Collagen mRNA expression detected by in situ hybridization in keloid tissue

The Keloid Disorder: Heterogeneity, Histopathology, Mechanisms and Models

Keloids constitute an abnormal fibroproliferative wound healing response in which raised scar tissue grows excessively and invasively beyond the original wound borders. This review provides a comprehensive overview of several important themes in keloid research: namely keloid histopathology, heterogeneity, pathogenesis, and model systems. Although keloidal collagen versus nodules and α-SMA-immunoreactivity have been considered pathognomonic for keloids versus hypertrophic scars, conflicting results have been reported which will be discussed together with other histopathological keloid characteristics. Importantly, histopathological keloid abnormalities are also present in the keloid epidermis. Heterogeneity between and within keloids exists which is often not considered when interpreting results and may explain discrepancies between studies. At least two distinct keloid phenotypes exist, the superficial-spreading/flat keloids and the bulging/raised keloids. Within keloids, the periphery is often seen as the actively growing margin compared to the more quiescent center, although the opposite has also been reported. Interestingly, the normal skin directly surrounding keloids also shows partial keloid characteristics. Keloids are most likely to occur after an inciting stimulus such as (minor and disproportionate) dermal injury or an inflammatory process (environmental factors) at a keloid-prone anatomical site (topological factors) in a genetically predisposed individual (patient-related factors). The specific cellular abnormalities these various patient, topological and environmental factors generate to ultimately result in keloid scar formation are discussed. Existing keloid models can largely be divided into in vivo and in vitro systems including a number of subdivisions: human/animal, explant/culture, homotypic/heterotypic culture, direct/indirect co-culture, and 3D/monolayer culture. As skin physiology, immunology and wound healing is markedly different in animals and since keloids are exclusive to humans, there is a need for relevant human in vitro models. Of these, the direct co-culture systems that generate full thickness keloid equivalents appear the most promising and will be key to further advance keloid research on its pathogenesis and thereby ultimately advance keloid treatment. Finally, the recent change in keloid nomenclature will be discussed, which has moved away from identifying keloids solely as abnormal scars with a purely cosmetic association toward understanding keloids for the fibroproliferative disorder that they are.

Surgical scar revision: an overview

Scar formation is an inevitable consequence of wound healing from either a traumatic or a surgical intervention. The aesthetic appearance of a scar is the most important criteria to judge the surgical outcome. An understanding of the anatomy and wound healing along with experience, meticulous planning and technique can reduce complications and improve the surgical outcome. Scar revision does not erase a scar but helps to make it less noticeable and more acceptable. Both surgical and non-surgical techniques, used either alone or in combination can be used for revising a scar. In planning a scar revision surgeon should decide on when to act and the type of technique to use for scar revision to get an aesthetically pleasing outcome. This review article provides overview of methods applied for facial scar revision. This predominantly covers surgical methods.

Hypertrophic versus non hypertrophic scars compared by immunohistochemistry and laser confocal microscopy: type I and III collagens

Although dermal collagens appear increased in hypertrophic scars, this has not been tested in tissue samples using objective methods. We compared the expression of types I and III collagen in hypertrophic and non hypertrophic scars at 6-12 and 18-24 months after burn using a quantitative method. Among 17 patients with extensive burns, 3 patients had acute scars, 8 had hypertrophic or non hypertrophic scars at 6-12 months after burn and 6 had hypertrophic or non hypertrophic scars at 18-24 months after burn. After clinical assessment of scars using the Vancouver scale, immunohistochemistry for types I and III collagens was performed. Images were captured with a laser scanning confocal microscope and the relative amounts of types I and III collagens were determined in superficial and deep dermis. The effects of time and scar type were assessed using two-way analysis of variance (ANOVA) and Tukey's test. Collagen III scar/normal ratios were higher in hypertrophic scars at both time points (P = 0.05). There were no differences in collagen I scar/normal ratios. Large variation was observed in scars during the acute phase regarding the expression of collagens. Easily accessed by immunohistochemistry and confocal microscopy, type III collagen deposition may help in determining scar phenotype, differentiating hypertrophic and non hypertrophic scars.

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.

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.

Epidemiology, aetiology and management of abnormal scarring: a review of the literature

Keloid and hypertrophic scars are the result of abnormal processes in scar formation. This paper reviews the literature and the many debates concerning the processes that cause abnormal scarring.

Treatment of keloids and hypertrophic scars with dermojet injections of bleomycin: a preliminary study

BACKGROUND

Numerous treatment modalities have been used to treat keloids and hypertrophic scars, but the optimal treatment has not been established.

OBJECTIVE

The aim of this study was to determine the efficacy and safety of intralesional jet injection of bleomycin as therapy for keloids and hypertrophic scars that are unresponsive to intralesional steroid injection.

METHODS

The study included 14 patients with 15 keloids or hypertrophic scars that had not responded to a minimum of three intralesional injections of triamcinolone acetonide. Multiple jet injections of 0.1 ml of bleomycin (1.5 IU/ml) were administered to each lesion, with injection sites spaced 0.5 mm apart. Injections were repeated each month. Scar height was measured, and scar pliability and erythema were scored at baseline and then monthly during the treatment and follow-up periods. Patients' self-assessments of subjective symptoms (pruritus and pain) were also scored. Clinical improvement was defined primarily on the basis of scar height reduction (percentage reduction from baseline), and was classified using the following scale: complete flattening (100%), highly significant flattening (> 90%), significant flattening (75-90%), moderate flattening (50-75%), and minimal flattening (< 50%). Pre- and post-treatment mean values for scar height, scar pliability, erythema, pruritus and pain were statistically compared.

RESULTS

The number of sessions required to successfully treat the lesions ranged from two to six. Eleven lesions (73.3%) showed complete flattening, one (6.7%) showed highly significant flattening, two (13.3%) showed significant flattening, and one scar (6.7%) showed moderate flattening. The mean scar height was significantly lower, and the mean scores for scar pliability and erythema were significantly better at the end of treatment (P < 0.001, P < 0.001 and P < 0.001, respectively). The mean scores for pruritus and pain also improved significantly (P < 0.001 and P = 0.01, respectively). The observed side-effects were hyperpigmentation (four lesions) and skin atrophy (three lesions). No recurrences were noted during follow up (mean duration of 19 months).

CONCLUSIONS

Intralesional jet injection of bleomycin is an effective and safe method of treating keloids and hypertrophic scars that are unresponsive to intralesional steroid therapy.

Dietary compounds inhibit proliferation and contraction of keloid and hypertrophic scar-derived fibroblasts in vitro: therapeutic implication for excessive scarring

BACKGROUND

Keloid and hypertrophic scars commonly occur after injuries. Overproliferation of fibroblasts, overproduction of collagen, and contraction characterize these pathologic scars. Current treatment of excessive scars with intralesional corticosteroid injections used individually or in combination with other methods often have unsatisfactory outcome, frustrating both the patient and the clinician. The phytochemical compounds are well known as potential anticancer agents. We have investigated the inhibitory effects of compounds on keloid fibroblasts (KF) and hypertrophic scar-derived fibroblasts (HSF).

METHODS

Fibroblasts were cultured from nontreated earlobe keloids and burn hypertrophic scars. Ten compounds (three hydroxybenzoic and four hydroxycinnamic acid derivatives, two flavonols [quercetin and kaempferol], and turmeric curcumin) were tested with fibroblasts. The inhibitory effects of compounds on fibroblasts was assessed by proliferation assays, fibroblast-populated collagen lattice (FPCL) contraction, and electron microscopy.

RESULTS

The phytochemicals significantly inhibited KF and HSF proliferation in a dose- and time-dependent manner. In the hydroxybenzoic and flavonol groups, increasing inhibitory effects seemed to depend on increasing numbers of hydroxyl groups in their chemical structures. This phenomenon was not observed in the hydroxycinnamic acid group. The phytochemicals inhibited fibroblast proliferation by inducing cell growth arrest but not apoptosis. The reversibility of growth inhibition occurred when the compounds were removed from the culture and fresh media was replaced. Slower reversibility of growth inhibition was observed in the groups treated with quercetin, chlorogenic acid, or curcumin. The compounds quercetin, gallic acid, protocatechuic acid, and chlorogenic acid were the strongest inhibitors of FPLC contraction by HTFs. When the compounds were washed out of the lattices and replaced by fresh medium, the FPCL contraction was resumed. The resumption of FPCL contraction was slowest in the quercetin-treated group, indicating again the strong inhibitory effect of quercetin.

CONCLUSION

From this in vitro study, quercetin seemed to have good potent effects to inhibit proliferation and contraction of excessive scar-derived fibroblasts.

Bethlem myopathy in a black creole pedigree

OBJECTIVES

To analyze the clinical and molecular features of a distinctive muscular dystrophy in a family of black Creole descent.

METHODS

We clinically characterized a four-generation pedigree and performed linkage analysis for all relevant autosomal-dominant muscular dystrophies.

RESULTS

Affected family members had minor neurologic dissimilarities from previously reported Bethlem myopathy pedigrees and a high incidence of keloid formation. Multipoint linkage analysis traced the family's disease to the region of the collagen genes COL6A1-COL6A2.

CONCLUSIONS

We report that Bethlem myopathy was linked to the collagen VIA1-2 region on chromosome 21q22.3 in a black Creole family. This is the first report of molecular-proven Bethlem myopathy in a family of either Creole or African-American descent. Although the correlation of Bethlem myopathy and keloids was not statistically significant, the possible connection between these two abnormalities raises the possibility of a common pathophysiological link involving collage VIA.

Fibroblasts cocultured with keloid keratinocytes: normal fibroblasts secrete collagen in a keloidlike manner

Keloid scars represent a pathological response to cutaneous injury, reflecting a new set point between synthesis and degradation biased toward extracellular matrix (ECM) collagen accumulation. Using a serum-free two-chamber coculture model, we recently demonstrated a significant increase in normal fibroblast proliferation when cocultured with keloid-derived keratinocytes. We hypothesized that similar keratinocyte-fibroblast interactions might influence fibroblast collagen production and examined conditioned media and cell lysate from coculture for collagen I and III production by Western blot, allied with Northern analysis for procollagen I and III mRNA. Normal fibroblasts cocultured with keloid keratinocytes produced increased soluble collagen I and III with a corresponding increase in procollagen I and III mRNA transcript levels. This was associated with decreased insoluble collagen from cell lysate. When keloid fibroblasts were cocultured with keloid keratinocytes, both soluble and insoluble collagen were increased with associated procollagen III mRNA upregulation. Transmission electron microscopy of normal fibroblasts cocultured with keloid keratinocytes showed an ECM appearance similar to in vivo keloid tissue, an appearance not seen when normal fibroblasts were cocultured with normal keratinocytes.

Type 1 procollagen as a marker of severity of scarring after sternotomy: effects of topical corticosteroids

AIMS

To determine whether the abundance of newly formed collagen in healing surgical wounds correlated with scar severity, and whether topical application of steroid cream reduced new collagen formation in patients who have undergone median sternotomy.

METHODS

Thirty three patients six weeks after sternotomy, and 12 controls were studied. Scars were photographed, and biopsy specimens from scars at sites treated or untreated with topical corticosteroids (clobetasol proprionate 0.5%) were examined using immunohistochemical staining for type 1 procollagen (PCP 1) and transforming growth factor beta (TGF-beta), and in situ hybridisation for type 1 procollagen messenger RNA (mRNA).

RESULTS

The degree of hypertrophy of the scar and the abundance of PCP 1 immunostaining were ranked independently, blind, and a correlation between these two variables was observed (r = 0.604, p < 0.001). The PCP 1 immunostaining was accompanied by a great abundance of PCP 1 mRNA and only a slight increase in TGF-beta immunostaining, when compared with normal skin or mature scars. Following the application of topical corticosteroids, for either 48 hours or twice daily for seven days, there was no reduction in PCP 1 immunostaining nor the abundance of PCP 1 mRNA.

CONCLUSIONS

These data suggest that the extent of new collagen formation as assessed by PCP 1 immunohistochemistry may be a useful marker of the exuberance of the scarring process following sternotomy, and that topical corticosteroids are ineffective in reducing this component of the fibrotic response.

Effects of x-irradiation on survival and extracellular matrix gene expression of cultured keloid fibroblasts

Survival and extracellular matrix gene expression were studied by viable cell count assay and Northern transfer analysis to compare the sensitivity of normal skin and keloid fibroblasts towards x-irradiation. As the dosage of radiation increased, the numbers of viable cells in irradiated groups were remarkably decreased exponentially, with no significant difference between normal and keloid cell lines. By Northern blot analysis, there was no change in size of the mRNAs for pro alpha 1(I) collagen, fibronectin and beta-actin. By slot-blot hybridization, pro alpha 1(I) collagen mRNA levels in x-irradiated fibroblasts were markedly decreased compared with non-irradiated controls. The amounts of fibronectin and beta-actin mRNAs were also decreased. This study suggests that both normal skin and keloid fibroblasts are sensitive to x-irradiation, and that extracellular matrix gene expression is also affected by such exposure.

The pathogenesis of hypertrophic/keloid scarring

The formation of hypertrophic and keloid scars after cutaneous wounding is of particular relevance to the practice of maxillofacial surgery. This paper reviews current knowledge of the local and systemic factors underlying the formation of these scars and outlines the current and potential treatment modalities for these lesions.

Decreased expression of collagen and fibronectin genes in striae distensae tissue

Striae distensae are characterized by a thinning of connective tissue stroma to produce linear, atrophic-appearing skin. Excessive adrenocortical activity, genetic factors and inherited defects of connective tissues, etc. are important causative factors in the formation of striae distensae, but the basic aetiology is not known. Total RNA was extracted from skin biopsies of five patients with striae distensae. The expression of genes coding for types I and III procollagen, elastin, fibronectin and beta-actin were studied and compared with those of four sex- and age-matched healthy individuals. The percentages of types I and III procollagen mRNA were 9.9 +/- 2.9% (mean +/- s.d.) and 10.6 +/- 1.6%, respectively, of the corresponding controls. The value for fibronectin mRNA in striae distensae was 7.3 +/- 1.8% of the control. The steady-state ratio fibronectin/type I procollagen mRNAs was 0.12 +/- 0.01 in striae distensae and 0.18 +/- 0.01 in the control. These observations suggest that expression of collagens, elastin and fibronectin genes are apparently decreased, and that there is a marked alteration of fibroblast metabolism, in striae distensae.

Hypertrophic or keloid scars?

Further attempts to achieve a clinical distinction between hypertrophic and keloid scars seem pointless. Research in recent years has shifted from the extracellular components towards the cells themselves. Much more work needs to be done to characterise the activities of the various cell lines and the mechanisms of their control. A key question is whether the cells are due to a different subpopulation of fibroblasts or whether they are normal wound-healing cells acting under some chemical or physical influence. Ultimately, most hypertrophic and keloid scars become flat and pale, although the time sequence is very variable and there is little understanding of the process of scar maturation. Meanwhile, the problem remains as a significant cause of human suffering deserving further investment of time and resources.