Mussel Adhesive Protein as a Promising Alternative to Fibrin for Scaffold Fixation during Cartilage Repair Surgery.

OBJECTIVE: Fibrin has been used as a standard material for scaffold fixation during cartilage repair surgery. Most of the commercially available fibrin preparations need an additional method for scaffold fixation, most often with sutures, thus damaging the surrounding healthy cartilage. There is therefore a need to find alternatives to this method. In our study, we have investigated the potential possibility to use mussel adhesive protein as such an alternative. METHODS: In this study, hydrophobic plastic was coated with the mussel adhesive protein Mefp-1 as well as with other cell adhesives (poly-lysine, fibronectin, and collagen). Human keratinocytes and chondrocytes were seeded on these substrates at 37°C in culture medium, followed by analysis of attachment and proliferation by crystal violet staining and metabolic labelling. Performance of Mefp-1 and fibrin as tissue glues were estimated by tensional force resistance measurement of moist porcine dermis (as a correlate to scaffold) glued to dermis, cartilage, or bone at 37°C. RESULTS: Mefp-1 supported maximal cell attachment at a coating density of approximately 1 µg/cm2. This was at least as good as the other adhesives tested. In addition, it supported cell proliferation at least as good as regular tissue culture plastic over a 7-day period. Measurement of tensional force resistance showed that Mefp-1 performed equally well as fibrin when porcine dermis was glued to cartilage and bone at the same concentration. Separation of the moist tissues after 15-minute incubation required a force of approximately 1 N/cm2 for both compounds. CONCLUSIONS: Mefp-1 show properties that qualify it as a compound that potentially could replace fibrin as a tissue glue for scaffold fixation. Given the possibilities to modify this protein by bioengineering, it is likely that the properties can be further improved.

IL-1α Counteract TGF-ß Regulated Genes and Pathways in Human Fibroblasts.

Dysregulated wound healing is commonly associated with excessive fibrosis. Connective tissue growth factor (CTGF/CCN2) is characteristically overexpressed in fibrotic diseases and stimulated by transforming growth factor-ß (TGF-ß) in dermal fibroblasts. We previously showed that interleukin-1 (IL-1α) counteracts TGF-ß-stimulated CTGF mRNA and protein expression in these cells. The aim of this study was to explore the effects of IL-1α on further genes and pathways in TGF-ß regulated fibroblasts. Transcriptional microarray and multiple comparison analysis showed that the antagonizing effects of IL-1α was much more prominent than the synergistic effects, both with respect to number of genes and extent of changes in gene expression. Moreover, comparing canonical pathways by gene set enrichment analysis and the Ingenuity Pathway Analysis tool revealed that IL-1α counteracted TGF-ß in the top six most confident pathways regulated by both cytokines. Interferon and IL-1 signaling, as well as two pathways involved in apoptosis signaling were suppressed by TGF-ß and activated by IL-1α. Pathways involving actin remodeling and focal adhesion dynamics were activated by TGF-ß and suppressed by IL-1α. Analyzing upstream regulators in part corroborate the comparison of canonical pathways and added cell cycle regulators as another functional group regulated by IL-1α. Finally, gene set enrichment analysis of fibrosis-related genes indicated that IL-1 moderately counteracts the collective effect of TGF-ß on these genes. Microarray results were validated by qPCR. Taken together, the results indicate prominent antagonistic effects of IL-1α on TGF-ß regulated interferon signaling, as well as on a wide variety of other genes and pathways in fibroblasts. J. Cell. Biochem. 117: 1622-1632, 2016. © 2015 Wiley Periodicals, Inc.

Electrochemotherapy - Evidence for Cell-type Selectivity In Vitro.

AIM: Electrochemotherapy (ECT) is a new cancer treatment modality that uses electroporation to potentiate chemotherapeutic agents, especially bleomycin. ECT causes both a direct toxic effect and an anti-vascular effect. The aim of the present study was to investigate a possible selective effect of ECT on the survival of fibroblasts, endothelial cells (HUVEC) and two squamous cell carcinoma cell lines (CAL-27 and SCC-4). MATERIALS AND METHODS: Cells were electroporated using two bleomycin concentrations. The survival rate was assessed 1, 2, 3 and 4 days after treatment, by two different assays. RESULTS: The survival rate of the fibroblasts was statistically significantly higher than the other cell lines at day 4. The HUVEC survival rate was statistically significantly lower than the other cell types at day 1 after electroporation-alone. CONCLUSION: A selective survival effect after ECT was observed in vitro, supporting the anti-vascular effect seen in vivo.

Keratinocytes and head and neck squamous cell carcinoma cells regulate urokinase-type plasminogen activator and plasminogen activator inhibitor-1 in fibroblasts.

BACKGROUND: To investigate possible differences in the effects of soluble factors from oral squamous cell carcinoma (SCC) cells (UT-SCC-87) and normal oral keratinocytes (NOK) on fibroblast expression of genes involved in tumor stroma turnover. MATERIALS AND METHODS: Transwell co-cultures with fibroblasts in collagen gels, and SCC cells or NOK in inserts were carried out. Fibroblast gene expression was measured with real-time polymerase chain reaction (PCR). RESULTS: The expression of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) was up-regulated in co-cultures with SCC cells but not with NOK. In contrast, both SCC cells and NOK regulated matrix metalloproteinase-1 (MMP1) and -3, and tissue inhibitor of metalloproteinases-2 (TIMP2) and -3 to a similar extent, while MMP2 and TIMP1 were largely unaffected. Interleukin 1 alpha (IL1α) up-regulated both MMP1 and MMP3 and down-regulated PAI-1, TIMP2 and -3. CONCLUSION: SCC and NOK regulate fibroblast expression of genes involved in tumor stroma turnover differentially in vitro. These observations may contribute to a better understanding of the mechanisms behind extracellular matrix turnover in tumors.

Staphylococcus epidermidis and Staphylococcus aureus trigger different interleukin-8 and intercellular adhesion molecule-1 in lung cells: implications for inflammatory complications following neonatal sepsis.

AIM: Staphylococci are a major contribution for neonatal sepsis, which is the main risk factor for bronchopulmonary dysplasia. This study investigated the expression of pro-inflammatory mediators in endothelial and respiratory cells from newborns exposed to staphylococci. METHODS: Human vascular endothelial cells and small airway epithelial cells were incubated with neonatal blood isolates of Staphylococcus epidermidis (n = 14) and Staphylococcus aureus (n = 14). The extracellular release of IL-8, IL-10, sICAM-1, ICAM-1 mRNA and the expression of membrane bound ICAM-1 were assessed by ELISA, RT-PCR and immunofluorescence microscopy. RESULTS: Staphylococcus epidermidis induced higher levels of IL-8 (mean 38.5 ng/mL) and ICAM-1 mRNA (mean ratio 1.037) in the small airway epithelial cells than S. aureus (IL-8 mean 22.2 ng/mL, p < 0.01 and ICAM-1 mRNA mean ratio 0.715, p < 0.01). In the endothelial cells, ICAM-1 remained more integrated in the cell membranes after exposure to S. epidermidis compared with S. aureus, which induced disintegration and release of soluble ICAM-1 into the supernatants. CONCLUSION: Staphylococcus epidermidis induced a higher chemoattractive response than S. aureus. A persistent transmigration of granulocytes into the lung tissue in neonatal S. epidermidis sepsis might contribute to the development of bronchopulmonary dysplasia.

Interleukin-1-mediated effects of normal oral keratinocytes and head and neck squamous carcinoma cells on extracellular matrix related gene expression in fibroblasts.

OBJECTIVES: The composition of tumor stroma and the activity of tumor associated fibroblasts are important for tumor growth. Interactions between carcinoma cells and fibroblasts regulate the turnover of extracellular matrix (ECM). Here, the in vitro effects of oral squamous cell carcinoma (SCC) cells (UT-SCC-30 and UT-SCC-87) on fibroblast expression of genes for ECM components and connective tissue growth factor (CTGF/CCN2), were compared to those of normal oral keratinocytes (NOK). MATERIALS AND METHODS: Cocultures with fibroblasts in collagen gels and keratinocytes with the two cell types separated by a semi permeable membrane were used, and relative gene expression was measured with real-time PCR. RESULTS: All investigated genes were regulated by NOK and the SCCs. The downregulation of pro-collagens α1(I) and α1(III) was more pronounced in cocultures with NOK, while the expression of CCN2 and fibronectin was downregulated by both NOK and the SCCs to a similar extent. UT-SCC-87, but not UT-SCC-30, secreted significantly more IL-1α than NOK. A recombinant interleukin-1 receptor antagonist reversed many of the observed effects on fibroblast gene expression suggesting involvement of IL-1 in cocultures with NOK as well as with SCCs. CONCLUSION: The observed differential effects on fibroblast gene expression suggest that NOK are more antifibrotic compared to UT-SCC-30 and UT-SCC-87. These findings may contribute to a better understanding of the mechanisms behind ECM turnover in tumors.

Regulation of fibroblast gene expression by keratinocytes in organotypic skin culture provides possible mechanisms for the antifibrotic effect of reepithelialization.

To investigate the mechanisms behind the antifibrotic effect associated with epidermal regeneration, the expression of 12 fibroblast genes important for the modulation of the extracellular matrix (ECM), as well as α-smooth muscle actin, was studied in a keratinocyte-fibroblast organotypic skin culture model. The study was performed over time during epidermal generation and in the presence or absence of the profibrotic factor transforming growth factor-ß. the Presence of epidermal differentiation markers in the model was essentially coherent with that of native skin. Fibroblast gene expression was analyzed with real-time polymerase chain reaction after removal of the epidermal layer. After 2 days of air-exposed culture, 11 out of the 13 genes studied were significantly regulated by keratinocytes in the absence or presence of transforming growth factor-ß. The regulation of connective tissue growth factor, collagen I and III, fibronectin, plasmin system regulators, matrix metalloproteinases and their inhibitors as well as α-smooth muscle actin was consistent with a suppression of ECM formation or contraction. Overall, the results support a view that keratinocytes regulate fibroblasts to act catabolically on the ECM in epithelialization processes. This provides possible mechanisms for the clinical observations that reepithelialization and epidermal wound coverage counteract excessive scar formation.

Protein adsorption to surface chemistry and crystal structure modification of titanium surfaces.

OBJECTIVES: To observe the early adsorption of extracellular matrix and blood plasma proteins to magnesium-incorporated titanium oxide surfaces, which has shown superior bone response in animal models. MATERIAL AND METHODS: Commercially pure titanium discs were blasted with titanium dioxide (TiO2) particles (control), and for the test group, TiO2 blasted discs were further processed with a micro-arc oxidation method (test). Surface morphology was investigated by scanning electron microscopy, surface topography by optic interferometry, characterization by X-ray photoelectron spectroscopy (XPS), and by X-ray diffraction (XRD) analysis. The adsorption of 3 different proteins (fibronectin, albumin, and collagen type I) was investigated by an immunoblotting technique. RESULTS: The test surface showed a porous structure, whereas the control surface showed a typical TiO2 blasted structure. XPS data revealed magnesium-incorporation to the anodic oxide film of the surface. There was no difference in surface roughness between the control and test surfaces. For the protein adsorption test, the amount of albumin was significantly higher on the control surface whereas the amount of fibronectin was significantly higher on the test surface. Although there was no significant difference, the test surface had a tendency to adsorb more collagen type I. CONCLUSIONS: The magnesium-incorporated anodized surface showed significantly higher fibronectin adsorption and lower albumin adsorption than the blasted surface. These results may be one of the reasons for the excellent bone response previously observed in animal studies.

Effects of synovial fluid from aseptic prosthesis loosening on collagen production in osteoblasts.

Synovial fluid from a loose prosthesis may act as a vehicle for factors that regulate bone turnover. The effect of such synovial fluid on osteoblasts has been studied. Synovial fluid obtained from patients who underwent revision hip arthroplasty because of aseptic prosthesis loosening was studied regarding the effect on protein synthesis, procollagen I mRNA expression, the secretion of procollagen I carboxyterminal propeptide (PICP) and osteocalcin in MG63 osteoblasts. Protein synthesis was increased and procollagen I mRNA expression was decreased by synovial fluid from patients with prosthesis loosening. Synovial fluid stimulated the total PICP in cell medium, but there was no change after correction for cell protein content in the cells. Synovial fluid in patients with prosthesis loosening has a general stimulatory effect on collagen formation and osteoblast proliferation because of a stimulatory effect on cell growth. Aseptic prosthesis loosening may be associated with an increase in bone formation.

Platelet-derived growth factor-beta receptor activation is essential for fibroblast and pericyte recruitment during cutaneous wound healing.

Connective tissue remodeling provides mammals with a rapid mechanism to repair wounds after injury. Inappropriate activation of this reparative process leads to scarring and fibrosis. Here, we studied the effects of platelet-derived growth factor receptor-beta blockade in vivo using the platelet-derived growth factor receptor (PDGFR)-beta inhibitor imatinib mesylate on tissue repair. After 7 days, healing of wounds was delayed with significantly reduced wound closure and concomitant reduction in myofibroblast frequency, expression of fibronectin ED-A, and collagen type I. Using a collagen type I transgenic reporter mouse, we showed that inhibiting PDGFR-beta activation restricted the distribution of collagen-synthesizing cells to wound margins and dramatically reduced cell proliferation in vivo. By 14 days, treated wounds were fully closed. Blocking PDGFR-beta signaling did not prevent the differentiation of myofibroblasts in vitro but potently inhibited fibroblast proliferation and migration. In addition, PDGFR-beta inhibition in vivo was accompanied by abnormal microvascular morphogenesis reminiscent of that observed in PDGFR-beta-/- mice with significantly reduced immunostaining of the pericyte marker NG2. Imatinib treatment also inhibited pericyte proliferation and migration in vitro. This study highlights the significance of PDGFR-beta signaling for the recruitment, proliferation, and functional activities of fibro-blasts and pericytes during the early phases of wound healing.

Analysis of gene expression in fibroblasts in response to keratinocyte-derived factors in vitro: potential implications for the wound healing process.

Cocultures of fibroblasts and keratinocytes, physically separated by a membrane, were carried out for 48 h, and large-scale gene expression in the fibroblasts was analyzed by Affymetrix microarrays of expressed mRNAs. Two independent experiments were performed with cells from different individuals. A total of 243 genes were upregulated twofold or more and 100 genes were negatively regulated (reduction by half or more) in both experiments. A total of 69 of these 343 genes coded for growth factors, cytokines, chemokines, or their receptors; extracellular matrix molecules or enzymes involved in their synthesis; adhesion receptors; proteinases/proteinase inhibitors or their receptors; cell cycle regulators; apoptosis-regulating factors; prostaglandin-related factors; or growth-factor-binding proteins. Most of the remaining genes coded for proteins involved in signal transduction or general metabolism. Sixteen genes selected from these groups were further analyzed by northern blot analysis to confirm the array data. Finally, experiments with interleukin-1 alpha (IL-1 alpha)-blocking antibodies or IL-1 receptor antagonists demonstrate that IL-1 alpha is one important factor involved in keratinocyte-mediated regulation of gene expression in fibroblasts. Taken together, the results suggest that keratinocytes regulate fibroblast gene expression with implications for the wound healing process during reepithelialization.

Keratinocytes inhibit expression of connective tissue growth factor in fibroblasts in vitro by an interleukin-1alpha-dependent mechanism.

The wound healing process concludes with downregulation of fibroblast activity. Clinical observations suggest that the regenerating epidermis suppresses this activity. An important regulator of fibroblast activity is the fibrogenic cytokine connective tissue growth factor. We hypothesized that epidermal keratinocytes may affect fibroblast activity via this cytokine. We demonstrate keratinocyte-mediated suppression of connective tissue growth factor at both the mRNA and protein levels by around 50% or more when fibroblasts were cultured in multiwell plates with keratinocyte cultures in accompanying semipermeable cell culture inserts, or stimulated by keratinocyte-conditioned media. Both basal and transforming-growth-factor-beta1-stimulated levels of connective tissue growth factor were inhibited. A 3 h coculture period with keratinocytes was sufficient to suppress connective tissue growth factor expression by fibroblasts, but the inhibition developed over a time period of around 16 h. The putative keratinocyte-derived factor(s) responsible for these effects was found to be soluble and stable. By analyzing cytokines secreted by keratinocytes we identified interleukin-1alpha as a potent inhibitor of connective tissue growth factor mRNA expression in fibroblasts. Involvement of this cytokine in keratinocyte-mediated connective tissue growth factor suppression was confirmed by using anti-interleukin-1alpha antibodies. Tumor necrosis factor alpha or prostaglandins did not appear to be involved. In conclusion, our results indicate that interleukin-1alpha secretion by keratinocytes provides a mechanism for the downregulation of connective tissue activity during the end-stage of wound healing, when epithelia coverage has developed over the wound area.