A model of scarless human fetal wound repair is deficient in transforming growth factor beta

Fetal Skin Wound Healing: Key Extracellular Matrix Components and Regulators in Scarless Healing

Fetal skin at early gestational stage is able to regenerate and heal rapidly after wounding. The exact mechanisms and molecular pathways involved in this process are however still largely unknown. The numerous differences in the skin of the early fetus versus skin in later developmental stages might provide clues for the mechanisms of scarless healing. This review summarizes the differences between mammalian fetal skin and the skin at later developmental phases in healthy and wounded conditions, focusing on extracellular matrix components, which are crucial factors in the microenvironment that direct cells and tissue functions and hence the wound healing process.

Fallopian tubal infertility: the result of Chlamydia trachomatis-induced fallopian tubal fibrosis

Chlamydia trachomatis is one of the most common pathogens of sexually transmitted diseases, and its incidence in genital tract infections is now 4.7% in south China. Infertility is the end result of C. trachomatis-induced fallopian tubal fibrosis and is receiving intense attention from scientists worldwide. To reduce the incidence of infertility, it is important to understand the pathology-related changes of the genital tract where C. trachomatis infection is significant, especially the mechanism of fibrosis formation. During fibrosis development, the fallopian tube becomes sticky and occluded, which will eventually lead to tubal infertility. At present, the mechanism of fallopian tubal fibrosis induced by C. trachomatis infection is unclear. Our study attempted to summarize the possible mechanisms of fibrosis caused by C. trachomatis infection in the fallopian tube by reviewing published studies and further providing potential therapeutic targets to reduce the occurrence of infertility. This study also provides ideas for future research. Factors leading to fallopian tube fibrosis include inflammatory factors, miRNA, ECT, cHSP, and host factors. We hypothesized that C. trachomatis mediates the transcription and translation of EMT and ECM via upregulating TGF signaling pathway, which leads to the formation of fallopian tube fibrosis and ultimately to tubal infertility.

Mathematical Modeling Can Advance Wound Healing Research

Significance: For over 30 years, there has been sustained interest in the development of mathematical models for investigating the complex mechanisms underlying each stage of the wound healing process. Despite the immense associated challenges, such models have helped usher in a paradigm shift in wound healing research. Recent Advances: In this article, we review contributions in the field that span epidermal, dermal, and corneal wound healing, and treatments of nonhealing wounds. The recent influence of mathematical models on biological experiments is detailed, with a focus on wound healing assays and fibroblast-populated collagen lattices. Critical Issues: We provide an overview of the field of mathematical modeling of wound healing, highlighting key advances made in recent decades, and discuss how such models have contributed to the development of improved treatment strategies and/or an enhanced understanding of the tightly regulated steps that comprise the healing process. Future Directions: We detail some of the open problems in the field that could be addressed through a combination of theoretical and/or experimental approaches. To move the field forward, we need to have a common language between scientists to facilitate cross-collaboration, which we hope this review can support by highlighting progress to date.

The Role of an IL-10/Hyaluronan Axis in Dermal Wound Healing

Scar formation is the typical endpoint of postnatal dermal wound healing, which affects more than 100 million individuals annually. Not only do scars cause a functional burden by reducing the biomechanical strength of skin at the site of injury, but they also significantly increase healthcare costs and impose psychosocial challenges. Though the mechanisms that dictate how dermal wounds heal are still not completely understood, they are regulated by extracellular matrix (ECM) remodeling, neovascularization, and inflammatory responses. The cytokine interleukin (IL)-10 has emerged as a key mediator of the pro- to anti-inflammatory transition that counters collagen deposition in scarring. In parallel, the high molecular weight (HMW) glycosaminoglycan hyaluronan (HA) is present in the ECM and acts in concert with IL-10 to block pro-inflammatory signals and attenuate fibrotic responses. Notably, high concentrations of both IL-10 and HMW HA are produced in early gestational fetal skin, which heals scarlessly. Since fibroblasts are responsible for collagen deposition, it is critical to determine how the concerted actions of IL-10 and HA drive their function to potentially control fibrogenesis. Beyond their independent actions, an auto-regulatory IL-10/HA axis may exist to modulate the magnitude of CD4⁺ effector T lymphocyte activation and enhance T regulatory cell function in order to reduce scarring. This review underscores the pathophysiological impact of the IL-10/HA axis as a multifaceted molecular mechanism to direct primary cell responders and regulators toward either regenerative dermal tissue repair or scarring.

Role of TGF-β in Skin Chronic Wounds: A Keratinocyte Perspective

Chronic wounds are characterized for their incapacity to heal within an expected time frame. Potential mechanisms driving this impairment are poorly understood and current hypotheses point to the development of an unbalanced milieu of growth factor and cytokines. Among them, TGF-β is considered to promote the broadest spectrum of effects. Although it is known to contribute to healthy skin homeostasis, the highly context-dependent nature of TGF-β signaling restricts the understanding of its roles in healing and wound chronification. Historically, low TGF-β levels have been suggested as a pattern in chronic wounds. However, a revision of the available evidence in humans indicates that this could constitute a questionable argument. Thus, in chronic wounds, divergences regarding skin tissue compartments seem to be characterized by elevated TGF-β levels only in the epidermis. Understanding how this aspect affects keratinocyte activities and their capacity to re-epithelialize might offer an opportunity to gain comprehensive knowledge of the involvement of TGF-β in chronic wounds. In this review, we compile existing evidence on the roles played by TGF-β during skin wound healing, with special emphasis on keratinocyte responses. Current limitations and future perspectives of TGF-β research in chronic wounds are discussed.

Comparative Proteomic Analysis in Scar-Free Skin Regeneration in Acomys cahirinus and Scarring Mus musculus

The spiny mouse, Acomys cahirinus displays a unique wound healing ability with regeneration of all skin components in a scar-free manner. To identify orchestrators of this regenerative response we have performed proteomic analyses of skin from Acomys and Mus musculus before and after wounding. Of the ~2000 proteins identified many are expressed at similar levels in Acomys and Mus, but there are significant differences. Following wounding in Mus the complement and coagulation cascades, PPAR signaling pathway and ECM-receptor interactions predominate. In Acomys, other pathways predominate including the Wnt, MAPK, the ribosome, proteasome, endocytosis and tight junction pathways. Notable among Acomys specific proteins are several ubiquitin-associated enzymes and kinases, whereas in Mus immuno-modulation proteins characteristic of inflammatory response are unique or more prominent. ECM proteins such as collagens are more highly expressed in Mus, but likely more important is the higher expression of matrix remodeling proteases in Acomys. Another distinctive difference between Acomys and Mus lies in the macrophage-produced arginase 1 is found in Mus whereas arginase 2 is found in Acomys. Thus, we have identified several avenues for experimental approaches whose aim is to reduce the fibrotic response that the typical mammal displays in response to wounding.

Basic science review of birth tissue uses in ophthalmology

The birth tissue is predominantly comprised of amniotic membrane (AM) and umbilical cord (UC), which share the same cell origin as the fetus. These versatile biological tissues have been used to treat a wide range of conjunctival and corneal conditions since 1940. The therapeutic benefits of the birth tissue stem from its anti-inflammatory and anti-scarring properties that orchestrate regenerative healing. Although the birth tissue also contains many cytokines, growth factors, and proteins, the heavy chain 1-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) matrix has been identified to be a major active tissue component responsible for AM/UC's multifactorial therapeutic actions. HC-HA/PTX3 complex is abundantly present in fresh and cryopreserved AM/UC, but not in dehydrated tissue. In this review, we discuss the tissue anatomy, the molecular mechanism of action based on HC-HA/ PTX3 to explain their therapeutic potentials, and the various forms available in ophthalmology.

[Effect of vacuum sealing drainage on expressions of transforming growth factor β 1 and its receptor in diabetic foot wound]

Objective

To investigate the changes of transforming growth factor β ₁ (TGF- β ₁) and type Ⅱ of TGF-β-receptor (TβRⅡ) expressions in wound tissue after the treatment of diabetic foot with vaccum sealing drainage (VSD), and to analyze the mechanism of accelerating wound healing.

Methods

Between May 2012 and May 2016, 80 patients with diabetic foot were randomly divided into 2 groups, 40 cases in each group. After the same basic treatment, the wounds of VSD group and control group were treated with VSD and external dressing, respectively. There was no significant difference in gender, age, disease duration, body mass, foot ulcer area, and Wagner grade between 2 groups ( P>0.05). The time of foundation preparation and hospitalization stay of 2 groups were recorded. The wound tissue was collected before treatment and at 7 days after treatment, and the positive indexes of TGF-β ₁ and TβRⅡexpressions were measured by immunohistochemical staining.

Results

Before skin grafting, the patients in VSD group were treated with VSD for 1 to 3 times (mean, 2 times), and the patients in control group were treated with dressing change for 1 to 6 times (mean, 4 times). The time of foundation preparation and hospitalization stay in VSD group were significantly shorter than those in control group ( t=-13.546, P=0.036; t=-12.831, P=0.041). The skin grafts of both groups survived smoothly and the wound healed well. Before treatment, immunohistochemical staining results showed that the positive indexes of TGF-β ₁ and TβRⅡ expressions in VSD group were 5.3±2.4 and 14.0±2.6, while those in control group were 4.4±2.3 and 14.7±3.1, respectively. There was no significant difference between 2 groups ( t=1.137, P=0.263; t=1.231, P=0.409). At 7 days after treatment, the positive indexes of TGF-β ₁ and TβRⅡ expressions in VSD group were 34.3±2.9 and 41.7±3.7, respectively, and those in control group were 5.8±2.0 and 18.1±2.5. There were significant differences between 2 groups ( t=-35.615, P=0.003; t=23.725, P=0.002).

Conclusion

VSD can increase the expressions of TGF-β ₁ and TβRⅡ in diabetic ulcer tissue, promote granulation tissue growth, and accelerate wound healing.

Wound healing related agents: Ongoing research and perspectives

Wound healing response plays a central part in chronic inflammation, affecting millions of people worldwide. It is a dynamic process that can lead to fibrosis, if tissue damage is irreversible and wound resolution is not attained. It is clear that there is a tight interconnection among wound healing, fibrosis and a variety of chronic disease conditions, demonstrating the heterogeneity of this pathology. Based on our further understanding of the cellular and molecular mechanisms underpinning tissue repair, new therapeutic approaches have recently been developed that target different aspects of the wound healing process and fibrosis. Nevertheless, several issues still need to be taken into consideration when designing modern wound healing drug delivery formulations. In this review, we highlight novel pharmacological agents that hold promise for targeting wound repair and fibrosis. We also focus on drug-delivery systems that may enhance current and future therapies.

Signalling by Transforming Growth Factor Beta Isoforms in Wound Healing and Tissue Regeneration

Transforming growth factor beta (TGFβ) signalling is essential for wound healing, including both non-specific scar formation and tissue-specific regeneration. Specific TGFβ isoforms and downstream mediators of canonical and non-canonical signalling play different roles in each of these processes. Here we review the role of TGFβ signalling during tissue repair, with a particular focus on the prototypic isoforms TGFβ1, TGFβ2, and TGFβ3. We begin by introducing TGFβ signalling and then discuss the role of these growth factors and their key downstream signalling mediators in determining the balance between scar formation and tissue regeneration. Next we discuss examples of the pleiotropic roles of TGFβ ligands during cutaneous wound healing and blastema-mediated regeneration, and how inhibition of the canonical signalling pathway (using small molecule inhibitors) blocks regeneration. Finally, we review various TGFβ-targeting therapeutic strategies that hold promise for enhancing tissue repair.

HC-HA/PTX3 Purified From Amniotic Membrane as Novel Regenerative Matrix: Insight Into Relationship Between Inflammation and Regeneration

PURPOSE

Human limbal palisade of Vogt is an ideal model for studying and practicing regenerative medicine due to their accessibility. Nonresolving inflammation is a common manifestation of limbal stem cell deficiency, which is the major cause of corneal blindness, and presents as a threat to the success of transplanted limbal epithelial stem cells. Clinical studies have shown that the efficacy of transplantation of limbal epithelial stem cells can be augmented by transplantation of cryopreserved human amniotic membrane (AM), which exerts anti-inflammatory, antiscarring, and antiangiogenic action to promote wound healing.

METHODS

Review of published data to determine the molecular action mechanism explaining how AM exerts the aforementioned therapeutic actions.

RESULTS

From the water-soluble extract of cryopreserved AM, we have biochemically purified one novel matrix component termed heavy chain (HC)-hyaluronan (HA)/pentraxin 3 (PTX3) as the key relevant tissue characteristic responsible for the aforementioned AM's efficacy. Heavy chain-HA is a complex formed by a covalent linkage between HA and HC1 of inter-α-trypsin inhibitor (IαI) by tumor necrosis factor-stimulated gene-6 (TSG-6). This complex may then be tightly associated with PTX3 to form HC-HA/PTX3 complex. Besides exerting an anti-inflammatory, antiscarring, and antiangiogenic effects, HC-HA/PTX3 complex also uniquely maintains limbal niche cells to support the quiescence of limbal epithelial stem cells.

CONCLUSIONS

We envision that HC-HA/PTX3 purified from AM can be used as a unique substrate to refine ex vivo expansion of limbal epithelial stem cells by maintaining stem cell quiescence, self-renewal and fate decision. Furthermore, it can also be deployed as a platform to launch new therapeutics in regenerative medicine by mitigating nonresolving inflammation and reinforcing the well-being of stem cell niche.

Niche Regulation of Limbal Epithelial Stem Cells: Relationship between Inflammation and Regeneration

Human limbal palisades of Vogt are the ideal site for studying and practicing regenerative medicine due to their accessibility. Nonresolving inflammation in limbal stroma is common manifestation of limbal stem cell (SC) deficiency and presents as a threat to the success of transplanted limbal epithelial SCs. This pathologic process can be overcome by transplantation of cryopreserved human amniotic membrane (AM), which exerts anti-inflammatory, antiscarring and anti-angiogenic action to promote wound healing. To determine how AM might exert anti-inflammation and promote regeneration, we have purified a novel matrix, HC-HA/PTX3, responsible for the efficacy of AM efficacy. HC-HA complex is covalently formed by hyaluronan (HA) and heavy chain 1 (HC1) of inter-α-trypsin inhibitor by the catalytic action of tumor necrosis factor-stimulated gene-6 (TSG-6) and are tightly associated with pentraxin 3 (PTX3) to form HC-HA/PTX3. In vitro reconstitution of the limbal niche can be established by reunion between limbal epithelial progenitors and limbal niche cells on different substrates. In 3-dimensional Matrigel, clonal expansion indicative of SC renewal is correlated with activation of canonical Wnt signaling and suppression of canonical bone morphogenetic protein (BMP) signaling. In contrast, SC quiescence can be achieved in HC-HA/PTX3 by activation of canonical BMP signaling and non-canonical planar cell polarity (PCP) Wnt signaling, but suppression of canonical Wnt signaling. HC-HA/PTX3 is a novel matrix mitigating nonresolving inflammation and restoring SC quiescence in the niche for various applications in regenerative medicine.

A Comparative Analysis of Gene Expression Profiles during Skin Regeneration in Mus and Acomys

The African spiny mouse (Acomys spp.) can heal full thickness excisional skin wounds in a scar-free manner with regeneration of all dermal components including hair and associated structures. Comparing Acomys scar-free healing from Mus scarring identifies gene expression differences that discriminate these processes. We have performed an extensive comparison of gene expression profiles in response to 8mm full-thickness excisional wounds at days 3, 5, 7 and 14 post-wounding between Acomys and Mus to characterize differences in wound healing, and identify mechanisms involved in scar-free healing. We also identify similarities with scar-free healing observed in fetal wounds. While wounding in Mus elicits a strong inflammatory response, wounding in Acomys produces a moderated immune response and little to no increase in expression for most cytokines and chemokines assayed. We also identified differences in the ECM profiles of the Acomys wounds, which appear to have a collagen profile more similar to fetal wounds, with larger increases in expression of collagen types III and V. In contrast, Mus wounds have very high levels of collagen XII. This data suggests that an overall lack of induction of cytokines and chemokines, coupled with an ECM profile more similar to fetal wounds, may underlie scar-free wound healing in Acomys skin. These data identify candidate genes for further testing in order to elucidate the causal mechanisms of scar-free healing.

The Suppression of Wound Healing Response with Sirolimus and Sunitinib Following Experimental Trabeculectomy in a Rabbit Model

PURPOSE

To investigate the effects of sirolimus and sunitinib on wound healing in experimental glaucoma filtering surgery (GFS).

MATERIAL AND METHODS

Thirty-five male New Zealand pigmented rabbits were randomly assigned to five groups, each including seven rabbits: The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the mitomycin-C (MMC) group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL MMC was applied intraoperatively to the scleral surgical site for three minutes. The rabbits in the sirolimus group underwent trabeculectomy and 30 ng/mL sirolimus-soaked sponge was applied intraoperatively to the scleral surgical site for three minutes. Sunitinib 0.5 mg/mL four drops in a day were applied in the sunitinib group for 14 days after surgery. On day 14 of the experiment, eyes were enucleated and histologically and immunohistochemically analyzed. Statistical analyses of the study were performed with Kruskal-Wallis variance analysis and Mann-Whitney U test.

RESULTS

The mean fibroblast and MNC numbers and the mean immunostaining intensities of transforming growth factor-β (TGF-β), fibroblast growth factor-β (FGF-β) and platelet derived growth factor (PDGF) in the MMC, sirolimus and sunitinib groups were statistically significantly lower than those of the sham group (p < 0.01). The mean fibroblast and MNC numbers and the mean immunostaining intensities of TGF-β, FGF-β and PDGF in the MMC, sirolimus and sunitinib groups were similar (p > 0.05).

CONCLUSIONS

Our study suggests that the applications of sirolimus and sunitinib effectively suppress the subconjunctival scarring after experimental GFS.

Transforming growth factor-β (TGF-β) signaling in healthy human fetal skin: a descriptive study

BACKGROUND

TGF-β plays an important role in growth and development but is also involved in scarring and fibrosis. Differences for this growth factor are known between scarless fetal wound healing and adult wound healing. Nonetheless, most of the data in this area are from animal studies or in vitro studies and, thus, information about the human situation is incomplete and scarce.

OBJECTIVE

The aim of this study was to compare the canonical TGF-β signaling in unwounded human fetal and adult skin.

METHODS

Q-PCR, immunohistochemistry, Western Blot and Luminex assays were used to determine gene expression, protein levels and protein localization of components of this pathway in healthy skin.

RESULTS

All components of the canonical TGF-β pathway were present in unwounded fetal skin. Compared to adult skin, fetal skin had differential concentrations of the TGF-β isoforms, had high levels of phosphorylated receptor-Smads, especially in the epidermis, and had low expression of several fibrosis-associated target genes. Further, the results indicated that the processes of receptor endocytosis might also differ between fetal and adult skin.

CONCLUSION

This descriptive study showed that there are differences in gene expression, protein concentrations and protein localization for most components of the canonical TGF-β pathway between fetal and adult skin. The findings of this study can be a starting point for further research into the role of TGF-β signaling in scarless healing.

Modulation of the inflammatory response by increasing fetal wound size or interleukin-10 overexpression determines wound phenotype and scar formation

Wound size impacts the threshold between scarless regeneration and reparative healing in the fetus with increased inflammation showed in fetal scar formation. We hypothesized that increased fetal wound size increases pro-inflammatory and fibrotic genes with resultant inflammation and fibroplasia and that transition to scar formation could be reversed by overexpression of interleukin-10 (IL-10). To test this hypothesis, 2-mm and 8-mm dermal wounds were created in mid-gestation fetal sheep. A subset of 8-mm wounds were injected with a lentiviral vector containing the IL-10 transgene (n = 4) or vehicle (n = 4). Wounds were harvested at 3 or 30 days for histology, immunohistochemistry, analysis of gene expression by microarray, and validation with real-time polymerase chain reaction. In contrast to the scarless 2-mm wounds, 8-mm wounds showed scar formation with a differential gene expression profile, increased inflammatory cytokines, decreased CD45+ cells, and subsequent inflammation. Lentiviral-mediated overexpression of the IL-10 gene resulted in conversion to a regenerative phenotype with decreased inflammatory cytokines and regeneration of dermal architecture. In conclusion, increased fetal wounds size leads to a unique gene expression profile that promotes inflammation and leads to scar formation and furthermore, these results show the significance of attenuated inflammation and IL-10 in the transition from fibroplasia to fetal regenerative healing.

Microarray-based characterization of differential gene expression during vocal fold wound healing in rats

The vocal fold (VF) mucosa confers elegant biomechanical function for voice production but is susceptible to scar formation following injury. Current understanding of VF wound healing is hindered by a paucity of data and is therefore often generalized from research conducted in skin and other mucosal systems. Here, using a previously validated rat injury model, expression microarray technology and an empirical Bayes analysis approach, we generated a VF-specific transcriptome dataset to better capture the system-level complexity of wound healing in this specialized tissue. We measured differential gene expression at 3, 14 and 60 days post-injury compared to experimentally naïve controls, pursued functional enrichment analyses to refine and add greater biological definition to the previously proposed temporal phases of VF wound healing, and validated the expression and localization of a subset of previously unidentified repair- and regeneration-related genes at the protein level. Our microarray dataset is a resource for the wider research community and has the potential to stimulate new hypotheses and avenues of investigation, improve biological and mechanistic insight, and accelerate the identification of novel therapeutic targets.

Impact of trastuzumab on wound healing in experimental glaucoma surgery

BACKGROUND

To investigate the effects of subconjunctivally administered trastuzumab on wound healing in experimental glaucoma filtration surgery.

DESIGN

Comparative, experimental study.

SAMPLES

Twenty eight eyes.

METHODS

Twenty-eight male New Zealand white rabbits were randomly assigned to four groups, each including seven rabbits: The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the mitomycin-C group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL mitomycin-C was applied intraoperatively to the scleral surgical site for 3 min. The rabbits in the trastuzumab group underwent trabeculectomy and were injected subconjunctivally once with 1.2 mg/0.1 mL of the drug. On day 14 of the experiment, the operated and control eyes were enucleated and immunohistochemically analyzed.

MAIN OUTCOME MEASURES

Mean values of fibroblast, mononuclear cell and immunostaining intensities of the transforming growth factor-β, fibroblast growth factor-β, and platelet derived growth factor.

RESULTS

The mean cell numbers and immunostaining intensities in the sham group were higher than those of the control group (P < 0.01). The mean cell numbers and immunostaining intensities in the mitomycin-C group and trastuzumab group were statistically significantly lower than those of the sham group (P < 0.01) while mean cell numbers and immunostaining intensities in the mitomycin-C group and trastuzumab group were similar (P > 0.05).

CONCLUSION

Subconjunctival trastuzumab injection effectively suppressed subconjunctival scarring after experimental glaucoma filtration surgery.

Fetal wound healing biomarkers

Fetal skin has the intrinsic capacity for wound healing, which is not correlated with the intrauterine environment. This intrinsic ability requires biochemical signals, which start at the cellular level and lead to secretion of transforming factors and expression of receptors, and specific markers that promote wound healing without scar formation. The mechanisms and molecular pathways of wound healing still need to be elucidated to achieve a complete understanding of this remodeling system. The aim of this paper is to discuss the main biomarkers involved in fetal skin wound healing as well as their respective mechanisms of action.

Topical infliximab for the suppression of wound healing following experimental glaucoma filtration surgery

Background

The purpose of this work was to look into the effects of infliximab on wound healing in experimental glaucoma filtration surgery and to compare the antifibrotic effects of this agent to that of mitomycin-C (MMC).

Methods

Twenty-eight male New Zealand White rabbits were randomly assigned to four groups, each including seven rabbits: control group, sham group, MMC group, and infliximab group. The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the MMC treatment group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL MMC was applied intraoperatively to the scleral surgical site for three minutes. The rabbits in the infliximab treatment group underwent trabeculectomy and one drop of 10 mg/mL infliximab was instilled four times a day for 14 days after surgery. On day 14 of the experiment, the operated and control eyes were enucleated and histologically and immunohistochemically analyzed.

Results

The mean fibroblast and mononuclear cell (MNC) numbers and the mean immunostaining intensities of transforming growth factor-β (TGF-β), fibroblast growth factor-β (FGF-β), and platelet-derived growth factor (PDGF) in the sham group were higher than those of the control group (P<0.01). The mean fibroblast and MNC numbers and the mean immunostaining intensities of TGF-β, FGF-β, and PDGF in the MMC and infliximab groups were statistically significantly lower than those of the sham group (P<0.01). The mean fibroblast and MNC numbers and the mean TGF-β, FGF-β, and PDGF immunostaining intensities of the MMC and infliximab groups were similar (P>0.05).

Conclusion

Our study suggests that topical infliximab effectively suppresses the subconjunctival wound healing response after experimental glaucoma filtration surgery, reducing the MNC and fibroblast numbers and immunostaining intensities of TGF-β, FGF-β, and PDGF.

Conditional knockout of CTGF affects corneal wound healing

PURPOSE

This study aimed to elucidate the role of connective tissue growth factor (CTGF) in healthy eyes and wounded corneas of mice and rabbits. Conditional knockout mice were used to determine the role of CTGF in corneal healing.

METHODS

CTGF expression was determined using transgenic mice carrying CTGF promoter driven-eGFP, quantitative RT-PCR, and immunofluorescent staining. Mice that carried two floxed CTGF alleles and a Cre/ERT2 transgene under the control of human ubiquitin C (ubc) promoter were used to conditionally delete CTGF gene in a tamoxifen-inducible manner. Phototherapeutic keratectomy (PTK) was used to generate an acute corneal wound and corneal re-epithelialization was assessed by fluorescein staining.

RESULTS

Connective tissue growth factor expression was found in multiple ocular tissues with relatively high levels in the corneal endothelium, lens subcapsular epithelium, and in the vasculature of the iris and retina. Wounded corneas responded with an immediate upregulation of CTGF in the epithelium at the wound margin and a sustained CTGF induction during re-epithelialization. At the onset of haze formation, CTGF protein becomes more focused in the basal epithelium. Deletion of the CTGF gene caused a 40% reduction (P < 0.01) in the cornea re-epithelialization rate in knockout mice compared with wild-type mice.

CONCLUSIONS

Connective tissue growth factor is expressed in the naïve cornea, lens, iris, and retina, and is expressed immediately after epithelial injury. Loss of CTGF impairs efficient re-epithelialization of corneal wounds.

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.

Altered TGF-β signaling in fetal fibroblasts: what is known about the underlying mechanisms?

Scarless wound healing is a unique and intrinsic capacity of the fetal skin that is not fully understood. Further insight into the underlying mechanisms of fetal wound healing may lead to new therapeutic approaches promoting adult scarless wound healing. Differences between fetal and adult wound healing are found in the extracellular matrix, the inflammatory reaction and the levels of growth factors present in the wound. This review focuses specifically on transforming growth factor β (TGF-β), as this growth factor is prominently involved in wound healing and fibroblast-to-myofibroblast differentiation. Although fetal fibroblasts do respond to TGF-β, they lack a proliferative and a contractile response and display short-lived myofibroblast differentiation, autocrine response, and collagen up-regulation in comparison with adult fibroblasts. Curiously, prolonged TGF-β activation is associated with fibrosis, and therefore, this short-lived response in fetal fibroblasts might contribute to scarless healing. This review gives an overview of the current knowledge on TGF-β signaling and the intracellular TGF-β signaling pathway in fetal fibroblasts. Furthermore, this review also describes the various components that regulate the cellular TGF-β response and hypothesizes about the possible roles these components might play in the altered response of fetal fibroblasts to TGF-β.

Transdermal siRNA-TGFβ1-337 patch for hypertrophic scar treatment

Hypertrophic scarring (HSc) is a fibroproliferative disorder of the dermis characterized by erythematous, swollen, and pruritic lesions of healing skin. An increased understanding of the role of TGFβ1 in the development of HSc provides the potential for treating HSc by down-regulating TGFβ1 expression. siRNAs that effectively interfered with TGFβ1 expression were screened. It was concluded that the siRNA-TGFβ1-337 was able to effectively down-regulate TGFβ1 expression in HSc fibroblasts. The effects of siRNA-TGFβ1-337 on cell proliferation, cell cycle, and apoptosis of HSc fibroblasts were investigated. It was shown that it inhibited cell proliferation, arrested cells in the G1 stage of the cell cycle, and induced apoptosis of HSc fibroblasts. The transdermal patch of siRNA-TGFβ1-337 was a combination of siRNA-TGFβ1-337 and a pressure-sensitive adhesive hydrogel. The treatment effects of the transdermal patch were assessed in an animal model established by transplanting human HSc to nude mice. Decreased expression of TGFβ1 was observed with treatment with the transdermal siRNA-TGFβ1-337 patch. Consequently, the treatment resulted in type I collagen down-regulation and regularly arranged scar fibroblasts being significantly reduced and undergoing apoptosis; the scar size was decreased significantly. Thus, our findings indicate that a transdermal siRNA-TGFβ1-337 patch is a potential treatment for hypertrophic scars.

Bulbine natalensis and Bulbine frutescens promote cutaneous wound healing

ETHNOPHARMACOLOGICAL RELEVANCE

The gel from the leaves of Bulbine natalensis (BN) and Bulbine frutescens (BF) is commonly used as a traditional medicine in South Africa for the treatment of skin wounds and burns. Treatment with both leaf gel extracts has previously been demonstrated to increase tensile strength and protein and DNA content in pig dermal wounds. This study examined the effect of the leaf gel extracts in vivo on histology of wound healing in pigs to elucidate the mechanism of increased tensile strength.

MATERIALS AND METHODS

Mirror imaged wounds on the dorsum of 12 post weaning female pigs were treated with either BN or BF, biopsied at days 2, 4, 7, 10 and 16 post-wounding and fixed. Sections of wound tissue were then stained with haematoxylin and eosin and Mallory's stain to analyse the general morphology and collagen arrangement; and smooth muscle actin, vascular endothelial growth factor (VEGF) and transforming growth factor β (TGFβ) receptors were immunolocalised.

RESULTS

Histological analysis of the wound tissue in the study indicated earlier wound contraction and collagen deposition in both treatment groups with re-organisation of the collagen (indicating collagen maturation) evident as early as at day 10.

CONCLUSION

The results of this study suggests that the leaf extracts increase tensile strength by increasing fibroplasia, differentiation of fibroblasts into myofibroblasts, and increased collagen deposition and maturation. This study further validates the use of the Bulbine leaf gels for the treatment of skin wounds.

Cellular and Molecular Characteristics of Scarless versus Fibrotic Wound Healing

The purpose of this paper is to compare and contrast the discrete biology differentiating fetal wound repair from its adult counterpart. Integumentary wound healing in mammalian fetuses is essentially different from wound healing in adult skin. Adult (postnatal) skin wound healing is a complex and well-orchestrated process spurred by attendant inflammation that leads to wound closure with scar formation. In contrast, fetal wound repair occurs with minimal inflammation, faster re-epithelialization, and without the accumulation of scar. Although research into scarless healing began decades ago, the critical molecular mechanisms driving the process of regenerative fetal healing remain uncertain. Understanding the molecular and cellular events during regenerative healing may provide clues that one day enable us to modulate adult wound healing and consequently reduce scarring.

Improved muscle healing after contusion injury by the inhibitory effect of suramin on myostatin, a negative regulator of muscle growth

BACKGROUND

Muscle contusions are the most common muscle injuries in sports medicine. Although these injuries are capable of healing, incomplete functional recovery often occurs.

HYPOTHESIS

Suramin enhances muscle healing by both stimulating muscle regeneration and preventing fibrosis in contused skeletal muscle.

STUDY DESIGN

Controlled laboratory study.

METHODS

In vitro: Myoblasts (C2C12 cells) and muscle-derived stem cells (MDSCs) were cultured with suramin, and the potential of suramin to induce their differentiation was evaluated. Furthermore, MDSCs were cocultured with suramin and myostatin (MSTN) to monitor the capability of suramin to neutralize the effect of MSTN. In vivo: Varying concentrations of suramin were injected in the tibialis anterior muscle of mice 2 weeks after muscle contusion injury. Muscle regeneration and scar tissue formation were evaluated by histologic analysis and functional recovery was measured by physiologic testing

RESULTS

In vitro: Suramin stimulated the differentiation of myoblasts and MDSCs in a dose-dependent manner. Moreover, suramin neutralized the inhibitory effect of MSTN on MDSC differentiation. In vivo: Suramin treatment significantly promoted muscle regeneration, decreased fibrosis formation, reduced myostatin expression in injured muscle, and increased muscle strength after contusion injury.

CONCLUSION

Intramuscular injection of suramin after a contusion injury improved overall skeletal muscle healing. Suramin enhanced myoblast and MDSC differentiation and neutralized MSTN's negative effect on myogenic differentiation in vitro, which suggests a possible mechanism for the beneficial effects that this pharmacologic agent exhibits in vivo.

CLINICAL RELEVANCE

These findings could contribute to the development of biological treatments to aid in muscle healing after experiencing a muscle injury.

Potential cellular and molecular causes of hypertrophic scar formation

A scar is an expected result of wound healing. However, in some individuals, and particularly in burn victims, the wound healing processes may lead to a fibrotic hypertrophic scar, which is raised, red, inflexible and responsible for serious functional and cosmetic problems. It seems that a wide array of subsequent processes are involved in hypertrophic scar formation, like an affected haemostasis, exaggerated inflammation, prolonged reepithelialization, overabundant extracellular matrix production, augmented neovascularization, atypical extracellular matrix remodeling and reduced apoptosis. Platelets, macrophages, T-lymphocytes, mast cells, Langerhans cells and keratinocytes are directly and indirectly involved in the activation of fibroblasts, which in turn produce excess extracellular matrix. Following the chronology of normal wound healing, we unravel, clarify and reorganize the complex molecular and cellular key processes that may be responsible for hypertrophic scars. It remains unclear whether these processes are a cause or a consequence of unusual scar tissue formation, but raising evidence exists that immunological responses early following wounding play an important role. Therefore, when developing preventive treatment modalities, one should aim to put the early affected wound healing processes back on track as quickly as possible.

Synergistic effects of combined cytotoxic and apoptosis-inducing drugs on Tenon's capsule fibroblasts in vitro and in vivo

BACKGROUND

Highly toxic antimetabolites have gained access to routine clinical use to modulate and reduce the amount of postoperative scarring following glaucomatous filtering procedures. It could be speculated that by combining two different antiproliferative substances with different mechanisms of action total amounts of the substances could be decreased and side effects reduced.

METHODS

Twenty-two substances were tested that had antiproliferative effects by acting cytotoxically, inhibiting growth factors, or inducing apoptosis. With combinations of each two substances, cell culture experiments using 3T3 and human Tenon's capsule fibroblasts were performed evaluating cell toxicity, proliferation and migration, the extent of free radicals, and the amount of apoptosis (TUNEL, electron microscopy). The five most potent combinations were used in an animal experiment with rabbits performing filtering procedures. The extent of episcleral scarring was evaluated by histopathology.

RESULTS

The results of the various assays revealed consistently strong effects in 5 of the 462 combinations. Of these five combinations, two were highly effective in the rabbit model. Substances with strong effects when applied in combination included staurosporine, mitomycin, and CD95L.

CONCLUSIONS

We found synergistic effects in assays that evaluated different aspects of cell function. The amount of scarring in an animal experiment was inhibited to a level comparable with a high single dose of mitomycin. Combination therapy of two antiproliferative acting substances may be a promising concept.

Immediate inflammatory response and scar formation in wounded vocal folds

OBJECTIVES

Vocal fold scarring is the major cause of voice disorders after voice surgery or laryngeal trauma. The role of inflammatory factors in vocal fold wound healing and fibrosis has not been adequately investigated. Scarless wound healing has been associated with decreased inflammatory responses. To understand scar formation and develop reliable treatments, it is necessary to control extracellular matrix production and inflammation. Thus, we examined the inflammation profile and extracellular matrix production in wounded vocal folds in the acute phase of wound healing.

METHODS

Vocal fold stripping was performed on 30 Sprague-Dawley rats. Vocal fold tissue was collected at 5 time points (4, 8, 16, 24, and 72 hours). We examined the in vivo messenger RNA expression profile of inflammatory factors interleukin 1beta, interferon gamma, tumor necrosis factor alpha, nuclear factor kappa beta, transforming growth factor beta, and cyclooxygenase 2, as well as hyaluronic acid synthases 1 and 2, procollagen subtypes I and III, and elastin synthase in scarred vocal folds after injury, compared to normal vocal folds, using real-time reverse transcription-polymerase chain reaction.

RESULTS

The inflammatory factors showed a time-dependent sequence of expression peaks, starting with interleukin 1beta, nuclear factor kappa beta, tumor necrosis factor alpha (4 and 8 hours), and transforming growth factor beta (72 hours). Interferon gamma decreased at 24 hours. Correspondingly, hyaluronic acid synthase 1 expression peaked first (4 and 8 hours), whereas hyaluronic acid synthase 2 expression peaked at 16 hours and again at 72 hours. Procollagen I expression peaked at 72 hours, whereas procollagen III decreased from 8 to 16 hours but peaked at 72 hours. Cyclooxygenase 2 expression was elevated, whereas elastin expression remained constant.

CONCLUSIONS

The results show a clear profile of vocal fold inflammation with corresponding changes in extracellular matrix production.

Effect of adenoviral mediated overexpression of fibromodulin on human dermal fibroblasts and scar formation in full-thickness incisional wounds

Fibromodulin, a member of the small leucine-rich proteoglycan family, has been recently suggested as a biologically significant mediator of fetal scarless repair. To assess the role of fibromodulin in the tissue remodeling, we constructed an adenoviral vector expressing human fibromodulin cDNA. We evaluated the effect of adenovirus-mediated overexpression of fibromodulin in vitro on transforming growth factors and metalloproteinases in fibroblasts and in vivo on full-thickness incisional wounds in a rabbit model. In vitro, we found that Ad-Fibromodulin induced a decrease of expression of TGF-beta(1) and TGF-beta(2) precursor proteins, but an increase in expression of TGF-beta(3) precursor protein and TGF-beta type II receptor. In addition, fibromodulin overexpression resulted in decreased MMP-1 and MMP-3 protein secretion but increased MMP-2, TIMP-1, and TIMP-2 secretion, whereas MMP-9 and MMP-13 were not influenced by fibromodulin overexpression. In vivo evaluation by histopathology and tensile strength demonstrated that Ad-Fibromodulin administration could ameliorate wound healing in incisional wounds. In conclusion, although the mechanism of scar formation in adult wounds remains incompletely understood, we found that fibromodulin overexpression improves wound healing in vivo, suggesting that fibromodulin may be a key mediator in reduced scarring.

Age-dependent recruitment of neutrophils by fetal endothelial cells: implications in scarless wound healing

PURPOSE

Fetal dermal wounds heal with minimal inflammation and absent fibrosis. Later in gestation, a transition to adult-like healing with marked inflammation and scarring is observed. Interaction with endothelial cells (ECs) is imperative for leukocyte transmigration, a critical step in the inflammatory cascade. This study was embarked upon to determine if gestational age-dependent differences in EC function modulate changes in inflammatory response and correlate with the healing phenotype.

METHODS

Fetal porcine ECs were harvested at days 65 (mid gestation), 85 (late gestation), and 100 (near-term) (term = 115 days). Confluent monolayers were activated with IL-1beta at 10 and 100 ng/mL and exposed to adult neutrophils under static (n = 4 per group) and continuous flow (n = 6 per group) conditions. Neutrophil-endothelial interaction was quantified and compared using analysis of variance.

RESULTS

Under static conditions, the lower cytokine dose elicited maximal neutrophil recruitment in later-gestation ECs, while midgestation ECs required higher stimulation. Midgestation ECs recruited significantly less neutrophils than later gestation ECs at both cytokine concentrations under flow conditions.

CONCLUSION

There is a gestational age-dependent variation in neutrophil recruitment by fetal ECs. With minimal stimulation, later-gestation ECs actively recruit neutrophils, whereas midgestation ECs do not. These findings correlate with the transition period to adult-like healing, supporting the potential role of fetal ECs in scarless healing.

Similarities and differences between induced organ regeneration in adults and early foetal regeneration

At least three organs (skin, peripheral nerves and the conjunctiva) have been induced to regenerate partially in adults following application of porous, degradable scaffolds with highly specific structure (templates). Templates blocked contraction and scar formation by inducing a reduction in the density of contractile fibroblasts (probably myofibroblasts) and by preventing these cells to organize themselves appropriately in the wound. In contrast, during early foetal healing, myofibroblasts were absent and wounds did not close by contraction but rather by spontaneous regeneration. The adult regenerative process has so far led to imperfect recovery of the physiological anatomy of skin (skin appendages were missing), while early foetal healing has led to apparently complete restoration. Furthermore, the mechanism of the adult regenerative process involves thwarting of myofibroblast function while, during early foetal healing, differentiation of myofibroblasts has not yet occurred. The data suggest that induced organ regeneration in the adult is the result of partial reversion to early foetal healing. If so, the adult may conceal a foetal response that may be subject to activation following application of highly active scaffolds or of other substances or cells.

Identification of a novel FcγRIII receptor that is up-regulated in fetal wound healing

The mid-gestation fetus is able to heal skin wounds rapidly and without scarring, an ability that is lost as development proceeds. The aim of this study was to identify novel genes involved in this process. We established an ex vivo wound model from embryonic rats and showed that over 72 hours, embryonic day 17 wounds reepithelialized and closed whereas day 19 wounds did not. To investigate the molecular basis of this phenomenon we analyzed changes in gene expression using differential display polymerase chain reaction. We characterized one transcript that was strongly up-regulated in the healing response of wounded, day 17 skin. It encodes a protein of 249 amino acids with striking similarity to the human low-affinity receptor for the Fc portion of IgG (FcgammaRIII), suggesting that it is a novel member of the FcgammaR family, which we named FcgammaRIII-X. A wound-healing timecourse shows that FcgammaRIII-X was up-regulated in healing, wounded day 17 skin but not in nonhealing, wounded day 19 skin and that its up-regulation was accelerated in skin with multiple wounds. We suggest that up-regulation of FcgammaRIII-X may contribute to scarless healing of fetal skin.

Wound Healing: An Overview

Understanding wound healing today involves much more than simply stating that there are three phases: inflammation, proliferation, and maturation. Wound healing is a complex series of reactions and interactions among cells and "mediators." Each year, new mediators are discovered and our understanding of inflammatory mediators and cellular interactions grows. This article will attempt to provide a concise overview on wound healing and wound management.

Hydrogen peroxide disrupts scarless fetal wound repair

Cutaneous wound healing is a complex process that leads to the formation of a permanent scar in adult skin. In contrast, early gestation fetal skin undergoes scarless repair. Normally, the repair process in the skin begins with an acute inflammatory response. However, one of the most important aspects of scarless fetal wound repair appears to be a lack of inflammation, suggesting that inflammation promotes scar formation in the skin. While it is well accepted that inflammation causes scar formation in the fetus, it is not known what specific factors produced during inflammation are responsible for these effects. Oxidants released by activated inflammatory cells have the potential to be involved, although this has never been examined. The present studies, using a murine fetal wound repair model, show that hydrogen peroxide interferes with scarless healing, possibly through the induction of transforming growth factor-beta1. Hydrogen peroxide also increased the proliferation of fetal fibroblasts, which could contribute to an increase in the fibrosis seen with hydrogen peroxide. Defining the factors produced during the inflammatory response that contribute to scar formation could be important for the development of new therapies designed to minimize scarring.

Neutrophil recruitment by fetal porcine endothelial cells: implications in scarless fetal wound healing

Fetal dermal wounds heal scarlessly and with a minimal inflammatory response. When a robust inflammatory response is induced at the site of fetal dermal wounds by the application of cytokines, healing results in fibrosis. To test the hypothesis that the reduced inflammatory response in fetal wounds is due to impaired fetal leukocyte-endothelial interactions, the contributions of fetal endothelial cells to the inflammatory response in the fetus were investigated. Endothelial cells isolated from blood vessels of adult and mid-gestational fetal pigs were cultured in media until confluent monolayers were established. Adult porcine neutrophils were isolated and resuspended at a concentration of 1 million cells/mL. Interactions between neutrophils and endothelial cells were observed under static and flow conditions. Endothelial monolayers were exposed to neutrophils with and without prior stimulation of the endothelial cells with tumor necrosis factor alpha (TNF-alpha) for 4 h. The neutrophil-endothelial interactions were observed and analyzed for neutrophil adhesion, rolling velocity, and transmigration. Endothelial P-selectin mRNA expression was determined by real-time polymerase chain reaction (PCR). A novel in vitro model of fetal inflammation is described. Both adult and fetal endothelial cells demonstrated a dose-dependent increase in neutrophil adhesion and transmigration with increasing doses of TNF-alpha. The fetal response was significantly lower than the adult. As expected, rolling velocity was lower at higher cytokine concentrations and had an inverse correlation with P-selectin mRNA expression. Fetal endothelial cells are less permissive to adhesion and transmigration of neutrophils than adult endothelial cells. This may contribute to the paucity of inflammation seen in the fetal response to dermal injury.

Wound Healing and Physiology of Skin Flaps

This article focuses on the dynamic process of wound healing, including the three phases of wound healing and the different types of wound healing. The physiology of skin flaps is described, with a focus on the vascular supply and biomechanics of skin flaps. The article reviews older and newer concepts of skin flap design.

Identification of novel AP-1 target genes in fibroblasts regulated during cutaneous wound healing

Mesenchymal-epithelial interactions are increasingly considered to be of vital importance for epithelial homeostasis and regeneration. In skin, the transcription factor AP-1 was shown to be critically involved in the communication between keratinocytes and dermal fibroblasts. After skin injury, the release of IL-1 from keratinocytes induces the activity of the AP-1 subunits c-Jun and JunB in fibroblasts leading to a global change in gene expression. To identify AP-1 target genes in fibroblasts, which are involved in the process of cutaneous repair, we performed gene expression profiling of wild-type, c-jun- and junB-deficient fibroblasts in response to IL-1, mimicking the initial phase of wound healing. Using a 15K cDNA collection, over 1000 genes were found to be Jun-dependent and additional 300 clones showed IL-1 responsiveness. Combinatorial evaluation allowed for the dissection of the specific contribution of either AP-1 subunit to gene regulation. Besides previously identified genes that are involved in cutaneous repair, we have identified novel genes regulated during wound healing in vivo and showed their expression by fibroblasts on wound sections. The identification of novel Jun target genes should provide a basis for understanding the molecular mechanisms underlying mesenchymal-epithelial interactions and the critical contribution of AP-1 to tissue homeostasis and repair.

The impact of cyclooxygenase-2 mediated inflammation on scarless fetal wound healing

Cyclooxygenase-2 (COX-2) and the prostaglandin products generated as a result of COX-2 activity mediate a variety of biological and pathological processes. Scarless healing occurs in fetal skin in the first and second trimesters of development. This scarless healing process is known to proceed without a significant inflammatory response, which appears to be important for the lack of scarring. Because the COX-2 pathway is an integral component of inflammation, we investigated its role in the fetal repair process using a mouse model of scarless fetal wound healing. COX-2 expression in scarless and fibrotic fetal wounds was examined. In addition, the ability of exogenous prostaglandin E(2) to alter scarless fetal healing was evaluated. The results suggest that the COX-2 pathway is involved in scar production in fetal skin and that targeting COX-2 may be useful for limiting scar formation in adult skin.

Effects of octreotide acetate and amniotic membrane on wound healing in experimental glaucoma surgery

Wound healing affects the success of glaucoma filtering surgery. Antimetabolites and antifibrotic agents are used in the modulation of surgical trauma. This study is performed to evaluate the effects of amniotic membrane and octreotide acetate on wound healing. Thirty pigmented rabbits were divided into three groups each including 10 animals. Trabeculectomy and topical postoperative prednisolone sodium phosphate four times daily for 7 days were applied to one eye of all the rabbits. After trabeculectomy, octreotide 10 microg three times daily applied topically to the octreotide group for 14 days and amniotic membrane transplantation was performed by suturing amniotic membrane between scleral flap and sclera to the amniotic membrane group. The operated eyes of the rabbits were enucleated on the 14th day of the operation and histopathological specimens were obtained from the bleb sites and they were evaluated by light microscope. Fibroblast and macrophage number per cm2 were counted and the average values were calculated. Compared with the control group, the fibroblasts and macrophages significantly decreased in the other two groups (p < 0.0001, p < 0.0001, respectively). The mean number of fibroblasts was lower than those of the control and amniotic membrane groups (p < 0.0001, p < 0.0001, respectively). Similarly the mean macrophage number was significantly lower in the octreotide group versus the control and amniotic membrane groups (p < 0.0001, p < 0.01, respectively). Octreotide administration and amniotic membrane transplantation might be alternative treatments in modulating the wound healing after trabeculectomy.

Ontogenetic transition in fetal wound transforming growth factor-beta regulation correlates with collagen organization

Fetal rat skin transitions from scarless fetal-type repair to adult-type repair with scar between day 16 (E16) and day 18 (E18) of gestation (term = 21.5 days). Deficient transforming growth factor (TGF)-beta 1 and -beta 2 injury response has been proposed as a mechanism for scarless fetal-type repair. However, previous fetal studies have inconsistently reported the degree of TGF-beta induction after injury. To minimize developmental variables in fetal versus adult TGF-beta regulation, we narrowed our study to wounded fetal animals. We hypothesize that TGF-beta ligand and receptor expression will be differentially regulated during the transition from early gestation (E16) wounds manifesting scarless fetal-type repair to late gestation (E19) wounds manifesting adult-type repair with scar. In this study, decreased and rapidly cleared TGF-beta 1 and -beta 2 expression accompanied by increased and prolonged TGF-beta 3 levels in wounded E16 animals correlated with organized collagen deposition. In contrast, increased and prolonged TGF-beta 1 and -beta 2 expression accompanied by decreased and delayed TGF-beta 3 expression in wounded E19 animals correlated with disorganized collagen architecture. Similarly, expression of TGF-beta receptors type I and II were also increased or prolonged in E19 animals. Our results implicate increased TGF-beta 1, -beta 2, and decreased TGF-beta 3 expression, as well as increased type I and II receptor expression in late gestation fetal scar formation.

Antifibrotic effects of suramin in injured skeletal muscle after laceration

Muscle injuries are very common in traumatology and sports medicine. Although muscle tissue can regenerate postinjury, the healing process is slow and often incomplete; complete recovery after skeletal muscle injury is hindered by fibrosis. Our studies have shown that decreased fibrosis could improve muscle healing. Suramin has been found to inhibit transforming growth factor (TGF)-beta1 expression by competitively binding to the growth factor receptor. We conducted a series of tests to determine the antifibrotic effects of suramin on muscle laceration injuries. Our results demonstrate that suramin (50 microg/ml) can effectively decrease fibroblast proliferation and fibrotic-protein expression (alpha-smooth muscle actin) in vitro. In vivo, direct injection of suramin (2.5 mg) into injured murine muscle resulted in effective inhibition of muscle fibrosis and enhanced muscle regeneration, which led to efficient functional muscle recovery. These results support our hypothesis that prevention of fibrosis could enhance muscle regeneration, thereby facilitating more efficient muscle healing. This study could significantly contribute to the development of strategies to promote efficient muscle healing and functional recovery.