Intradermal Tacrolimus prevent scar hypertrophy in a rabbit ear model. A clinical, histological and spectroscopic analysis

Background: Keloids and hypertrophic scars (HSc) affect 4.5-16% of the population. Thus far, the different approaches of keloid treatment are not very efficient, with a 50% relapse rate and many ongoing researches are looking for simple, safe and more efficient therapeutic methods. Tacrolimus is an immunomodulator that could be useful in treating keloid. Objectives: The objective of this study is to evaluate the effectiveness of Tacrolimus in inhibiting HSc formation on rabbits' ears model and to check optical skin spectroscopy in tissue characterization. Methods: Our study was carried out on 20 New-Zealand female white rabbits. HSc were obtained by wounding rabbits' ear. These wounds were treated with intradermal injections of tacrolimus (0.2-0.5 mg/cm2) or a vehicule. The assessment of treatment efficacy was performed by clinical examinations, histological assay and skin spectrometry. Results: Tacrolimus did not induce general or local side-effects. The scar elevation index in treated subjects was half less than that of the untreated ones. Furthermore, dermal thickness and inflammatory cellular density were both significantly smaller for treated scars than for the control ones. In vivo optical skin spectroscopy can characterize hypertrophic and normal skin with high sensibility and specificity. Conclusion: Intradermal injection of tacrolimus at 0.5 mg/cm2 is an efficient way to prevent HSc in our experiment model and its tolerance is correct. Optical spectroscopy could be a good non-invasive tool to evaluate HSc treatment. These promising results might be proposed for patients suffering from keloid.