The effect of acemannan immunostimulant on a wound healing model

Abstract

Acemannan is a complex carbohydrate composed primarily of acetylated mannans and galacturonic acid. It is prepared by sequential ethanol precipitation of the A loe vera L. leaf gel. Acemannan has several important therapeutic properties including acceleration of wound healing, reduction of inflammation, immunomodulation, and antitumor effects. The process by which acemannan induces these therapeutic properties is not completely understood. This study was designed to investigate the manner by which acemannan accelerates wound healing by examining wound fluid and granulation tissue. The wire mesh wound chamber allows for sequential analysis of the wound fluid, provides a physical barrier between new granulation tissue and preexistent tissue, and the contents of the chamber proceed naturally through the healing process. Wound chambers were surgically implanted subcutaneously in the lateral dorsal area then injected with either 2 mg/ml acemannan or saline as a control. Wound fluid was extracted every other day for fourteen days and at the end of the treatment period the wound chambers were removed and the tissue was extracted. Wound fluid was analyzed for nitric oxide, metalloproteinase activity, cell proliferative effects, protein composition and binding proteins. Wound chamber tissue was analyzed both histologically and chemically for collagen content. Total protein and nitric oxide levels were not significantly different between acemannan and control. Acemannan treated wound fluid contained a higher percentage of total neutrophils and neutrophils having degenerative morphological characteristics. Acemannan treated wound fluid contained a lower percentage of macrophages than the control. The most significant difference was observed in collagen content of chamber granulation tissue. Tissue from treated chambers contained more collagen; as meaned by both biochemical and morphological analyses. Studies were conducted to determine the effects of exposure to wound fluid on fibroblasts and endothelial cells. Acemannan treated wound fluid induced significantly greater fibroblast proliferation and cytoplasmic spreading in endothelial cells. These studies suggest that acemannan accelerates the rate of wound healing through increased collagen deposition, stimulation of tissue repair cells, and modulation of inflammatory cells.