Regulating inflammation using acid-responsive electrospun fibrous scaffolds for skin scarless healing

Skin injury in adult mammals brings about a series of events and inflammation in the wounded area is initiated first and provides lots of inflammatory factors, which is critical for the final scar formation. While the postinjured skin of fetus and nude mice heals scarlessly owing to the absence of inflammation or immunodeficient, we designed a feasible acid-responsive ibuprofen-loaded poly(L-lactide) (PLLA) fibrous scaffolds via doping sodium bicarbonate to prevent excessive inflammation and achieve scarless healing finally. The morphological results of in vivo experiments revealed that animals treated with acid-responsive ibuprofen-loaded PLLA fibrous scaffolds exhibited alleviative inflammation, accelerated healing process, and regulated collagen deposition via interference in the collagen distribution, the α-smooth muscle actin (α-SMA), and the basic fibroblast growth factor (bFGF) expression. The lower ratios of collagen I/collagen III and TGF-β1/TGF-β3 and higher ratio of matrix metalloproteinase-1 (MMP-1)/tissue inhibitor of metalloproteinase-1 (TIMP-1) in acid-responsive ibuprofen-loaded PLLA fibrous scaffolds group were confirmed by real-time qPCR as well. These results suggest that inhibiting the excessive inflammation will result in regular collagen distribution and appropriate ratio between the factors, which promote or suppress the scar formation, then decrease the scar area, and finally achieve the scarless healing.

Fibromodulin-deficiency alters temporospatial expression patterns of transforming growth factor-β ligands and receptors during adult mouse skin wound healing

Fibromodulin (FMOD) is a small leucine-rich proteoglycan required for scarless fetal cutaneous wound repair. Interestingly, increased FMOD levels have been correlated with decreased transforming growth factor (TGF)-β1 expression in multiple fetal and adult rodent models. Our previous studies demonstrated that FMOD-deficiency in adult animals results in delayed wound closure and increased scar size accompanied by loose package collagen fiber networks with increased fibril diameter. In addition, we found that FMOD modulates in vitro expression and activities of TGF-β ligands in an isoform-specific manner. In this study, temporospatial expression profiles of TGF-β ligands and receptors in FMOD-null and wild-type (WT) mice were compared by immunohistochemical staining and quantitative reverse transcriptase-polymerase chain reaction using a full-thickness, primary intention wound closure model. During the inflammatory stage, elevated inflammatory infiltration accompanied by increased type I TGF-β receptor levels in individual inflammatory cells was observed in FMOD-null wounds. This increased inflammation was correlated with accelerated epithelial migration during the proliferative stage. On the other hand, significantly more robust expression of TGF-β3 and TGF-β receptors in FMOD-null wounds during the proliferative stage was associated with delayed dermal cell migration and proliferation, which led to postponed granulation tissue formation and wound closure and increased scar size. Compared with WT controls, expression of TGF-β ligands and receptors by FMOD-null dermal cells was markedly reduced during the remodeling stage, which may have contributed to the declined collagen synthesis capability and unordinary collagen architecture. Taken together, this study demonstrates that a single missing gene, FMOD, leads to conspicuous alternations in TGF-β ligand and receptor expression at all stages of wound repair in various cell types. Therefore, FMOD critically coordinates temporospatial distribution of TGF-β ligands and receptors in vivo, suggesting that FMOD modulates TGF-β bioactivity in a complex way beyond simple physical binding to promote proper wound healing.

New insights into vertebrate skin regeneration

Regeneration biology has experienced a renaissance as clinicians, scientists, and engineers have combined forces to drive the field of regenerative medicine. Studies investigating the mechanisms that regulate wound healing in adult mammals have led to a good understanding of the stereotypical processes that lead to scarring. Despite comparative studies of fetal wound healing in which no scar is produced, the fact remains that insights from this work have failed to produce therapies that can regenerate adult human skin. In this review, we analyze past and contemporary accounts of wound healing in a variety of vertebrates, namely, fish, amphibians, and mammals, in order to demonstrate how examples of skin regeneration in adult organisms can impact traditional wound-healing research. When considered together, these studies suggest that inflammation and reepithelialization are necessary events preceding both scarring and regeneration. However, the extent to which these processes may direct one outcome over another is likely weaker than currently accepted. In contrast, the extent to which newly deposited extracellular matrix in the wound bed can be remodeled into new skin, and the intrinsic ability of new epidermis to regenerate appendages, appears to underlie the divergence between scar-free healing and the persistence of a scar. We discuss several ideas that may offer areas of overlap between researchers using these different model organisms and which may be of benefit to the ultimate goal of scar-free human wound healing.

Arrhythmogenic right ventricular dysplasia/cardiomyopathy type 1: a light on molecular mechanisms

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited cardiomyopathy associated with cardiac arrhythmias originating in the right ventricle, heart failure, and sudden cardiac death. Development of ARVD/C type 1 has been attributed to differential expression of transforming growth factor beta 3 (TGF β 3). Several mechanisms underlying the molecular basis of ARVD/C type 1 have been proposed. Evaluating previously described mechanisms might elucidate how TGF β 3 contributes to disease progression in ARVD/C type 1. Here we review how TGF β 3 can induce fibrogenesis through Smad and/or β -catenin signaling. Moreover, the role of apoptosis is addressed. Finally the extent to which the immune system has been demonstrated to be a modulating and amplifying agent in the onset and progression of ARVD/C in general is discussed.

TGF-β3 modulates the inflammatory environment and reduces scar formation following vocal fold mucosal injury in rats

Transforming growth factor (TGF)-β1 and TGF-β3 have been reported to exert differential effects on wound healing, and possibly even account for tissue-specific differences in scar formation. Scarring is particularly detrimental in the vocal fold mucosa (VFM), where destruction of the native extracellular matrix causes irreparable biomechanical changes and voice impairment. Here, in a series of in vitro and in vivo experiments, we identified differences in TGF-β1 and TGF-β3 transcription and immunolocalization to various cell subpopulations in naïve and injured rat VFM, compared with oral mucosa (which undergoes rapid healing with minimal scar) and skin (which typically heals with scar). Treatment of cultured human vocal fold fibroblasts with TGF-β3 resulted in less potent induction of profibrotic gene transcription, extracellular matrix synthesis and fibroblast-myofibroblast differentiation, compared with treatment with TGF-β1 and TGF-β2. Finally, delivery of exogenous TGF-β3 to rat VFM during the acute injury phase modulated the early inflammatory environment and reduced eventual scar formation. These experiments show that the TGF-β isoforms have distinct roles in VFM maintenance and repair, and that TGF-β3 redirects wound healing to improve VFM scar outcomes in vivo.

TSG-6 released from intradermally injected mesenchymal stem cells accelerates wound healing and reduces tissue fibrosis in murine full-thickness skin wounds

Proper activation of macrophages (Mφ) in the inflammatory phase of acute wound healing is essential for physiological tissue repair. However, there is a strong indication that robust Mφ inflammatory responses may be causal for the fibrotic response always accompanying adult wound healing. Using a complementary approach of in vitro and in vivo studies, we here addressed the question of whether mesenchymal stem cells (MSCs)-due to their anti-inflammatory properties-would control Mφ activation and tissue fibrosis in a murine model of full-thickness skin wounds. We have shown that the tumor necrosis factor-α (TNF-α)-stimulated protein 6 (TSG-6) released from MSCs in co-culture with activated Mφ or following injection into wound margins suppressed the release of TNF-α from activated Mφ and concomitantly induced a switch from a high to an anti-fibrotic low transforming growth factor-β1 (TGF-β1)/TGF-β3 ratio. This study provides insight into what we believe to be a previously undescribed multifaceted role of MSC-released TSG-6 in wound healing. MSC-released TSG-6 was identified to improve wound healing by limiting Mφ activation, inflammation, and fibrosis. TSG-6 and MSC-based therapies may thus qualify as promising strategies to enhance tissue repair and to prevent excessive tissue fibrosis.

TSG-6 released from intradermally injected mesenchymal stem cells accelerates wound healing and reduces tissue fibrosis in murine full-thickness skin wounds

Proper activation of macrophages (Mφ) in the inflammatory phase of acute wound healing is essential for physiological tissue repair. However, there is a strong indication that robust Mφ inflammatory responses may be causal for the fibrotic response always accompanying adult wound healing. Using a complementary approach of in vitro and in vivo studies, we here addressed the question of whether mesenchymal stem cells (MSCs)-due to their anti-inflammatory properties-would control Mφ activation and tissue fibrosis in a murine model of full-thickness skin wounds. We have shown that the tumor necrosis factor-α (TNF-α)-stimulated protein 6 (TSG-6) released from MSCs in co-culture with activated Mφ or following injection into wound margins suppressed the release of TNF-α from activated Mφ and concomitantly induced a switch from a high to an anti-fibrotic low transforming growth factor-β1 (TGF-β1)/TGF-β3 ratio. This study provides insight into what we believe to be a previously undescribed multifaceted role of MSC-released TSG-6 in wound healing. MSC-released TSG-6 was identified to improve wound healing by limiting Mφ activation, inflammation, and fibrosis. TSG-6 and MSC-based therapies may thus qualify as promising strategies to enhance tissue repair and to prevent excessive tissue fibrosis.

Embryonic wound healing: a primer for engineering novel therapies for tissue repair

Scar is the default tissue repair used by the body in response to most injuries-a response that occurs in wounds ranging in seriousness from minor skin cuts to complete severance of the spinal cord. By contrast, before the third trimester of pregnancy embryonic mammals tend to heal without scarring due to a variety of mechanisms and factors that are uniquely in operation during development in utero. The goal of tissue engineering is to develop safe and clinically effective biological substitutes that restore, maintain, or improve tissue function in patients. This review provides a comparative overview of wound healing during development and maturation and seeks to provide a perspective on just how much the embryo may be able teach us in the engineering of new therapies for tissue repair.

A Paradigm of Fibroblast Activation and Dermal Wound Contraction to Guide the Development of Therapies for Chronic Wounds and Pathologic Scars

SIGNIFICANCE

Delayed wound healing and pathologic scarring are abnormal processes that can be thought of as occurring on a wound healing continuum, where insufficient wound contraction leads to nonhealing wounds, and overexuberant wound contraction leads to scarring. Chronic nonhealing wounds, including diabetic foot wounds, decubitus ulcers, and venous stasis ulcers, affect millions of people annually in the United States and costs billions of dollars. Similarly, pathologic scaring affects more than 40 million Americans annually and also costs billions of dollars.

CRITICAL ISSUES

While there are multiple factors that contribute to chronic nonhealing wounds and pathologic scars, a derangement in wound contraction is common to both. In this article, we will present a paradigm of dermal wound contraction, derived from clinical observations and basic science evidence, which pertains to chronic nonhealing wounds and pathologic scars.

RECENT ADVANCES

We will review how select therapies currently under investigation and in development fit the paradigm.

FUTURE DIRECTIONS

The paradigm will facilitate translational research and enable the development of future innovative therapies.

Candesartan, an angiotensin II AT₁-receptor blocker and PPAR-γ agonist, reduces lesion volume and improves motor and memory function after traumatic brain injury in mice

Traumatic brain injury (TBI) results in complex pathological reactions, the initial lesion worsened by secondary inflammation and edema. Angiotensin II (Ang II) is produced in the brain and Ang II receptor type 1 (AT₁R) overstimulation produces vasoconstriction and inflammation. Ang II receptor blockers (ARBs) are neuroprotective in models of stroke but little is known of their effect when administered in TBI models. We therefore performed controlled cortical impact (CCI) injury on mice to investigate whether the ARB candesartan would mitigate any effects of TBI. We administered candesartan or vehicle to mice 5 h before CCI injury. Candesartan treatment reduced the lesion volume after CCI injury by approximately 50%, decreased the number of dying neurons, lessened the number of activated microglial cells, protected cerebral blood flow (CBF), and reduced the expression of the cytokine TGFβ1 while increasing expression of TGFβ3. Candesartan-treated mice also showed better motor skills on the rotarod 3 days after injury, and improved performance in the Morris water maze 4 weeks after injury. These results indicate that candesartan is neuroprotective, reducing neuronal injury, decreasing lesion volume and microglial activation, protecting CBF and improving functional behavior in a mouse model of TBI. Co-treatment with a peroxisome proliferator-activated receptor-gamma (PPARγ) antagonist significantly reduced some of the beneficial effects of candesartan after CCI, suggesting that PPARγ activation may contribute to part or to all of the neuroprotective effect of candesartan. Overall, our data suggest that ARBs with dual AT₁R-blocking and PPARγ activation properties may have therapeutic value in treating TBI.

Transforming growth factor Beta 3 is required for excisional wound repair in vivo

Wound healing is a complex process that relies on proper levels of cytokines and growth factors to successfully repair the tissue. Of particular interest are the members of the transforming growth factor family. There are three TGF-ß isoforms-TGF- ß 1, 2, and 3, each isoform showing a unique expression pattern, suggesting that they each play a distinct function during development and repair. Previous studies reported an exclusive role for TGF-ß 3 in orofacial development and a potent anti-scarring effect. However, the role of TGF- ß 3 in excisional wound healing and keratinocyte migration remains poorly understood. We tested the effect of TGF-ß 3 levels on excisional cutaneous wounds in the adult mouse by directly injecting recombinant TGF-ß 3 or neutralizing antibody against TGF-ß 3 (NAB) in the wounds. Our results demonstrate that TGF-ß 3 does not promote epithelialization. However, TGF-ß 3 is necessary for wound closure as wounds injected with neutralizing antibody against TGF-ß 3 showed increased epidermal volume and proliferation in conjunction with a delay in keratinocyte migration. Wild type keratinocytes treated with NAB and Tgfb3-deficient keratinocytes closed an in vitro scratch wound with no delay, suggesting that our in vivo observations likely result from a paracrine effect.

Mechanosignaling pathways in cutaneous scarring

Mechanotransduction is the process by which physical forces are sensed and converted into biochemical signals that then result in cellular responses. The discovery and development of various molecular pathways involved in this process have revolutionized the fundamental and clinical understanding regarding the formation and progression of cutaneous scars. The aim of this review is to report the recent advances in scar mechanosignaling research. The mechanosignaling pathways that participate in the formation and growth of cutaneous scars can be divided into those whose role in mechanoresponsiveness has been proven (the TGF-β/Smad, integrin, and calcium ion pathways) and those who have a possible but as yet unproven role (such as MAPK and G protein, Wnt/β-catenin, TNF-α/NF-κB, and interleukins). During scar development, these cellular mechanosignaling pathways interact actively with the extracellular matrix. They also crosstalk extensively with the hypoxia, inflammation, and angiogenesis pathways. The elucidation of scar mechanosignaling pathways provides a new platform for understanding scar development. This better understanding will facilitate research into this promising field and may help to promote the development of pharmacological interventions that could ultimately prevent, reduce, or even reverse scar formation or progression.

New strategies in clinical care of skin wound healing

The prevalence of chronic wounds is closely correlated to the aging population and so-called civilizational diseases. Therefore, they are causing morbidity and mortality of millions of patients worldwide, with an unbroken upward trend. As a consequence, chronic wounds induce enormous and rapidly growing costs for our health care systems and society in general. Thus, medically effective and cost-efficient treatment methods are urgently needed. Methods of 'regenerative medicine' might offer innovative scientific solutions, including the use of stem cells, growth factors and new bioactive materials. These tools are experimentally well described but clinically poorly performed. The main reasons for this are both legislative and economic. This review describes state-of-the-art techniques, up-to-date research projects, innovative preclinical and clinical approaches in wound care, and activities to translate these innovative techniques into clinical routine.

Alpha-lipoic acid reduces peridural fibrosis after laminectomy of lumbar vertebrae in rabbits

BACKGROUND

Peridural fibrosis is an inevitable healing process causing failed back surgery syndrome after lumbar spinal operations. In this study, alpha-lipoic acid (ALA), reported to reduce fibrosis in liver, oral mucosa, and peritoneum, investigated as a potential candidate for prevention of peridural fibrosis.

METHOD

Twelve adult New Zealand white male rabbits were divided into control (n = 5) and ALA groups (n = 7). Laminectomy of lumbar spine was performed and ALA was applied on the exposed dura mater topically in ALA group.

RESULTS

According to histological peridural grading, the ALA group (median grade 1) showed significantly less peridural fibrosis than the control group (median grade 3, p = 0.005).

CONCLUSIONS

ALA is a promising substance in the prevention of peridural fibrosis, especially in early preoperative and postoperative period.

Clinical strategies for the alleviation of contractures from a predictive mathematical model of dermal repair

Hypertrophic scars arise when there is an overproduction of collagen during wound healing. These are often associated with poor regulation of the rate of programmed cell death (apoptosis) of the cells synthesizing the collagen or by an exuberant inflammatory response that prolongs collagen production and increases wound contraction. Severe contractures that occur, e.g., after a deep burn, can cause loss of function especially if the wound is over a joint such as the elbow or knee. Recently, we have developed a morphoelastic mathematical model for dermal repair that incorporates the chemical, cellular, and mechanical aspects of dermal wound healing. Using this model, we examine pathological scarring in dermal repair by first assuming a smaller than usual apoptotic rate for myofibroblasts, and then considering a prolonged inflammatory response, in an attempt to determine a possible optimal intervention strategy to promote normal repair, or terminate the fibrotic scarring response. Our model predicts that in both cases it is best to apply the intervention strategy early in the wound healing response. Further, the earlier an intervention is made, the less aggressive the intervention required. Finally, if intervention is conducted at a late time during healing, a significant intervention is required; however, there is a threshold concentration of the drug or therapy applied, above which minimal further improvement to wound repair is obtained.

Extracellular matrix molecules implicated in hypertrophic and keloid scarring

Tissue regeneration repairs the fabric of the skin to maintain homeostasis after injury. The expression and proliferation of extracellular matrix (ECM) molecules in the dermis, mediated by a range of growth factors and cytokines, is a fundamental element of wound repair. Previous work focused on how these complex molecular mechanisms relate to the formation of raised dermal scars, including keloid and hypertrophic scars, characterized by excessive deposition of ECM molecules. However, the mechanisms in the wound repair pathway which lead to the differential expression and organization of ECM molecules observed in different types of scar tissue are not fully understood. To summarize what is known about the expression and composition of ECM molecules in abnormal scarring, an extensive search of the literature was conducted, focusing on keywords connected to skin scarring, hypertrophic scars and keloid disease. The transcription and translation of collagen I and III, fibronectin, laminin, periostin and tenascin are all increased in raised dermal scar tissue. However, hyaluronic acid, dermatopontin and decorin are decreased, and the expression and localisation of fibrillin and elastin fibres in the dermis are altered compared with normal skin and scars. Recent whole genome profiling and proteomic studies have led to the identification of regulatory elements with different expression profiles in hypertrophic and keloid tissue. If the mechanisms of raised dermal scar formation are to be elucidated and effective therapeutic treatments developed, an integrated approach to research is required, focussing on the interactions between ECM molecules, regulatory elements and pathways.

Early growth response-2 expression in uterine leiomyoma cells: regulation and function

OBJECTIVE

To investigate the regulation of early growth response-2 (Egr-2) by transforming growth factor β3 (TGF-β3) and its functions in cultured human uterine leiomyoma smooth muscle cells.

DESIGN

Laboratory research.

SETTING

Academic medical center.

PATIENT(S)

Primary leiomyoma cells from patients with symptomatic leiomyomata.

INTERVENTION(S)

Tissue culture followed by RNA and protein analysis.

MAIN OUTCOME MEASURE(S)

Cell proliferation, alteration in extracellular matrix component expression.

RESULT(S)

In vivo mRNA levels of Egr-2 were statistically significantly higher in leiomyoma tissues compared with matched myometrial tissues, and showed a statistically significant correlation with TGF-β3 messenger RNA (mRNA) levels in leiomyoma tissues. In primary leiomyoma smooth muscle cells, TGF-β3 statistically significantly induced Egr-2 gene expression in a dose-dependent and time-dependent manner. Small interfering RNA (siRNA) knockdown of Egr-2 markedly increased the level of the proliferation marker proliferating cell nuclear antigen and the expression of proto-oncogene c-myc. On the other hand, ablation of Egr-2 stimulated collagen-1A1 and collagen-3A1 transcription and inhibited dermatopontin gene expression. However, the mRNA levels of α-smooth muscle actin and fibronectin were not affected by Egr-2 knockdown.

CONCLUSION(S)

We demonstrated that TGF-β3 regulated Egr-2 gene expression and presented evidence that Egr-2 decreases collagen production and stimulates dermatopontin gene expression.

Phase 2 cross-over multicenter trial on the efficacy and safety of topical cyanoacrylates compared with topical silicone gel in the prevention of pathologic scars

BACKGROUND

Many clinical studies on scar therapy are reported in the literature, but only silicone gel sheeting and corticosteroid injections are supported by accurate prospective controlled studies. This prospective multicenter cross-over phase 2 study tested the effectiveness of a topical cyanoacrylate compared with silicone gel in improving postsurgical scars

METHODS

Patients presenting with symmetric breast scars after augmentation or reduction mammaplasty were enrolled in the study. From the same day as stitch removal, the cyanoacrylate was applied on one side every 3 to 5 days and the silicone gel on the other side twice a day for 3 months. Assessments of patients and external observers using a visual analog scale were recorded at scheduled visits during 1 year, and scars were photographed. Objective evaluations included measurements of scar width, length, and elevation. The statistical significance of objective parameter modifications was analyzed using the Wilcoxon test

RESULTS

Positive effects of both tested products were observed during the scar maturation process, and final scars of good quality were achieved without any major adverse effect. The topical cyanoacrylate proved to be more efficacious in preventing scar widening, and this result was statistically significant

CONCLUSIONS

The tested topical cyanoacrylate had a positive effect on the scar maturation process at least comparable with that of topical silicone gel.

A synthetic gene increases TGFβ3 accumulation by 75-fold in tobacco chloroplasts enabling rapid purification and folding into a biologically active molecule

Human transforming growth factor-β3 (TGFβ3) is a new therapeutic protein used to reduce scarring during wound healing. The active molecule is a nonglycosylated, homodimer comprised of 13-kDa polypeptide chains linked by disulphide bonds. Expression of recombinant human TGFβ3 in chloroplasts and its subsequent purification would provide a sustainable source of TGFβ3 free of animal pathogens. A synthetic sequence (33% GC) containing frequent chloroplast codons raised accumulation of the 13-kDa TGFβ3 polypeptide by 75-fold compared to the native coding region (56% GC) when expressed in tobacco chloroplasts. The 13-kDa TGFβ3 monomer band was more intense than the RuBisCO 15-kDa small subunit on Coomassie blue-stained SDS-PAGE gels. TGFβ3 accumulated in insoluble aggregates and was stable in leaves of different ages but was not detected in seeds. TGFβ3 represented 12% of leaf protein and appeared as monomer, dimer and trimer bands on Western blots of SDS-PAGE gels. High yield and insolubility facilitated initial purification and refolding of the 13-kDa polypeptide into the TGFβ3 homodimer recognized by a conformation-dependent monoclonal antibody. The TGFβ3 homodimer and trace amounts of monomer were the only bands visible on silver-stained gels following purification by hydrophobic interaction chromatography and cation exchange chromatography. N-terminal sequencing and electronspray ionization mass spectrometry showed the removal of the initiator methionine and physical equivalence of the chloroplast-produced homodimer to standard TGFβ3. Functional equivalence was demonstrated by near-identical dose-response curves showing the inhibition of mink lung epithelial cell proliferation. We conclude that chloroplasts are an attractive production platform for synthesizing recombinant human TGFβ3.

Transforming growth factor-β3 regulates assembly of a non-fibrotic matrix in a 3D corneal model

Corneal tissue engineering has attracted the attention of many researchers over the years, in part due to the cornea's avascularity and relatively straightforward structure. However, the highly organized and structured nature of this optically clear tissue has presented a great challenge. We have previously developed a model in which human corneal fibroblasts (HCFs) are stimulated by a stable vitamin C (VitC) derivative to self-assemble an extracellular matrix (ECM). Addition of TGFβ1 enhanced the assembly of ECM; however, it was accompanied by the upregulation of specific fibrotic markers. In this study, we tested the effects of all three TGFβ isoforms (-β1, -β2 and -β3) on ECM production, as well as expression of fibrotic markers. HCFs were grown in four media conditions for 4 weeks: control, VitC only; T1, VitC + TGFβ1; T2, VitC + TGFβ2; and T3, VitC + TGFβ3. The cultures were analysed with western blots, TEM and indirect immunofluorescence (IF). Compared to controls, all TGFβ isoforms stimulated matrix production by about three-fold. IF showed the presence of type III collagen and smooth muscle actin (SMA) in T1 and T2; however, T3 showed little to no expression. In western blots, T3 stimulated a lower type III:type I collagen ratio when compared to the other conditions. In addition, TEM indicated that T3 stimulated a higher level of matrix alignment and organization. HCFs stimulated by VitC and TGFβ3 appear to generate a matrix that mimics the normal adult or developing human cornea, whereas TGF-β1 and -β2 drive the constructs towards a more fibrotic path.

Scarless skin wound healing in FOXN1 deficient (nude) mice is associated with distinctive matrix metalloproteinase expression

Similar to mammalian fetuses FOXN1 deficient (nude) mice are able to restore the structure and integrity of injured skin in a scarless healing process by mechanisms independent of the genetic background. Matrix metalloproteinases (MMPs) are required for regular skin wound healing and the distinctive pattern of their expression has been implicated to promote scarless healing. In this study, we analyzed the temporal and spatial expression patterns of these molecules during the incisional skin wounds in adult nude mice. Macroscopic and histological analyses of skin wounds revealed an accelerated wound healing process, minimal granulation tissue formation and markedly diminished scarring in nude mice. Quantitative RT-PCR (Mmp-2, -3, -8, -9, -10, -12, -13, -14 and Timp-1, -2, -3), Western blots (MMP-13) and gelatin zymography (MMP-9) revealed that MMP-9 and MMP-13 showed a unique, bimodal pattern of up-regulation during the early and late phases of wound healing in nude mice. Immunohistochemically MMP-9 and MMP-13 were generally detected in epidermis during the early phase and in dermis during the late (remodeling) phase. Consistent with these in vivo observations, dermal fibroblasts cultured from nude mice expressed higher levels of types I and III collagen, MMP-9 and MMP-13 mRNA levels and higher MMP enzyme activity than wild type controls. Collectively, these finding suggest that the bimodal pattern of MMP-9 and MMP-13 expression during skin repair process in nude mice could be a major component of their ability for scarless healing.

The reinnervation and revascularisation pattern of scarless murine fetal wounds

Fetal wounds can heal without scarring. There is evidence that the sensory nervous system plays a role in mediating inflammation and healing, and that the reinnervation pattern of adult wounds differs from that of unwounded skin. Ectoderm is required for development of the cutaneous nerve plexus in early gestation. It was hypothesised that scarless fetal wounds might completely regenerate their neural and vascular architecture. Wounds were made on mouse fetuses at embryonic day 16.5 of a 19.5-day gestation, which healed without visible scars. Immunohistochemical analysis of wound sites was performed to assess reinnervation, using antibodies to the pan neuronal marker PGP9.5 as well as to the neuropeptides calcitonin gene-related peptide (CGRP) and substance P (SP). Staining for the endothelial marker von Willebrand factor (VWF) allowed comparison of reinnervation and revascularisation. Wounds were harvested at timepoints from day 1 after wounding to postnatal day 6. Quantification of wound reinnervation and revascularisation was performed for timepoints up to 6 days post-wounding. Hypervascularisation of the wounds occurred within 24 h, and blood vessel density within the wounds remained significantly elevated until postnatal day 2 (4 days post- wounding), after which VWF immunoreactivity was similar between wound and control groups. Wound nerve density returned to a level similar to that of unwounded skin within 48 h of wounding, and PGP9.5 immunoreactive nerve fibre density remained similar to control skin thereafter. CGRP and SP immunoreactivity followed a similar pattern to that of PGP9.5, although wound levels did not return to those of control skin until postnatal day 1. Scarless fetal wounds appeared to regenerate their nerve and blood vessel microanatomy perfectly after a period of hypervascularisation.

Some properties and applications of cell lines and clones established from tet-responsive-SV40 tag mice and mES cell lines

In this article, 11 cell lines established from transgenic mice and mouse embryonic stem cells (mESC) expressing SV40Tag under control of tetracycline/doxycycline (tet-off, tet-on) are described. Several cell lines were further transfected with a plasmid vector containing genes coding for a cytokine/protein under tet-regulation to obtain tet-co-regulated expression of cytokine/protein. A total of 29 clones and 234 subclones have been established so far. Partial characterization of these tet-responsive cell lines, clones and subclones was performed. Questions related to the rare frequency of establishing permanent cycling cell lines from this source, the unusual expression pattern of SV40Tag protein in the subcellular compartment and the phenotype of 'stemness' of several such cell lines are raised. Some future applications of these cells, related to immunology and transplantation, are discussed.

Delayed wound closure in fibromodulin-deficient mice is associated with increased TGF-β3 signaling

Fibromodulin (FMOD), a small leucine-rich proteoglycan, mediates scarless fetal skin wound repair through, in part, transforming growth factor-β (TGF-β) modulation. Using an adult fmod-null (fmod(-/-)) mouse model, this study further elucidates the interplay between FMOD and TGF-β expression during cutaneous repair and scar formation. Full-thickness skin wounds on fmod(-/-) and wild-type (WT) mice were closed primarily and analyzed. Histomorphometry revealed delayed dermal cell migration leading to delayed wound closure and significantly increased scar size in fmod(-/-) mice relative to WT, which was partially rescued by exogenous FMOD administration. In addition, fmod(-/-) wounds exhibited early elevation (within 24  hours post-wounding) of type I and type II TGF-β receptors as well as unexpectedly high fibroblast expression of TGF-β3, a molecule with reported antifibrotic and antimigratory effects. Consistent with elevated fibroblastic TGF-β3, fmod(-/-) fibroblasts were significantly less motile than WT fibroblasts. fmod(-/-) fibroblasts were also more susceptible to migration inhibition by TGF-β3, leading to profound delays in dermal cell migration. Increased scarring in fmod(-/-) mice indicates that TGF-β3's antimotility effects predominate over its antifibrotic effects when high TGF-β3 levels disrupt early fibroblastic wound ingress. These studies demonstrate that FMOD presence is critical for proper temporospatial coordination of wound healing events and normal TGF-β bioactivity.

TGF-ß in wound healing: a review

TGF-ß, a growth factor involved in various stages of the wound healing process, exists in three different isoforms. Experimental models have shown these isoforms to be functionally different and one of them, TGF-ß3, has the potential to reduce scarring in clinical practice. This literature review explores the role of TGF- in wound healing, examining the research to date.

Gene delivery of a mutant TGFβ3 reduces markers of scar tissue formation after cutaneous wounding

The transforming growth factor-β (TGFβ) family plays a critical regulatory role in repair and coordination of remodeling after cutaneous wounding. TGFβ1-mediated chemotaxis promotes the recruitment of fibroblasts to the wound site and their resultant myofibroblastic transdifferentiation that is responsible for elastic fiber deposition and wound closure. TGFβ3 has been implicated in an antagonistic role regulating overt wound closure and promoting ordered dermal remodeling. We generated a mutant form of TGFβ3 (mutTGFβ3) by ablating its binding site for the latency-associated TGFβ binding protein (LTBP-1) in order to improve bioavailability and activity. The mutated cytokine is secreted as the stable latency-associated peptide (LAP)-associated form and is activated by normal intracellular and extracellular mechanisms including integrin-mediated activation but is not sequestered. We show localized intradermal transduction using a lentiviral vector expressing the mutTGFβ3 in a mouse skin wounding model reduced re-epithelialization density and fibroblast/myofibroblast transdifferentiation within the wound area, both indicative of reduced scar tissue formation.

Therapeutic improvement of scarring: mechanisms of scarless and scar-forming healing and approaches to the discovery of new treatments

Scarring in the skin after trauma, surgery, burn or sports injury is a major medical problem, often resulting in loss of function, restriction of tissue movement and adverse psychological effects. Whilst various studies have utilised a range of model systems that have increased our understanding of the pathways and processes underlying scar formation, they have typically not translated to the development of effective therapeutic approaches for scar management. Existing treatments are unreliable and unpredictable and there are no prescription drugs for the prevention or treatment of dermal scarring. As a consequence, scar improvement still remains an area of clear medical need. Here we describe the basic science of scar-free and scar-forming healing, the utility of pre-clinical model systems, their translation to humans, and our pioneering approach to the discovery and development of therapeutic approaches for the prophylactic improvement of scarring in man

Therapies with emerging evidence of efficacy: avotermin for the improvement of scarring

Many patients are dissatisfied with scars on both visible and non-visible body sites and would value any opportunity to improve or minimise scarring following surgery. Approximately 44 million procedures in the US and 42 million procedures in the EU per annum could benefit from scar reduction therapy. A wide range of non-invasive and invasive techniques have been used in an attempt to improve scarring although robust, prospective clinical trials to support the efficacy of these therapies are lacking. Differences in wound healing and scar outcome between early fetal and adult wounds led to interest in the role of the TGFbeta family of cytokines in scar formation and the identification of TGFbeta3 (avotermin) as a potential therapeutic agent for the improvement of scar appearance. Extensive pre-clinical and human Phase I and II clinical trial programmes have confirmed the scar improving efficacy of avotermin which produces macroscopic and histological improvements in scar architecture, with improved restitution of the epidermis and an organisation of dermal extracellular matrix that more closely resembles normal skin. Avotermin is safe and well tolerated and is currently in Phase III of clinical development, with the first study, in patients undergoing scar revision surgery, fully recruited.

Effects of pulsed electromagnetic fields on interleukin-1 beta and postoperative pain: a double-blind, placebo-controlled, pilot study in breast reduction patients

BACKGROUND

Surgeons seek new methods of pain control to reduce side effects and speed postoperative recovery. Pulsed electromagnetic fields are effective for bone and wound repair and pain and edema reduction. This study examined whether the effect of pulsed electromagnetic fields on postoperative pain was associated with differences in levels of cytokines and angiogenic factors in the wound bed.

METHODS

In this double-blind, placebo-controlled, randomized study, 24 patients, undergoing breast reduction for symptomatic macromastia received pulsed electromagnetic field therapy configured to modulate the calmodulin-dependent nitric oxide signaling pathway. Pain levels were measured by a visual analogue scale, and narcotic use was recorded. Wound exudates were analyzed for interleukin (IL)-1 beta, tumor necrosis factor-alpha, vascular endothelial growth factor, and fibroblast growth factor-2.

RESULTS

Pulsed electromagnetic fields produced a 57 percent decrease in mean pain scores at 1 hour (p < 0.01) and a 300 percent decrease at 5 hours (p < 0.001), persisting to 48 hours postoperatively in the active versus the control group, along with a concomitant 2.2-fold reduction in narcotic use in active patients (p = 0.002). Mean IL-1 beta concentration in the wound exudates of treated patients was 275 percent lower (p < 0.001). There were no significant differences found for tumor necrosis factor-alpha, vascular endothelial growth factor, or fibroblast growth factor-2 concentrations.

CONCLUSIONS

Pulsed electromagnetic field therapy significantly reduced postoperative pain and narcotic use in the immediate postoperative period. The reduction of IL-1 beta in the wound exudate supports a mechanism that may involve manipulation of the dynamics of endogenous IL-1 beta in the wound bed by means of a pulsed electromagnetic field effect on nitric oxide signaling, which could impact the speed and quality of wound repair.

Unique complications of foot and ankle injuries secondary to warfare

This article discusses the common complications associated with lower extremity trauma and amputations secondary to combat injuries. The complications include retained fragments, soft tissue adhesions, poor wound healing, painful bursae, neuroma formation, heterotopic ossification, and depleted uranium. Although there is some literature on these topics, most is based on noncombat injuries, indicating a need for further research into the management of these devastating injuries.

Scar and contracture: biological principles

Dysregulated wound healing and pathologic fibrosis cause abnormal scarring, leading to poor functional and aesthetic results in hand burns. Understanding the underlying biologic mechanisms involved allows the hand surgeon to better address these issues, and suggests new avenues of research to improve patient outcomes. In this article, the authors review the biology of scar and contracture by focusing on potential causes of abnormal wound healing, including depth of injury, cytokines, cells, the immune system, and extracellular matrix, and explore therapeutic measures designed to target the various biologic causes of poor scar.

Interactions between extracellular matrix and growth factors in wound healing

Dynamic interactions between growth factors and extracellular matrix (ECM) are integral to wound healing. These interactions take several forms that may be categorized as direct or indirect. The ECM can directly bind to and release certain growth factors (e.g., heparan sulfate binding to fibroblast growth factor-2), which may serve to sequester and protect growth factors from degradation, and/or enhance their activity. Indirect interactions include binding of cells to ECM via integrins, which enables cells to respond to growth factors (e.g., integrin binding is necessary for vascular endothelial growth factor-induced angiogenesis) and can induce growth factor expression (adherence of monocytes to ECM stimulates synthesis of platelet-derived growth factor). Additionally, matrikines, or subcomponents of ECM molecules, can bind to cell surface receptors in the cytokine, chemokine, or growth factor families and stimulate cellular activities (e.g., tenascin-C and laminin bind to epidermal growth factor receptors, which enhances fibroblast migration). Growth factors such as transforming growth factor-beta also regulate the ECM by increasing the production of ECM components or enhancing synthesis of matrix degrading enzymes. Thus, the interactions between growth factors and ECM are bidirectional. This review explores these interactions, discusses how they are altered in difficult to heal or chronic wounds, and briefly considers treatment implications.

Avotermin: A Novel Antiscarring Agent

Published literature shows that both physicians and their patients are highly concerned about scarring, even relatively minor scars and those that can be concealed by clothing. Furthermore, both patients and their physicians value any opportunities to improve or minimize scarring. While a range of treatment paradigms have been evaluated, no single therapy has been adopted as a universally accepted standard of care and, currently, there are no marketed pharmaceuticals for the prophylactic reduction of scarring. Many of the available treatments are used empirically and most have not been evaluated in robust prospective, randomized, controlled clinical trials. To address this unmet medical need, translational research into the molecular mechanisms of scarring has led to the discovery and commercial development of a new class of prophylactic medicines that promote the regeneration of normal skin and improve scar appearance. Avotermin, the first agent identified in this class, is the clinical application of human recombinant transforming growth factor β3 (TGFβ3), a key protein involved in scar-free healing observed in embryos. Controlled, double-blind, randomized phase I/II clinical studies have shown that avotermin, administered as an intradermal injection at the time of surgery, leads to both short-term and longer-term (at ≥12 months) improvements in the appearance of scars compared with placebo and standard wound care.