Evaluation of Two Medium-Depth Peels: Glycolic Acid 70% Versus Trichloroacetic Acid 35%: A Histological and Immunohistochemichal Study on Rat Skin

Abstract

Background: Chemical peels represent useful tool for improving skin texture and the effects of ageing. With the advent of newer chemical peels, there is now a wide range of peeling agents that can be applied on specific patients. Aim of the work: The present work was designed to evaluate and compare histologically between two of the most commonly used peeling agents in medium depth chemical peel: TCA (35%) and GA (70 %). Materials and Methods: This study was carried out on forty adult male albino rats. They were divided into five groups, eight rats each. Group І: Control rats that received no peeling session. Groups П and ПI: Received a peel session of TCA 35% and skin specimens were taken after one week and three weeks respectively. Groups IV and Group V: Received a peel session of glycolic acid 70% and skin specimens were taken after one week and three weeks respectively. Sections were prepared to be stained by H&E, Masson's trichrome, Orcein and immunohistochemichal staining for CD34, which is a marker for stem cells in hair follicle bulge region. Morphometric measurements of epidermal thickness, dermal thickness, area percent of collagen and elastic fibers, area percent and optical density of immunopositive cells for CD34 were done by image analyzer. Data obtained were statistically analyzed. Results: The present study revealed that after one week of medium depth chemical peel (by TCA (35%) or GA (70 %), the skin showed increase in epidermal and dermal thickness, increase in elastic and collagen fibers which became more organized and regularly arranged. It also showed pronounced increase in CD34 immunopositive cells (hair bulge stem cells, spindle cells of the reticular dermis, endothelial cells of dermal vessels and sebaceous glands). Three weeks after the chemical peel, the skin showed further significant increase in epidermal thickness, dermal thickness, collagen and elastic fibers. However, there was marked decrease in area percent and optical density of CD34 immunopositive cells. Conclusion: The present study revealed that both TCA (35%) and GA (70%) are effective in stimulation bulge stem cells and in improving the skin morphology with no significant difference between the two reagents.