Secreted protein acidic and rich in cysteine (SPARC) and a disintegrin and metalloproteinase with thrombospondin type 1 motif (ADAMTS1) increments by the renin-angiotensin system induce renal fibrosis in deoxycorticosterone acetate-salt hypertensive rats.

Secreted protein acidic and rich in cysteine (SPARC), an extracellular matrix (ECM) protein, was recently shown to induce collagen deposition through the production of a disintegrin and metalloproteinase with thrombospondin type 1 motif (ADAMTS1) in the aging heart. ADAMTS1 regulates ECM turnover by degrading ECM components, and its excessive activation contributes to various pathological states, including fibrosis. The present study investigated the pathophysiological regulation and role of SPARC and ADAMTS1 in renal fibrosis using uninephrectomized rats treated with deoxycorticosterone acetate (DOCA, 40 mg/kg/week, subcutaneously) and salt (1% in drinking water). The administration of DOCA and salt gradually and significantly elevated systolic blood pressure during the 3-week treatment period, induced proteinuria, decreased creatinine clearance, and increased NADPH oxidase-derived superoxide production, malondialdehyde concentrations, and monocyte chemoattractant protein-1 and osteopontin expression in the kidneys. Glomerulosclerosis, fibrillar collagen deposition, and transforming growth factor-ß expression increased in a time-dependent manner, and SPARC and ADAMTS1 expression showed a similar pattern to these changes. The angiotensin II type-1 receptor blocker losartan suppressed the overexpression of SPARC and ADAMTS1, and an in vitro exposure to angiotensin II induced the production of both SPARC and ADAMTS1 in renal fibroblast NRK-49F cells. Knockdown of the SPARC gene with small interfering RNA reduced all forms (the 110-kDa latent and 87- and 65-kDa bioactive forms) of ADAMTS1 expression as well as collagen production. These results suggest that SPARC is induced by the renin-angiotensin system and may be a fibrogenic factor, at least in part, by producing ADAMTS1 in hypertensive renal disease.

Irregular pacing of ventricular cardiomyocytes induces pro-fibrotic signalling involving paracrine effects of transforming growth factor beta and connective tissue growth factor.

AIMS: Atrial fibrillation is the most prevalent sustained arrhythmia associated with arrhythmic ventricular contractions, incident heart failure, increased morbidity and mortality. The relationship between arrhythmic contractions and ventricular remodelling is incompletely understood. The aim of this study was to characterize the influence of irregular contractions on pro-fibrotic signalling in neonatal rat ventricular cardiomyocytes (NRVM). METHODS AND RESULTS: Neonatal rat ventricular cardiomyocytes were paced via field stimulation at 3 Hz for 24 h. Irregularity was created by pseudorandomized variation of stimulation intervals and compared to regular pacing. Treatment of neonatal cardiac fibroblasts (NCF) with medium of irregularly paced NRVM increased protein expression of collagen I (206 ± 62%, P = 0.0121) and collagen III (51 ± 37%, P = 0.0119). To identify the underlying mechanism, expression of pro-fibrotic connective tissue growth factor (CTGF) and transforming growth factor beta (TGF-ß) was assessed. In irregularly paced NRVM, increased protein expression of CTGF (80 ± 22%, P = 0.0035) and TGF-ß (122 ± 31%, P = 0.0022) was associated with enhanced excretion of both proteins into the medium. Electron paramagnetic resonance spectroscopy revealed an increased production of reactive oxygen species (46 ± 21%, P = 0.0352) after irregular pacing accompanied by increased 8-hydroxydeoxyguanosine staining (214 ± 53%, P = 0.0011). Irregular pacing was associated with elevated mRNA levels of anti-oxidative superoxide dismutase 1 (25 ± 7%, P = 0.0175), superoxide dismutase 3 (20 ± 7%, P = 0.0309), and catalase (20 ± 7%, P = 0.046). CONCLUSION: These data demonstrate that irregular pacing is an important inductor of pro-fibrotic signalling in NRVM involving paracrine effects of CTGF and TGF-ß as well as increased oxidative stress. Thus, irregularity of the heart beat might directly be involved in the progression of maladaptive remodelling processes in atrial fibrillation.

Intratumoral injection of gels containing losartan microspheres and (PLG-g-mPEG)-cisplatin nanoparticles improves drug penetration, retention and anti-tumor activity.

Intratumoral injection of chemotherapy agents may be employed in the treatment of cancers. However, its anti-tumor efficacy is significantly impeded by collagen fibers in the tumor which decrease drug penetration into the tumor tissues. To improve the penetration, collagen inhibiting drug exposure is required. In this study, microspheres were fabricated by the modified double emulsion-solvent evaporation method as the drug delivery system of losartan potassium (LP MSs), with 5% gelatin as the inner phase. The collagen inhibiting experiment analyzed by Sirius Red stains demonstrated that LP MSs may effectively inhibit collagen I synthesis in B16 tumors. In addition, 15% F127 was used as the solvent to fix the formulations at the injection site, with poly (α-l-glutamate) grafted polyethylene glycol mono methyl ether (PLG-g-mPEG)-cisplatin loaded nanoparticles (CDDP NPs) as the model drug. The in vivo live imaging system showed that formulations dissolved in 15% F127 had 54.91% CDDP NPs retained in tumors at the end of 10 days, in comparison with 19.72% for those solved in water, suggesting strong intratumoral retention property of the in situ gel. In addition, confocal laser scanning microscope (CLSM) and Energy-Dispersive Analysis of X-ray spectroscopy combined with scanning electron microscope (SEM-EDAX) tests showed that LP MSs can effectively enhance the distribution and penetration of CDDP NPs within tumors. Furthermore, tumors i.t. treated with LP MSs/CDDP NPs gel could be significantly halted, or even reduced to 200 mm3, comparing with a volume of about 12000 mm3 incontrol group at the end of the anti-tumor effect experiment. These results provided important guiding principles for prolonged and localized drug delivery system of intratumoral collagen inhibitor. The improvements of intratumoral penetration method made in this study provided practical significance for the treatment of cancer, especially for mass tumors.

Analysis of collagen and elastin cross-links.

Fibrillar collagens represent the most abundant extracellular matrix proteins in vertebrates providing tissues and organs with form, stability, and connectivity. For such mechanical functions, the formation of covalent intermolecular cross-linking between molecules is essential. This process, the final posttranslational modification during collagen biosynthesis, is initiated by conversion of specific lysine and hydroxylysine residues to the respective aldehydes by the action of lysyl oxidases. This conversion triggers a series of condensation reactions with the juxtaposed lysine-aldehyde, lysine, hydroxylysine, and histidine residues within the same and neighboring molecules resulting in di-, tri-, and tetravalent cross-links. Elastin, another class of extracellular matrix protein, is also stabilized by the lysyl oxidase-mediated mechanism but involving only lysine residues leading to the formation of unique tetravalent cross-links. This chapter presents an overview of fibrillar collagen cross-linking, and the analytical methods for collagen and elastin cross-links we have developed.

Fibrillar collagen genes are not coordinately upregulated with TGF ß1 expression in finasteride-treated prostate.

Benign prostatic hyperplasia (BPH) is the most common cause of lower urinary tract symptoms (LUTS) in older men. In this regard, recent studies have attempted to define the relationships between prostatic fibrosis, LUTS, and increased expression of transforming growth factor ß1 (TGF ß1) in BHP. Therapeutic approaches for BPH such as 5-α-reductase inhibitors and alpha-adrenergic blocking agents increase TGF ß1 expression in the prostatic tissue. Here, we investigated the effects of the 5-α-reductase inhibitor-finasteride-on rat ventral prostate tissue, especially with regard to the tissue distribution and gene expression of fibrillar collagens. Adult Wistar rats (n = 15) were treated with finasteride (25 mg/kg/day) by subcutaneous injection for 7 and 30 days. Age-matched, vehicle-treated (n = 15) adult Wistar rats were used as control. Finasteride treatment reduced prostate size and increased the area of types I and III collagen fibers in the prostatic stroma. As expected, TGF ß1 mRNA expression was upregulated by finasteride treatment. However, COL1A1 and COL3A1 mRNA expressions decreased after both 7 and 30 days of finasteride treatment, suggesting that finasteride treatment promotes prostate parenchyma and stroma changes, which lead to the observed types I and III collagen remodeling without de novo collagen synthesis. The upregulation of TGF ß1 mRNA and protein associated with the 5-α-reductase inhibitor is more closely related to epithelial and stromal cell death pathways than to prostatic fibrosis.

Hyperocclusion stimulates the expression of collagen type XII in periodontal ligament.

OBJECTIVES: It is known that excessive mechanical force exerted by hyperocclusion induces occlusal trauma. However, the mechanism of the process remains unclear. In the present study, we employed an in vivo hyperocclusion rodent model to examine morphological and biological mechanisms of occlusal trauma in periodontal ligament tissue. DESIGN: To investigate alveolar bone resorption, tooth sections were stained to detect osteoclasts. To investigate the relationship between hyperocclusion and the regeneration of the cell matrix, we examined the effect of hyperocclusal force on the expression of collagens using immunohistochemistry and quantitative PCR methods. RESULTS: The arrangement of collagen fibers in the furcation area of the teeth was undisturbed before hyperocclusion (control). Type I collagen was localized in the extracellular area at the furcation and there was faint expression and localization of type XII collagen in the periodontal ligament. The number of osteoclasts significantly increased in the furcation and lingual cervical regions on day 4 after hyperocclusion was induced. Type XII collagens were gradually up-regulated following the induction of hyperocclusion, in a time-dependent manner. Although type I collagen mRNA expression was stable before and after hyperocclusion, type XII collagen mRNA was significantly up-regulated on day 2 and day 4 after hyperocclusion treatment. CONCLUSIONS: Our findings indicate that hyperocclusal force predominantly up-regulates the expression of type XII collagen in periodontal tissue, but not type I collagen, suggesting that there is a mechanism for regeneration of periodontal tissues as a response to occlusal trauma.

Effect of single- and double-row rotator cuff repair at the tendon-to-bone interface: preliminary results using an in vivo sheep model.

INTRODUCTION: The clinical superiority of the double-row technique is still a subject of controversial debate in rotator cuff repair. We hypothesised that the expression of different collagen types will differ between double-row and single-row rotator cuff repair indicating a faster healing response by the double-row technique. MATERIALS AND METHODS: Twenty-four mature female sheep were randomly assembled to two different groups in which a surgically created acute infraspinatus tendon tear was fixed using either a modified single- or double-row repair technique. Shoulder joints from female sheep cadavers of identical age, bone maturity, and weight served as untreated control cluster. Expression of type I, II, and III collagen was observed in the tendon-to-bone junction along with recovering changes in the fibrocartilage zone after immunohistological tissue staining at 1, 2, 3, 6, 12, and 26 weeks postoperatively. RESULTS: Expression of type III collagen remained positive until 6 weeks after surgery in the double-row group, whereas it was detectable for 12 weeks in the single-row group. In both groups, type I collagen expression increased after 12 weeks. Type II collagen expression was increased after 12 weeks in the double-row versus single-row group. Clusters of chondrocytes were only visible between week 6 and 12 in the double-row group. CONCLUSIONS: The study demonstrates differences regarding the expression of type I and type III collagen in the tendon-to-bone junction following double-row rotator cuff repair compared to single-row repair. The healing response in this acute repair model is faster in the double-row group during the investigated healing period.

ß-Arrestins regulate human cardiac fibroblast transformation and collagen synthesis in adverse ventricular remodeling.

Cardiac fibroblasts (CFs) produce and degrade the myocardial extracellular matrix and are critical in maladaptive ventricular remodeling that can result in heart failure (HF). ß-Arrestins are important signaling molecules involved in ß-adrenergic receptor (ß-AR) desensitization and can also mediate signaling in a G protein-independent fashion. We hypothesize that ß-arrestins play an important role in the regulation of adult human CF biology with regard to myofibroblast transformation, increased collagen synthesis, and myocardial fibrosis which are important in the development of HF. ß-Arrestin1 & 2 expression is significantly upregulated in adult human CF isolated from failing left ventricles and ß-AR signaling is uncoupled with loss of ß-agonist-mediated inhibition of collagen synthesis versus normal control CF. Knockdown of either ß-arrestin1 or 2 restored ß-AR signaling and ß-agonist mediated inhibition of collagen synthesis. Overexpression of ß-arrestins in normal CF led to a failing phenotype with increased baseline collagen synthesis, impaired ß-AR signaling, and loss of ß-agonist-mediated inhibition of collagen synthesis. ß-Arrestin knockdown in failing CF diminished TGF-ß stimulated collagen synthesis and also inhibited ERK phosphorylation. Overexpression of ß-arrestins in normal CF increased basal ERK1/2 and Smad2/3 phosphorylation and enhanced TGF-ß-stimulated collagen synthesis. This was prevented by pre-treatment with a MEK1/2 inhibitor. Enhanced ß-arrestin signaling appears to be deleterious in CF by promoting a pro-fibrotic phenotype via uncoupling of ß-AR signaling as well as potentiating ERK and Smad signaling. Targeted inhibition of ß-arrestins in CF may represent a therapeutic strategy to prevent maladaptive myocardial fibrosis.

Gene expression analysis in patients with traumatic anterior shoulder instability suggests deregulation of collagen genes.

Shoulder dislocation occurs in 1-2% of the population. Capsular deformation is a key factor in shoulder dislocation; however, little is known about capsule biology. We evaluated, for the first time in literature, the expression of COL1A1, COL1A2, COL3A1 and COL5A1 in the antero-inferior, antero-superior and posterior regions of the glenohumeral capsule of 31 patients with anterior shoulder instability and eight controls. The expression of collagen genes was evaluated by quantitative reverse transcription-PCR. The expression of COL1A1, COL3A1 and the ratio of COL1A1/COL1A2 were increased in all three portions of the capsule in patients compared to controls (p < 0.05). COL1A2 expression was upregulated in the antero-superior and posterior sites of the capsule of patients (p < 0.05). The ratio of COL1A2/COL3A1 expression was reduced in capsule antero-inferior and posterior sites of patients compared to controls (p < 0.05). In the capsule antero-inferior site of patients, the ratios of COL1A1/COL5A1, CO1A2/COL5A1 and COL3A1/COL5A1 expression were increased (p < 0.05). In patients, COL1A1/COL5A1 was also increased in the posterior site (p < 0.05). We found deregulated expression of collagen genes across the capsule of shoulder instability patients. These molecular alterations may lead to modifications of collagen fibril structure and impairment of the healing process, possibly with a role in capsular deformation.

A substrate preference for the rough endoplasmic reticulum resident protein FKBP22 during collagen biosynthesis.

The biosynthesis of collagens occurs in the rough endoplasmic reticulum and requires a large numbers of molecular chaperones, foldases, and post-translational modification enzymes. Collagens contain a large number of proline residues that are post-translationally modified to 3-hydroxyproline or 4-hydroxyproline, and the rate-limiting step in formation of the triple helix is the cis-trans isomerization of peptidyl-proline bonds. This step is catalyzed by peptidyl-prolyl cis-trans isomerases. There are seven peptidyl-prolyl cis-trans isomerases in the rER, and so far, two of these enzymes, cyclophilin B and FKBP65, have been shown to be involved in collagen biosynthesis. The absence of either cyclophilin B or FKBP65 leads to a recessive form of osteogenesis imperfecta. The absence of FKBP22 leads to a kyphoscoliotic type of Ehlers-Danlos syndrome (EDS), and this type of EDS is classified as EDS type VI, which can also be caused by a deficiency in lysyl-hydroxylase 1. However, the lack of FKBP22 shows a wider spectrum of clinical phenotypes than the absence of lysyl-hydroxylase 1 and additionally includes myopathy, hearing loss, and aortic rupture. Here we show that FKBP22 catalyzes the folding of type III collagen and interacts with type III collagen, type VI collagen, and type X collagen, but not with type I collagen, type II collagen, or type V collagen. These restrictive interactions might help explain the broader phenotype observed in patients that lack FKBP22.

Multiple fractional erbium: yttrium-aluminum-garnet laser sessions for upper facial rejuvenation: clinical and histological implications and expectations.

BACKGROUND: Fractional photothermolysis is a modern resurfacing technique, in which microscopic zones of thermal injury are created, stimulating turnover of both epidermis and dermis. Fractional laser rejuvenation has been developed to overcome the drawbacks of traditional ablative laser. OBJECTIVES: To objectively evaluate the effectiveness of multiple sessions of fractional Er:YAG laser rejuvenation for aging upper face clinically, histologically and immunohistochemically. PATIENTS/METHODS: Ten volunteers asking for facial rejuvenation were subjected to multiple sessions (3-5) of fractional Er:YAG laser. Clinical evaluation with both histopathological and immunohistochemical assessment for skin biopsies was carried out before, after 1 month and 6 months of laser resurfacing. Histometry for epidermal thickness and quantitative assessment for neocollagen formation, collagen I, III, and VII, elastin and tropoelastin were carried out for all skin biopsies. RESULTS: Comparing before, after 1 month and 6 months of fractional Er:YAG laser resurfacing resulted in improved clinical appearance with increased epidermal thickness (P < 0.001). Dermal collagen showed increased neocollagen formation (P = 0.006), with increased concentration of collagen types I (P < 0.001), III (P < 0.001), and VII (P = 0.001). Dermal elastic tissue studies revealed decreased elastin, while tropoelastin concentration increased after laser resurfacing (P < 0.001). An increase in collagen (I and III) and tropoelastin level and decreased elastin content was encountered with increasing the number of sessions, yet it was not significant. CONCLUSIONS: Multiple sessions are effective in rejuvenation of the aging face with high safety, short downtime, and no adverse effects. They stimulated formation of new collagen (type I, III, and VII) up to 6 months after treatment with better improvement in skin texture and fine wrinkles. The variable number of fractional Er:YAG laser sessions (3-5) showed no significant difference as regards efficacy.

Observation of collagen fibrils produced by osteosarcoma cells using atomic force microscopy.

The present study examined the three-dimensional process of collagen fibril formation in the human osteosarcoma cell line NOS-1 by conventional scanning electron microscopy (SEM) and atomic force microscopy (AFM). SEM images showed collagen fibril formation on the bottom of culture dishes after 1 week of culture. The collagen fibrils had diameters of 30-100 nm. The surfaces of individual fibrils had characteristic grooves and ridges with periodicities of 60-70 nm. AFM images showed that the newly formed collagen fibrils were 30-300 nm in diameter and possessed characteristic grooves and ridges with periodicities of 60-70 nm. The thicker collagen fibrils contained thinner (approximately 30 nm thick) subfibrils that ran in a helical direction along the long axis of the thicker fibrils. Furthermore, twisted structures of collagen fibrils, which possessed a characteristic rope-like structure, were also identified. The ultrastructure of the collagen fibrils was clearly imaged in liquid medium by AFM, and the process of collagen fibril assembly was successfully analyzed under conditions much closer to the physiological state than those afforded by transmission electron microscopy or SEM. AFM also provided a precise morphological measurement, particularly of the vertical distance, of collagen fibrils with nanometer-scale resolution in liquid conditions.

Flexible and elastic scaffolds for cartilage tissue engineering prepared by stereolithography using poly(trimethylene carbonate)-based resins.

The aim of this study is to investigate the applicability of flexible and elastic poly(trimethylene carbonate) (PTMC) structures prepared by stereolithography as scaffolds for cartilage tissue engineering. A three-armed methacrylated PTMC macromer with a molecular weight of 3100 g mol(-1) is used to build designed scaffolds with a pore diameter of 350 ± 12 µm and a porosity of 54.0 ± 2.2%. Upon seeding of bovine chondrocytes in the scaffolds, the cells adhere and spread on the PTMC surface. After culturing for 6 weeks, also cells with a round morphology are present, indicative of the differentiated chondrocyte phenotype. Sulphated glycosaminoglycans and fibrillar collagens are deposited by the cells. During culturing for 6 weeks, the compression moduli of the constructs increases 50% to approximately 100 kPa.

Collagen expression in various degenerative meniscal changes: an immunohistological study.

PURPOSE. To examine changes in acid mucopolysaccharides and collagen expression during meniscal degeneration, tearing, and repair, using menisci excised from knee joint surgeries. METHODS. Menisci excised from 23 patients aged 15 to 80 years who underwent meniscal surgery for flap and bucket handle tears (n=11) and total knee arthroplasty (TKA) for osteoarthritis (n=12) were examined histologically. Staining images were converted to greyscale images to measure the mean grey levels, which indicated densitometry. Comparisons were made between acutely injured menisci and menisci with and without degeneration (from patients with osteoarthritis) in terms of acid mucopolysaccharides, collagen types I, II, and III expression. RESULTS. In menisci with no degeneration, acid mucopolysaccharides, collagen types I and II were expressed throughout the entire meniscus except for the circulating area. Collagen type III was intensely expressed at the exterior peripheral border and on the surface. During progression of meniscal degeneration, the expression of acid mucopolysaccharides increased, and the expression of collagen types I, II, and III decreased. In acutely injured menisci, collagen types II and III disappeared first, followed by collagen type I, resulting in the abrogation of fibre construction. CONCLUSION. In normal menisci, acid mucopolysaccharides and collagen types I, II, and III were well-balanced, and meniscal function was maintained. When the limits of repair were exceeded, the meniscus tissue deteriorated owing to the disappearance of collagen types II and III and a decrease in collagen type I, resulting in the abrogation of meniscus fabric construction.

TGF-ß1-induced synthesis of collagen fibers in skeletal muscle-derived stem cells.

The aim of this study was to investigate the mechanism of deposition of extracellular matrix induced by TGF-ß1 in skeletal muscle-derived stem cells (MDSCs). Rat skeletal MDSCs were obtained by using preplate technique, and divided into four groups: group A (control group), group B (treated with TGF-ß1, 10 ng/mL), group C (treated with TGF-ß1 and anti-connective tissue growth factor (CTGF), both in 10 ng/mL), and group D (treated with anti-CTGF, 10 ng/mL). The expression of CTGF, collagen type-I (COL-I) and collagen type-III (COL-III) in MDSCs was examined by using RT-PCR, Western blot and immunofluorescent stain. It was found that one day after TGF-ß1 treatment, the expression of CTGF, COL-I and COL-III was increased dramatically. CTGF expression reached the peak on the day 2, and then decreased rapidly to a level of control group on the day 5. COL-I and COL-III mRNA levels were overexpresed on the day 2 and 3 respectively, while their protein expression levels were up-regulated on the day 2 and reached the peak on the day 7. In group C, anti-CTGF could partly suppress the overexpression of COL-I and COL-II induced by TGF-ß1 one day after adding CTGF antibody. It was concluded that TGF-ß1 could induce MDSCs to express CTGF, and promote the production of COL-I and COL-III. In contrast, CTGF antibody could partially inhibit the effect of TGF-ß1 on the MDSCs by reducing the expression of COL-I and COL-III. Taken together, we demonstrated that TGF-ß1-CTGF signaling played a crucial role in MDSCs synthesizing collagen proteins in vitro, which provided theoretical basis for exploring the methods postponing skeletal muscle fibrosis after nerve injury.

Continuous cyclic stretch induces osteoblast alignment and formation of anisotropic collagen fiber matrix.

Bone tissue geometry shows a highly anisotropic architecture, which is derived from its genetic regulation and mechanical environment. Osteoblasts are responsible not only for bone formation, through the secretion of collagen type I, but also for sensing the mechanical stimuli due to bone surface strain. Mechanotransduction by osteoblasts is therefore considered one of the regulators of anisotropic bone tissue morphogenesis. The orientation of osteoblasts and the secreted collagen matrix was successfully regulated by applying a continuous mechanical stress on osteoblasts for a long period. Under a continuous cyclic stretch of 4% magnitude at a rate of 2 cycles min(-1), osteoblasts reoriented their actin stress fibers in the direction that minimizes the strain applied to them. Extended culture of up to 2weeks resulted in the formation of collagen fibers in the extracellular spaces, and the preferred orientation of these fibers was parallel to the direction of cell elongation. To the best of our knowledge, this is the first report to establish anisotropic bone matrix architecture following the alignment of osteoblasts under mechanical stimuli for long-term cultivation.

Cellular mechanisms of tissue fibrosis. 2. Contributory pathways leading to myocardial fibrosis: moving beyond collagen expression.

While the term "fibrosis" can be misleading in terms of the complex patterns and processes of myocardial extracellular matrix (ECM) remodeling, fibrillar collagen accumulation is a common consequence of relevant pathophysiological stimuli, such as pressure overload (PO) and myocardial infarction (MI). Fibrillar collagen accumulation in both PO and MI is predicated on a number of diverse cellular and extracellular events, which include changes in fibroblast phenotype (transdifferentiation), posttranslational processing and assembly, and finally, degradation. The expansion of a population of transformed fibroblasts/myofibroblasts is a significant cellular event with respect to ECM remodeling in both PO and MI. The concept that this cellular expansion within the myocardial ECM may be due, at least in part, to endothelial-mesenchymal transformation and thereby not dissimilar to events observed in cancer progression holds intriguing future possibilities. Studies regarding determinants of procollagen processing, such as procollagen C-endopeptidase enhancer (PCOLCE), and collagen assembly, such as the secreted protein acidic and rich in cysteine (SPARC), have identified potential new targets for modifying the fibrotic response in both PO and MI. Finally, the transmembrane matrix metalloproteinases, such as MMP-14, underscore the diversity and complexity of this ECM proteolytic family as this protease can degrade the ECM as well as induce a profibrotic response. The growing recognition that the myocardial ECM is a dynamic entity containing a diversity of matricellular and nonstructural proteins as well as proteases and that the fibrillar collagens can change in structure and content in a rapid temporal fashion has opened up new avenues for modulating what was once considered an irreversible event--myocardial fibrosis.

In vitro phenotypic modulation of chondrocytes from knees of patients with osteochondritis dissecans: implications for chondrocyte implantation procedures.

We attempted to characterise the biological quality and regenerative potential of chondrocytes in osteochondritis dissecans (OCD). Dissected fragments from ten patients with OCD of the knee (mean age 27.8 years (16 to 49)) were harvested at arthroscopy. A sample of cartilage from the intercondylar notch was taken from the same joint and from the notch of ten patients with a traumatic cartilage defect (mean age 31.6 years (19 to 52)). Chondrocytes were extracted and subsequently cultured. Collagen types 1, 2, and 10 mRNA were quantified by polymerase chain reaction. Compared with the notch chondrocytes, cells from the dissecate expressed similar levels of collagen types 1 and 2 mRNA. The level of collagen type 10 message was 50 times lower after cell culture, indicating a loss of hypertrophic cells or genes. The high viability, retained capacity to differentiate and metabolic activity of the extracted cells suggests preservation of the intrinsic repair capability of these dissecates. Molecular analysis indicated a phenotypic modulation of the expanded dissecate chondrocytes towards a normal phenotype. Our findings suggest that cartilage taken from the dissecate can be reasonably used as a cell source for chondrocyte implantation procedures.

Filtek™ Silorane and Filtek™ Supreme XT resins: tissue reaction after subcutaneous implantation in isogenic mice.

The aim of this study was to evaluate the tissue compatibility of a silorane-based resin system (Filtek™ Silorane) and a methacrylate-based nanoparticle resin (Filtek™ Supreme XT) after implantation in the subcutaneous connective tissue of isogenic mice. One hundred and thirty five male isogenic BALB/c mice were randomly assigned to 12 experimental and 3 control groups, according to the implanted material and the experimental period of 7, 21 and 63 days. At the end of each period, the animals were killed and the tubes with the surrounding tissues were removed and processed for microscopic analysis. Samples were subjected to a descriptive and a semi-quantitative analyses using a 4-point scoring system (0-3) to evaluate the collagen fiber formation and inflammatory infiltrate. Data were statistically analyzed using the Kruskal Wallis test (α=0.05). The results showed that there was no significant difference between the experimental and control groups considering the three evaluation periods (p>0.05). The silorane-based and the methacrylate-based nanoparticle resins presented similar tissue response to that of the empty tube (control group) after subcutaneous implantation in isogenic mice.

FiltekTM Silorane and FiltekTM Supreme XT resins: tissue reaction after subcutaneous implantation in isogenic mice

The aim of this study was to evaluate the tissue compatibility of a silorane-based resin system (FiltekTM Silorane) and a methacrylate-based nanoparticle resin (FiltekTM Supreme XT) after implantation in the subcutaneous connective tissue of isogenic mice. One hundred and thirty five male isogenic BALB/c mice were randomly assigned to 12 experimental and 3 control groups, according to the implanted material and the experimental period of 7, 21 and 63 days. At the end of each period, the animals were killed and the tubes with the surrounding tissues were removed and processed for microscopic analysis. Samples were subjected to a descriptive and a semi-quantitative analyses using a 4-point scoring system (0-3) to evaluate the collagen fiber formation and inflammatory infiltrate. Data were statistically analyzed using the Kruskal Wallis test (?=0.05). The results showed that there was no significant difference between the experimental and control groups considering the three evaluation periods (p>0.05). The silorane-based and the methacrylate-based nanoparticle resins presented similar tissue response to that of the empty tube (control group) after subcutaneous implantation in isogenic mice.

O objetivo do presente estudo foi avaliar a compatibilidade tecidual de um sistema resinoso à base de silorane (FiltekTM Silorane) e de uma resina nanoparticulada à base de metacrilato (FiltekTM Supreme XT), após implantação no tecido conjuntivo subcutâneo de camundongos isogênicos. Um total de 135 camundongos isogênicos BALB/c machos foram randomicamente divididos em 12 grupos experimentais e em 3 grupos controles, de acordo com o material implantado e com o período experimental (7, 21 e 63 dias). Ao final de cada período, os animais foram mortos, sendo os tubos removidos com o tecido circundante e processados para análise microscópica. As lâminas foram submetidas a análise descritiva e análise semi-quantitativa empregando um sistema de escores de 4 pontos (0-3), a fim de avaliar a formação de fibras colágenas e o infiltrado inflamatório. Os dados obtidos foram submetidos à análise estatística por meio do teste de Kruskal Wallis (?=0,05). Os resultados mostraram que não houve diferença estatisticamente significante entre os grupos experimentais e controles, considerando os três períodos de avaliação (p>0,05). As resinas à base de silorane e à base de metacrilato apresentaram resposta tecidual semelhante à do tubo vazio (controle), após implantação no tecido conjuntivo de camundongos isogênicos.