[Emerging strategies for the prevention and therapy of excessive scars]

Tacrolimus action pathways in an ointment base for hypertrophic scar prevention in a rabbit ear model

BACKGROUND

Tacrolimus is used to prevent unaesthetic scars due to its action on fibroblast activity and collagen production modulation.

OBJECTIVES

To evaluate the action pathways, from the histopathological point of view and in cytokine control, of tacrolimus ointment in the prevention of hypertrophic scars.

METHODS

Twenty-two rabbits were submitted to the excision of two 1-cm fragments in each ear, including the perichondrium. The right ear received 0.1% and 0.03% tacrolimus in ointment base twice a day in the upper wound and in the lower wound respectively. The left ear, used as the control, was treated with petrolatum. After 30 days, collagen fibers were evaluated using special staining, and immunohistochemistry analyses for smooth muscle actin, TGF-β and VEGF were performed.

RESULTS

The wounds treated with 0.1% tacrolimus showed weak labeling and a lower percentage of labeling for smooth muscle actin, a higher proportion of mucin absence, weak staining, fine and organized fibers for Gomori's Trichrome, strong staining and organized fibers for Verhoeff when compared to controls. The wounds treated with 0.03% tacrolimus showed weak labeling for smooth muscle actin, a higher proportion of mucin absence, strong staining for Verhoeff when compared to the controls. There was absence of TGF-β and low VEGF expression.

STUDY LIMITATIONS

The analysis was performed by a single pathologist. Second-harmonic imaging microscopy was performed in 2 sample areas of the scar.

CONCLUSIONS

Both drug concentrations were effective in suppressing TGF-β and smooth muscle actin, reducing mucin, improving the quality of collagen fibers, and the density of elastic fibers, but only the higher concentration influenced elastic fiber organization.

Keloids and Hypertrophic Scars: A Spectrum of Clinical Challenges

Since their earliest description, keloids and hypertrophic scars have beleaguered patients and clinicians alike. These scars can be aesthetically disfiguring, functionally debilitating, emotionally distressing, and psychologically damaging, culminating in a significant burden for patients. Our current understanding of keloid pathophysiology has grown and continues to advance while molecular biology, genetics, and technology provide ever-deepening insight into the nature of wound healing and the pathologic perturbations thereof. Greater understanding will lead to the development and application of refined therapeutic modalities. This article provides an overview of our current understanding of keloids, highlighting clinical characteristics and diagnostic criteria while providing a comprehensive summary of the many therapeutic modalities available. The proposed mechanism, application, adverse events, and reported efficacy of each modality is evaluated, and current recommendations are summarized.

Management of keloids and hypertrophic scars: current and emerging options

In the context of growing aesthetic awareness, a rising number of patients feel disappointed with their scars and are frequently seeking help for functional and aesthetic improvement. However, excessive scarring following surgery or trauma remains difficult to improve despite a plethora of advocated treatment strategies as frequently observed in daily clinical routine. It is thus still preferable to prevent scarring by minimizing risk factors as much as possible. Hence, it remains crucial for the physician to be aware of basic knowledge of healing mechanisms and skin anatomy, as well as an appreciation of suture material and wound closure techniques to minimize the risk of postoperative scarring. Next to existing, well known prophylactic and therapeutic strategies for the improvement of excessive scarring, this article discusses emerging techniques such as intralesional cryotherapy, intralesional 5-fluorouracil, interferon, and bleomycin. Some of them have been successfully tested in well-designed trials and already have extended or may extend the current spectrum of excessive scar treatment in the near future. Innovative options such as imiquimod 5% cream, photodynamic therapy, or botulinum toxin A may also be of certain importance; however, the data currently available is too contradictory for definite recommendations.