Recent evidence from in vitro and in vivo experiments suggests that topical antimicrobials may be toxic to fibroblasts and keratinocytes and retard wound healing. The purpose of this study was to determine the effects of Aloe, a potential wound-healing agent, on wound contraction in excisional wounds treated with topical antimicrobials. Sprague-Dawley rats were prepared with four 1.5 cm2 dorsal defects through the skin and panniculus. The animals were divided into five groups (n = 10 per group): (1) Aloe, (2) NaOCl solution (0.025%), (3) mafenide acetate, (4) mafenide acetate + Aloe, and (5) control. Wounds were treated topically for 14 days 3 times a day. Serial standard photographs and serial wound planimetry were performed weekly. Following healing, the breaking strength of each resultant scar was determined using an Instron tensiometer. Kruskal-Wallis, ANOVA, and multiple comparison methods were used for data analysis. Aloe and NaOCl solution significantly accelerated wound contraction (p < 0.05). In the mafenide acetate + Aloe group, contraction was similar to the control, whereas the mafenide acetate alone retarded wound healing. The addition of Aloe in combination and alone in wounds increased the breaking energy when compared to controls (p < 0.05). Aloe appears to expedite wound contraction and neutralize the wound retardant effect seen with the topical mafenide acetate alone. This effect appears to be due to an increased collagen activity, which is enhanced by a lectin, consequently improving the collagen matrix and enhancing the breaking strength.

The effect of topical recombinant murine and human GM-CSF, 1 or 10 micrograms/cm2 for one to ten days, on the contraction and healing of acute and chronic granulating wounds infected with Escherichia coli was studied in Sprague-Dawley rats. Bacterial contamination of wounds produced significant inhibition of wound contraction. Application of GM-CSF at either dose level to infected wounds markedly increased the rate of wound closure compared to the rate in infected untreated controls. Ten days treatment was found to be more effective than a single application. An advanced stage of wound healing was observed at ten days in the GM-CSF-treated rats compared with controls. Bacterial counts decreased in the GM-CSF-treated wounds which may suggest bactericidal activity. Topical treatment with GM-CSF was shown to effectively inhibit the retardation of wound closure produced by bacterial contamination and may therefore be useful in the management of patients with infected wounds.

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The effects of topical antibacterials were studied in an acute wound healing model. Sprague-Dawley rats after appropriate anaesthesia received four 1.5 cm2 dorsal defects through the skin and panniculus carnosus. Skin defects were treated for 14 days with 2% mupirocin ointment, 1% clindamycin cream, 1% silver sulfadiazine cream +Aloe ueru gel, and silver sulfadiazine combined with Aloe gel. An untreated group served as controls. Each group was comprised of 10 animals each to achieve statistical significance. Wound closure rate was assessed by serial planimetry. Following healing, the breaking strength of each resultant scar was determined. Wound half-lives and overall healing rates were calculated by regressing the log of the areas of all wounds over time. Overall healing rates of aU the treated groups were significantly different compared with control group (p < 0.05). The Aloe group had the shortest half-life and healed faster than the control group. All the other treated groups had no longer half-lives when compared with the control group. While silver sulfadiazine +Aloe increased the breaking strength of the healed wound, Aloe alone did not, but demonstrated an increase over the control. Topical Aloe significantly enhances the rate of wound healing and when combined with silver sulfadiazine reverses the wound retardant effect observed with silver sulfadiazine. Clindamycin and mupirocin significantly delay wound closure. However mupirocin enhanced the breaking strength of the wound.

Spontaneous wound healing occurs partly by wound contraction, a process that requires intact functioning fibroblasts, and collagen production. Disruption of fibroblasts by the topical antimicrobials, silver sulfadiazine and mafenide acetate has been demonstrated in vitro. An acute rat wound model was used to show that wound contraction in vivo is significantly impeded by silver sulfadiazine and mafenide acetate. Key words: mafenide, rats, silver s u l f a d i n e , wound healing.

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Interleukin-4 increases the synthesis of extracellular matrix proteins, including types I and III collagen and fibronectin, by both human and rat fibroblasts. Because fibroblasts are the final common effector cells of most phases of tissue repair, this study set out to investigate the effects of interleukin-4 on the healing of three different types of wounds. Acute excisional and chronic granulating wounds inoculated with Escherichia coli and incisional wounds in streptozotocin-induced diabetic Sprague-Dawley rats were used. Recombinant murine or human interleukin-4 was applied topically to the open wounds at doses of 0.1, 1.0, or 10.0 microg/cm(2)/wound for 5 or 10 days. Incisional wounds received the same doses once-at the time of wounding. The time taken to achieve wound closure or wound breaking strength measurements of wounds was recorded and compared with relevant untreated control groups. Wound contraction was impaired in the presence of bacteria, and this was reversed by all doses of recombinant murine interleukin-4. Recombinant murine interleukin-4 had no effect on the wound closure of noncontaminated wounds; it reduced wound breaking strength in acute excisional wounds, except in a contaminated setting when wounds were treated with 1.0 pg/cm(2)/wound. Recombinant interleukin-4 (1.0 microg) improved breaking strength of both diabetic and normal incisional wounds. The apparent pleiotropic effect of interleukin-4 on wound breaking strength under different wound conditions may be related not only to the activity of the fibroblast but also the ratio of cross-linked collagen/total collagen content of wounds. This study suggests that interleukin-4 may be a useful agent for accelerating closure of wounds, particularly where healing is impaired.