The Effect of Spirulina Extract on the Healing of Skin Wounds in Adult Albino Rats: A Light and Scanning Electron Microscopic Study

Abstract

Wounds are common in clinical practice. Poor and/or prolonged wound healing is a clinical problem resulting in long hospital stay and considerable economic costs. Spirulina, a blue-green algae, is consumed as a dietary supplement. Its therapeutic implications in cases of diabetes, arthritis, anemia, cardiovascular diseases and cancer were reported. However, few studies were conducted using spirulina extract topically on skin wounds. Therefore, the aim of this study was to determine the effect of topical application of spirulina extract on the healing process in a rat model of excisional skin wound. In the present study, 96 adult male albino rats weighing 180-200 g were used. An excisional skin wound of 2 cm diameter was performed on their mid-back. The animals were divided into four groups (24 rats per group): group I (untreated control group), group II (xanthan gum treated group) which was used as vehicle for spirulina, group III (carboxymethyl cellulose (CMC) treated group) which was the reference group and group IV (spirulina treated group). Animals of group II were treated with 0.2 ml of xanthan gum in normal saline. Animals of group III were treated with 0.2 ml of CMC in 20 % propylene glycol. Animals of group IV were treated with 0.2 ml of aqueous extract of spirulina preparation in the vehicle. In these groups the material was topically applied twice daily until the end of each experimental period. Each group was divided into 4 subgroups (6 rats each) and sacrificed on day 3, 7, 12 and 14 post-wounding. Specimens from the site of the wound and 2 mm of adjacent normal skin were collected. Some of them were fixed in 10% neutral formalin for paraffin section preparation which were stained with hematoxylin and eosin and Mallory's trichrome. Other specimens were fixed immediately in 2.5% glutaraldehyde and processed for scanning electron microscopic examination. Morphometric study was performed using image analyzer for the following parameters: counting the number of newly formed blood vessels, macrophages and fibroblasts and also calculating area % of collagen fibers deposition. Statistical analysis was done using ANOVA test. In the present study, the histological findings of skin wound of the rats of group I (control group) and of the rats of group II (xanthan gum treated group) showed similar findings on day 3, 7, 12 and 14 post-wounding. Also morphometric study showed a statistical non-significant results for all parameters of group II compared to control group I. Examination of the hematoxylin and eosin stained skin sections of the wound on day 3 post-wounding showed presence of thin scab with absence of epidermis at the wound area in all groups. However, beginning of re-epithelialization was observed in spirulina treated group in the form of migrating keratinocytes which were proliferated and arranged in an undifferentiated layers. Beneath the scab, the newly formed granulation tissue was observed in all groups filling the wound gap and containing blood vessels, macrophages and many fibroblasts. Also a heavy inflammatory cell infiltrate was noted in control and CMC treated groups, however few inflammatory cells were detected in spirulina treated group. Examination of the hematoxylin and eosin stained skin sections of the wound on day 7 post-wounding revealed persistence of the scab in all groups. Beginning of newly formed epidermis was demonstrated in the control group I and CMC treated (group III) that showed immature differentiation. However, the epidermis of the spirulina treated (group IV) extended towards the center of the wound and showed mature differentiation and was regularly arranged in four layers. The underlying granulation tissue showed persistence of inflammation with intense inflammatory cell infiltrate only in control and CMC treated groups. Examination of the hematoxylin and eosin stained skin sections of the wound on day 12 post-wounding showed absence of the scab in all groups.