-1 cells. However, the cell migration-stimulatory activity of serum was not significantly different between the two age groups. A study on the effects of concentration of human serum on the migration of TIG-1 cells showed that cell migration-stimulatory activity of serum declined linearly with increasing concentrations of sera from subjects in their teens (16-19 years) and 50s (50-59 years), and was the same between the two age groups. These results imply that substance(s) inhibitory to cell migration may not have accumulated in serum during the ageing process in humans, although human serum contained substance(s) inhibitory to cell migration.