Development of a wound dressing composed of hyaluronic acid sponge containing arginine and epidermal growth factor

Hyaluronic acid (HA) has the ability to promote wound healing. Epidermal growth factor (EGF) is able to promote the proliferation of various cell types, in addition to epidermal cells. A novel wound dressing was designed using high-molecular-weight hyaluronic acid (HMW-HA) and low-molecular-weight hyaluronic acid (LMW-HA). Spongy sheets composed of cross-linked high-molecular-weight hyaluronic acid (c-HMW-HA) were prepared by freeze-drying an aqueous solution of HMW-HA containing a crosslinking agent. Each spongy sheet was immersed into an aqueous solution of LMW-HA containing arginine (Arg) alone or both Arg and epidermal growth factor (EGF), and were then freeze-dried to prepare two types of product. One was a wound dressing composed of c-HMW-HA sponge containing LMW-HA and Arg (c-HMW-HA/LMW-HA + Arg; Group I). The other was a wound dressing composed of c-HMW-HA sponge containing LMW-HA, Arg and EGF (c-HMW-HA/LMW-HA + Arg + EGF; Group II). The efficacy of these products was evaluated in animal tests using rats. In the first experiment, each wound dressing was applied to a full-thickness skin defect with a diameter of 35 mm in the abdominal region of Sprague-Dawley (SD) rats, leaving an intact skin island measuring 15 mm in diameter in the central area of this skin defect. Commercially available polyurethane film dressing was then applied to each wound dressing as a covering material. In the control group, the wound surface was covered with polyurethane film dressing alone. Both wound dressings (Group I and Group II) potently decreased the size of the full-thickness skin defect and increased the size of the intact skin island, when compared with the control group. The wound dressing in Group II showed particularly potent activity in increasing the distance of epithelization from the intact skin island. This suggests that EGF release from the spongy sheet serves to promote epithelization. The wound dressing in Group II enhanced early-stage inflammation after 1 week, as compared with the other two groups. In the second experiment, each wound dressing was applied to a full-thickness skin defect measuring 35 mm in diameter in the abdominal region of SD rats, after removing necrotic skin caused by dermal burns. Polyurethane film dressing was applied to each wound dressing as a covering material. In the control group, the wound surface was covered with polyurethane film dressing alone. Both wound dressings (Group I and Group II) potently decreased the size of the full-thickness skin defect and increased epithelization from the wound margin, as compared with the control group. The wound dressing in Group II was found to enhance early-stage inflammation after 1 week, as compared with the other two groups. The findings in both experiments indicate that the wound dressing composed of HA-based spongy sheets containing Arg and EGF potently promotes wound healing by inducing moderate inflammation. The release of EGF in the early stages of wound healing induces moderate inflammation. This suggests that wound healing is facilitated directly by topical application of EGF, and indirectly by cytokines derived from inflammatory cells stimulated by EGF.