Exogenous transforming growth factor beta(2) modulates collagen I and collagen III synthesis in proliferative scar xenografts in nude rats

In Vitro, Ex Vivo, and In Vivo Approaches for Investigation of Skin Scarring: Human and Animal Models

Significance: The cutaneous repair process naturally results in different types of scarring that are classified as normal or pathological. Affected individuals are often affected from an esthetic, physical (functional), and psychosocial perspective. The distinct nature of scarring in humans, particularly the formation of pathological scars, makes the study of skin scarring a challenge for researchers in this area. Several established experimental models exist for studying scar formation. However, the increasing development and validation of newly emerging models have made it possible to carry out studies focused on different variables that influence this unique process. Recent Advances: Experimental models such as in vitro, ex vivo, and in vivo models have obtained different degrees of success in the reproduction of the scar formation in its native milieu and true environment. These models also differ in their ability to elucidate the molecular, cellular, and structural mechanisms involved in scarring, as well as for testing new agents and approaches for therapies. The models reviewed here, including cells derived from human skin and in vivo animal models, have contributed to the advancement of skin scarring research. Critical Issues and Future Directions: The absence of experimental models that faithfully reproduce the typical characteristics of the different types of human skin scars makes the improvement of validated models and the establishment of new ones a critical unmet need. The fields of wound healing research combined with tissue engineering have offered newer alternatives for experimental studies with the potential to provide clinically useful knowledge about scar formation.

Comparison of the efficacy of seven types of microneedles for treating a rabbit hypertrophic scar model

Microneedle technology can effectively suppress the formation of hypertrophic scarring in both animals and humans. Our previous research has revealed that this is due to the physical contact inhibition effect by using microneedles made of liquid-crystal polymers as the model device. One important factor we didn't study is the influence of the fabrication materials of microneedles. Therefore, this article examines this key point on a rabbit ear hypertrophic scar model. We monitor the thickness of the scars, and the expression of α-SMA and Ki-67 protein, and TGF-β1 mRNA in a period of 42 days. Among microneedles made of 6 polymeric materials and stainless steel, polymethylmethacrylate microneedles present superiority in all aspects including the reduction of tissue fibrosis, and the expression of α-SMA, Ki-67 protein and TGF-β1 mRNA. On the other hand, polycarbonates, polyurethane, and polylactic-co-glycolic acid microneedles could suppress three biomarker expressions.

Triamcinolone acetonide intralesional injection for the treatment of keloid scars: patient selection and perspectives

Keloids are pathological scars presenting as nodular lesions that extend beyond the area of injury. They do not spontaneously regress, often continuing to grow over time. The abnormal wound-healing process underlying keloid formation results from the lack of control mechanisms self-regulating cell proliferation and tissue repair. Keloids may lead to cosmetic disfigurement and functional impairment and affect the quality of life. Although several treatments were reported in the literature, no universally effective therapy was found to date. The most common approach is intralesional corticosteroid injection alone or in combination with other treatment modalities. Triamcinolone acetonide (TAC) is the most commonly used intralesional corticosteroid. The aim of this article was to review the use of TAC, alone or in combination, in the treatment of keloid scars. The response to corticosteroid injection alone is variable with 50-100% regression and a recurrence rate of 33% and 50% after 1 and 5 years, respectively. Compared to verapamil, TAC showed a faster and more effective response even though with a higher complication rate. TAC combined with verapamil was proved to be effective with statistically significant overall improvements of scars over time and long-term stable results. TAC and 5-fluorouracil (5-FU) intralesional injections were found to achieve comparable outcomes when administered alone, although 5-FU was more frequently associated with side effects. Conversely, the combination of 5-FU and TAC was more effective and showed fewer undesirable effects compared to TAC or 5-FU alone. Several kinds of laser treatments were reported to address keloids; however, laser therapy alone was burdened with a high recurrence rate. Better results were described by combining CO2, pulsed-dye or Nd: YAG lasers with TAC intralesional injections. Further options such as needle-less intraepidermal drug delivery are being explored, but more studies are needed to establish safety, feasibility and effectiveness of this approach.

Effects and safety of triamcinolone acetonide-controlled common therapy in keloid treatment: a Bayesian network meta-analysis

Background

Triamcinolone acetonide (TAC) is used frequently in the treatment of keloid scars, but has presented controversial results. In this study, we aim to evaluate the effectiveness of TAC compared with other common therapies used in keloid treatment.

Methods

MEDLINE, Embase, Web of Science and the Cochrane Library databases were searched until January 2018. Key data were extracted from eligible randomized controlled trials. Both pairwise and network meta-analyses were conducted for synthesizing data from eligible studies.

Results

Ten randomized controlled trials were included in this meta-analysis. The relative risk of keloids associated with seven adjuvants was analyzed, including placebo, pulsed dye laser (PDL), 5-fluorouracil (5-FU), silicone, verapamil, TAC+5-FU and TAC+5-FU+PDL. Patients treated with the following adjuvants appeared to not have significantly reduced risk of keloid in relation to those treated with TAC: placebo (OR=1.86, 95% CI 1.12–2.61), PDL (OR=1.32, 95% CI 0.53–3.30), 5-FU (OR=1.13, 95% CI 0.48–2.68), silicone (OR=1.28, 95% CI 0.59–2.78), verapamil (OR=1.86, 95% CI 0.67–5.14), TAC+5-FU (OR=0.77, 95% CI 0.38–1.58) and TAC+5-FU+PDL (OR=0.80, 95% CI 0.16–4.03). The surface under the cumulative ranking curve values for each adjuvant were as follows: TAC, 59.9%; placebo, 17.4%; PDL, 46.3%; 5-FU, 48.9%; silicone, 56.2%; verapamil, 84.7%; TAC+5-FU, 68.5% and TAC+5-FU+PDL, 18.1%.

Conclusion

There were no differences between the efficacy of TAC and other common therapies in keloid treatment. TAC also acts as an effective alternative modality in the prevention and treatment of keloids. Incorporating adjuvants particularly verapamil appeared to be significantly associated with a decreased risk of keloids.

Evidence-Based Scar Management: How to Improve Results with Technique and Technology

BACKGROUND

Scars represent the visible sequelae of trauma, injury, burn, or surgery. They may induce distress in the patient because of their aesthetically unpleasant appearance, especially if they are excessively raised, depressed, wide, or erythematous. They may also cause the patient symptoms of pain, tightness, and pruritus. Numerous products are marketed for scar prevention or improvement, but their efficacy is unclear.

METHODS

A literature review of high-level studies analyzing methods to prevent or improve hypertrophic scars, keloids, and striae distensae was performed. The evidence from these articles was analyzed to generate recommendations. Each intervention's effectiveness at preventing or reducing scars was rated as none, low, or high, depending on the strength of the evidence for that intervention.

RESULTS

For the prevention of hypertrophic scars, silicone, tension reduction, and wound edge eversion seem to have high efficacy, whereas onion extract, pulsed-dye laser, pressure garments, and scar massage have low efficacy. For the treatment of existing hypertrophic scars, silicone, pulsed-dye laser, CO2 laser, corticosteroids, 5-fluorouracil, bleomycin, and scar massage have high efficacy, whereas onion extract and fat grafting seem to have low efficacy. For keloid scars, effective adjuncts to excision include corticosteroids, mitomycin C, bleomycin, and radiation therapy. No intervention seems to have significant efficacy in the prevention or treatment of striae distensae.

CONCLUSION

Although scars can never be completely eliminated in an adult, this article presents the most commonly used, evidence-based methods to improve the quality and symptoms of hypertrophic scars, as well as keloid scars and striae distensae.

Inhibition of 14q32 microRNA miR-495 reduces lesion formation, intimal hyperplasia and plasma cholesterol levels in experimental restenosis

BACKGROUND AND AIMS

We aimed at investigating the role of 14q32 microRNAs in intimal hyperplasia and accelerated atherosclerosis; two major contributors to restenosis. Restenosis occurs regularly in patients treated for coronary artery disease and peripheral arterial disease. We have previously shown that inhibition of 14q32 microRNAs leads to increased post-ischemic neovascularization, and microRNA miR-494 also decreased atherosclerosis, while increasing plaque stability. We hypothesized that 14q32 microRNA inhibition has beneficial effects on intimal hyperplasia, as well as accelerated atherosclerosis.

METHODS

Non-constrictive cuffs were placed around both femoral arteries of C57BL/6J mice to induce intimal hyperplasia. Accelerated atherosclerotic plaque formation was induced in hypercholesterolemic ApoE^-/- mice by placing semi-constrictive collars around both carotid arteries. 14q32 microRNAs miR-329, miR-494 and miR-495 were inhibited in vivo using Gene Silencing Oligonucleotides (GSOs).

RESULTS

GSO-495 administration led to a 32% reduction of intimal hyperplasia. Moreover, the number of macrophages in the arterial wall of mice treated with GSO-495 was reduced by 55%. Inhibition of miR-329 and miR-494 had less profound effects on intimal hyperplasia. GSO-495 administration also decreased atherosclerotic plaque formation by 52% and plaques of GSO-495 treated animals showed a more stable phenotype. Finally, cholesterol levels were also decreased in GSO-495 treated animals, via reduction of the VLDL-fraction.

CONCLUSIONS

GSO-495 administration decreased our primary outcomes, namely intimal hyperplasia, and accelerated atherosclerosis. GSO-495 administration also favourably affected multiple secondary outcomes, including macrophage influx, plaque stability and total plasma cholesterol levels. We conclude that 14q32 microRNA miR-495 is a promising target for prevention of restenosis.

Transplanting Human Skin Grafts onto Nude Mice to Model Skin Scars

Hypertrophic scar (HTS) is a common outcome of deep dermal wound healing mainly followed mechanical, chemical, and thermal injuries in the skin. Because of the lack of the most effective prevention and treatment, it is particularly important to establish an ideal dermal animal model for improving the understanding of the pathogenesis and exploring therapeutic approaches of HTS. Compared to other dermal fibrotic animal models in rabbits, red Duroc pigs, guinea pigs, rats, and mice, the approach that uses normal human split-thickness skin grafted onto nude or other immunodeficient mice which develop scars that resemble human HTS offers the advantages of lower cost, easier manipulation, and shorter research period. In this chapter, we will introduce the detailed procedures to create the ideal dermal fibrotic mouse model.

The Efficacy of Triamcinolone Acetonide in Keloid Treatment: A Systematic Review and Meta-analysis

Keloid is a cutaneous dermal outgrowth resulting from uncontrolled deposition of collagen and glycosaminoglycan around the wound. The uncontrolled and persistent growth of keloids scar will result in cosmetic disfigurement, functional impairment, and affect the quality of life. Triamcinolone acetonide (TAC) is traditionally employed in treating keloid scars. In this study, we aim to evaluate the effectiveness of TAC and compare it with other common therapy employed in keloid treatment. Only randomized controlled trial (RCT) and controlled trial were included. Inverse variance risk ratio, weighted mean difference, and corresponding 95% confidence intervals were calculated to evaluate the effect of intervention. Meta-analysis indicated that TAC treatment significantly reduced the size of keloid compared to untreated control. Reduction in size was statistically different in favor of TAC compared to silicone gel sheet. Significant difference in favor of TAC was observed compared with verapamil in term of vascularity and scar pliability. TAC treatment was more effective in reducing scar thickness in comparison with cryotherapy. However, the current meta-analysis has several limitations. Only a limited number of trials with the same comparison are available. Most trials recruited a small number of patients and used inconsistent outcome assessment. Most trials did not provide detail information on allocation concealment and blinding. Therefore, further evaluation in multi-center RCTs with consistent comparisons and outcome measurements are warrant to reach a consensus on the selection between TAC and different treatment modalities.

Experimental Keloid Scar Models: A Review of Methodological Issues

Background:

Keloid scars are benign fibrous proliferations in the dermis that arise after dermal trauma. The scars are raised in appearance and extend beyond the boundaries of the original wound. Scarring in predisposed individuals is out of proportion to the severity of the inciting wound. Current treatments sometimes yield early benefit but scars often resume exuberant growth. The pathophysiology of keloid scars is still poorly understood. In order for new treatments to be developed, the mechanisms leading to the formation of keloid scars must be further elucidated. The search for improved experimental models is of critical importance because such models have an important role to play in both the study of keloid formation and in the development of new therapies.

Objective:

The objective of this article is to introduce the reader to the experimental models available for studying keloid scars and to outline the advantages and limitations of animal and tissue culture models.

Conclusion:

Both models may help to elucidate the pathways of keloid formation and promote development and testing of therapies. Tissue culture is better suited to studies of pathogenesis, whereas the animal models are more suitable for therapeutic testing.

Decorin reduces hypertrophic scarring through inhibition of the TGF-β1/Smad signaling pathway in a rat osteomyelitis model

Chronic osteomyelitis is a bone infection that results in hypertrophic scarring of the soft tissue surrounding the infected bone. This scarring can create functional problems and its treatment is challenging. The aim of the present study was to evaluate the efficacy of decorin in treating scar formation in osteomyelitis and the underlying mechanism of its action. A rat osteomyelitis model was used, and animals were divided into three groups, as follows: Group A (control), group B (osteomyelitis model) and group C (decorin-treated). X-ray scans, hematoxylin and eosin (H&E) staining and Masson's trichrome staining were performed to observe changes in femur and muscle tissue. In order to assess the role of the transforming growth factor β1 (TGF-β1)/Smad signaling pathway in scar formation in osteomyelitis, alterations in muscle tissue morphology and in the activation of key members of the TGF-β1/Smad signaling pathway were investigated in groups A and B. According to the results of H&E staining, evident fibrosis in muscle tissue were observed at days 14 and 28 in group B. Simultaneously, the expression levels of key members of the TGF-β1/Smad signaling pathway were increased. Subsequent to treatment with decorin in group C, scarring was reduced, and significant downregulation of collagen I, TGF-β1, phosphorylated (p)Smad2 and pSmad3 protein expression levels was observed at days 14 and 28 compared with the osteomyelitis group. In conclusion, these results suggest that activation of TGF-β1 may serve an important role in the formation of scars in osteomyelitis and that decorin can reduce scar formation in an osteomyelitis rat model through inhibition of the TGF-β1/Smad signaling pathway.

The Burn Wound Microenvironment

Significance: While the survival rate of the severely burned patient has improved significantly, relatively little progress has been made in treatment or prevention of burn-induced long-term sequelae, such as contraction and fibrosis. Recent Advances: Our knowledge of the molecular pathways involved in burn wounds has increased dramatically, and technological advances now allow large-scale genomic studies, providing a global view of wound healing processes. Critical Issues: Translating findings from a large number of in vitro and preclinical animal studies into clinical practice represents a gap in our understanding, and the failures of a number of clinical trials suggest that targeting single pathways or cytokines may not be the best approach. Significant opportunities for improvement exist. Future Directions: Study of the underlying molecular influences of burn wound healing progression will undoubtedly continue as an active research focus. Increasing our knowledge of these processes will identify additional therapeutic targets, supporting informed clinical studies that translate into clinical relevance and practice.

Extracorporeal Shock Wave Therapy: An Emerging Treatment Modality for Retracting Scars of the Hands

Prolonged and abnormal scarring after trauma, burns and surgical procedures often results in a pathologic scar. We evaluated the efficacy of unfocused shock wave treatment, alone or in combination with manual therapy, on retracting scars on the hands. Scar appearance was assessed by means of the modified Vancouver Scar Scale; functional hand mobility was evaluated using a range-of-motion scale, whereas a visual analogue score was implemented for detecting any improvements in referred pain. Additionally, biopsy specimens were collected for clinico-pathologic correlation. For each active treatment group, statistically significant improvements in modified Vancouver Scar Scale were recorded as early as five treatment sessions and confirmed 2 wk after the last treatment session. Analogous results were observed when assessing pain and range of movement. Histopathological examination revealed significant increases in dermal fibroblasts in each active treatment group, as well as in neoangiogenetic response and type-I collagen concentration.

Human hypertrophic and keloid scar models: principles, limitations and future challenges from a tissue engineering perspective

Most cutaneous wounds heal with scar formation. Ideally, an inconspicuous normotrophic scar is formed, but an abnormal scar (hypertrophic scar or keloid) can also develop. A major challenge to scientists and physicians is to prevent adverse scar formation after severe trauma (e.g. burn injury) and understand why some individuals will form adverse scars even after relatively minor injury. Currently, many different models exist to study scar formation, ranging from simple monolayer cell culture to 3D tissue-engineered models even to humanized mouse models. Currently, these high-/medium-throughput test models avoid the main questions referring to why an adverse scar forms instead of a normotrophic scar and what causes a hypertrophic scar to form rather than a keloid scar and also, how is the genetic predisposition of the individual and the immune system involved. This information is essential if we are to identify new drug targets and develop optimal strategies in the future to prevent adverse scar formation. This viewpoint review summarizes the progress on in vitro and animal scar models, stresses the limitations in the current models and identifies the future challenges if scar-free healing is to be achieved in the future.

Models of abnormal scarring

Keloids and hypertrophic scars are thick, raised dermal scars, caused by derailing of the normal scarring process. Extensive research on such abnormal scarring has been done; however, these being refractory disorders specific to humans, it has been difficult to establish a universal animal model. A wide variety of animal models have been used. These include the athymic mouse, rats, rabbits, and pigs. Although these models have provided valuable insight into abnormal scarring, there is currently still no ideal model. This paper reviews the models that have been developed.

High phosphorus diet-induced changes in NaPi-IIb phosphate transporter expression in the rat kidney: DNA microarray analysis

The mechanism by which phosphorus levels are maintained in the body was investigated by analyzing changes in gene expression in the rat kidney following administration of a high phosphorus (HP) diet. Male Wistar rats were divided into two groups and fed a diet containing 0.3% (control) or 1.2% (HP) phosphorous for 24 days. Phosphorous retention was not significantly increased in HP rats, but fractional excretion of phosphorus was significantly increased in the HP group compared to controls, with an excessive amount of the ingested phosphorus being passed through the body. DNA microarray analysis of kidney tissue from both groups revealed changes in gene expression profile induced by a HP diet. Among the genes that were upregulated, Gene Ontology (GO) terms related to ossification, collagen fibril organization, and inflammation and immune response were significantly enriched. In particular, there was significant upregulation of type IIb sodium-dependent phosphate transporter (NaPi-IIb) in the HP rat kidney compared to control rats. This upregulation was confirmed by in situ hybridization. Distinct signals for NaPi-IIb in both the cortex and medulla of the kidney were apparent in the HP group, while the corresponding signals were much weaker in the control group. Immunohistochemical analysis showed that NaPi-IIb localized to the basolateral side of kidney epithelial cells surrounding the urinary duct in HP rats but not in control animals. These data suggest that NaPi-IIb is upregulated in the kidney in response to the active excretion of phosphate in HP diet-fed rats.

Inflammatory regulation of valvular remodeling: the good(?), the bad, and the ugly

Heart valve disease is unique in that it affects both the very young and very old, and does not discriminate by financial affluence, social stratus, or global location. Research over the past decade has transformed our understanding of heart valve cell biology, yet still more remains unclear regarding how these cells respond and adapt to their local microenvironment. Recent studies have identified inflammatory signaling at nearly every point in the life cycle of heart valves, yet its role at each stage is unclear. While the vast majority of evidence points to inflammation as mediating pathological valve remodeling and eventual destruction, some studies suggest inflammation may provide key signals guiding transient adaptive remodeling. Though the mechanisms are far from clear, inflammatory signaling may be a previously unrecognized ally in the quest for controlled rapid tissue remodeling, a key requirement for regenerative medicine approaches for heart valve disease. This paper summarizes the current state of knowledge regarding inflammatory mediation of heart valve remodeling and suggests key questions moving forward.

Functional genomics unique to week 20 post wounding in the deep cone/fat dome of the Duroc/Yorkshire porcine model of fibroproliferative scarring

BACKGROUND

Hypertrophic scar was first described over 100 years ago; PubMed has more than 1,000 references on the topic. Nevertheless prevention and treatment remains poor, because 1) there has been no validated animal model; 2) human scar tissue, which is impossible to obtain in a controlled manner, has been the only source for study; 3) tissues typically have been homogenized, mixing cell populations; and 4) gene-by-gene studies are incomplete.

METHODOLOGY/PRINCIPAL FINDINGS

We have assembled a system that overcomes these barriers and permits the study of genome-wide gene expression in microanatomical locations, in shallow and deep partial-thickness wounds, and pigmented and non-pigmented skin, using the Duroc(pigmented fibroproliferative)/Yorkshire(non-pigmented non-fibroproliferative) porcine model. We used this system to obtain the differential transcriptome at 1, 2, 3, 12 and 20 weeks post wounding. It is not clear when fibroproliferation begins, but it is fully developed in humans and the Duroc breed at 20 weeks. Therefore we obtained the derivative functional genomics unique to 20 weeks post wounding. We also obtained long-term, forty-six week follow-up with the model.

CONCLUSIONS/SIGNIFICANCE

1) The scars are still thick at forty-six weeks post wounding further validating the model. 2) The differential transcriptome provides new insights into the fibroproliferative process as several genes thought fundamental to fibroproliferation are absent and others differentially expressed are newly implicated. 3) The findings in the derivative functional genomics support old concepts, which further validates the model, and suggests new avenues for reductionist exploration. In the future, these findings will be searched for directed networks likely involved in cutaneous fibroproliferation. These clues may lead to a better understanding of the systems biology of cutaneous fibroproliferation, and ultimately prevention and treatment of hypertrophic scarring.

Oral administration of Enterococcus faecalis EC-12 cell preparation improves villous atrophy after weaning through enhancement of growth factor expression in mice

Lactic acid bacteria, either alive or dead, can improve villous atrophy caused by weaning in both piglets and mice. In this experiment, we tried to detect the molecules involved in this phenomenon with a real-time RT-PCR array approach. Weaning pups of mice were administered either a suspension of an Enterococcus faecalis EC-12 dried cell preparation (EC-12) or saline for 11 consecutive days after weaning. The jejunal and ileal villous heights were measured histologically, and the expression levels of 86 genes were analyzed for the jejunal and ileal epithelial cells and the lamina propria (LP). EC-12 induced significantly higher villous height in the jejunum and the ileum. Interleukin (IL)-6, fibroblast growth factor (FGF)-7, -10, and -22, and the platelet-derived growth factor (PDGF) beta in the jejunal and the ileal LP were the most enhanced genes by EC-12. The possible role of these molecules in the improvement of villous atrophy is discussed.

Low-level laser therapy (LLLT; 780 nm) acts differently on mRNA expression of anti- and pro-inflammatory mediators in an experimental model of collagenase-induced tendinitis in rat

Low-level laser therapy (LLLT) has been found to produce anti-inflammatory effects in a variety of disorders. Tendinopathies are directly related to unbalance in expression of pro- and anti-inflammatory cytokines which are responsible by degeneration process of tendinocytes. In the current study, we decided to investigate if LLLT could reduce mRNA expression for TNF-α, IL-1β, IL-6, TGF-β cytokines, and COX-2 enzyme. Forty-two male Wistar rats were divided randomly in seven groups, and tendinitis was induced with a collagenase intratendinea injection. The mRNA expression was evaluated by real-time PCR in 7th and 14th days after tendinitis. LLLT irradiation with wavelength of 780 nm required for 75 s with a dose of 7.7 J/cm(2) was administered in distinct moments: 12 h and 7 days post tendinitis. At the 12 h after tendinitis, the animals were irradiated once in intercalate days until the 7th or 14th day in and them the animals were killed, respectively. In other series, 7 days after tendinitis, the animals were irradiated once in intercalated days until the 14th day and then the animals were killed. LLLT in both acute and chronic phases decreased IL-6, COX-2, and TGF-β expression after tendinitis, respectively, when compared to tendinitis groups: IL-6, COX-2, and TGF-β. The LLLT not altered IL-1β expression in any time, but reduced the TNF-α expression; however, only at chronic phase. We conclude that LLLT administered with this protocol reduces one of features of tendinopathies that is mRNA expression for pro-inflammatory mediators.

The emerging role of antineoplastic agents in the treatment of keloids and hypertrophic scars: a review

The management of keloids and hypertrophic scars continues to challenge health-care providers. Though both forms of pathologic scarring are distinct entities at the macro and microscopic level, their etiologies and treatment are often similar. Potential treatment approaches are progressing, and combinations of treatment options have been proposed in the literature with promising outcomes. The treatment evolution has reached a level where molecular therapeutic modalities are being investigated. Currently, no gold standard treatment exists. Overall success rates and patient satisfaction seem to be slowly climbing, but additional investigational studies must continue to be performed. Several studies have investigated antineoplastic agents, and there seems to be a marked improvement in rates of recurrence, patient satisfaction, and overall quality of scar when these agents are used. Intralesional injection and/or wound irrigation with interferon-a2b, interferon-g, mitomycin-C, bleomycin, or 5-fluorouracil seems to have a positive effect on the reduction of pathologic scars. There is mounting evidence that these drugs used alone or in combination therapy, have the potential to be an integral part of the treatment paradigm for hypertrophic scars and keloids.

Genetics of keloid scarring

Keloid scarring, also known as keloid disease (KD), is a common, abnormally raised fibroproliferative cutaneous lesion that can occur following even minor skin trauma. The aetiopathogenesis of KD has remained an enigma todate compounded by an ill-defined clinical management. There is strong evidence suggesting a genetic susceptibility in individuals affected by KD, including familial heritability, common occurrence in twins and high prevalence in certain ethnic populations. This review aims to address the genetic aspects of KD that have been described in present literature that include inheritance patterns, linkage studies, case-control association studies, whole genome gene expression microarray studies and gene pathways that were significant in KD. In addition to our clinical and scientific background in KD, we used search engines, Scopus, Scirus and PubMed, which searched for key terms covering various genetic aspects of KD. Additionally, genes reported in seven whole genome gene expression microarray studies were separately compared in detail. Our findings indicate a varied inheritance pattern in KD (predominantly autosomal dominant), linkage loci (chromosomes 2q23 and 7p11), several human leukocyte antigen (HLA) alleles (HLA-DRB1*15, HLA-DQA1*0104, DQ-B1*0501 and DQB1*0503), negative candidate gene case-control association studies and at least 25 dysregulated genes reported in multiple microarray studies. The major pathways reportedly proposed to be involved in KD include apoptosis, mitogen-activated protein kinase, transforming growth factor-beta, interleukin-6 and plasminogen activator inhibitor-1. In summary, involvement of more than one gene is likely to be responsible for susceptibility to KD. A better understanding of the genes involved in KD may potentially lead to the development of more effective diagnostic, therapeutic and prognostic measures.

Dermal transforming growth factor-beta responsiveness mediates wound contraction and epithelial closure

Stromal-epithelial interactions are important during wound healing. Transforming growth factor-beta (TGF-beta) signaling at the wound site has been implicated in re-epithelization, inflammatory infiltration, wound contraction, and extracellular matrix deposition and remodeling. Ultimately, TGF-beta is central to dermal scarring. Because scarless embryonic wounds are associated with the lack of dermal TGF-beta signaling, we studied the role of TGF-beta signaling specifically in dermal fibroblasts through the development of a novel, inducible, conditional, and fibroblastic TGF-beta type II receptor knockout (Tgfbr2(dermalKO)) mouse model. Full thickness excisional wounds were studied in control and Tgfbr2(dermalKO) back skin. The Tgfbr2(dermalKO) wounds had accelerated re-epithelization and closure compared with controls, resurfacing within 4 days of healing. The loss of TGF-beta signaling in the dermis resulted in reduced collagen deposition and remodeling associated with a reduced extent of wound contraction and elevated macrophage infiltration. Tgfbr2(dermalKO) and control skin had similar numbers of myofibroblastic cells, suggesting that myofibroblastic differentiation was not responsible for reduced wound contraction. However, several mediators of cell-matrix interaction were reduced in the Tgfbr2(dermalKO) fibroblasts, including alpha1, alpha2, and beta1 integrins, and collagen gel contraction was diminished. There were associated deficiencies in actin cytoskeletal organization of vasodilator-stimulated phosphoprotein-containing lamellipodia. This study indicated that paracrine and autocrine TGF-beta dermal signaling mechanisms mediate macrophage recruitment, re-epithelization, and wound contraction.

Expression of collagen genes in the cones of skin in the Duroc/Yorkshire porcine model of fibroproliferative scarring

During the past decades there has been minimal improvement in prevention and treatment of hypertrophic scarring. Reasons include the lack of a validated animal model, imprecise techniques to dissect scar into the histologic components, and limited methodology for measurement of gene expression. These problems have been addressed with the Duroc/Yorkshire model of healing, laser capture microdissection, and the Affymetrix Porcine GeneChip. Here we compared collagen gene expression in fibroproliferative healing in the Duroc breed to nonfibroproliferative healing in the Yorkshires. We made shallow and deep dorsal wounds, biopsied at 1, 2, 3, 12, and 20 weeks. We sampled the dermal cones by laser capture microdissection, extracted and amplified the RNA, and hybridized Affymetrix Porcine GeneChips. We also obtained samples of human hypertrophic scar approximately 20 weeks postinjury. Data were normalized and statistical analysis performed with mixed linear regression using the Bioconductor R/maanova package. Genes for further analysis were also restricted with four biologic criteria, including that the 20-week deep Duroc expression match the human samples. Eleven collagen genes and seven collagen types were differentially over expressed in deep Duroc wounds including 1a1, 1a2, 3a1, 4a1, 4a2, 5a1, 5a2, 5a3, 6a3 (transcript variant 5), 14a1 and 15a1. COL7a1 gene was differentially under expressed in deep Duroc wounds. The results suggest that collagens I, III, IV, V, VI, VII, XIV, and XV [corrected] are involved in the process of fibroproliferative scarring. With these clues, we will attempt to construct the regulatory pathway(s) of fibroproliferative healing.

Scars: a review of emerging and currently available therapies

BACKGROUND

With the investigation and potential introduction of several novel scar-reducing therapies to the market within the next several years, it is germane to review both the pathophysiology of scarring and the safety and efficacy of currently available and emerging therapeutic agents.

METHODS

An extensive review of the English-language literature was conducted using the MEDLINE database.

RESULTS

A comprehensive review of the pathophysiology of scarring and scar management, including both emerging and currently available therapies, was completed. Current clinical studies are limited by small sample sizes, lack of well-designed controls, and lack of standardized scar outcome measurement parameters.

CONCLUSIONS

A prominent challenge in the study of scar management is the paucity of well-designed, large, randomized, controlled studies examining existing scar-reducing techniques. The greatest improvement in scar-reducing protocols likely entails a polytherapeutic strategy for management. Further investigation into the role of inflammation in scarring is paramount to the development of improved scar-reducing agents. There is a need for large controlled trials using a polytherapeutic strategy that combines existing and novel agents to provide a standardized evidence-based evaluation of efficacy.

Review of the female Duroc/Yorkshire pig model of human fibroproliferative scarring

Hypertrophic scarring after burns is an unsolved problem and remains as devastating today as it was in the 40s and it may be that the main reason for this is the lack of an accepted, useful animal model. The female, red Duroc pig was described as a model of hypertrophic scarring nearly 30 years ago but then vanished from the literature. This seemed strange since the authors reported that 12 of 12 pigs developed thick scar. In the mid 90s we explored the model and found that, indeed, the red Duroc pig does make thick scar. Other authors have established that the Yorkshire pig does not heal in this fashion so there is the possibility of a same species control. We have continued to explore the Duroc/Yorkshire model and herein describe our experiences. Is it a perfect model of hypertrophic scarring? No. Is it a useful model of hypertrophic scarring? Time will tell. We have now obtained gene expression data from the Duroc/Yorkshire model and analysis is underway.

A novel truncated TGF-beta receptor II downregulates collagen synthesis and TGF-beta I secretion of keloid fibroblasts

Hypertrophic scars and keloid are dermal proliferative disorders in wound healing. Transforming growth factor beta (TGF-beta) has been implicated in scar formation through the activation of fibroblasts and the acceleration of collagen deposition. Our study aimed to design a novel truncated (27-123 residues) type II TGF-beta receptor (tTGFbetaRII) and to determine its effects on the proliferation of keloid fibroblasts and the collagen synthesis as well as TGF-beta I expression of the cells. The coding sequences of TGF-beta I and tTGFbetaRII were amplified using RT-PCR and then cloned into pGBKT7 and pGADT7 vectors. A yeast two-hybrid experiment and a glutathione S-transferase (GST)-pull down assay were performed to verify the affinity of tTGFbetaRII to TGF-beta I. Our results indicated that treatment with tTGFbetaRII inhibited the growth of keloid fibroblasts and suppressed the synthesis of type I collagen in keloid fibroblasts in a concentration-dependent manner. Moreover, northern and western blot analysis revealed a decline of the TGF-beta I expression at both mRNA and protein levels after exposure to 5, 10 or 20 mug/ml of tTGFbetaRII. Together, our data suggested that the exogenous tTGFbetaRII can efficiently trap TGF-beta I from access to wild-type receptors and can suppress TGF-beta I triggered signals. Thus it may potentially be clinically applied to scar therapy.

The Microvasculature in Cutaneous Wound Healing in the Female Red Duroc Pig Is Similar to That in Human Hypertrophic Scars and Different From That in the Female Yorkshire Pig

The female red Duroc pig has been found to be a promising model of hypertrophic scarring. The female Yorkshire pig has been demonstrated to heal in a very different manner, more resembling human normotrophic scarring. Given these observations, we studied microvessel density, an important aspect of wound healing, in human hypertrophic scars and the scars of the female Duroc and Yorkshire pigs. We studied microvessel density in uninjured skin; hypertrophic scars at 6 months or less, 7 to 12, and longer than 12 months; female Duroc tissues at 3 weeks and 3 and 5 months; and similar Yorkshire tissue, including uninjured skin and shallow and deep wounds. Antifactor VIII-related antigen was used to mark the endothelial cells. Computed assessment of microvessel density was used to quantify the microvasculature. In human hypertrophic scars, the microvessels were increased dramatically, and microvessel density and area were significantly elevated. We found similar results in the Duroc tissues at 5 months after deep wounding. In contrast, we found far less microvasculature and, at 5 months, the values had returned to normal in the Yorkshire tissues. This quantitative study of microvessel density further validates the female Duroc pig as an animal model of hypertrophic scarring and the female Yorkshire pig as a control.

Differential expression of matrix metalloproteinases and tissue-derived inhibitors of metalloproteinase in fetal and adult skins

Matrix metalloproteinases and their tissue-derived inhibitors determine the architecture of the extracellular matrix. In early gestation, the amount and organization of extracellular matrix may be associated with scarless repair of fetal skin wounds. To elucidate the part of the mechanism(s) underlying the phenotypic transition from scarless to scar-forming healing observed during fetal gestation, the ontogeny of matrix metalloproteinase-2, -9, -14 and their tissue inhibitors was characterized in non-wounded fetal human skin with different gestational ages from 13 to 33 weeks and adult skin using reverse transcriptase-polymerase chain reaction, immunohistochemical staining and western blot protocols. We showed that the levels of gene expressions for matrix metalloproteinase-2, -9, -14 and their endogenous inhibitors were significantly more in late gestational and adult skins than that in early gestational skin. Similar results were noted in terms of protein contents of these enzymes and inhibitors in fetal and adult skins. We concluded that the endogenous matrix metalloproteinase-2, -9, -14 and their endogenous inhibitors might be involved in skin development and in maintenance of cutaneous structure and function. Lower protein contents of tissue-derived inhibitor-1, -2 in early gestational skin might provide a predominantly antiscarring signal while higher protein expression of these two inhibitors might be associated with scar-forming healing in late gestational and adult skins.

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.

Histology of the thick scar on the female, red Duroc pig: final similarities to human hypertrophic scar

The etiology and treatment of hypertrophic scar remain puzzles even after decades of research. A significant reason is the lack of an accepted animal model of the process. The female, red Duroc pig model was described long ago. Since the skin of the pig is similar to that of humans, we are attempting to validate this model and found it to be encouraging. In this project we quantified myofibroblasts, mast cells and collagen nodules in the thick scar of the Duroc pig and compared these to the values for human hypertrophic scar. We found the results to be quite similar and so further validated the model. In addition, we observed that soon after wounding an inflammatory cell layer forms. The thickness of the inflammatory layer approaches the thickness of the skin removed as if the remaining dermis "knows" how much dermis is gone. In deep wounds this inflammatory layer thickens and this thickness is predictive of the thickness of the ultimate scar.

Down-regulating causes of fibrosis with tamoxifen: a possible cellular/molecular approach to treat rhinophyma

Fibrosis and proliferative scarring are prominent features of the severe forms of rhinophyma. Up-regulation of growth and fibroblast kinetics are hallmarks of fibrosis. Persistent overexpression or dysregulated activation of the fibrogenic isoforms of transforming growth factor beta (TGF-beta) is associated with the increased fibroblast function leading to fibrotic conditions such as rhinophyma. Tamoxifen, a synthetic nonsteroidal antiestrogen, can neutralize or down-regulate TGF-beta. Fibroblast-populated collagen lattices (FPCLs) were constructed from fibroblasts cultured from rhinophyma or normal nasal skin. One-half of each set of FPCLs was treated with Tamoxifen. Lattice contraction was serially measured over 5 days, and the supernatants of the cultures were analyzed for TGF-beta-2 by immunoassay. Tamoxifen significantly decreased fibroblast activity by decreasing contraction of the treated lattices (P < 0.05) and significantly decreased the production/secretion of TGF-beta-2 by rhinophyma fibroblasts (P < 0.001). These results suggest a possible new cellular/molecular approach to the treatment of the fibrotic varieties of rhinophyma.

Transforming growth factor beta (TGFbeta) and keloid disease

Keloids are benign fibroproliferative diseases of unknown aetiology. They occur as a result of derangement of the normal wound healing process in susceptible individuals. Although several factors have been postulated in the aetiopathogenesis of this condition, there has been growing evidence to suggest a role for Transforming Growth Factor beta (TGFbeta) family members in its pathogenesis. TGFbeta has also been found to be associated with fibrotic diseases affecting different organs of the body including liver, kidney, lung as well as skin. In this review article, we will discuss the morphology and mechanism of action of TGFbeta and its isoforms and present the most up to date literature discussing the role of TGFbeta isoforms, their receptors, and intracellular signalling pathways (the SMAD pathway) in the pathogenesis of keloid disease. Understanding the role of TGFbeta in keloid disease could lead to the development of clinically useful therapeutic modalities for treatment of this condition.

Upregulation of TGF-β1 Expression May Be Necessary but Is Not Sufficient for Excessive Scarring

Transforming growth factor beta 1 (TGF-beta1) upregulation has been implicated in hypertrophic scars and keloids, but it is unclear if it is the cause or an effect of excessive scar formation. In this study, we overexpressed TGF-beta1 in fibroblasts and characterized its role. Normal human dermal fibroblasts were genetically modified to overexpress TGF-beta1 as the wild-type latent molecule or as a mutant constitutively active molecule. TGF-beta1 secretion was measured, as were the effects of TGF-beta1 upregulation on cell proliferation, expression of smooth muscle cell alpha actin (SMC alpha-actin) and ability to contract collagen lattices. Fibroblasts were implanted intradermally into athymic mice and tissue formation was analyzed over time by histology and immunostaining. Gene-modified fibroblasts secreted approximately 20 times the TGF-beta1 released by control cells, but only cells expressing mutant TGF-beta1 secreted it in the active form. Fibroblasts expressing the active TGF-beta1 gene had increased levels of SMC alpha-actin and enhanced ability to contract a collagen lattice. After intradermal injection into athymic mice, only fibroblasts expressing active TGF-beta1 formed "keloid-like" nodules containing collagen, which persisted longer than implants of the other cell types. We conclude that upregulation of TGF-beta1 by fibroblasts may be necessary, but is not sufficient for excessive scarring. Needed are other signals to activate TGF-beta1 and prolong cell persistence.

Upregulation of transforming growth factor-beta1 and vascular endothelial growth factor in cultured keloid fibroblasts: relevance to angiogenic activity

Keloids are tumor-like lesions that result from excessive scar formation during healing of wounds. Histologically, keloids show an increased blood vessel density compared with normal dermis or normal scars. However, the angiogenic activity of keloid fibroblasts remains unknown. In this study, we investigated angiogenic activity of keloid fibroblasts. Transforming growth factor-beta1 (TGF-beta1) and vascular endothelial growth factor (VEGF) were investigated as elements of the angiogenic factors. Expressions of TGF-beta1 and VEGF in conditioned medium were measured with enzyme-linked immunosorbent assay (EIA) and Northern blot analysis. Participation of TGF-beta1 in the production of VEGF was also investigated with addition of TGF-beta1 and a neutralizing anti-TGF-beta1 antibody. A modified Boyden chamber assay was performed to assess the chemotactic activity of vascular endothelial cells. Angiogenic activity in vivo was evaluated by neovascularization of nodules formed by implantation of fibroblasts into severe combined immunodeficiency (SCID) mice. EIA showed that the concentrations of TGF-beta1 and VEGF in conditioned medium were increased 2.5- and 6-fold, respectively, after the culture of keloid fibroblasts compared with normal fibroblasts. Northern blot analysis revealed that the expression of TGF-beta1 and VEGF mRNA was upregulated 3.6- and 6-fold, respectively, in keloid fibroblasts compared with normal fibroblasts. Addition of TGF-beta1 to keloid fibroblast cultures increased VEGF production by 3.5-fold, while there was a 6-fold in culture of normal fibroblasts. A neutralizing anti-TGF-beta1 antibody reduced VEGF secretion to control levels, suggesting that TGF-beta1 mediated the upregulation of VEGF expression. A modified Boyden chamber assay demonstrated that the chemotactic activity of vascular endothelial cells was more strongly (sevenfold) induced by keloid fibroblast-conditioned medium than by normal fibroblast-conditioned medium. Anti-VEGF antibody inhibited chemotaxis to basal levels. When SCID mice underwent implantation of fibroblasts into the back, the nodules formed by keloid fibroblasts were three times larger than those formed by normal fibroblasts. Although abundant neovascularization was observed in keloid fibroblast nodules, neovascularization was scarce in normal fibroblast nodules. Both in vitro and in vivo studies confirmed the significantly higher angiogenic activity of keloid fibroblasts compared with normal fibroblasts, and TGF-beta1 and VEGF were clearly shown to be involved. These results suggest that angiogenesis in keloids is promoted by endogenous TGF-beta1 and VEGF.

Intralesional 5-fluorouracil in the treatment of keloids: an open clinical and histopathologic study

BACKGROUND

The treatment of keloids remains unsatisfactory. Intralesional 5-fluorouracil (FU) has not been much investigated as a monotherapy in the treatment of keloids.

OBJECTIVE

We sought to evaluate the use of intralesional injections of 5-FU in the treatment of keloids.

METHODS

A total of 20 patients (11 male and 9 female) were treated once weekly with intralesional injections of 5-FU (50 mg/mL). Patients received an average of 7 treatments. Average injection volumes were 0.2 to 0.4 mL/cm2. All patients had full blood cell count, liver function tests, and renal function tests before and after treatment was commenced. A total of 10 patients had biopsy specimens taken before starting treatment as a baseline and after 6 sessions. Routine hematoxylin-eosin and immunohistochemical analysis detecting Ki-67 and transforming growth factor-beta were performed on paraffin sections. All patients were followed up for 12 months, or until recurrence was noted.

RESULTS

Of 20 patients, 17 (85%) showed more than 50% improvement. Only one did not respond favorably. Small and previously untreated lesions improved the most. Pain (20 of 20), hyperpigmentation (20 of 20), and tissue sloughing (6 of 20) were the main adverse effects. Histopathologic and immunohistochemical evaluation were consistent with the clinical observations. Ki-67 proliferative index was significantly reduced (P = .0001) after treatment. Transforming growth factor-beta was reduced less significantly. Recurrence was noted in 47% (9 of 19) of patients who responded to treatment within 1 year. A correlation was found ( P = .028) between the duration of the lesions and recurrence.

CONCLUSION

Our study demonstrates that intralesional 5-FU may be effective in the treatment of keloids, but recurrence is common and further investigation is required.

Studies of transforming growth factors beta 1-3 and their receptors I and II in fibroblast of keloids and hypertrophic scars

Keloids are benign skin tumours occurring during wound healing in genetically predisposed patients. They are characterized by an abnormal deposition of extracellular matrix components, particularly collagen. There is uncertain evidence that transforming growth factor-beta (TGFss) is involved in keloid formation. Therefore we investigated the expression of TGFss1, 2 and 3 and their receptors in keloids, hypertrophic scars and normal skin. Dermal fibroblasts were obtained from punch biopsies of patients with keloids and hypertrophic scars and from normal skin of healthy individuals. Total RNA was isolated and the expression of TGFss1, 2 and 3 and of TGFss receptors I and II (TGFssRI and II) was analysed by real-time PCR using the Lightcycler technique. Our data demonstrate significantly lower TGFss2 mRNA expression in hypertrophic scar fibroblasts as compared with fibroblasts derived from keloids and normal skin (p<0.05). In contrast, TGFss3 mRNA expression was significantly lower in keloid fibroblasts in comparison with fibroblasts derived from hypertrophic scar and normal skin (p<0.01). TGFssRI mRNA expression was significantly decreased in hypertrophic scar fibroblasts (p<0.01) and TGFssRII mRNA expression was decreased in keloids compared with hypertrophic scar fibroblasts (p<0.001). The ratio of TGFssRI/TGFssRII expression was increased in keloids compared with hypertrophic scar and normal skin fibroblasts. As recently supposed, an increased TGFssRI/TGFssRII ratio could promote fibrosis. Therefore our data support a possible role of TGFssRI and TGFssRII in combination with a certain TGFss expression pattern as fibrosis-inducing factors in keloids.

Local administration of TGF-β1 to reinforce the anterior abdominal wall in a rat model of incisional hernia

The purpose of this study was to investigate different forms of the local application of TGF-beta(1) for augmentation of the anterior abdominal wall in an appropriate model of an incisional hernia. Sixty male Sprague-Dawley rats were divided into six groups. Artificial defects of the anterior abdominal wall were closed with one of the following methods: running Prolene suture, Vicryl mesh, prolene suture followed by an intramuscular injection of 1 mug TGF-beta(1), Vicryl mesh coated with 1 mug TGF-beta(1), and prolene suture coated with 1 mug TGF-beta(1). A control group did not receive any defect and treatment. Six weeks after operation, tensile strength, collagen content, gene expression of collagen I and III, blood vessels, and thickness of collagen fibres were evaluated. Tensile strength was strongest in the controls (14.2 (10.5-18 N)). There was no increase in tensile strength due to the administration of TGF-beta(1). On the contrary, bolus injection of the growth factor resulted in a significantly decreased strength of the wound tissue when compared to the groups 1, 4, 5, and 6 (9.1 (4.2-9.1 N)). These results correlated with the gene expression of collagen I and III. Local application of TGF-beta(1) did not augment the strength of the abdominal wall after 6 weeks.

Enhanced Dupuytren's disease fibroblast populated collagen lattice contraction is independent of endogenous active TGF-beta2

Background

Dupuytren's disease (DD) is a debilitating fibro-proliferative disorder of the hand characterized by the appearance of fibrotic lesions (nodules and cords) leading to flexion contractures of the fingers and loss of hand function. Although the molecular mechanism of DD is unknown, it has been suggested that transforming growth factor-β₂ (TGF-β₂) may play an important role in the underlying patho-physiology of the disease. The purpose of this study was to further explore this hypothesis by examining the effects of TGF-β₂ on primary cell cultures derived from patient-matched disease and normal palmar fascia tissue using a three-dimensional collagen contraction assay.

Methods

Fibroblast-populated collagen lattice (FPCL) contraction assays using primary cell cultures derived from diseased and control fascia of the same DD patients were studied in response to exogenous TGF-β₂ and neutralizing anti-TGF-β₂ antibodies.

Results

Contraction of the FPCLs occurred significantly faster and to a greater extent in disease cells compared to control cells. The addition of TGF-β₂ enhanced the rate and degree of collagen contraction in a dose-dependent fashion for both control and diseased cells. Neutralizing anti-TGF-β₂ antibodies abolished exogenous TGF-β₂ stimulated collagen contraction, but did not inhibit the enhanced basal collagen contraction activity of disease FPCL cultures.

Conclusions

Although exogenous TGF-β₂ stimulated both disease and control FPCL contraction, neutralizing anti-TGF-β₂ antibodies did not affect the elevated basal collagen contraction activity of disease FPCLs, suggesting that the differences in the collagen contraction activity of control and disease FPCL cultures are not due to differences in the levels of endogenous TGF-β₂ activity.

TGF beta-like regulation of matrix metalloproteinases by anti-transforming growth factor-beta, and anti-transforming growth factor-beta 1 antibodies in dermal fibroblasts: Implications for wound healing

Transforming growth factor beta (TGF-beta) stimulates collagen and matrix metalloproteinase-2 expression and inhibits MMP-1 expression in dermal fibroblasts. Anti-TGF-beta antibodies have been proposed in the prevention of wound scars. The goal of this research was to investigate the regulation of matrix metalloproteinases-1 and -2 expression at the protein, mRNA, and transcriptional levels using an anti-TGF-beta antibody to TGF-beta 1, 2, 3, and 5 (all isoforms), and specifically by an anti-TGF-beta 1 antibody. Both antibodies, though at doses lower than the recommended neutralization dose, stimulated the expression of TGF-beta, and exhibited TGF-beta-like regulation of the matrix metalloproteinases. The antibodies inhibited matrix metalloproteinase-1 protein, mRNA, and promoter activity. The protein levels of matrix metalloproteinase-2 were up-regulated to a greater extent than the matrix metalloproteinase-2 mRNA level by both antibodies. These effects of anti-TGF-beta and anti-TGF-beta 1 antibodies on matrix metalloproteinase regulation were mimicked by exogenous TGF-beta 1 but not rabbit or chicken IgG. We infer that the anti-TGF-beta1 isoform that forms part of the composition of the anti-TGF-beta antibody to all isoforms may be responsible for the feedback stimulation of TGF-beta and the resultant alterations in the expression of the matrix metalloproteinases by the anti-TGF-beta antibodies.

Genetic susceptibility to keloid disease: transforming growth factor beta receptor gene polymorphisms are not associated with keloid disease

Keloid disease (KD) is an abnormal form of scarring with a familial predisposition. Genetic studies have yet to identify the genes involved in KD. Transforming growth factor beta (TGF-beta) has multiple cellular activities including cellular proliferation, differentiation and extracellular matrix production. TGF-beta family members such as TGF-beta(1) and TGF-beta(2) are known to be involved in KD formation. However, we previously demonstrated a lack of association between common TGF-beta(1) and TGF-beta(2) polymorphisms and KD. Other studies have implicated TGF-beta receptors in KD pathogenesis. TGF-beta receptors were therefore selected as candidate-susceptibility genes for this condition. Single-nucleotide polymorphisms (SNPs) in TGF-beta receptors I, II and III (TGF-betaRI, TGF-betaRII and TGF-betaRIII) were identified and investigated for association with the risk of developing KD. A polymerase chain reaction-restriction fragment length polymorphism method was used for genotyping novel and known TGF-beta receptor polymorphisms. DNA samples from 92 KD cases and 181 controls were examined. There were no statistically significant differences in genotype or allele frequency distributions between cases and controls for the TGF-beta receptor SNPs. Therefore, these TGF-beta receptor polymorphisms are unlikely to be associated with keloid scarring. It is possible that other SNPs in other TGF-beta family members are associated with KD. To our knowledge, this is the first report of a case-control association study with KD and TGF-beta receptor gene polymorphisms.

Hypertrophic scars and keloids: etiology and management

Keloid and hypertrophic scars have affected patients and frustrated physicians for centuries. Keloid and hypertrophic scars result from excessive collagen deposition, the cause of which remains elusive. Clinically, these scars can be disfiguring functionally, aesthetically, or both. A thorough understanding of the pathophysiology and clinical nature of the scar can help define the most appropriate treatment strategy. Although many articles have been published on the management of hypertrophic and keloid scars, there is no universally accepted treatment protocol. Prevention of keloid and hypertrophic scars remains the best strategy; therefore, those patients with a predisposition to develop excessive scar formation should avoid nonessential surgery. Once a scar is present, there are many treatments from which to choose. Hypertrophic scars and keloids have been shown to respond to radiation, pressure therapy, cryotherapy, intralesional injections of corticosteroid, interferon and fluorouracil, topical silicone or other dressings, and pulsed-dye laser treatment. Simple surgical excision is usually followed by recurrence unless adjunct therapies are employed. Biologic agents that are directed towards the aberrant collagen proliferation that characterizes keloid and hypertrophic scars might be an important addition to the current armamentarium of modalities in the near future.

Proliferative scarring

Proliferative scarring in all organ systems is an enigma. Treatment has been difficult to impossible because the pathobiology of exuberant scarring and fibrosis was unclear. With the concept that proliferative scarring can be viewed on the healing trajectory and dissected into variations of the normal wound healing cellular processes mediated by soluble cytokine messengers, one can begin to understand how excessive scar formation occurs. Realizing that overexpression or dysregulated activity of the fibrogenic isoforms of TGF-beta and its attendant effect on apoptosis may be responsible for proliferative scarring opens the route to propose rational molecular manipulations that can be tested for the prevention or treatment of this enigmatic condition.

Full-thickness human foreskin transplantation onto nude rats as an in vivo model of acute human wound healing

Current wound-healing models do not fully duplicate the in vivo human environment. The feasibility of grafting human full-thickness foreskin onto nude rats, as a model of acute wound healing, was evaluated. Incisions were then created on the grafted skin, and wound healing was evaluated. Full-thickness human skin was obtained after elective circumcision and was grafted subcutaneously onto the dorsal thorax of nude rats. At 10 days after transplantation, graft beds were judged for graft viability, on the basis of gross appearance, texture, and adherence. Full-thickness wounds were then made in the foreskin. Graft wounds were left to close by secondary intention. The wounds were allowed to heal for 7 days. Wounds were excised and tested for breaking stress. Histological evaluations included proliferating cell nuclear antigen, factor VIII, hematoxylin and eosin, and trichrome staining. Twenty grafts were performed, with 100 percent viability. Upon incision, all grafts bled freely, indicating a rich vascular supply and tissue viability. Graft viability was confirmed by the presence of proliferating cells in the parabasal stratum of the epithelium. Furthermore, there was evidence of angiogenesis, as confirmed by staining for factor VIII. Breaking stress was evaluated by tensiometry, 7 days after wounding. Histological evaluations revealed viable grafts and active wound-healing events. Full-thickness human skin can be successfully transplanted onto nude rats, providing a larger, more physiological model of human wound healing. This model closely parallels the in vivo situation, providing a promising model for study of the complex biological processes of acute human wound healing, in a reproducible manner.

Matrix metalloproteinases and the ontogeny of scarless repair: the other side of the wound healing balance

Early gestation mammalian fetuses possess the remarkable ability to heal cutaneous wounds in a scarless fashion. Over the past 20 years, scientists have been working to decipher the mechanisms underlying this phenomenon. Much of the research to date has focused on fetal correlates of adult wound healing that promote fibrosis and granulation tissue formation. It is important to remember, however, that wound repair consists of a balance between tissue synthesis, deposition, and degradation. Relatively little attention has been paid to this latter component of the fetal wound healing process. In this study, we examined the ontogeny of ten matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in nonwounded fetal rat skin and fibroblasts as a function of gestational age. We used a semiquantitative polymerase chain reaction protocol to analyze these important enzymes at time points that represent both the scarless and scar-forming periods of rat gestation. The enzymes evaluated were collagenase-1 (MMP-1), stromelysin-1 (MMP-3), gelatinase A (MMP-2), gelatinase B (MMP-9), membrane-type matrix metalloproteinases (MT-MMPs) 1, 2, and 3, and TIMPs 1, 2, and 3. Results demonstrated marked increases in gene expression for MMP-1, MMP-3 and MMP-9 that correlated with the onset of scar formation in nonwounded fetal skin. Similar results were noted in terms of MMP-9 gene expression in fetal fibroblasts. These results suggest that differences in the expression of these matrix metalloproteinases may have a role in the scarless wound healing phenotype observed early in fetal rat gestation. Furthermore, our data suggest that the differential expression of gelatinase B (MMP-9) may be mediated by the fetal fibroblasts themselves.

Further evidence for the role of fibrosis in the pathobiology of rhinophyma

Recent evidence suggests that fibrosis may play an important role in the pathobiology of rhinophyma. The fibrogenic cytokine transforming growth factor (TGF)-beta2 has been reported to be up-regulated in rhinophyma tissue. Of the three common isoforms of TGF-beta, TGF-beta1 and TGF-beta2 are considered fibrogenic, whereas TGF-beta3 has antiscarring properties. To provide further evidence for the role of fibrosis in the pathobiology of rhinophyma, specimens from 8 patients with rhinophyma were compared with nine specimens of normal nasal skin. Immunohistochemistry was used to compare intensity levels of TGFbeta1 and TGFbeta3 proteins, and quantitative reverse transcription-polymerase chain reaction was used to determine messenger ribonucleic acid (mRNA) expression levels of TGFbeta1 and TGFbeta3. TGF-beta1 was elevated significantly in rhinophyma tissue (p < 0.001), whereas TGF-beta3 was no different in the rhinophyma specimens compared with normal nasal skin (p = 0.06). TGFbeta1 mRNA expression was five-fold higher in rhinophyma tissue compared with normal skin (p < 0.001). The mRNA expression of TGF-beta3 was the same for both pathological and normal tissue (p < 0.09). These data, together with previously published observations, present further evidence that fibrosis mediated by the fibrogenic cytokines TGFbeta1 and TGFbeta2 play a role in the pathobiology of rhinophyma and suggest a means of treatment by neutralizing or down-regulating these cytokines.