Correction to: Comparison of healing of full-thickness skin wounds grafted with multidirectional or unidirectional autologous artificial dermis: differential delivery of healing biomarkers.

In the original article text presenting and discussing results shown in Fig. 6 omitted to mention that quantification of TGF-ß2 and TGF-ß3 was not included in Fig. 6a, c, e.

Comparison of healing of full-thickness skin wounds grafted with multidirectional or unidirectional autologous artificial dermis: differential delivery of healing biomarkers.

Cytokines, chemokines, and growth and remodeling factors orchestrate wound healing when skin damage occurs. During early stages, when the wound is still open, detection and quantification of these compounds might provide biomarkers of skin wound healing, which could aid to complete the scenario provided by clinical follow-up data and histological and histomorphometric analyses. This work assessed and compared the healing of full-thickness skin wounds grafted with artificial dermis made with autologous skin fibroblasts and unidirectional or multidirectional type I collagen scaffolds to test this hypothesis. Biomarkers of healing were detected and quantified in the culture medium of artificial dermis and exudates from the grafted wounds. Clinical follow-up of animals and histological and histomorphometric analysis showed differences in graft integration, wound closure, and histological and histomorphometric parameters. Surface plasmon resonance quantification of 13 healing biomarkers indicated differential secretion of most of the quantified factors in culture medium by the multidirectional and unidirectional artificial dermis. Also, there were significant differences between the concentration of some of the factors analyzed in the exudates of wounds grafted with the evaluated artificial dermis. These findings suggest that differential delivery of healing biomarkers induced by the directionality of the scaffold used to produce the multidirectional and unidirectional dermis was sufficient to create two skin wound microenvironments that determined a different outcome of healing. Overall, data indicate that healing of wounds grafted with multidirectional autologous artificial dermis is better than that of the wounds grafted with the unidirectional one.

Two-dimensional and three-dimensional models for studying atherosclerosis pathogenesis induced by periodontopathogenic microorganisms.

Epidemiological studies have established a clinical association between periodontal disease and atherosclerosis. Bacteremia and endotoxemia episodes in patients with periodontitis appear to link these two diseases by inducing a body-wide production of cardiovascular markers. The presence of oral bacteria in atherosclerotic lesions in patients with periodontitis suggests that bacteria, or their antigenic components, induce alterations in the endothelium associated with atherosclerosis. Therefore, a causal mechanism explaining the association between both diseases can be constructed using in vitro models. This review presents current experimental approaches based on in vitro cell models used to shed light on the mechanism by which periodontal pathogenic microorganisms, and their antigenic components, induce proatherosclerotic endothelial activity. Monolayer cultures of endothelial vascular or arterial cells have been used to assess periodontal pathogenic bacteria and their antigenic compounds and endothelial activation. However, these models are not capable of reflecting the physiological characteristics of the endothelium inside vascularized tissue. Therefore, the shift from two-dimensional (2D) cellular models toward three-dimensional (3D) models of endothelial cells resembling an environment close to the physiological environment of the endothelial cell within the endothelium is useful for evaluating the physiological relevance of results regarding the endothelial dysfunction induced by periodontopathogens that are currently obtained from 2D models. The use of in vitro 3D cellular models can also be relevant to the search for therapeutic agents for chronic inflammatory diseases such as atherosclerosis. Here, we present some strategies for the assembly of 3D cultures with endothelial cells, which is useful for the study of periodontopathogen-mediated disease.

Multifactor analysis on the effect of collagen concentration, cross-linking and fiber/pore orientation on chemical, microstructural, mechanical and biological properties of collagen type I scaffolds.

This work evaluates the effect of processing variables on some physicochemical and mechanical properties of multi- and unidirectional laminar collagen type I scaffolds. The processing variables considered in this study included microstructure orientation (uni- and multidirectional fiber/pore controlled by freeze-drying methodology), cross-linking (chemical - using genipin and glutaraldehyde, and physical - using a dehydrothermal method), and collagen concentration (2, 5 and 8mg/ml). The biocompatibility of the scaffolds obtained in each of the evaluated manufacturing processes was also assessed. Despite previous research on collagen-based platforms, the effects that these processing variables have on the properties of collagen scaffolds are still not completely understood. Unidirectional scaffolds presented higher resistance to failure under stress than multidirectional ones. The cross-linking degree was found to decrease when the concentration of collagen increased whilst using chemical cross-linkers, and to increase with the concentration of collagen for the dehydrothermal cross-linked scaffolds. Pore orientation indexes of both unidirectional and multidirectional scaffolds were not influenced by collagen concentration. Cross-linked scaffolds were more hydrophobic than non-cross-linked ones, and presented water vapor permeability adequate for use in low-to-moderate exuding wounds. Pore size ranges were compatible with cell in-growth, independently of the employed cross-linking and freezing methodologies. Moreover, scaffolds cross-linked with glutaraldehyde presented higher in-growth of primary oral mucosa fibroblasts than those cross-linked with genipin or with the dehydrothermal treatment. This multi-factor analysis is expected to contribute to the design of collagen type I platforms, which are usable on several potential soft tissue-engineering applications.

Preclinical evaluation of collagen type I scaffolds, including gelatin-collagen microparticles and loaded with a hydroglycolic Calendula officinalis extract in a lagomorph model of full-thickness skin wound.

Previously, we have developed collagen type I scaffolds including microparticles of gelatin-collagen type I (SGC) that are able to control the release of a hydroglycolic extract of the Calendula officinalis flower. The main goal of the present work was to carry out the preclinical evaluation of SGC alone or loaded with the C. officinalis extract (SGC-E) in a lagomorph model of full-thickness skin wound. A total of 39 rabbits were distributed in three groups, of 13 animals each. The first group was used to compare wound healing by secondary intention (control) with wound healing observed when wounds were grafted with SGC alone. Comparison of control wounds with wounds grafted with SGC-E was performed in the second group, and comparison of wounds grafted with SGC with wounds grafted with SGC-E was performed in the third group. Clinical follow-ups were carried in all animals after surgery, and histological and histomorphometric analyses were performed on tissues taken from the healed area and healthy surrounding tissue. Histological and histomorphometric results indicate that grafting of SGC alone favors wound healing and brings a better clinical outcome than grafting SGC-E. In vitro collagenase digestion data suggested that the association of the C. officinalis extract to SGC increased the SGC-E cross-linking, making it difficult to degrade and affecting its biocompatibility.

Basic fibroblast growth factor decreases elastin gene transcription through an AP1/cAMP-response element hybrid site in the distal promoter.

Previous studies demonstrated that basic fibroblast growth factor (bFGF) decreases elastin gene transcription in pulmonary fibroblasts. In this study we pursue the identification of the element and the trans-acting factors responsible. Gel shift analyses show that bFGF increases protein binding to a sequence located at -564 to -558 base pairs (bp), which possesses homology to both AP1 and cAMP-response consensus elements yet displays a unique affinity for heterodimer binding. Site-directed mutation of the -564- to -558-bp sequence results in an increase in promoter activity and abrogates the effect of bFGF. Western blot analysis shows that bFGF induces a sustained increase in the steady-state levels of Fra 1, and co-transfection of a Fra 1 expression vector with an elastin promoter reporter construct results in an inhibition of elastin promoter activity. Overall the results suggest that bFGF represses elastin gene transcription by increasing the amount of the Fra 1 that subsequently binds to the -564- to -558-bp as a heterodimer with c-Jun to form an inhibitory complex. We propose that the identified bFGF response element can serve to down-regulate elastin transcription in elastogenic cells and, conversely, can serve to up-regulate elastogenesis in cells where endogenous bFGF signaling is attenuated or altered.

Insulin-like growth factor-I regulates transcription of the elastin gene through a putative retinoblastoma control element. A role for Sp3 acting as a repressor of elastin gene transcription.

Previous studies have demonstrated that insulin-like growth factor-I (IGF-I) increases elastin gene transcription in aortic smooth muscle cells and that this up-regulation is accompanied by a loss of protein binding to the proximal promoter. Sp1 has been identified as one of the factors whose binding is lost, and in the present study we show that Sp3 binding is also abrogated by IGF-I, but in a selected manner. In functional analyses using Drosophila SL-2 cells, Sp1 expression can drive transcription from the elastin proximal promoter, while co-expression of Sp3 results in a repression of Sp1 activity. Footprint and gel shift analyses position the IGF-I responsive sequences to a putative retinoblastoma control element (RCE). Mutation of the putative RCE sequence as assessed by transient transfection of smooth muscle cells results in an increase in reporter activity equal in magnitude to that conferred by IGF-I on the wild type promoter. Together these results support the hypothesis that IGF-I-mediated increase in elastin transcription occurs via a mechanism of derepression involving the abrogation of a repressor that appears to be Sp3 binding to the RCE.